Slides - Physics Seminar - Desy
Slides - Physics Seminar - Desy
Slides - Physics Seminar - Desy
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m-<br />
Heavy flavour <br />
physics with<br />
the CMS experiment<br />
m+<br />
Vincenzo Chiochia<br />
Physik-Institut - University of Zurich<br />
19-20 November 2013<br />
DESY<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013 !1
Why heavy flavor physics?<br />
Recent<br />
results!<br />
<strong>Physics</strong> of beauty and charm quarks in p-p collisions<br />
Research area with rich of phenomenology:<br />
Heavy flavor production measurements<br />
• Tests of QCD (hard scattering, fragmentation, NRQCD, etc.)<br />
Spectroscopy and particle properties<br />
• Heavy baryon spectroscopy<br />
• Spectrum of standard and exotic quarkonium states<br />
• Particle lifetimes, masses, etc.<br />
Rare beauty decays<br />
• Complementary to direct searches: can access multi-TeV<br />
energy scales through loop contributions<br />
CMS published 24 journal articles in the heavy flavor domain<br />
https://twiki.cern.ch/twiki/bin/view/CMSPublic/<strong>Physics</strong>ResultsBPH<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!2
The Large Hadron Collider<br />
pp, B-<strong>Physics</strong>, <br />
Our “toys”.<br />
CP Violation<br />
General<br />
Purpose,<br />
pp, heavy ions<br />
Heavy ions, pp<br />
G. Tonelli, CERN/INFN/UNIPI CHIPP_Grindelwald January 21-25 2012 3<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!3
LHC performance - pp run<br />
LHC : Performance Limitations<br />
Parameter/Effects Limitations Now<br />
Beam energy<br />
limited by maximum dipole field. Industrially<br />
available technology.<br />
Bunch and total beam intensity<br />
beam-beam effect (tune spread), small allowed<br />
space in Q-space, collimators (impedance,<br />
collective instabilities), electron cloud, radiation<br />
Legend:<br />
7 TeV 3.5 -> 4 TeV<br />
N ~ 1.5 10 11<br />
0.6 m<br />
σ ~ 20 µm<br />
N < 1.7 10 11<br />
N nom = 1.15 10 11<br />
I < 0.85 A<br />
Normalized emittance<br />
Limited by injectors and main dipole aperture ε n
Datasets and luminosity<br />
CMS Integrated Luminosity, pp<br />
Total Integrated Luminosity (fb ¡1 )<br />
25<br />
20<br />
15<br />
10<br />
5<br />
0<br />
1 Apr<br />
Data included from 2010-03-30 11:21 to 2012-12-16 20:49 UTC<br />
1 May<br />
1 Jun<br />
2010, 7 TeV, 44.2 pb ¡1<br />
2011, 7 TeV, 6.1 fb ¡1<br />
2012, 8 TeV, 23.3 fb ¡1 £ 100<br />
5<br />
0<br />
1 Jul<br />
1 Aug<br />
1 Sep<br />
Date (UTC)<br />
1 Oct<br />
1 Nov<br />
1 Dec<br />
25<br />
20<br />
15<br />
10<br />
CMS Peak Luminosity Per Day, pp<br />
2010: ~40/pb at Linst~10 32 cm -2 s -1<br />
2011: ~6/fb at Linst
The CMS detector<br />
CMS DETECTOR<br />
Total weight<br />
Overall diameter<br />
Overall length<br />
Magnetic field<br />
: 14,000 tonnes<br />
: 15.0 m<br />
: 28.7 m<br />
: 3.8 T<br />
COMPACT<br />
STEEL RETURN YOKE<br />
12,500 tonnes<br />
SILICON TRACKERS<br />
Pixel (100x150 μm) ~16m2 ~66M channels<br />
Microstrips (80x180 μm) ~200m2 ~9.6M channels<br />
SUPERCONDUCTING SOLENOID<br />
Niobium titanium coil carrying ~18,000A<br />
MUON CHAMBERS<br />
Barrel: 250 Drift Tube, 480 Resistive Plate Chambers<br />
Endcaps: 468 Cathode Strip, 432 Resistive Plate Chambers<br />
PRESHOWER<br />
Silicon strips ~16m2 ~137,000 channels<br />
FORWARD CALORIMETER<br />
Steel + Quartz fibres ~2,000 Channels<br />
CRYSTAL<br />
ELECTROMAGNETIC<br />
CALORIMETER (ECAL)<br />
~76,000 scintillating PbWO4 crystals<br />
HADRON CALORIMETER (HCAL)<br />
Brass + Plastic scintillator ~7,000 channels<br />
MULTI-PURPOSE!<br />
SOLENOID<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!6
CMS: Tracker<br />
Insertion of the CMS<br />
pixel detector<br />
Tracker inner barrel during<br />
final integration<br />
CMS is equipped with a full-silicon tracking detector<br />
Three layers and two disks of pixel sensors (~66M channels)<br />
Ten barrel layers and 3+9 endcap wheels of strip sensors (~10M channels)<br />
Pseudorapidity coverage up to 2.4. Transverse momentum resolution 2-3%.<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!7
to the primary vertex; and (d) longitudinal impact parameter, d z , with respect to the primary<br />
vertex.<br />
CMS: Pixel detector<br />
3.2 Track Impact Parameter Resolution<br />
The analysis described in this section is based on the 7 TeV data collected by CMS up to the<br />
27th of May 2010 and corresponding to 10.9 nb 1 . In addition ~98% to the operational general selection during detailed data taking<br />
in Section 1.1, the events used for the measurement of the IP resolutions are required also to<br />
pass the uncorrected 6 GeV jet trigger. The usage of a common Hit efficiency trigger ensures >99% that the tracks<br />
used in both data and simulation are comparable in terms of track multiplicity and distribution<br />
of particle kinematic variables. The measurement of the Excellent impact parameter understanding resolution starts of detector resolution:<br />
from the selection of high quality tracks that have a high probability<br />
Hit position,<br />
of havingimpact been produced<br />
parameter, vertices<br />
promptly in the pp collision: a track must have its p T greater than 0.3 GeV/c and valid measurements<br />
on at least 7 consecutive layers of the tracker, including a measurement on the innermost<br />
Hit resolution vs. cluster size<br />
Transverse ~ 10 mm<br />
pixel layers (either the barrel or one of the endcap disks). Simulation studies predict that this<br />
Longitudinal ~ 20 mm<br />
simple selection is expected to reduce the fraction of fake tracks to the per mil level. For transverse<br />
momenta smaller than 4 GeV/c (20 GeV/c), the<br />
4<br />
fraction of non-prompt tracks that are<br />
2 Pr<br />
selected is less than 2% (10%) of the total.<br />
CMS preliminary 2010<br />
110<br />
Transv.Impact Parameter Resolution (µm)<br />
100<br />
90<br />
80<br />
70<br />
60<br />
50<br />
40<br />
30<br />
20<br />
10<br />
Data track | η | < 0.4<br />
Simulation track | η | < 0.4<br />
Excellent modeling<br />
of pixel hit resolution,<br />
multiple scattering,<br />
alignment<br />
s = 7 TeV<br />
2 4 6 8 10 12 14 16 18 20<br />
Track p (GeV/c)<br />
T<br />
CMS preliminary 2010<br />
130<br />
Longit.Impact Parameter Resolution (µm)<br />
120<br />
110<br />
100<br />
90<br />
80<br />
70<br />
60<br />
50<br />
40<br />
30<br />
Data track | η | < 0.4<br />
Simulation track | η | < 0.4<br />
s = 7 TeV<br />
Vertex resolution vs.<br />
number of tracks and<br />
average pT<br />
2 4 6 8 10 12 14 16 18 20<br />
Track p (GeV/c)<br />
T<br />
CMS-PAS-TRK-10-005<br />
Eur.Phys.J. C70 (2010) p.1165<br />
V. Chiochia (Zürich University) (a) – Heavy flavour physics with the CMS experiment (b) - 19-20/11/2013 (a)<br />
!8
CMS: Muon system<br />
Tracks:<br />
Excellent pT resolution ≈ 2-3%<br />
Efficiency above 99% for central muons<br />
Impact parameter resolution ~15 mm<br />
Muon candidates:<br />
Match between muon segments and a silicon<br />
track<br />
Large pseudorapidity coverage: |η| < 2.4<br />
Muon efficiencies evaluated with<br />
MC methods<br />
Data-driven methods: Tag & Probe<br />
Muon misidentification rates from data:<br />
D*→D 0 p, D 0 →Kp<br />
Ks→pp<br />
L→pp<br />
CMS-PAS-MUO-10-002<br />
DT coverage<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!9
quark production at the LHC<br />
LHC RUN 1<br />
~ 2 MHz at<br />
7.5x10 33 cm -2 s -1<br />
Enormous b quark production<br />
rate at the LHC Run 1<br />
Expected to more than<br />
double in Run 2<br />
High rates implies very<br />
selective requirements at<br />
trigger level to store<br />
interesting b decays<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!10
Triggers for heavy flavor physics<br />
Trigger selections based on:<br />
• pT and |η| of dimuons<br />
• dimuon invariant mass<br />
• secondary vertex probability<br />
• impact parameter<br />
• flight length significance<br />
• pointing angle<br />
Trigger requirements tightened following the increase in instantaneous luminosity.<br />
About 10% of CMS bandwidth assigned to heavy flavor physics<br />
Single muon trigger efficiencies measured from data (tag&probe), dimuon correlations from MC<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!11
Understanding the rates:<br />
Production<br />
measurements<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013 !12
dy (pb/GeV)<br />
σ/dp<br />
2<br />
b-jet d<br />
T<br />
9<br />
10<br />
8<br />
10<br />
7<br />
10<br />
10<br />
6<br />
5<br />
10<br />
4<br />
10<br />
3<br />
10<br />
2<br />
10<br />
10<br />
Inclusive B production<br />
-1<br />
CMS L = 34 pb<br />
MC@NLO<br />
Exp. uncertainty<br />
Anti-k T<br />
R=0.5<br />
s = 7 TeV<br />
|y| < 0.5 (×625)<br />
0.5 < |y| < 1 (×125)<br />
1 < |y| < 1.5 (×25)<br />
1.5 < |y| < 2 (×5)<br />
2 < |y| < 2.2<br />
1<br />
20 30 40 50 100 200<br />
b-jet p (GeV)<br />
T<br />
(pb/GeV)<br />
b-jet dσ/dp<br />
T<br />
6<br />
10 |y | < 2.2<br />
b-jet<br />
5<br />
10<br />
4<br />
10<br />
3<br />
10<br />
2<br />
10<br />
-1<br />
CMS L = 3-34 pb<br />
Jet based<br />
Muon based<br />
MC@NLO<br />
ATLAS jet<br />
ATLAS muon<br />
s = 7 TeV<br />
20 40 60 80 100 120 140 160 180 200<br />
b-jet p (GeV)<br />
T<br />
1<br />
0 0.05 0.1 0.15 0.2<br />
2<br />
0<br />
d xy [cm]<br />
-2<br />
pp ! bX ! µX 6 1 |⌘| < 2.1 1.32 ± 0.01 ± 0.30 ± 0.15 0.95 +0.41<br />
0.21<br />
[1]<br />
pp ! b¯bX ! µµX 4 1 |⌘| < 2.1 (26.18 ± 0.14 ± 2.82 ± 1.05) ⇥ 10 3 (19.95 +4.68<br />
4.33 ) ⇥ 10 3 [4]<br />
pp ! b jet X 30 1 |y| < 2.4 2.14 ± 0.01 ± 0.41 ± 0.09 1.83 +0.64<br />
0.42<br />
[5]<br />
pp ! B + X 5 1 |y| < 2.4 28.3 ± 2.4 ± 2.0 ± 1.1 25.5 +8.8<br />
5.4<br />
[9]<br />
pp ! B 0 X 5 1 |y| < 2.2 33.2 ± 2.5 ± 3.1 ± 1.3 25.2 +9.6<br />
6.2<br />
[10]<br />
pp ! B s X ! J/ X 8 50 |y| < 2.4 (6.9 ± 0.6 ± 0.5 ± 0.3) ⇥ 10 3 (4.9 +1.9<br />
1.7 ) ⇥ 10 3 [11]<br />
Source: http://arxiv.org/abs/1201.6677<br />
JHEP 04 (2012) 084<br />
Table 1. Summary of measured b-quark cross sections in inclusive (top) and exclusive (bottom) channels and comparison with NLO JHEP 06 (2012) 110<br />
QCD expectations. The experimental uncertainties indicate (from left to right) the statistical, systematic and luminosity. Theoretical<br />
V. Chiochia uncertainties (Zürich University) are obtained– from Heavy scaleflavour variations. 4physics with the CMS experiment - 19-20/11/2013<br />
!13<br />
6<br />
Number / 0.004 cm<br />
Pull<br />
5<br />
10 CMS s = 7 TeV, L = 27.9/pb Data<br />
int<br />
BB<br />
µ<br />
µ<br />
p > 4 GeV, |η | < 2.1 CC<br />
4<br />
T<br />
10<br />
DD<br />
BD<br />
BC<br />
3<br />
10<br />
CD<br />
PP<br />
2<br />
10<br />
10<br />
0 0.05 0.1 0.15 0.2<br />
d xy [cm]<br />
Inclusive B cross sections using tagged jets and events with two semileptonic muons<br />
NLO in agreement with data but systematically below<br />
Further measurements needed to pin down high-pt and rapidity regions<br />
• MC@NLO and POWHEG EPJgiving Web ofsomewhat Conferences different predictions<br />
Process p T range (Pseudo)-rapidity Cross section NLO QCD Ref.<br />
[GeV/c] range [µb] [µb]
6.6 ± 0.4, and n(L b )=7.6 ± 0.4.<br />
recent<br />
The larger<br />
result [42]<br />
n value<br />
from the<br />
for<br />
LHCb<br />
L b indicates<br />
Collaboration<br />
a more<br />
measures<br />
steeply<br />
a strong<br />
falling<br />
p<br />
p T<br />
distribution than observed for the mesons, also suggesting that the production of L hadron production<br />
T dependence of the ratio of<br />
L b production to B-meson production, f Lb /( f u + f d ), with f Lbb ⌘baryons,<br />
B(b ! L b ) and f q ⌘ B(b !<br />
relative to B mesons, varies as a function B q ). Largerof f Lb pvalues T , with areaobserved larger at Llower b /B ratio p T , which at lower suggests transverse that the discrepancy observed<br />
between the LEP and<br />
momentum. The right plot of Fig. 3 shows the p L Tevatron b<br />
T spectrum data may shape be due compared to the lower to p B+ T of the L<br />
and B b 0 baryons produced at<br />
,<br />
the Tevatron.<br />
where the distributions are normalized to the common bin with p T = 10 13 GeV.<br />
(pp→ b-hadron X) (µb/GeV)<br />
dσ/dp<br />
T<br />
-1<br />
10<br />
-2<br />
10<br />
10<br />
10<br />
1<br />
-3<br />
(10-13 GeV))<br />
)/(dσ/dp<br />
(dσ/dp<br />
T<br />
T<br />
-2<br />
10<br />
10 20 30 40 50<br />
10 20 30 40 50<br />
b-hadron p (GeV)<br />
b-hadron p (GeV)<br />
T<br />
T<br />
Figure CMS 3: Preliminary, Comparison s=7 of TeV production rates Spring for 2012 B + [6], B 0 [7], B 0 s [9], and L b versus p T . The left<br />
4.8<br />
plot shows the absolute comparison, where the inner error bars correspond to the total bin-tobin<br />
uncertainties, while the outer error bars represent the total bin-to-bin and normalization<br />
value ± stat. ± syst. ± lum. error<br />
(luminosity)<br />
NLO predictions compatible with data<br />
pp → Λ b<br />
X → J/ψ Λ X<br />
11.6 ± 0.6 ± 1.2 ± 2.0<br />
uncertainties P T>10 GeV, |y|5 GeV, |y|
Spectroscopy:<br />
A new heavy baryon<br />
and other peaks<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013 !15
On the media<br />
First particle discovery at CMS!<br />
May 1st, 2012<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!16
Ξ<br />
-<br />
b<br />
B<br />
Y<br />
The Jb baryon family<br />
B=-1<br />
Σ -<br />
bbb<br />
J=3/2 +<br />
Σ<br />
*- ddb<br />
udb uub Σ<br />
*+<br />
b b<br />
dsb usb<br />
π"<br />
ssb<br />
dsb<br />
usb<br />
Δ - ddd<br />
uuu Δ ++<br />
ssb<br />
dds<br />
uus<br />
uds<br />
dss<br />
Σ +<br />
n<br />
$<br />
-<br />
b p<br />
uss<br />
Ξ - sss<br />
Ξ o<br />
5791 γ" ddu<br />
duu<br />
"<br />
Ω - ! - dds<br />
J=1/2 +<br />
uds ! o uus<br />
Y<br />
dss<br />
uss<br />
dbb<br />
ubb<br />
#<br />
Ξ’ o<br />
b I 3<br />
sbb<br />
!<br />
dsb<br />
usb • Charm sector cousin: c(2645)<br />
ssb<br />
!<br />
0 !<br />
n<br />
Ω<br />
-<br />
b p<br />
ddu<br />
duu<br />
Λ<br />
dds uds Σ o uus Σ +<br />
Width < 1MeV <br />
dss<br />
uss<br />
Ξ - Ξ o<br />
I 3<br />
B=-2<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
Ξ b<br />
*<br />
Σ<br />
-<br />
ddb udb Λ b<br />
uub<br />
b Σ<br />
+<br />
b<br />
• B-baryon multiplets:<br />
B<br />
Mass [MeV]<br />
Analog to charmed baryon spectrum<br />
Q value: M(Jb *0 )-M(Jb - )-M(p + )≈11-29 MeV<br />
“Heavy neutron” with u-s-b quarks<br />
• Given the predicted Q, Γ(Ξb* 0 ) < 1 MeV.<br />
Introduction<br />
J=1/2 +<br />
#<br />
- dbb<br />
ubb<br />
b<br />
#’ b<br />
sbb<br />
!<br />
-<br />
ddb udb " b<br />
uub<br />
b !<br />
+<br />
b<br />
?<br />
?<br />
" - dd<br />
(known)<br />
# b<br />
*-<br />
# - + c ⇡<br />
Phys. Rev. Let<br />
Phys. Rev. D 66, 014502 (2002)<br />
• Expected Q(Ξb* 0 ) = M(Ξb* 0 ) − M(Ξb − ) − M(π + ) ~ 11-29 M<br />
! +<br />
Phys. Rev. D 77, 034012 (2008)<br />
Phys. Rev. D 79, 014502 (2009)<br />
Phys. Rev. D 84, 014025 (2011)<br />
arXiv:1203.3378v1 [hep-lat]<br />
arXiv:1203.3378v1 !17
Jb* 0 decay chain<br />
Introduction<br />
• Ξb *0 decay chain:<br />
p +<br />
Secondary<br />
vertices<br />
⇡ ⇤<br />
c ( 0 )=7.89 cm<br />
c (<br />
)=4.91 cm<br />
⇤ 0<br />
Can decay beyond pixel volume<br />
Requires reconstruction of very<br />
displaced tracks and vertices<br />
⇡ ⌅<br />
c ( b<br />
) = 470 µm<br />
⌅<br />
PV<br />
⌅ ⇤0<br />
b<br />
⌅ b<br />
⇡ + PV<br />
J/<br />
µ<br />
µ +<br />
Displaced J/c decay vertex<br />
within pixel volume<br />
& c.c.<br />
Ernest Aguiló (HEPHY) 6<br />
June 26th 2012<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!18
candidates per 20 MeV<br />
-<br />
Ξ b<br />
70<br />
60<br />
50<br />
40<br />
30<br />
20<br />
10<br />
Observation of the Jb* 0 baryon<br />
CMS<br />
pp, s = 7 TeV<br />
-1<br />
L = 5.3 fb<br />
Jb→JJ/c<br />
-<br />
Ξ b<br />
data<br />
Opposite-sign pπ Ξ<br />
Same-sign pπ Ξ<br />
Signal+background fit<br />
Background fit<br />
108 ± 14 candidates<br />
M=5795.0 ± 3.1 MeV<br />
s=23.7 ± 3.2 MeV<br />
0<br />
5.6 5.7 5.8 5.9 6 6.1<br />
-<br />
M(J/ψΞ ) [GeV]<br />
Additional<br />
prompt pion<br />
candidates per 2 MeV<br />
*0<br />
Ξ b<br />
16<br />
14<br />
12<br />
10<br />
8<br />
6<br />
4<br />
2<br />
21 events observed, 3.0±1.4<br />
background expected<br />
Resolution from MC: sMC=1.9±0.1 MeV<br />
CMS<br />
pp, s = 7 TeV<br />
-1<br />
L = 5.3 fb<br />
(b)<br />
Opposite-sign data<br />
Signal+background fit<br />
Background<br />
0<br />
0 10 20 30 40 50<br />
- +<br />
-<br />
M(J/ψΞ π ) - M(J/ψΞ ) - M(π) [MeV]<br />
Q=<br />
Jb *0 →JJ/cp<br />
Q = 14.8 ± 0.7 ± 0.3 MeV<br />
M(Jb) = 5945.0 ± 0.7(stat.) ± 0.3(syst.) ± 2.7(PDG) MeV<br />
GBW=2.1±1.7 MeV (Theory: ! 0.93 MeV)<br />
Significance from ln(Ls+b/Lb)=6.9<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
Phys. Rev. Lett. 108, 252002 (2012)<br />
!19
Possible Speculations<br />
Exotic mesons<br />
Many new charmonium(–like) do not fit into<br />
quark model spectrum easily. Theoretical<br />
speculations include:<br />
• Molecular states: loosely bound states composed of a<br />
pair of mesons, probably bound by the long-range colorsinglet<br />
pion exchange<br />
• Tetraquarks: bound states of four quarks, bound by<br />
colored-force between quarks, decay through<br />
rearrangement, some are charged or carry strangeness, there<br />
are many states within the same multiplet<br />
• Hybrid charmonium: bound states composed of a<br />
pair of quarks and one excited gluon<br />
• Conventional charmonium: quark model spectrum<br />
could be distorted by the coupled-channel effects<br />
9<br />
Courtesy: S.Zhu<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!20
Exotic mesons<br />
TABLE 9: As in Table 4, but for new unconventional states in the c¯c and b¯b regions, ordered by mass. For X(3872), the values<br />
given are based only upon decays to ⇡ + ⇡ J/ . X(3945) and Y (3940) have been subsumed under X(3915) due to compatible<br />
properties. The state known as Z(3930) appears as the c2(2P )inTable4. See also the reviews in [81–84]<br />
Well established<br />
at CMS<br />
JHEP 04 (2013) 154<br />
Seen also at D0<br />
arXiv:1309.6580<br />
Seen also at<br />
D0, Belle<br />
arXiv:1010.5827<br />
State m (MeV) (MeV) J PC Process (mode) Experiment (# ) Year Status<br />
X(3872) 3871.52±0.20 1.3±0.6 1 ++ /2 + B ! K(⇡ + ⇡ J/ ) Belle [85, 86] (12.8),BABAR [87] (8.6) 2003 OK<br />
(
Search for X(4140)<br />
First evidence (3.8s) for a near-threshold<br />
narrow peak in the J/cf system, reported by<br />
CDF in B + →J/c(mm)f(KK)K + decays in 2009,<br />
based on 2.7 fb -1 .<br />
Result updated in 2011 with 6 fb -1 , significance<br />
over 5s. Assuming relativistic BW:<br />
M1=4143.0 +2.9 -3.0(stat)±0.6(syst) MeV<br />
G1=15.3 +10.4 -6.1(stat)±2.5(syst) MeV<br />
Evidence (3.1s) for a second structure:<br />
0<br />
0<br />
5.2 5.3 5.4<br />
1 1.01 1.02<br />
+<br />
2<br />
M2=4274.4 +8.4 -6.7(stat)±1.9(syst) MeV<br />
m(J/ Kφψ ) [GeV/c<br />
] 5 m K<br />
G2=32.3+21.9(stat)±7.6(syst) MeV<br />
PRL 102, 242002 (2009)<br />
Could be cc bound state but well above opencharm<br />
threshold (3740 MeV). Some models: line is a fit to the data with a Gaussian signal fun<br />
FIG. 1: (a) The mass distribution of J/ψφK + arXiv:1101.6058 ;the<br />
40<br />
10<br />
10<br />
6<br />
CDF 2011<br />
a)<br />
Molecular linear background function. (b) The K + K − mass<br />
(Ds Ds) state b)<br />
a)<br />
19±7 b)<br />
L=6 fb c)<br />
-1<br />
8 candidates<br />
8<br />
4<br />
30<br />
tions inside the B mass window (black solid) and<br />
Hybrid particle (qqg)<br />
2<br />
sidebands (red dotted).<br />
Four-quark combination (ccss)<br />
6<br />
6 22±8<br />
20<br />
candidates<br />
0<br />
No significant first structure from Belle 1 1.1 1.2 in 1.3 1.4 1.5 1.6 1.7<br />
6<br />
4<br />
4<br />
exclusive B decays. 3.2s evidence for second<br />
m(µ + µ − K + K − ) − m(µ + µ − 4<br />
) for events in<br />
structure 10 at 4350 MeV in gg→J/cf<br />
2<br />
2<br />
2<br />
mass window. Events from reference [12] and f<br />
Exclusion limits on partial width disfavor<br />
0<br />
data are shown in (a) top and bottom. In the<br />
5.4<br />
1 molecular 1.01 1.02 scenarios 1.03 with 1.040 ++ , 2 ++ 0 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 0<br />
0<br />
1 1.1 1.2 1.3 1.4 1.5<br />
1 1.1 1.2 1.3 2<br />
2<br />
eV/c<br />
]<br />
m [GeV/c ]<br />
signal region (∆M < 1.07GeV/c 2 1.4 1.5<br />
- + -<br />
-<br />
2<br />
), the new da<br />
+ -<br />
K K<br />
m(µ + µ K K )-m(µ + - + -<br />
-<br />
2<br />
µ ) GeV/c m(µ + )-m(µ + - + -<br />
-<br />
2<br />
µ K K µ ) [GeV/c ] m(µ + µ K K )-m(µ + µ ) [GeV/c ]<br />
within 1σ of the expectation (6 events compar<br />
expected). Over the entire examined region<br />
stribution V. Chiochia of (Zürich J/ψφK University) + ;thesolidblue<br />
– Heavy flavour physics FIG. with 2: (a) the The CMS experiment mass difference,<br />
data sets<br />
- 19-20/11/2013 ∆M, betweenµ<br />
are consistent at the + µ − K<br />
7% + K<br />
probability −<br />
!22 l<br />
2<br />
Candidates/2 MeV/c<br />
2<br />
Events/10 MeV/c<br />
+ − +<br />
2<br />
Candidates per 5 MeV/c<br />
60<br />
50<br />
40<br />
30<br />
20<br />
10<br />
2<br />
Candidates per 10 MeV/c<br />
115±12 B +<br />
candidates<br />
CDF 2011<br />
L=6 fb -1<br />
a)<br />
2<br />
Candidates per 10 MeV/c<br />
2<br />
Candidates/2 MeV/c<br />
40<br />
30<br />
B + X(4140)<br />
→ K + → J/cf K<br />
X(4270)<br />
+<br />
?<br />
20<br />
10
Search for X(4140)<br />
3<br />
5 GeV<br />
8 GeV<br />
round<br />
4 5.45<br />
+<br />
) [GeV]<br />
) / 20 MeV<br />
+<br />
Candidates / 5 MeV<br />
N(B<br />
CMS,<br />
400<br />
100<br />
350<br />
300<br />
250<br />
200<br />
150<br />
100<br />
50<br />
−1<br />
s = 7 TeV, L = 5.2 fb<br />
arXiv:1309.6920<br />
−<br />
1.0125 < m(K<br />
+<br />
K ) < 1.0265 GeV<br />
Δm < 1.568 GeV<br />
Data<br />
Fit<br />
Background<br />
5.15 0<br />
5.2 5.25 5.3 5.35 + −<br />
5.4 +<br />
5.45 5<br />
m(J/ψK K K ) [GeV]<br />
with the standard event selection (left) and the tighter<br />
-1<br />
CMS, s = 7 TeV, L=5.2 fb<br />
300<br />
how the result of fitting these distributions Data to a Gausomial<br />
background 250 while the dashed Three-body curves PS (global showfit)<br />
the<br />
Global fit<br />
±1σ uncertainty band<br />
+<br />
200<br />
Event-mixing (J/ψ, φ, K )<br />
+<br />
Event-mixing (J/ψ, φ K )<br />
1D fit<br />
150<br />
ibed below. With the exception of this cross-check, all<br />
tive criteria.<br />
Search based on 5.2 fb -1 in B + →J/cfK + decays:<br />
Largest sample so far: 2480±160 B + candidates<br />
Fitted Dm distribution corrected for detector<br />
efficiency<br />
Efficiency fairly uniform over mass spectrum (
Searches for Xb<br />
Search for the X(3872) counterpart in the<br />
bottomonium sector - called here Xb<br />
Decay channel Y(1S)p + p -<br />
Mass predicted close to the BB or BB*<br />
threshold. Search scans 10-11 GeV mass<br />
range<br />
Search in two rapidity regions due to<br />
different mass resolution<br />
Dipion mass distribution assumed to be as<br />
for Y(2S) and similar to X(3872)<br />
“R” ratio of observed Xb and Y(2S)<br />
candidates corrected for detector efficiency<br />
R=6.56% motivated by X(3872) case<br />
would yield >5s observation over the full<br />
mass range<br />
No excess observed. 95% CL upper bounds<br />
on R within (0.9 - 5.4)%.<br />
First upper limit on possible Xb state at<br />
hadron collider<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
numbers of U(2S) ! U(1S)p + p events are 7100 ± 150 an<br />
cap regions, where the uncertainties are statistical. The<br />
the U(2S) resonance are shown in Fig. 2 for the barrel and<br />
the fits superimposed.<br />
6 5 Summary<br />
regions. The systematic uncertainties mentioned above are implemented as nuisance parame<br />
ters in the fit, assuming log-normal or flat priors. The expected discovery potential is estimated<br />
by injecting various amounts of signal events into the fits and evaluating the resulting p-values<br />
The expected signal significance for the assumption R = 6.56%, motivated by the ratio of pro<br />
duction cross sections times branching fractions for X(3872) and y(2S) reported in Ref. [8], i<br />
larger than five standard deviations Υ (2S)(s) across Υ(3S)<br />
the explored X b CMS mass barrel range, as shown by th<br />
dashed curve in Fig. 8000 3. The observed p-values displayed in Fig. s = 38 by TeVthe solid line show no<br />
-1<br />
indication of an X L = 20.7 fb<br />
b signal. The smallest local p-value is 0.004 at 10.46 GeV, corresponding 4000 to<br />
p > 13.5 GeV<br />
a statistical significance of 2.6s, which is reduced to 0.8s when taking T into account the “look<br />
6000<br />
|y| < 1.2<br />
elsewhere effect” [29]. The expected and observed 95% confidence level upper limits on R<br />
derived using a modified frequentist approach (CL S ) [30, 31], are shown in Fig. 4 as a function<br />
of the X b mass. The4000<br />
observed upper limits on R are in the range 0.9–5.4% at 95% confidenc<br />
2000<br />
level. The expected upper limits, which are derived for a pure background hypothesis, are les<br />
stringent than those obtained from the p-value calculations. This is because the p-value calcu<br />
lations are only concerned<br />
2000<br />
with the probability of the background fluctuating to a signal-lik<br />
peak in the invariant-mass distribution, while the upper limits on R also include the system<br />
atic uncertainties in the signal normalization from the signal decay model and X b polarization<br />
assumptions. 9.8 10 10.2 10.4 10.6 10.8 11<br />
9.8<br />
[GeV]<br />
p-value<br />
Candidates / 6 MeV<br />
M + Υ(1S)π<br />
-<br />
π<br />
Figure 1 1: The reconstructed invariant-mass distributions<br />
and endcap (right) regions. Peaks corresponding to U(<br />
U(1S)p + 2σ<br />
-2<br />
10<br />
CMS<br />
p decays are indicated with the arrows. 3σ<br />
-4<br />
10<br />
4 10 -6<br />
Results<br />
-8<br />
10<br />
s = 8 TeV<br />
-1<br />
L = 20.7 fb<br />
The search for the X b is performed in the mass<br />
6σ<br />
regions 1<br />
-10<br />
10<br />
Observed<br />
cluding the mass intervals around the U(2S) and U(3S) r<br />
Expected for R=6.56%<br />
-12<br />
10<br />
7σ<br />
10 10.2 10.4 10.6 10.8 11<br />
CMS<br />
M Xb<br />
[GeV]<br />
± 1σ Expected<br />
-1<br />
Figure 3: Observed 10%<br />
(solid s = curve) 8 TeVand expected for R = 6.56% (dotted ± 2σ Expected curve) local p-values, a<br />
a function of the8%<br />
assumed L X b mass. -1<br />
= 20.7 fb<br />
6.56% Median expected<br />
6%<br />
Observed<br />
Upper limit on R<br />
4%<br />
5 Summary<br />
A search for an exotic bottomonium state in the decay channel X b ! U(1S)p + p , followed by<br />
U(1S) ! µ + 2%<br />
µ , in pp collisions at p s = 8 TeV at the LHC has been presented. This analysi<br />
was performed using data collected by the CMS experiment, corresponding to an integrated<br />
luminosity of 20.7 fb 1 -2<br />
. Candidates were reconstructed from two identified muons and two<br />
1% 10<br />
additional charged tracks assumed to be pions. The search was conducted in the kinemati<br />
region p T (U(1S)p + 10 p ) > 10.13.510.2 GeV and 10.3 |y(U(1S)p 10.4 10.5 + p 10.6 )| < 10.7 2.0. The 10.8U(2S) 10.9! 11 U(1S)p + p<br />
process was used as a normalization channel, canceling many of the systematic M Xb<br />
[GeV] uncertainties<br />
Excluding the known U(2S) and U(3S) resonances, no significant excess above the!24<br />
background<br />
Figure 4: Upper limits at the 95% confidence level on R, the production cross section for the X<br />
arXiv:1309.0250<br />
4σ<br />
5σ<br />
Candidates / 6 MeV
Looking outside the box:<br />
Rare B decays<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013 !25
Why searching for Bs,d→m + m - ?<br />
otivation: search for new physics<br />
otivation: Decays highly suppressed search in SM for new physics<br />
Forbidden at tree level<br />
Decays b →s(d) highly FCNC suppressed transitions only through in Standard Penguin or Model<br />
DecaysBox highly diagrams suppressed in Standard Model<br />
⇥ effective FCNC, helicity suppression<br />
⇥ effective Cabibbo FCNC, (|Vtd| |V td |)<br />
⇥ Cabibbo-enhancement of B 0 (|V ts | > |V td |)<br />
s ⇥ µ + µ over B 0 ⇥ µ + µ<br />
Sensitivity to new physics, e.g. extended<br />
of only<br />
Higgs<br />
Bs 0 in ⇥ MFV<br />
sector<br />
µ + µ models<br />
and<br />
over<br />
SUSY<br />
Bparticles:<br />
0 ⇥ µ + µ<br />
only in MFV models<br />
Indirect 2HDM sensitivity branching ~(tanb) to new 4 and physics m(H + )<br />
MSSM branching ~(tanb) 6<br />
Indirect sensitivity to new physics<br />
⇥ 2HDM: Leptoquarks B ⇤ (tan ) 4 ,m H +; MSSM: B ⇤ (tan ) 6<br />
4th generation top<br />
⌅ sensitivity to extended Higgs boson sectors<br />
⌅ sensitivity constraints toon extended parameter Higgs regions boson sectors<br />
⌅ constraints on parameter regions<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
b<br />
b<br />
B s<br />
B s<br />
b<br />
b<br />
s<br />
s<br />
s(d)<br />
s(d)<br />
⇥ 2HDM: B ⇤ (tan ) 4 ,m H +; MSSM: B ⇤ (tan ) 6<br />
B 0 s ⇥ µ + µ<br />
considered as golden channel<br />
t<br />
+ t<br />
Z 0 0 0<br />
+<br />
, H ,h , ...<br />
W , H<br />
+<br />
Z 0 0 0<br />
+<br />
, H ,h , ...<br />
W , H<br />
t<br />
t<br />
+ χ ~ 0<br />
W<br />
+ χ ~ ,<br />
W ,<br />
0<br />
~ ~ t,c,u d l ν<br />
~ ~ t,c,u d l ν<br />
−<br />
W , χ<br />
~ 0<br />
−<br />
W , χ<br />
~ 0<br />
µ − +<br />
µ<br />
µ<br />
l<br />
+<br />
l<br />
l<br />
−<br />
l<br />
µ − +<br />
[1] JHEP 1307 (2013) 77<br />
[2] PRL 109, 041801 (2012), arXiv:1208.0934<br />
[3] Phys. Rev. D85: 033005, 2011<br />
+<br />
−<br />
!26
A 30-years quest!<br />
PHYSICAL REVIEW D VOLUME 30, NUMBER 11 1 DECEMBER 1984<br />
Two-body<br />
decays of B mesons<br />
R. Giles, J. Hassard, M. Hernpstead, K. Kinoshita, W. W. MacKay, F. M. Pipkin, and Richard Wilson<br />
Harvard University, Cambridge, Massachusetts 02138<br />
P. Haas, T. Jensen, H. Kagan, and R. Kass<br />
Ohio State University, Columbus, Ohio, 43210<br />
S. Behrends, K. Chadwick, J. Chauveau, T. Gentile, Jan M-. Guida, Joan A. Guida, A. C. Melissinos,<br />
S. L. Olsen, G. Parkhurst, D. Peterson, R. Poling, C. Rosenfeld, E. H. Thorndike, and P. Tipton<br />
University ofRochester, Rochester, Xetv York 14627<br />
PRL 111, 101804 (2013) PHYSICAL REVIEW LETTERS<br />
week e<br />
6 SEPTEMB<br />
D. Besson, J. Green, R. Namjoshi, F. -Sannes, P. Skubic, f A. Snyder, ~ and R. Stone<br />
Rutgers University, New Brunswick, New Jersey 08854<br />
A. Chen, M. Goldberg, M. E. Hejazifar, N. Horwitz, A. Jawahery, P. Lipari, G. C. Moneti,<br />
C. G. Trahern, and H. van Hecke<br />
Syracuse University, Syracuse, New York 13210<br />
M. S. Alam, S. E. Csorna, L. Garren, M. D. Mestayer, R. S. Panvini, and Xia Yi<br />
Vanderb< University, Nashville, Tennessee 37235<br />
P. Avery, C. Bebek, K. Berkelman, D. G. Cassel, J. W. DeWire, R. Ehrlich, T. Ferguson, R. Galik,<br />
M. G. D. Gilchriese, B. Gittelman, M. Hailing, D. L. Hartill, S. Holzner, M. Ito, J. Kandaswamy,<br />
D. L. Kreinick, Y. Kubota, N. B. Mistry, F. Morrow, E. Nordberg, M. Ogg, K. Read, A. Silverman,<br />
P. C. Stein, S. Stone, R. Wilcke, ~ and Xu Kezun<br />
Cornell University, Ithaca, New York 14853<br />
A. J. Sadoff<br />
Ithaca College, Ithaca, New York 14850<br />
(Received 8 June 1984; revised manuscript received 10 September 1984)<br />
Various exclusive and inclusive decays of B mesons have been studied using data taken with the<br />
CLEO detector at the Cornell Electron Storage Ring. The exclusive modes examined are mostly decays<br />
into two hadrons. The branching ratio for a B meson to decay into a charmed meson and a DOI: 10.1103/PhysRevLett.111.101804<br />
charged pion is found to be about 2%. Upper limits are quoted for other final states PE, m.+m<br />
pox, p+p, e+e, and p e+. +— We also give an upper limit on inclusive g production and improved<br />
charged multiplicity measurements.<br />
In the standard model (SM) of particle physics, treelevel<br />
diagrams do not contribute to flavor-changing<br />
neutral-current (FCNC) decays. However, FCNC decays<br />
I. INTRODUCTION<br />
may proceed through higher-order loop diagrams, and this<br />
&4/o at 90% confidence level, a charmed particle should<br />
be present in almost all 8-meson<br />
opens up the possibility for contributions from non-SM<br />
decays.<br />
Even if we assume that the spectator model (Fig. 1) de-<br />
Weak decays of 8 mesons provide a unique testing<br />
ground for both electroweak theory and quantum chromodynamics<br />
(QCD). 8 þ possible have wayssmall to branching fractions of BðB 0 s !<br />
scribes 8 decay, there are still many <br />
mesons are composed of a b antiquark<br />
and a light quark, either a d (8 ) or a u (8+). In final-state primary partons interact þ withÞ¼ð3:57 each other 0:30Þ10 9 , corresponding to the<br />
describe how hadrons might form. In one model, the four<br />
the standard electroweak model' the b quark can decay without regard to color or chargedecay-time and produce integrated hadron branching fraction, and BðB 0 !<br />
into the c quark or the u quark by emitting a virtual intermediate<br />
vector boson. The possible decay schemes of native model is based on the fact that QCD requires had-<br />
states proportional to the available phase space. An alter-<br />
þ Þ¼ð1:07 0:10Þ10 10 [1,2]. Charge conjugation<br />
which is implied we call throughout the this Letter. Several extensions of<br />
V. B and<br />
Chiochia B are shown in<br />
(Zürich<br />
Fig. 1University) for both the b~e and rons<br />
– Heavy<br />
to be color singlets. In this model,<br />
flavour physics with the CMS experiment - 19-20/11/2013<br />
b~u cases. In the "spectator" diagrams the B meson de-<br />
"spectator model without color mixing, " the quarks from<br />
8'<br />
Measurement of the B 0 s ! þ Branching Fraction and Search<br />
for B 0 ! þ with the CMS Experiment<br />
S. Chatrchyan et al.*<br />
(CMS Collaboration)<br />
(Received 18 July 2013; published 5 September 2013)<br />
Results are presented from a search for the rare decays B 0 s ! þ and B 0 ! þ in pp collisions<br />
pffiffi<br />
at s ¼ 7 and 8 TeV, with data samples corresponding to integrated luminosities of 5 and 20 fb 1 ,<br />
respectively, collected by the CMS experiment at the LHC. An unbinned maximum-likelihood fit to the<br />
dimuon invariant mass distribution gives a branching fraction BðB 0 s ! þ Þ¼ð3:0 þ1:0<br />
0:9 Þ10 9 ,<br />
where the uncertainty includes both statistical and systematic contributions. An excess of B 0 s ! þ <br />
events with respect to background is observed with a significance of 4.3 standard deviations. For the decay<br />
B 0 ! þ an upper limit of BðB 0 ! þ Þ < 1:1 10 9 at the 95% confidence level is determined.<br />
Both results are in agreement with the expectations from the standard model.<br />
particles. In the SM, the rare FCNC decays B 0 s ðB 0 Þ !<br />
the SM, such as supersymmetric models with nonuniversal<br />
PACS numbers: 13.20.He, 12.15.Mm<br />
p<br />
corresponding<br />
ffiffi<br />
to integrated luminosities of 5<br />
s ¼ 7 TeV and 20 fb 1 at 8 TeV collected<br />
Compact Muon Solenoid (CMS) experiment at th<br />
Hadron Collider (LHC). For these data, the peak l<br />
ity varied from 3:5 10 30 to 7:7 10 33 cm 2 s<br />
average number<br />
pffiffi<br />
of interactions per bunch crossing<br />
was 9 (21) at s ¼ 7ð8Þ TeV.<br />
The search for the B ! þ signal, w<br />
denotes B 0 s or B 0 ,isperformedinthedimuoni<br />
mass regions around the B 0 s and B 0 masses. T<br />
possible biases, the signal region 5:20
Event characteristics<br />
Key ingredients:<br />
Good dimuon vertex, correct B mass assignment,<br />
isolation, • Signal B s 0 momentum ⇥ µ + pointing to interaction point<br />
µ<br />
Analysis overview<br />
µ<br />
_ µ<br />
B<br />
⇤<br />
two<br />
two<br />
muons<br />
muons<br />
from<br />
from<br />
one<br />
one<br />
decay<br />
decay vertex<br />
vertex<br />
Signal characteristics: mass around m<br />
mass around B 0 0 s s<br />
Two muons from long-lived a well reconstructed B<br />
long-lived decay vertex<br />
well reconstructed<br />
Mass compatible with Bs (or B 0 secondary vertex<br />
well reconstructed)<br />
secondary vertex<br />
momentum aligned with flight direction<br />
momentum aligned with flight direction B<br />
Dimuon momentum aligned with B flight !<br />
• Background<br />
Background<br />
⇤ two semileptonic (B) decays (gluon splitting)<br />
⇤ two semileptonic (B) decays (gluon splitting)<br />
Background sources:<br />
⇤ one semileptonic (B) decay and one misidentified hadron<br />
⇤ one semileptonic (B) decay and one misidentified hadron<br />
Two semi-leptonic ⇤ rare<br />
⇤ rare B single<br />
single decays B decays<br />
decays (e.g. from gluon splitting)<br />
peaking (B<br />
One semi-leptonic peaking B decay (Bs 0 s 0 ⇥ ⇥ + K+ K )<br />
K+ misidentified K ) hadron _<br />
non-peaking (B Hadronic B decays<br />
non-peaking (Bs 0 s 0 ⇥ K µ+ ⇥)<br />
⇥ K µ+ ⇥)<br />
B<br />
⇥ mass resolution<br />
mass resolution<br />
• Peaking: ⇥ notBs→K well-reconstructed - K +<br />
secondary vertex<br />
–<br />
not<br />
More<br />
well-reconstructed<br />
problematic within the B<br />
secondary 0 mass window<br />
vertex B<br />
⇥ pointing angle<br />
• Rare<br />
⇥<br />
semileptonic:<br />
pointing angle<br />
Bs→K - m + n, Lb→pmn<br />
⇤ High signal efficiency and high background reduction<br />
High signal efficiency and high background reduction<br />
⇤<br />
µ<br />
µ<br />
µ<br />
Urs Langenegger Search for B<br />
Urs Langenegger Search for B<br />
s(d) 0 s(d) 0 ⇥ µ+ µ with the CMS experiment (2011/07/22) 5<br />
⇥ µ+ µ with the CMS experiment (2011/07/22) 5<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!28
Discriminating variables<br />
Boosted decision tree (BDT) selection<br />
-1<br />
4<br />
Trained on signal MC sample and dimuon data 10 sidebands<br />
Data (sideband)<br />
Same BDT for normalization (B + →J/cK) and control (Bs→J/cf) channels<br />
3<br />
0 -<br />
" µ + µ (MC)<br />
Candidates<br />
10<br />
10<br />
2<br />
10<br />
! Mass windows: 5.2-5.3 GeV for B and 5.3-5.4<br />
! Split into barrel (both |" ! | < 1.4) and endcap<br />
! l 3D > 15 or 20 , # 3D < 0.050 or 0.025<br />
! p T! > 4.5 or 4.0 GeV, p TB > 6.5 GeV,<br />
! B fit $ 2 /dof < 1.6, dca min > 0.15 mm (endca<br />
12 input variables: kinematic, Tracker only, Muon only,Tracker+Muon variables<br />
Robustness studies<br />
CMS, 1.14 fb s = 7 TeV<br />
Insensitive to invariant mass using MC signal events with shifted mass<br />
Output independent on high- or low-mass sideband<br />
Insensitive to multiple collisions (pileup)<br />
B s<br />
PV<br />
l 3D<br />
µ<br />
Secondary<br />
vertex<br />
µ<br />
! 3D<br />
6000 Dimuon<br />
data sidebands<br />
-<br />
B → µ +<br />
s µ<br />
5000<br />
4000<br />
3000<br />
2000<br />
1000<br />
CMS L = 20 fb ( s = 8 TeV)<br />
-1<br />
500<br />
400<br />
300<br />
200<br />
100<br />
CMS L = 20 fb ( s = 8 TeV)<br />
-1<br />
Dimuon<br />
data sidebands<br />
B → µ +<br />
s µ<br />
1<br />
Examples of background separation variables<br />
-1<br />
10<br />
-1<br />
CMS L = 20 fb ( s = 8 TeV)<br />
0 20 40 60 80 100 5000<br />
1000<br />
Dimuon l 3D<br />
/!(l )<br />
3D<br />
" Select best primary vertex based on<br />
consistency with B candidate<br />
momentum<br />
-1<br />
direction<br />
L = 20 fb ( s<br />
" Average of 5.5 primary vertices per<br />
-<br />
-<br />
B → µ µ<br />
9/1/11800<br />
Keith Ulmer -- University of Colorad<br />
+<br />
s<br />
4000<br />
-<br />
B → µ +<br />
s µ<br />
600<br />
400<br />
200<br />
data sidebands<br />
3000<br />
2000<br />
1000<br />
EPS-HEP 2013<br />
CMS = 8 TeV)<br />
Dimuon<br />
data sidebands<br />
0 50 100<br />
l 3D<br />
/σ(l )<br />
3D<br />
Flight length<br />
significance<br />
0 0.05 0.1<br />
α 3D<br />
Pointing<br />
angle<br />
0 1 2 3 4<br />
δ 3D<br />
/σ(δ )<br />
3D<br />
Impact parameter<br />
significance<br />
0 1 2 3 4<br />
χ 2 /dof<br />
B-vertex reduced<br />
chi 2<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!29
Isolation variables<br />
Relative isolation of muon pairs<br />
8000<br />
7000<br />
6000<br />
5000<br />
4000<br />
3000<br />
2000<br />
1000<br />
Cone with DR=0.7 around di-muon momentum<br />
Include all tracks with pT>0.9 GeV from same PV or<br />
dCA
Signal normalization<br />
Branching ratios calculated w.r.t. normalization channel B + →J/c(m + m - )K +<br />
Many systematic uncertainties cancel in ratio<br />
No need for absolute luminosity and b-quark cross section<br />
Large B + yield and well known branching ratio to J/cK + (3% uncertainty)<br />
Ratio of b-quark fragmentation fractions to Bs/B + : fs/fu=(256±20)×10 -3 [JHEP 04 (2013) 001]<br />
From LHCb<br />
Br(B s ! µ + µ )= N(B s ! µ + µ ) f u ✏ B+<br />
tot<br />
N(B + ! J/ K + ) f s<br />
✏ B s<br />
tot<br />
Br(B + ! J/ K + )<br />
Candidates / 0.010 GeV<br />
CMS L = 20 fb ( s = 8 TeV)<br />
40000<br />
35000<br />
30000<br />
25000<br />
20000<br />
15000<br />
10000<br />
5000<br />
-1<br />
Barrel<br />
~82’700<br />
candidates<br />
Candidates / 0.010 GeV<br />
6000<br />
5000<br />
4000<br />
3000<br />
2000<br />
1000<br />
CMS L = 20 fb ( s = 8 TeV)<br />
-1<br />
Endcap<br />
2011-12<br />
B + Candidates:<br />
380×10 3 barrel<br />
90×10 3 endcap<br />
5 5.2 5.4 5.6 5.8<br />
[GeV]<br />
m µµK<br />
5 5.2 5.4 5.6 5.8<br />
[GeV]<br />
m µµK<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!31
Branching ratio measurement<br />
BDT output divided into 4 (2) bins for 2012 (2011) data and barrel/endcap categories<br />
Simultaneous UML fit of Bs and B 0 candidates:<br />
B s and B 0 decays signal<br />
Peaking backgrounds (e.g. B 0 →Kp, Bs→KK)<br />
Rare s-l backgrounds (e.g. Lb→pmn)<br />
Combinatorial background<br />
Event-per-event mass resolution included<br />
BR(B S<br />
→ µµ) = ( 3.0 +0.9 −0.8<br />
(stat) +0.6 −0.4<br />
(syst))×10 −9<br />
BR(B d<br />
→ µµ) = ( 3.5 +2.1 −1.8<br />
(stat+syst))×10 −10<br />
Significances<br />
Bs→µµ: 4.3 σ (exp. median 4.8 σ)<br />
B 0 →µµ: 2.0 σ<br />
CMS+LHCb combination<br />
(~24% precision)<br />
CMS-PAS-BPH-13-007<br />
−1<br />
LHCb 3fb<br />
SM<br />
−1<br />
CMS 25fb<br />
CMS+LHCb<br />
preliminary<br />
(2.9±0.7)×10 -9<br />
0 1 2 3 4 5 6 7<br />
0 − −9<br />
B(Bs→ µ + µ ) [10 ]<br />
CMS: Phys.Rev.Lett. 111 (2013) 101804<br />
LHCb: Phys. Rev. Lett. 08 (2013) 117<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!32
Exclusion limits on B 0 →m + m - !33<br />
No significant excess observed in the B0 mass window<br />
Upper limit on BR computed using CLs method<br />
BR(B d<br />
→ µµ)
4 References<br />
Future sensitivity<br />
Table 1: Number of expected events for B 0 s ! µ + µ and B 0 ! µ + µ at different integrated<br />
Table luminosity 1: Number values. of We expected also report events the expected for B 0 uncertainty in the branching fraction measurement<br />
for the B 0 s ! µ + µ and B 0 ! µ + s ! µ + µ and B 0 ! µ + µ at different integrated<br />
luminosity values. We also report the expected µ , the range uncertainty of significance in theof branching B 0 ! µ + µ fraction (the range measurement<br />
indicates for the the B±1s 0 of the distribution of significance), and the relative uncertainty on the B 0 to<br />
B 0 s ! µ + µ and B 0 ! µ + µ , the range of significance of B 0 ! µ + µ (the range<br />
s branching fractions.<br />
indicates the ±1s of the distribution of significance), and the relative uncertainty on the B 0 to<br />
B 0 s branching fractions.<br />
CMS PAS FTR-13-022<br />
L (fb 1 ) No. of B 0 s No. of B 0 dB/B(B 0 s ! µ + µ ) dB/B(B 0 ! µ + µ ) B 0 sign. d B(B0 !µ + µ )<br />
B(B 0 s !µ + µ )<br />
20 16.5 2.0 35% >100% 0.0–1.5 s >100%<br />
L (fb 1 ) No. of B 0 s No. of B 0 dB/B(B 0 s ! µ + µ ) dB/B(B 0 ! µ + µ ) B 0 sign. d B(B0 !µ + µ )<br />
100 144 18 15% 66% 0.5–2.4 s 71% B(B 0 s !µ + µ )<br />
20 300 16.5 433 54 2.0 12% 35% 45% >100% 1.3–3.3 0.0–1.5 s s 47% >100%<br />
100 3000 2096 144 256 18 12% 15% 18% 66% 5.4–7.6 0.5–2.4 s s 21% 71%<br />
300 433 54 12% 45% 1.3–3.3 s 47%<br />
3000 2096 256 12% 18% 5.4–7.6 s 21%<br />
S/(S+B) weighted events / ( 0.02 GeV)<br />
S/(S+B) weighted events / ( 0.02 GeV)<br />
120<br />
100<br />
120<br />
80<br />
100<br />
60<br />
80<br />
40<br />
60<br />
40<br />
CMS Simulation - Scaled to L = 300 fb<br />
-1<br />
CMS Simulation - Scaled to L = 300 fb<br />
20<br />
-1<br />
data<br />
full PDF<br />
-<br />
B s →µ + µ<br />
-<br />
B d<br />
→µ + µ<br />
data<br />
combinatorial bkg<br />
full PDF<br />
semileptonic - bkg<br />
B<br />
peaking s →µ + µ<br />
bkg -<br />
B d<br />
→µ + µ<br />
combinatorial bkg<br />
semileptonic bkg<br />
peaking bkg<br />
0<br />
0<br />
4.9 5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9<br />
4.9 100 5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9<br />
20<br />
m µµ (GeV)<br />
m µµ (GeV)<br />
50<br />
Figure 1: Fit results of the invariant mass distribution for 300 fb 1 and 3000 fb 1 . The improvement in<br />
0<br />
the mass resolution for the 3000 fb 1 0<br />
4.9 5 5.1 5.2 5.3 5.4 5.5 5.6projection 5.7 5.8 is 5.9expected from 4.9 an 5 improved 5.1 5.2 5.3 inner 5.4tracker 5.5 5.6 system 5.7 and 5.8 5.9<br />
removing endcap candidates.<br />
(GeV)<br />
(GeV)<br />
Figure<br />
5 Summary<br />
1: Fit results of the invariant mass distribution for 300 fb 1 and 3000 fb 1 . The improvement in<br />
the mass resolution for the 3000 fb 1 projection is expected from an improved inner tracker system and<br />
removing In the coming endcapyears, candidates. the LHC accelerator and the CMS detector will undergo a series of upgrades<br />
in two major steps. The first will result in a data sample corresponding to 300 fb 1<br />
5of integrated Summary luminosity and the second to 3000 fb<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment 1 . With the increased data sample sizes it<br />
- 19-20/11/2013<br />
will be possible to reduce both systematic and statistical errors leading to high precision mea-<br />
m µµ<br />
S/(S+B) weighted events / ( 0.01 GeV)<br />
S/(S+B) weighted events / ( 0.01 GeV)<br />
CMS Simulation - Scaled to L = 3000 fb<br />
450<br />
data<br />
full -1PDF<br />
400 CMS Simulation - Scaled to L = 3000 -<br />
B<br />
fb s →µ + µ<br />
-<br />
450<br />
B d<br />
→µ + µ<br />
350<br />
data<br />
combinatorial bkg<br />
full PDF<br />
400<br />
semileptonic bkg -<br />
300<br />
B<br />
peaking s →µ<br />
bkg<br />
+ µ<br />
-<br />
350<br />
250<br />
200300<br />
150250<br />
100200<br />
50150<br />
-1<br />
B d<br />
→µ + µ<br />
combinatorial bkg<br />
semileptonic bkg<br />
peaking bkg<br />
m µµ<br />
!34
H eff =<br />
New physics in b→s transitions?<br />
4 Analysis method<br />
Described by effective hamiltonian in operator product expansion<br />
b→s transitions sensitive to O (‘) 7,9,104 Analysis method<br />
4G F<br />
p<br />
2<br />
V tb V ⇤<br />
ts<br />
2<br />
4<br />
i=1<br />
Decay B 0 →K*l - l + provides<br />
samples sufficiently large to<br />
measure observables sensitive to<br />
effective coefficients. E.g:<br />
One very famous variable:<br />
A FB ∝−Re[(2C eff<br />
7 + q2<br />
C eff<br />
m 2 9 )C 10 ]<br />
b<br />
requirement are greater thanselections 99%. and haveGeneral a reconstructed description B 0 compatible of Hamiltonian with the in operator generatedproduct B 0 in theexp<br />
ev<br />
to the number of events that pass the acceptance criteria. The compatibility of gen<br />
reconstructed p particles is enforced by requiring the reconstructed K + , p , µ + , and<br />
(Dh)2 +(Dj) 2 < 0.3 for hadrons and 0.004 for muons, where Dh and Dj are the<br />
The analysis measures A in h and j between the reconstructed and generated particles, and j is the azimuth<br />
FB , F L , and dB/dq 2 of the decay B 0 ! K ⇤0 µ + µ as a function of q 2 .<br />
Figure 1 shows the relevantthe angular planeobservables perpendicular needed to thetobeam define direction. the decay: Theq efficiency and purity of this co<br />
K is the angle<br />
requirement are greater than 99%.<br />
between the kaon momentum and the direction opposite to the B<br />
b → s transitions 0 B 0 in the K<br />
are sensitive ⇤0 K<br />
to O (′ ⇤0 )<br />
7 , rest )<br />
O(′ 9 , )<br />
frame, q O(′ l is the angle between the positive (negative) muon momentum and the direction op-<br />
10<br />
posite to the B 0 B 0 in the dimuon rest frame, and f is the angle between the plane containing<br />
the two muons and the plane containing the kaon and pion. Since the extracted<br />
The analysis measures 3 i=1,2 Tree A FB , F L , and dB/dq 2 angular parameters<br />
A<br />
of the decay B 0 ! K ⇤0 µ + µ as a fun<br />
FB and F L and the acceptance times efficiency i-3-6,8 Gluon dopenguin<br />
not depend on f, f is integrated out.<br />
6X<br />
Although<br />
X<br />
the K<br />
C(µ)O(µ)+<br />
+ p invariant<br />
Figure<br />
mass<br />
1 shows the relevant angular observables needed to define the decay: q<br />
(C(µ)O(µ)+C 0 must<br />
(µ)O 0 (µ)) 5bei=7 consistent Photon penguin with a K ⇤0 , there can be contributions<br />
K i<br />
from a spinless (S-wave) K between the kaon i=9,10 momentum Electroweak and penguin the direction opposite to the B 0 B 0 in the K ⇤0<br />
i=7,. . . ,10,P,S<br />
i=S Higgs (scalar) penguin<br />
LH LH + p combination. This is parametrized with two terms related to<br />
the S-wave fraction, F S , andframe, theRH<br />
interference q l is the angle between the positive (negative) muon momentum and the di<br />
i=P amplitude Pseudoscalar between penguin the S-wave and P-wave decays,<br />
A posite to B 0 B 0 S . Including this component, the angular distribution in the dimuon of rest B 0 ! frame, K ⇤0 µ and + µ fcan is the be written angle between the plane<br />
as [18]:<br />
the two muons and the plane containing the kaon and pion. Since the extracted angu<br />
eters A FB and F L and the acceptance times efficiency do not depend on f, f is inte<br />
1 d 3 G<br />
Although the K + p invariant mass must be consistent with a K ⇤0 , there can be co<br />
G dcos q K dcos<br />
from<br />
q l dq<br />
a 2 = 9 ⇢apple 2<br />
spinless<br />
16<br />
(S-wave)<br />
3 F S + 4 3 A K + S cos q K 1 cos 2 q l<br />
h p combination. This is parametrized with two term<br />
the S-wave + (1 fraction, F S ) 2F<br />
B 0 F S L , cos and 2 qthe → K ∗ K<br />
l + 1interference l − cos 2 amplitude SM between theBSM<br />
q l<br />
S-wave and<br />
cays, A S . Including this component, the is angular the most distribution prominent of(large B 0 ! statistic K ⇤0 µ and + µ flavou can<br />
as [18]: + 1 (1)<br />
2 (1 F f-integrated Studies L) 1 cos 2 q<br />
statistical K angular 1 + cos<br />
limited 2 distribution<br />
q l<br />
B s → φµ + µ − , Λ b → Λµ + µ<br />
1 d 3 G<br />
G dcos q K dcos q l dq 2 = 9 ⇢apple 2<br />
+ 4 i<br />
16 3 F S + 4 3 A S cos q K 1 cos 2 q<br />
3 A FB 1 cos 2 q K cos q l .<br />
l<br />
h<br />
+ (1 F S ) 2F L cos 2 q K 1 cos 2 q l<br />
Angular ϕanalysis<br />
forward<br />
μ −<br />
θl<br />
B 0<br />
backward<br />
θK<br />
+ 1 2 (1 F L) 1 cos 2 q K 1 + cos 2 q l<br />
+ 4 i<br />
3 A FB 1 cos 2 q K cos q l .<br />
q 2 = dimuon invariant mass<br />
ϕ<br />
μ + K + π −<br />
Introduce 3 relative angles to describe angular distribution of final state particles.<br />
Ci eff are linear combinations of C(m)<br />
Folding φ → φ + π if φ < 0 increase Figure sensitivity 1: Sketchfor showing some coefficients.<br />
the definition of the angular observables for the decay B 0 !<br />
K ⇤0 (K + p )µ + µ .<br />
B 0<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the e.g. CMS A FB<br />
experiment = 3 - 19-20/11/2013<br />
4 (1 − F L)A Re θl<br />
T<br />
μ − K + θK<br />
!35
B 0 →K*mm angular analysis<br />
K* longitudinal polarization Muon F-B asymmetry Differential branching fraction<br />
CMS data: arXiv:1308.3409<br />
SM: Phys. Rev. D 87 (2013) 034016<br />
Angular fit of the Kpmm system in bins of dimuon invariant mass q 2<br />
Signal yields ranging from 23 to 103 events in each bin<br />
Vertical shaded bands correspond to J/c and c(2S) resonances<br />
Results consistent with SM predictions and previous<br />
measurements<br />
World’s most precise measurement of AFB and FL at high q 2 !36<br />
Next: analyze 2012 samples and measure more angular variables<br />
see the localized excesses observed by LHCb [arXiv:1308.1707] and interpretations<br />
[e.g.: arXiv:1308.1501, arXiv:1309.2466, ...]<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013
Summary<br />
The excellent performance of the CMS detector and LHC<br />
have allowed key contributions to the field heavy flavor<br />
physics<br />
Wide range of topics covered: Standard Model physics<br />
and the great beyond<br />
Several aspects of heavy flavor production are not yet<br />
well understood and spectroscopy is not a closed chapter!<br />
No sign of physics beyond the Standard Model yet, but we<br />
keep on searching!<br />
Analysis of the large datasets collected in 2012 is in<br />
progress. Expect new results (and perhaps surprises?) at<br />
the forthcoming conferences!<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!37
BACKUP SLIDES<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!38
Future upgrades<br />
The HL-LHC scenario<br />
40 fb -1 /year<br />
13/14 TeV<br />
>50 fb -1 /year<br />
13/14 TeV<br />
End of Phase 1<br />
300-500 fb -1<br />
PHASE 1 PHASE 2<br />
HL-LHC<br />
14 TeV<br />
>250 fb-1/year<br />
LHCb Upgrade<br />
ATLAS/CMS Upgrades phase 1<br />
ATLAS/CMS<br />
Upgrades phase 2<br />
At HL-LHC ~140 events/bx spread over ±15 cm (3 σ)<br />
~3000 fb -1 expected in 10 years running<br />
~3000 fb -1 expected in 10 years running<br />
Excellent opportunity to search for (rare) and new phenomena<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!39
in Table 2.3. Comparing the efficiencies at zero pileup with and without the dynamic ROC data<br />
Figure 2.1 shows a conceptual layout for the Phase 1 upgrade pixel detector. The current 3-layer<br />
loss expected for 2 ⇥ 10<br />
barrel (BPIX),<br />
Phase<br />
2-disk endcap (FPIX)<br />
1:<br />
system<br />
CMS<br />
is replaced with<br />
Pixel<br />
a 4-layer 34 cm<br />
barrel, 2 s 1 (25 ns crossing time), the dynamic data losses cause a only<br />
upgrade<br />
3-disk endcap<br />
3.5% (4.0%) loss of tracking efficiency for muons (t¯t) with the current pixel detector. However<br />
system for four hit coverage. Moreover the addition of the fourth barrel layer at a radius of<br />
at the pileup conditions for 2 ⇥ 10<br />
16 cm provides a safety margin in case the first silicon strip layer of the Tracker 34 cm<br />
Inner 2 s<br />
Barrel<br />
1 (25 ns crossing time) simulations show that the<br />
expected loss in efficiency due to the dynamic data loss increases to 8.6% (5.2%) for muons (t¯t).<br />
2.1.<br />
(TIB)<br />
Simulation<br />
degrades more<br />
Setup<br />
rapidly<br />
and Reconstruction<br />
than expected, but its main role is in providing redundancy in<br />
With much lower dynamic data loss for the upgrade 17 pixel detector, the resultant loss in tracking<br />
pattern recognition and reducing fake rates with high pile-up.<br />
efficiency is less than 0.5% in both pileup conditions. The track fake rate is hardly affected by<br />
the dynamic data loss.<br />
Table 2.2: Total material weight for the pixel barrel and forward pixel detectors, and for the carbon<br />
fiber tube outside of the pixel barrel thatTo is isolate neededthe foreffects Upgrade<br />
the TIB ofand highfor pileup, beamwe pipe canbakeout.<br />
compare the performance at zero pileup with those<br />
Upgrade<br />
Outer rings at high pileup without any ROC dynamic data loss simulated. The results in Table 2.3 for which<br />
=0 =0.5 =1.0<br />
=1.5<br />
=2.0<br />
Four barrel layers and three endcap<br />
Volume<br />
28 the ROC data loss was not implemented Chaptershow 2. Expected that thePerformance pileup conditions & <strong>Physics</strong> for 2Capabilities<br />
⇥ 10<br />
Mass (g)<br />
34 cm 2 s 1<br />
=2.5 (25 ns crossing time) by itself would cause a 7.3% disks (4.7%) on each loss of side tracking efficiency for muons<br />
Inner rings<br />
Present (t¯t) in Detector the current Phase pixel 1 detector. UpgradeThe Detector extra pixel layer in the upgrade detector adds information<br />
that reduces this loss in efficiency by more thanCarbon half to 3.2%<br />
fibre<br />
(1.3%)<br />
structure,<br />
for muons<br />
CO2 (t¯t), and decreases<br />
50.0 cm<br />
BPIX |h| < 2.16 16801 6686<br />
the fake rate by about a factor of two. evaporative cooling, first layer closer<br />
FPIX |h| < 2.50 Current 8582 7040 to interaction point (2.9 cm)<br />
=2.5 With both 3 barrel the layerseffects of dynamic data loss and the high pileup expected for 2 ⇥ 10 34 cm 2 s 1<br />
Current<br />
Barrel Outer Tube |h| < 2.16 9474 9474 Analog readout with on-chip<br />
=2.0 (25 ns crossing time), the loss in tracking efficiency for the current detector is 15.9% (9.9%) for<br />
=0<br />
=0.5<br />
=1.0<br />
=1.5<br />
muons (t¯t), while for the upgraded detector itdigitization<br />
is reduced by more than a factor of 4 (6) to 3.7%<br />
Figure 2.1: Left: Conceptual layout comparing(1.5%) the different for muons layers (t¯t). andAlthough disks in the thiscurrent not catastrophic, and the degradation is worse than linear<br />
New (Old): 79 (48) million pixel cells<br />
black<br />
upgrade<br />
points.<br />
pixel<br />
Note<br />
detectors.<br />
that the<br />
Right:<br />
“barrel<br />
Transverse-oblique<br />
outer tube”<br />
and<br />
mentioned<br />
is expected view comparing<br />
above<br />
to become<br />
and<br />
the<br />
in<br />
unacceptable pixel<br />
Table<br />
barrel<br />
2.2 is included<br />
layers at moderately in<br />
in<br />
higher pileup as illustrated in Figure 2.6.<br />
the two detectors.<br />
distributed over 1184 (768) detector<br />
the material budget for both present and upgrade<br />
The track<br />
pixel<br />
fake<br />
detectors<br />
rate also<br />
for<br />
rapidly<br />
the comparisons<br />
increases with<br />
shown<br />
pileup is about a factor of two lower for the<br />
upgrade pixel detector.<br />
modules<br />
in Figure 2.2.<br />
Pixels<br />
Pixels<br />
Current Pixel Detector<br />
Upgrade Pixel Detector<br />
100 50<br />
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50<br />
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15<br />
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45<br />
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V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!41
Lifetime measurements<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013 !42
Lb lifetime<br />
Events / ( 0.006 GeV )<br />
-n fit )/<br />
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significance cut.<br />
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mass and proper decay time fit<br />
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t(Lb)=1.503 ± 0.052(stat.) ± 0.031(syst.) ps<br />
World average: 1.425 ± 0.032 ps<br />
B 0 lifetime determined in J/cKs decays as<br />
cross check compatible with PDG<br />
Dominant systematic uncertainty from proper<br />
decay time efficiency<br />
Compatible with ATLAS determination and<br />
world average<br />
JHEP 07 (2013) 163<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!43
Bs lifetime difference<br />
-2<br />
-1012345<br />
-3<br />
-4<br />
-5<br />
pull<br />
0.05 0.1 0.15 0.2 0.25 0.3<br />
proper decay length [cm]<br />
B s<br />
troduction<br />
Bs lifetime difference DGs=GH-GL<br />
Figure 3: Proper decay length projection of the five-dimensional maximum CMS PAS likelihood BPH-11-006 fit to<br />
the data. The points are the data distribution, the solid blue line shows the full fit, the green<br />
Events / ( 0.0045 GeV )<br />
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dash-dotted line is the signal model component, with the CP-even (odd) component Signal shown<br />
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1600<br />
in blue short dashed line (magenta<br />
~15k<br />
dash-dot-dotted Fit line), and the red long dashed CP line even is the<br />
1400<br />
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signal<br />
¯B s). The resulting mass eigenstates background from mixing component. The pull between the proper decay length distribution and the fit is<br />
Selecting decays to J/cf candidates,<br />
candidates Bs→J/cf<br />
with J/c→mm and f→KK.<br />
cay of a B s meson is characterized by the possibility that it may go through the mixeen<br />
its two flavour eigenstates (B s<br />
ected to have sizeable mass and decay width difference. Since the CP-violating mixing<br />
s expected to be small in the Standard Model, the two mass eigenstates are approxiequal<br />
to CP eigenstates. The light mass eigenstate is expected to be a CP-even state<br />
shorter lifetime than the heavy mass eigenstate which is a CP-odd state [1]. The decay<br />
ifference of the two B s eigenstates is found to be several percent of the mean decay<br />
. In the decay B s ! J/yf with J/y ! µ + µ and f ! K + K , the final state is an admixthe<br />
CP-even and CP-odd eigenstates. A measurement of the lifetime difference (DG s) of<br />
mass eigenstates can be performed using the proper decay time distribution of B s me-<br />
]. The additional information required to separate the light and heavy mass eigenstates<br />
btained from the angular distribution of the final decay products.<br />
1200<br />
1000<br />
shown in the histogram below.<br />
800 0.05 0.1 0.15 0.2 0.25 0.3<br />
10<br />
600<br />
uncertainty is evaluated by 400 generating pseudo-data with the modified scale factor and fitting<br />
5D fit of mass, proper decay 200<br />
with the time nominal and value. 3<br />
0<br />
angular variables to separate CP states<br />
To evaluate the effect of assuming f s to be zero in the fitting model, pseudo-experiments have<br />
-2<br />
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-1012345<br />
-2<br />
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been generated with f -1012345<br />
s = 0.04 -4 rad, which is the Standard Model -4 expected value. Similarly,<br />
-5<br />
-5<br />
5.25 5.3 5.35 5.4 5.45<br />
0.05 0.1 0.15 0.2 0.25 0.3<br />
The two CP<br />
+ -<br />
Invariant mass J/ψ K K [GeV]<br />
B proper decay length [cm]<br />
Compatible with world average<br />
the systematic uncertainties due to non-inclusion of S-wave components in the signal<br />
s<br />
PDF is<br />
estimated using pseudo-experiments by adding the model components of the S-wave by setting<br />
the |A s | 2 to 0.03 and the phase equal to previous measurements. In both cases, the pull mean<br />
e B s is a pseudo-scalar meson while the J/y and f are vector mesons, the orbital angular<br />
tum of the two decay products can have the values L = 0, 1, and 2.<br />
ents can be statistically disentangled by measuring the angular distributions of the<br />
cay products. A set of three angles Q =(q T , y T , j T ) in the transversity basis [4], as<br />
ted in Fig. 1, is used to describe the decay topology. Here, q T and j T are the polar and<br />
hal angles of the µ + in the rest frame of the J/y respectively, where the x-axis is defined<br />
irection of the B s and the xy-plane by the decay plane of f ! K + K . The helicity angle<br />
e angle of the K + in the f rest frame with respect to the negative B s flight direction.<br />
T<br />
0<br />
-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1<br />
cos(ψ )<br />
T<br />
1: Definition of the three angles, (q T , y T and j T ), used for the description of the decay<br />
y.<br />
Events / ( 0.1 )<br />
1600<br />
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-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1<br />
cos(θ T )<br />
1200 0.05 0.1 0.15 0.2 0.25 0.3<br />
Figure 4: The angular projection of the five-dimensional maximum likelihood fit to the data.<br />
V. Chiochia (Zürich University) – Heavy Theflavour plots show physics thewith projections the CMS onexperiment the angular- variables 19-20/11/2013 cos(y T ), cos(q T ) and the angle f. The !44<br />
ay of vector mesons is further described by the time evolution of three different ampliith<br />
different angular dependencies. The amplitudes at time t = 0 are defined using the<br />
dinal component A 0 (0) for L = 0, which is CP-even, and the transverse components<br />
T<br />
T<br />
Events / ( 0.1 )<br />
1000<br />
800<br />
600<br />
400<br />
200<br />
-1<br />
CMS preliminary, 5 fb<br />
s = 7 TeV<br />
Events / ( 0.0034 cm )<br />
pull<br />
Events / ( π/10)<br />
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CMS preliminary, 5 fb<br />
s = 7 TeV<br />
0<br />
-3 -2 -1 0 1 2 3<br />
φ [rad]<br />
T
Summary of CPV in Bs decays<br />
Rather consistent picture from Tevatron and LHC experiments<br />
Closing on the SM value also in this case<br />
CMS currently working on the determination of the CP violating phase fs<br />
0.25<br />
0.20<br />
0.15<br />
LHCb 1.0 fb –1 + CDF 9.6 fb –1 + D 8 fb – 1<br />
+ ATLAS 4.9 fb – 1<br />
D<br />
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Fall 2012<br />
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( )<br />
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0.10<br />
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CMS<br />
0.05<br />
CDF<br />
SM<br />
ATLAS<br />
0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!45
Baryon and meson<br />
spectroscopy<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013 !46
Heavy baryons with beauty<br />
In heavy quark effective theory an heavy baryon is made of<br />
Static color field from heavy quark<br />
B baryon spectrum<br />
Cloud corresponding to the light di-quark system<br />
“Hydrogen atom of QCD”<br />
This talk<br />
Q<br />
q<br />
q<br />
Thomas Kuhr, EKP, Uni KA Lattice QCD Workshop, Dec. 11 2007<br />
page 4<br />
Antisymmetric flavor configuration [q1,q2]: L-type baryons<br />
Symmetric flavor configuration {q1,q2}: S-type baryons<br />
Lb 0 =|bdu><br />
Sb=|buu><br />
qi is a strange quark: Jb family - both qi are strange quarks: Vb -<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!47
Jb - selection<br />
Ξb − selection<br />
• Full 2011 dataset (5.3 fb −1 )<br />
• Ξb − reconstruction:<br />
• Displaced + prompt J/ψ trigger.<br />
Muons matched to trigger objects.<br />
p +<br />
⇡ ⇤<br />
• Two tracks forming a very displaced<br />
vertex. Proton: highest |p| track.<br />
• Mass constrained kinematic fit<br />
• J/ψ mass constr. kinematic fit<br />
• Same track<br />
not used twice<br />
• Choose closest PV, in 3D,<br />
to Ξb − trajectory.<br />
⌅<br />
µ +<br />
⇤ 0<br />
20 MeV Ks mass veto<br />
J/<br />
PV<br />
µ<br />
PDG: 5790.5 ± 2.7 MeV<br />
V. Chiochia Ernest (Zürich Aguiló University) (HEPHY) – Heavy flavour physics with the CMS 8 experiment - 19-20/11/2013 June 26th 2012!48
Jb - selection<br />
Ξb − selection<br />
• Full 2011 dataset (5.3 fb −1 )<br />
• Ξb − reconstruction:<br />
• Displaced + prompt J/ψ trigger.<br />
Muons matched to trigger objects.<br />
p +<br />
⇡ ⇤<br />
• Two tracks forming a very displaced<br />
vertex. Proton: highest |p| track.<br />
• Mass constrained kinematic fits<br />
• J/ψ mass constr. kinematic fit<br />
• Same track<br />
not used twice<br />
• Choose closest PV, in 3D,<br />
to Ξb − trajectory.<br />
⌅<br />
µ +<br />
⇤ 0<br />
⇡ ⌅<br />
20 MeV Ks mass veto<br />
20 MeV Ω − mass veto<br />
To save CPU time, before the<br />
kinematic fit:<br />
PV<br />
J/<br />
µ<br />
• |Minv(Λπ) −MPDG(Ξ)| < 50 MeV<br />
• 5.5 GeV < Minv(J/ψΞ) < 6.2 GeV<br />
V. Chiochia Ernest (Zürich Aguiló University) (HEPHY) – Heavy flavour physics with the CMS 9 experiment - 19-20/11/2013 June 26th 2012 !49
Jb - selection<br />
Ξb − selection<br />
• Full 2011 dataset (5.3 fb −1 )<br />
• Ξb − reconstruction:<br />
• Displaced + prompt J/ψ trigger.<br />
Muons matched to trigger objects.<br />
p +<br />
⇡ ⇤<br />
• Two tracks forming a very displaced<br />
vertex. Proton: highest |p| track.<br />
• Mass constrained kinematic fits<br />
• J/ψ mass constr. kinematic fit<br />
• Same track<br />
not used twice<br />
• Choose closest PV, in 3D,<br />
to Ξb − trajectory.<br />
⌅<br />
µ +<br />
⇤ 0<br />
20 MeV Ks mass veto<br />
20 MeV Ω − mass veto<br />
⇡ ⌅<br />
To save CPU time, before the<br />
kinematic fit:<br />
PV<br />
⌅ b<br />
J/<br />
µ<br />
• |Minv(Λπ) −MPDG(Ξ)| < 50 MeV<br />
• 5.5 GeV < Minv(J/ψΞ) < 6.2 GeV<br />
PDG: 5790.5 ± 2.7 MeV<br />
V. Chiochia Ernest (Zürich Aguiló University) (HEPHY) – Heavy flavour physics with the 10 CMS experiment - 19-20/11/2013 June 26th 2012 !50
Candidates / 5 MeV<br />
100<br />
80<br />
60<br />
3<br />
×10<br />
X(3872) production<br />
1<br />
10 < p < 50 GeV<br />
T<br />
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Candidates / 3.125 MeV<br />
3<br />
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16<br />
14<br />
12<br />
CMS<br />
s = 7 TeV<br />
-1<br />
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total fit<br />
background<br />
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/dp<br />
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R fiducial<br />
10<br />
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10<br />
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prompt<br />
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LO NRQCD CMS s = 7 TeV<br />
LO NRQCD uncertainty -1<br />
L = 4.8 fb<br />
CMS CMS s = s7 = TeV 7 TeV<br />
|y| < 1.2<br />
-1 -1<br />
L = L 4.8 = 4.8 fb fb<br />
|y| < LO |y| 1.2 < NRQCD 1.2<br />
LO NRQCD uncertainty<br />
LO NRQCD<br />
LO NRQCD uncertainty<br />
40<br />
0.07<br />
0.07<br />
10<br />
-2<br />
3.75 3.8 3.85 3.9 3.95 4 10 10 15 20<br />
m(J/ψ π + π - ) [GeV]<br />
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(J/ψ π + 25 30<br />
p π ) [GeV]<br />
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-2<br />
T<br />
20<br />
10<br />
Figure<br />
11910<br />
6: Measured<br />
candidates<br />
differential cross 0.05 section for prompt X(3872) production times 0.05branching<br />
10 15 20<br />
-<br />
(J/ψ π<br />
0<br />
+ 25 30<br />
fraction B(X(3872) ! J/yp + p ) as a function of p T . The inner p error bars π ) [GeV] indicate the statistical<br />
0.04<br />
T<br />
0.04<br />
3.6 3.7 uncertainty 3.8 and3.9 the outer error 4 bars represent 10 10 20 the 15total30 uncertainty. 20<br />
-<br />
p (J/ψ π + 40 50 10 20 30<br />
-<br />
) [GeV]<br />
p (J/ψ π + 40 50<br />
-<br />
m(J/ψ π + -<br />
π ) [GeV]<br />
(J/ψ π + 25Predictions 30 from a NRQCD<br />
model [11] Figure are shown 6: Measured by the solid differential line, withcross the dotted sectionp<br />
lines for prompt representing π ) X(3872) [GeV] theproduction uncertainty. times Thebranching<br />
π ) [GeV]<br />
T T<br />
T<br />
data pointsfraction are placed B(X(3872) where the ! J/yp value + p of the ) astheoretical a function of prediction p T . The inner is equal error tobars its mean indicate value the statistical<br />
uncertainty and Figure outer3: error Ratios barsof represent the X(3872) the total anduncertainty. y(2S) crossPredictions sections times from branching a NRQCD fractions, without<br />
Important measurement<br />
over each bin, according<br />
to better<br />
to the<br />
(R fiducial<br />
constraint<br />
prescription in<br />
, left) andthe [28].<br />
with particle (R, right) nature<br />
model [11] are shown by the solid line, with the dotted acceptance lines representing corrections thefor uncertainty. the muonThe<br />
and pion pairs, as a<br />
function of p T . The inner error bars indicate the statistical uncertainty and the outer error bars<br />
Measured at central data rapidities points are using placed where J/c(mm)pp the valuedecays of the theoretical and assuming prediction Jequal PC =1 to ++ its mean value<br />
these results, over theeach measured bin, according integrated represent tocross the prescription total section uncertainty. for prompt [28]. The X(3872) data points production are placed timesat branching<br />
section fractionlargely is: dominated by prompt production<br />
the centre of each p T bin.<br />
Total cross (~75%)<br />
dσ<br />
Β [nb/GeV]<br />
⋅<br />
/dp<br />
1<br />
T<br />
-1<br />
prompt<br />
X(3872)<br />
dσ<br />
10<br />
1<br />
-1<br />
CMS s = 7 TeV<br />
-1<br />
L = 4.8 fb<br />
|y| < 1.2<br />
Ratio to c(2S) cross these section results, and the measured Table non-prompt 4: integrated Relativefraction variations, cross section independent for percent, prompt ofX(3872) the on integrated pT production cross times section branching<br />
! X(3872)+anything)<br />
ratio R for different<br />
X(3872) and y(2S) polarization hypotheses: transversely (longitudinally) polarized J/y are<br />
NRQCD underestimates s prompt (pp<br />
fraction is:<br />
the measured denoted<br />
·B(X(3872)<br />
as cross CST (CSL) section ! J/yp<br />
in the + p<br />
Collins–Soper<br />
)=1.06 ± 0.11<br />
frame<br />
(stat.)<br />
and<br />
± 0.15<br />
HXT<br />
(syst.)<br />
(HXL)<br />
nb.<br />
in the helicity frame. Unpolarized<br />
scenarios (labelled unpol) are also included.<br />
This result assumes<br />
s prompt that the X(3872) and y(2S) states are unpolarized.<br />
(pp ! X(3872)+anything) ·B(X(3872) Polarization ! J/yp + The NRQCD prediction<br />
Prompt cross section Relative Polarization Relative<br />
for the prompt = X(3872) cross section times branching<br />
X(3872)<br />
fraction<br />
y(2S)<br />
in the p kinematic )=1.06 ±<br />
shifts (%) X(3872)<br />
region 0.11 (stat.)<br />
y(2S)<br />
of this ± 0.15 (syst.) nb.<br />
shifts (%)<br />
NRQCD analysis=<br />
is 4.01 ± 0.88 nb [11],(10 significantly < pT < 30 GeV, above CST |y| the < 1.2) measured CSL (>3s value. larger 28than data) CST unpol 8<br />
Non-prompt fraction = This 0.263±0.028 result assumes that the X(3872) and CSL y(2S) CST states are unpolarized. +31 CSLThe NRQCD unpol prediction +22<br />
for the prompt X(3872) cross sectionHXT times branching HXL fraction +86 in the HXTkinematic unpol region +28 of this<br />
7 Measurement analysis is 4.01 of ± 0.88 thenb p [11], + psignificantly invariant-mass HXL above HXT the measured distribution<br />
49 value. HXL unpol 31<br />
CST CST 1 unpol CST +8<br />
The decay properties of the X(3872) are further investigated with a measurement of the p<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS CSL experiment CSL - 19-20/11/2013<br />
5 unpol CSL + p<br />
22<br />
invariant-mass distribution from X(3872) decays !51<br />
HXT<br />
to J/yp + HXT<br />
p . Here, the<br />
6<br />
same event<br />
unpol<br />
selection<br />
HXT<br />
as<br />
27<br />
R<br />
0.12<br />
0.11<br />
0.1<br />
0.09<br />
0.08<br />
7 Measurement of the p + p invariant-mass distribution<br />
13<br />
JHEP 04 (2013) 154<br />
CMS s = 7 TeV<br />
-1<br />
L = 4.8 fb<br />
|y| < 1.2<br />
9
Summary of X(4140) searches<br />
M1 (MeV) G1 (MeV) M2 (MeV) G2 (MeV)<br />
Belle - - 4350 +4.6 -5.1±0.7 13 +18 -9±4<br />
CDF<br />
4143.0 +2.9 -3.0±0.6 15.3 +10.4 -6.1±2.5 4274.4 +8.4 -6.7±1.9 32.3+21.9±7.6<br />
CMS 4148.0±2.4±6.3 28 +15 -11±19 4313.8±5.3±7.3 38 +30 -16±16<br />
D0 4159.0±4.3±6.6 19.9±12.6 +1.0 -8.0 4328.5±12.0 30 (constrained)<br />
LHCb - - - -<br />
>5s >3s N.A.<br />
V. Chiochia (Zürich University) – Heavy flavour physics with the CMS experiment - 19-20/11/2013<br />
!52