J/ψ Production at the LHC - LHCb - Cern
J/ψ Production at the LHC - LHCb - Cern
J/ψ Production at the LHC - LHCb - Cern
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J/<strong>ψ</strong> <strong>Production</strong> <strong>at</strong> <strong>the</strong> <strong>LHC</strong><br />
7 th Workshop on B Physics<br />
Orsay, France 4 th –5 th October 2010
CERN and <strong>the</strong> <strong>LHC</strong><br />
p p<br />
"NOMINAL (2011) :<br />
"√s =14 TeV<br />
"L = 2·10 32 cm -2 s -1 (<strong>LHC</strong>b specific)<br />
"pp collider : NOW :<br />
➡ @ √s = 7 TeV<br />
➡ L ≈ 1-2·10 31 cm -2 s -1<br />
4.10.2010 Giulia Manca<br />
3<br />
""<br />
345./3-6<br />
+,-./012<br />
()*<br />
!"#<br />
$%#<br />
&'#
The four <strong>LHC</strong> Detectors<br />
p p<br />
4.10.2010 Giulia Manca<br />
4
Rapidity Range<br />
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J/<strong>ψ</strong> <strong>Production</strong><br />
<strong>ψ</strong> J<br />
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J/<strong>ψ</strong> <strong>Production</strong><br />
<strong>ψ</strong> J<br />
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[nb/(GeV/ c)]<br />
( J / ! )<br />
"<br />
d<br />
Inclusive cross section measurements<br />
T<br />
p<br />
d<br />
4<br />
10<br />
3<br />
10<br />
2<br />
10<br />
<strong>LHC</strong>b d<strong>at</strong>a<br />
ALICE<br />
<strong>LHC</strong>b<br />
Preliminary<br />
s = 7 TeV<br />
L=14.2 nb<br />
<strong>LHC</strong>b simul<strong>at</strong>ion (PYTHIA<br />
6.3 Color Singlet)<br />
<strong>LHC</strong>b simul<strong>at</strong>ion (+ PYTHIA<br />
6.4 Color Octet)<br />
0 2 4 6 8 10<br />
p [GeV/ c]<br />
T<br />
-1<br />
2.5
[nb/(GeV/ c)]<br />
( J / ! )<br />
"<br />
d<br />
T<br />
p<br />
d<br />
4<br />
10<br />
3<br />
10<br />
2<br />
10<br />
Cross section measurements<br />
[nb / GeV/c]<br />
T<br />
/ dydp<br />
"<br />
d<br />
#<br />
)<br />
µ<br />
µ<br />
$<br />
!<br />
BR(J/<br />
<strong>LHC</strong>b d<strong>at</strong>a<br />
2<br />
10<br />
10<br />
1<br />
<strong>LHC</strong>b simul<strong>at</strong>ion (PYTHIA<br />
<strong>LHC</strong>b simul<strong>at</strong>ion (+ PYTHIA<br />
<strong>LHC</strong>b<br />
Preliminary<br />
s = 7 TeV<br />
L=14.2 nb<br />
6.3 Color Singlet)<br />
6.4 Color Octet)<br />
0 2 4 6 8 10<br />
p [GeV/ c]<br />
T<br />
-1<br />
10<br />
<strong>LHC</strong><br />
-1<br />
Preliminary<br />
s = 7 TeV<br />
BR (nb/GeV/c)<br />
"<br />
T<br />
/dp<br />
d#<br />
10<br />
10<br />
Inclusive -2 J/<br />
10<br />
2<br />
1<br />
-1<br />
s = 7 TeV<br />
-1<br />
L = 100 nb<br />
! CMS Preliminary<br />
CEM<br />
CASCADE<br />
-1<br />
CMS 100 nb 1.4 < |y| < 2.4<br />
-1<br />
ATLAS 17.5 nb 10<br />
-1<br />
<strong>LHC</strong>b 14.2 nb 2.5 < y < 4.0<br />
ALICE scaled 2.7 < y < 3.8<br />
PYTHIA<br />
1.5 < |y| < CMS 2.25 d<strong>at</strong>a<br />
|y| < 2.4<br />
0 5 10 15 20 25 30<br />
J/ !<br />
p (GeV/c)<br />
0 2 4 6 8 10 12 14 16<br />
p [GeV/c]<br />
4.10.2010 Giulia Manca J/ !<br />
14<br />
T<br />
T
from B-hadrons<br />
!<br />
fraction of J/<br />
0.5<br />
0.4<br />
0.3<br />
0.2<br />
0.1<br />
0<br />
Non prompt J/<strong>ψ</strong><br />
CMS 100 nb<br />
CMS 100 nb<br />
-1<br />
-1<br />
-1<br />
<strong>LHC</strong>b 14.2 nb<br />
-1<br />
ATLAS 17.5 nb<br />
<strong>LHC</strong> s = 7 TeV<br />
Preliminary<br />
1.4 < |y| < 2.4<br />
|y| < 1.4<br />
2.5 < y < 4.0<br />
|y| < 2.25<br />
CDF<br />
s = 1.96 TeV |y| < 0.6<br />
PRD 71 (2005) 032001<br />
0 2 4 6 8 10 12 14 16 18<br />
J/ !<br />
p [GeV/c]<br />
4.10.2010 Giulia Manca 16<br />
T
4.10.2010<br />
Influence of J/<strong>ψ</strong> Polaris<strong>at</strong>ion<br />
Detector acceptance as a function of helicity angle cosθ<br />
Example:<br />
helicity frame<br />
J/<strong>ψ</strong> rest frame<br />
J/<strong>ψ</strong> – lab virtual<br />
flight direction<br />
➡ acceptance gener<strong>at</strong>es an artificial polaris<strong>at</strong>ion<br />
large influence of polaris<strong>at</strong>ion on measurement<br />
MC with no polaris<strong>at</strong>ion:<strong>LHC</strong>b<br />
Both mu
[nb/(GeV/ c)]<br />
)<br />
( J / !<br />
"<br />
d<br />
T<br />
p<br />
d<br />
3<br />
10<br />
2<br />
10<br />
Different polaris<strong>at</strong>ion scenarios<br />
# =0<br />
# =-1<br />
# =+1<br />
<strong>LHC</strong>b<br />
<strong>LHC</strong>b<br />
Preliminary<br />
s = 7 TeV<br />
L=14.2 nb<br />
0 2 4 6 8 10<br />
p [GeV/ c]<br />
T<br />
-1<br />
Up to 20%<br />
CMS<br />
CMS<br />
ATLAS<br />
4.10.2010 Giulia Manca 18
Experiment<br />
Range<br />
Luminosity<br />
Integr<strong>at</strong>ed cross section<br />
measurements<br />
<strong>LHC</strong>b (in µb)<br />
pT
Back-up<br />
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Inclusive cross section measurements<br />
• Extrapola)ons with PYTHIA 6.4 (LEP hadroniza)on frac)ons assumed)<br />
1. ½ produc)on cross sec)on for b or b in <strong>LHC</strong>b acceptance<br />
2. Total bb produc)on cross sec)on<br />
An independent σ( bb) measurement by <strong>LHC</strong>b with results in excellent<br />
agreement. Averaging:<br />
333±17±49<br />
88.3±4.5±13.0<br />
LEP b hadroniza)on frac)ons<br />
TeV<strong>at</strong>ron b hadroniza)on frac)ons<br />
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J/<strong>ψ</strong>→ee mass distribution<br />
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Angular<br />
acceptance :<br />
10
<strong>LHC</strong>b Trigger<br />
Measure muon trigger efficiencies using trigger lines not involving muons<br />
L0 x HLT1 Efficiency J/<strong>ψ</strong>->µµ<br />
4.10.2010 Giulia Manca<br />
26
Primary Vertex resolution<br />
4.10.2010 Giulia Manca 29
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