Search for Dark Matter Captured in the Sun with ... - KICP Workshops
Search for Dark Matter Captured in the Sun with ... - KICP Workshops
Search for Dark Matter Captured in the Sun with ... - KICP Workshops
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<strong>Search</strong> <strong>for</strong> <strong>Dark</strong> <strong>Matter</strong> <strong>Captured</strong> <strong>in</strong> <strong>the</strong> <strong>Sun</strong> <strong>with</strong><br />
<strong>the</strong> IceCube Neutr<strong>in</strong>o Observatory<br />
Matthias Dann<strong>in</strong>ger <strong>for</strong> <strong>the</strong> IceCube Collaboration<br />
The Oscar Kle<strong>in</strong> Centre <strong>for</strong> Cosmoparticle Physics, Stockholm University<br />
9th International Conference "Identification of <strong>Dark</strong> <strong>Matter</strong>, 2012"<br />
Chicago, USA on July 23-27, 2012
Results from a search<br />
<strong>Search</strong> <strong>for</strong> <strong>Dark</strong> <strong>Matter</strong> <strong>Captured</strong> <strong>in</strong> <strong>the</strong> <strong>Sun</strong> <strong>with</strong><br />
<strong>the</strong> IceCube Neutr<strong>in</strong>o Observatory<br />
<strong>in</strong> <strong>the</strong> 79-str<strong>in</strong>g configuration<br />
Matthias Dann<strong>in</strong>ger <strong>for</strong> <strong>the</strong> IceCube Collaboration<br />
The Oscar Kle<strong>in</strong> Centre <strong>for</strong> Cosmoparticle Physics, Stockholm University<br />
9th International Conference "Identification of <strong>Dark</strong> <strong>Matter</strong>, 2012"<br />
Chicago, USA on July 23-27, 2012
Solar <strong>Dark</strong> <strong>Matter</strong> <strong>Search</strong> <strong>with</strong> IceCube<br />
All processes depend on WIMP mass<br />
Annihilation channel (branch<strong>in</strong>g ratios)<br />
Annihilation cross-section<br />
Capture (scatter<strong>in</strong>g)<br />
→ Scatter<strong>in</strong>g cross-sections (SI & SD)<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
Proposed by:<br />
Silk, Olive & Srednicki '85<br />
Gaisser, Steigman & Tilav '86<br />
Freese '86<br />
Krauss, Srednicki & Wilzcek '86<br />
1
Solar <strong>Dark</strong> <strong>Matter</strong> <strong>Search</strong> <strong>with</strong> IceCube<br />
All processes depend on WIMP mass<br />
Annihilation channel (branch<strong>in</strong>g ratios)<br />
Annihilation cross-section<br />
Capture (scatter<strong>in</strong>g)<br />
→ Scatter<strong>in</strong>g cross-sections (SI & SD)<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
1
Solar <strong>Dark</strong> <strong>Matter</strong> <strong>Search</strong> <strong>with</strong> IceCube<br />
All processes depend on WIMP mass<br />
Annihilation channel (branch<strong>in</strong>g ratios)<br />
Annihilation cross-section<br />
Capture (scatter<strong>in</strong>g)<br />
→ Scatter<strong>in</strong>g cross-sections (SI & SD)<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
ma<strong>in</strong> analysis backgrounds:<br />
atm. ν∼Ο (10³ trigger<strong>in</strong>g events/day)<br />
1
Solar <strong>Dark</strong> <strong>Matter</strong> <strong>Search</strong> <strong>with</strong> IceCube<br />
All processes depend on WIMP mass<br />
Annihilation channel (branch<strong>in</strong>g ratios)<br />
Annihilation cross-section<br />
Capture (scatter<strong>in</strong>g)<br />
→ Scatter<strong>in</strong>g cross-sections (SI & SD)<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
ma<strong>in</strong> analysis backgrounds:<br />
atm. ν∼Ο (10³ trigger<strong>in</strong>g events/day)<br />
atm. μ∼Ο (10⁸ trigger<strong>in</strong>g events/day)<br />
1
Solar <strong>Dark</strong> <strong>Matter</strong> <strong>Search</strong> <strong>with</strong> IceCube<br />
All processes depend on WIMP mass<br />
Annihilation channel (branch<strong>in</strong>g ratios)<br />
Annihilation cross-section<br />
Capture (scatter<strong>in</strong>g)<br />
→ Scatter<strong>in</strong>g cross-sections (SI & SD)<br />
Strik<strong>in</strong>g signature:<br />
High-E ν excess<br />
over background<br />
from <strong>Sun</strong> direction<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
ma<strong>in</strong> analysis backgrounds:<br />
atm. ν∼Ο (10³ trigger<strong>in</strong>g events/day)<br />
atm. μ∼Ο (10⁸ trigger<strong>in</strong>g events/day)<br />
1
Solar <strong>Dark</strong> <strong>Matter</strong> <strong>Search</strong> <strong>with</strong> IceCube<br />
All processes depend on WIMP mass<br />
Annihilation channel (branch<strong>in</strong>g ratios)<br />
Annihilation cross-section<br />
Capture (scatter<strong>in</strong>g)<br />
→ Scatter<strong>in</strong>g cross-sections (SI & SD)<br />
± 23˚<br />
Strik<strong>in</strong>g signature:<br />
High-E ν excess<br />
over background<br />
from <strong>Sun</strong> direction<br />
*Bl<strong>in</strong>d analysis <strong>with</strong> respect to true <strong>Sun</strong> azimuth<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
ma<strong>in</strong> analysis backgrounds:<br />
atm. ν∼Ο (10³ trigger<strong>in</strong>g events/day)<br />
atm. μ∼Ο (10⁸ trigger<strong>in</strong>g events/day)<br />
1
IceCube 86-str<strong>in</strong>gs<br />
✗ 1.5 km ‐ 2.5 km deep<br />
✗ typically 125 m spac<strong>in</strong>g between str<strong>in</strong>gs<br />
IceCube detector<br />
(~70 m <strong>in</strong> DeepCore,10x higher DOM density)<br />
✗ 60 Modules per str<strong>in</strong>g<br />
✗ 1 km ‐‐ 1 Gton <strong>in</strong>strumented volume<br />
✗ O(km) muon tracks from νμ CC<br />
✗ O(10m) cascades from νe CC,<br />
low energy ντ CC, and νx NC<br />
✗ Cherenkov radiation detected by<br />
3D array of optical sensors (DOMs)<br />
*More details <strong>in</strong> plenary talk by C. Rott<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
ν<br />
μ<br />
DeepCore<br />
8 add. densely<br />
<strong>in</strong>strumented str<strong>in</strong>gs<br />
2
IceCube-79 str<strong>in</strong>g analysis details<br />
● Analysis <strong>for</strong> <strong>the</strong> whole year! Used 317 days livetime<br />
ν<br />
(151 days austral w<strong>in</strong>ter & 166 days austral summer)<br />
● more than 60 billion recorded events<br />
● Up-go<strong>in</strong>g<br />
IceCube<br />
DC<br />
1<br />
● No conta<strong>in</strong>ment<br />
μ<br />
● Up-go<strong>in</strong>g<br />
IceCube<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
ν<br />
DC<br />
2<br />
● strong conta<strong>in</strong>ment<br />
μ<br />
*new*<br />
● At f<strong>in</strong>al level ~25000 signal-like events selected <strong>in</strong> 3 <strong>in</strong>dependent samples<br />
● With DeepCore, analysis reaches neutr<strong>in</strong>o energies as low as 10-20GeV<br />
ν<br />
● Down-go<strong>in</strong>g<br />
IceCube<br />
DC<br />
μ<br />
3<br />
*new*<br />
● strong conta<strong>in</strong>ment<br />
3
IceCube-79 str<strong>in</strong>g analysis details<br />
Dedicated onl<strong>in</strong>e filters<br />
target<strong>in</strong>g:<br />
● muon events<br />
● Low energy muon<br />
events (IceCube)<br />
● DeepCore events<br />
● DeepCore events<br />
(summer)<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
● By compar<strong>in</strong>g signal simulation & data, cuts are<br />
placed that reduces <strong>the</strong> content of atmospheric<br />
muon events<br />
● Early analysis cuts:<br />
dedicated onl<strong>in</strong>e-filter → offl<strong>in</strong>e high-level<br />
reconstructions → first modest cuts<br />
(track quality/direction + conta<strong>in</strong>ment)<br />
Summer<br />
4
IceCube-79 str<strong>in</strong>g analysis details<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
● By compar<strong>in</strong>g signal simulation & data, cuts are<br />
placed that reduces <strong>the</strong> content of atmospheric<br />
muon events<br />
● Early analysis cuts:<br />
dedicated onl<strong>in</strong>e-filter → offl<strong>in</strong>e high-level<br />
reconstructions → first modest cuts<br />
(track quality/direction + conta<strong>in</strong>ment)<br />
● Signal event topology very different <strong>for</strong><br />
low & high WIMP mass<br />
→ f<strong>in</strong>d geometrical cut to split dataset<br />
<strong>in</strong>to 2 non-overlap<strong>in</strong>g datasets<br />
5
Multivariate analysis step (BDT variable)<br />
event selection 1 (w<strong>in</strong>ter, high energy) event selection 3 (summer, low energy)<br />
data<br />
atm. ν atm. μ<br />
signal (scaled)<br />
“ mis” -reconstructed atm. μ background “ well” -reconstructed atm. μ background<br />
→ 1 separate BDT <strong>for</strong> each event selection<br />
→ tra<strong>in</strong><strong>in</strong>g on off-source exp. data + separate signal simulation<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
6
atm. ν<br />
atm. μ<br />
Multivariate analysis step (f<strong>in</strong>al cut applied)<br />
event selection 1 (w<strong>in</strong>ter, high energy) event selection 3 (summer, low energy)<br />
Total Bg<br />
data<br />
→ 1 separate BDT <strong>for</strong> each event selection<br />
→ tra<strong>in</strong><strong>in</strong>g on off-source exp. data + separate signal simulation<br />
→ Optimized f<strong>in</strong>al cut on BDT-output: run llh-analysis <strong>for</strong> various BDT cuts, to<br />
determ<strong>in</strong>e cut value <strong>with</strong> best sensitivity (MRF & MDP)<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
7
Reconstructed zenith (f<strong>in</strong>al analysis level)<br />
event selection 1 (w<strong>in</strong>ter, high energy) event selection 3 (summer, low energy)<br />
atm. ν<br />
atm. μ<br />
Total Bg<br />
data<br />
→ 1 separate BDT <strong>for</strong> each event selection<br />
→ tra<strong>in</strong><strong>in</strong>g on off-source exp. data + separate signal simulation<br />
→ Optimized f<strong>in</strong>al cut on BDT-output: run llh-analysis <strong>for</strong> various BDT cuts, to<br />
determ<strong>in</strong>e cut value <strong>with</strong> best sensitivity (MRF & MDP)<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
8
The observed angle to <strong>the</strong><br />
<strong>Sun</strong> is fitted <strong>with</strong> signal and<br />
background pdf:s<br />
Maximum llh-analysis<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
background expectation from data<br />
signal simulation (e.g. 1000 GeV)<br />
Angle between event track and direction<br />
from <strong>the</strong> <strong>Sun</strong><br />
10
The observed angle to <strong>the</strong><br />
<strong>Sun</strong> is fitted <strong>with</strong> signal and<br />
background pdf:s<br />
Maximum llh-analysis<br />
How many signal events can be<br />
consistent <strong>with</strong> <strong>the</strong> observation?<br />
Evaluate shape fit <strong>with</strong> log−<br />
likelihood rank (Feldman-Cous<strong>in</strong>s)<br />
to construct confidence regions<br />
<strong>for</strong> <strong>the</strong> number of signal events μs<br />
where L is <strong>the</strong> pdf product over <strong>the</strong><br />
f<strong>in</strong>al sample<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
background expectation from data<br />
Angle between event track and direction<br />
from <strong>the</strong> <strong>Sun</strong><br />
observation<br />
signal simulation (e.g. 1000 GeV)<br />
10
The observed angle to <strong>the</strong><br />
<strong>Sun</strong> is fitted <strong>with</strong> signal and<br />
background pdf:s<br />
Maximum llh-analysis<br />
How many signal events can be<br />
consistent <strong>with</strong> <strong>the</strong> observation?<br />
Evaluate shape fit <strong>with</strong> log−<br />
likelihood rank (Feldman-Cous<strong>in</strong>s)<br />
to construct confidence regions<br />
<strong>for</strong> <strong>the</strong> number of signal events μs<br />
where L is <strong>the</strong> pdf product over <strong>the</strong><br />
f<strong>in</strong>al sample<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
background expectation from data<br />
Angle between event track and direction<br />
from <strong>the</strong> <strong>Sun</strong><br />
observation<br />
signal simulation (e.g. 1000 GeV)<br />
Scale to multiple datasets<br />
10
Unbl<strong>in</strong>d<strong>in</strong>g results (expected sensitivity)<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
11
Unbl<strong>in</strong>d<strong>in</strong>g results (events observed)<br />
event selection 1 (w<strong>in</strong>ter, high energy) event selection 2 (w<strong>in</strong>ter, low energy)<br />
event selection 3 (summer, low energy)<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
observed events<br />
background expectation<br />
Upper limit on number of<br />
signal events (example)<br />
12
Unbl<strong>in</strong>d<strong>in</strong>g results (observed results)<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
13
Systematic uncerta<strong>in</strong>ties<br />
Prelim<strong>in</strong>ary evaluation of systematic uncerta<strong>in</strong>ties<br />
Source of uncerta<strong>in</strong>ty Estimated effect<br />
Neutr<strong>in</strong>o oscillations pend<strong>in</strong>g<br />
DOM sensetivity spread*<br />
pend<strong>in</strong>g<br />
Interaction cross-section 3.6 – 7.1 %<br />
Muon propagation <strong>in</strong> ice < 1 %<br />
Ice model*<br />
Absolute DOM efficiency*<br />
1 – 20 %<br />
14 – 51 %<br />
time/position callibration < 3 – 5 %<br />
Statistical error on signal < 2 %<br />
* Full analysis per<strong>for</strong>med <strong>with</strong> an alternative signal simulation,<br />
<strong>in</strong>clud<strong>in</strong>g maximum llh-analysis (change <strong>in</strong> acceptance + PSF)<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
14
Unbl<strong>in</strong>d<strong>in</strong>g results (muon flux limit)<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
15
Unbl<strong>in</strong>d<strong>in</strong>g results (SI-cross-section limit)<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
16
Unbl<strong>in</strong>d<strong>in</strong>g results (SD-cross-section limit)<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
17
Summary<br />
✗ New results from 79-str<strong>in</strong>g data (~1y livetime)<br />
✗ First <strong>Dark</strong> <strong>Matter</strong> analysis <strong>in</strong>clud<strong>in</strong>g DeepCore<br />
✗ First full year-round IceCube solar <strong>Dark</strong> <strong>Matter</strong> search<br />
✗ No excess of events from <strong>the</strong> <strong>Sun</strong> over expected backgrounds<br />
✗ New very competitive SD-cross-section limits<br />
→ most str<strong>in</strong>gent limits <strong>in</strong> large parts of WIMP mass range<br />
→ new LKP limits <strong>with</strong> same search (not discussed <strong>in</strong> talk)<br />
✗ The near future ..........<br />
IceCube already took data <strong>for</strong> more than 1 year <strong>in</strong> <strong>the</strong> full<br />
86-str<strong>in</strong>g configuration<br />
→ 2 more DeepCore str<strong>in</strong>gs (even lower energy threshold)<br />
→ many many years of data to come....<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
18
Additional slides<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012
Multivariate analysis step (BDT variable)<br />
event selection 2 (w<strong>in</strong>ter, low energy)<br />
data<br />
atm. ν<br />
atm. μ<br />
signal<br />
→ 1 separate BDT <strong>for</strong> each event selection<br />
→ tra<strong>in</strong><strong>in</strong>g on off-source exp. data + separate signal simulation<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
6
Reconstructed zenith & BDT output<br />
(f<strong>in</strong>al analysis level)<br />
event selection 2 (w<strong>in</strong>ter, low energy) event selection 2 (w<strong>in</strong>ter, low energy)<br />
Total Bg<br />
data<br />
atm. ν<br />
atm. μ<br />
→ 1 separate BDT <strong>for</strong> each event selection<br />
→ tra<strong>in</strong><strong>in</strong>g on off-source exp. data + separate signal simulation<br />
→ Optimized f<strong>in</strong>al cut on BDT-output: run llh-analysis <strong>for</strong> various BDT cuts, to<br />
determ<strong>in</strong>e cut value <strong>with</strong> best sensitivity (MRF & MDP)<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
8
Analysis: f<strong>in</strong>al cut on BDT-output<br />
1000 GeV hard<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
Optimized f<strong>in</strong>al cut on BDT-output:<br />
run full llh-analysis <strong>for</strong> various BDT cuts, to<br />
determ<strong>in</strong>e <strong>the</strong> cut value <strong>with</strong> <strong>the</strong> best sensitivity:<br />
● each dataset <strong>in</strong>dividually<br />
● calculate MRF<br />
● calculate MDP (Punzi)<br />
● check <strong>for</strong> many mass/channel comb<strong>in</strong>ations<br />
Want to f<strong>in</strong>d 1 s<strong>in</strong>gle cut per dataset<br />
→ (robustness ra<strong>the</strong>r than f<strong>in</strong>e-tun<strong>in</strong>g)<br />
Still very<br />
efficient
Sensitivity extends to<br />
WIMP masses of 20 GeV<br />
Only 1 year of data<br />
Data unbl<strong>in</strong>d<strong>in</strong>g soon!<br />
also search <strong>for</strong> UED<br />
models (not shown here)<br />
IceCube 79 str<strong>in</strong>g sensitivity<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
prelim<strong>in</strong>ary
New model <strong>in</strong>dependent method <strong>for</strong><br />
<strong>the</strong>ories of new physics<br />
(Solar <strong>Dark</strong> <strong>Matter</strong> searches)<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012
New SUSY analysis <strong>with</strong> IceCube<br />
What can <strong>the</strong> muon signal tell me?<br />
Roughly:<br />
✗ Number – how much annihilation is go<strong>in</strong>g on <strong>in</strong> <strong>the</strong> <strong>Sun</strong><br />
⇒ <strong>in</strong>fo on σSD , σSI and <br />
✗ Spectrum – sensitive to WIMP mass mχ and branch<strong>in</strong>g<br />
fractions BF <strong>in</strong>to different annihilation channels χ<br />
✗ Direction – how likely it is that <strong>the</strong>y come from <strong>the</strong> <strong>Sun</strong><br />
In model-<strong>in</strong>dependent analyses a lot of this <strong>in</strong><strong>for</strong>mation is ei<strong>the</strong>r discarded or not<br />
given <strong>with</strong> f<strong>in</strong>al limits<br />
Goal:<br />
Use as much of this <strong>in</strong><strong>for</strong>mation on σSD , σSI , , mχ and BF (χ ) as possible to<br />
directly constra<strong>in</strong> specific po<strong>in</strong>ts and regions <strong>in</strong> WIMP model parameter spaces<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012<br />
More details: P.Scott, C.Savage, J. Edsjö<br />
& <strong>the</strong> IceCube Collaboration, arXiv:1207.0810
Include IceCube event level data <strong>in</strong> a global statistical fit.<br />
→ parameter estimation ra<strong>the</strong>r than model exclusion<br />
Composite likelihood made up of observations from all over:<br />
<strong>Dark</strong> matter relic density from WMAP<br />
Precision electroweak tests at LEP & LEP limits on sparticle masses<br />
B-factory data (rare decays, b → sγ)<br />
Muon anomalous magnetic moment<br />
LHC searches, direct detection (not yet <strong>in</strong>cluded <strong>in</strong> examples)<br />
+ IceCube<br />
Global SUSY analysis <strong>with</strong> IceCube<br />
More details: P.Scott, C.Savage, J. Edsjö & <strong>the</strong> IceCube Collaboration, arXiv:1207.0810<br />
unb<strong>in</strong>ned likelihood<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012
Global SUSY analysis <strong>with</strong> IceCube<br />
More details: P.Scott, C.Savage, J. Edsjö & <strong>the</strong> IceCube Collaboration, arXiv:1207.0810<br />
CMSSM, IceCube-22<br />
✗ Contours <strong>in</strong>dicate 1σ and 2σ credible regions<br />
✗ Grey contours correspond to fit <strong>with</strong>out IceCube data<br />
✗ Shad<strong>in</strong>g+contours <strong>in</strong>dicate relative probability only, not overall goodness of fit<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012
Global SUSY analysis <strong>with</strong> IceCube<br />
More details: P.Scott, C.Savage, J. Edsjö & <strong>the</strong> IceCube Collaboration, arXiv:1207.0810<br />
CMSSM, IceCube-22 <strong>with</strong> 100x boosted effective area<br />
(<strong>in</strong>dication <strong>for</strong> IceCube-79 and 86-str<strong>in</strong>g prospects)<br />
✗ Contours <strong>in</strong>dicate 1σ and 2σ credible regions<br />
✗ Grey contours correspond to fit <strong>with</strong>out IceCube data<br />
✗ Shad<strong>in</strong>g+contours <strong>in</strong>dicate relative probability only, not overall goodness of fit<br />
23/07/12 Matthias Dann<strong>in</strong>ger IDM 2012