fpcp 2003 : 3-6 june 2003 ecole polytechnique, paris status and prospects of atlas and cms for b...
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FPCP 2003 : 3-6 June 2003 Ecole Polytechnique, Paris
Status and Prospects of ATLAS and CMS for B Physics and CP Violation
Fairouz Ohlsson-MalekLPSC-Grenoble/IN2P3/ATLAS 1
Status and Prospects of ATLAS and CMS
for B Physics and CP Violation
Overview of the Detector Status Overview of the physics potential B physics reach:
•Trigger,Tagging and off-line strategies•Precision physics•Physics of Bs meson•Potential for rare decays•B hadron production
Conclusions
FPCP 2003 : 3-6 June 2003 Ecole Polytechnique, Paris
Status and Prospects of ATLAS and CMS for B Physics and CP Violation
Fairouz Ohlsson-MalekLPSC-Grenoble/IN2P3/ATLAS 4
LHC reach
• high detector granularity large event size (O(1) MByte)
• high collision rate (~ 108 – 109 per sec )
Collision Energy 14 TeV
Design Luminosity
1034 cm-2 s-1
Interactions per Bunch Crossing
23
Bunch spacing 25 ns
B-meson decays, precise measurementsB-meson decays, precise measurements•CP violation CP violation •BBss mesons mesons•Rare decaysRare decaysB-hadron production B-hadron production •Double heavy flavor mesons Double heavy flavor mesons •QCD tests of beauty production at LHC QCD tests of beauty production at LHC central regioncentral region•Physics of Beauty baryons, production Physics of Beauty baryons, production polarizationpolarization
FPCP 2003 : 3-6 June 2003 Ecole Polytechnique, Paris
Status and Prospects of ATLAS and CMS for B Physics and CP Violation
Fairouz Ohlsson-MalekLPSC-Grenoble/IN2P3/ATLAS 5
100b
230b
LHC
total= 100 mb
inelastic = 80 mb
bb = 500 b
ATLAS & CMS
Central detectors
LHCb
Forward detector
|| < 2.5 , pT> 10 GeV
B-hadron = 100 b
1.9 < < 4.9, pT>2 GeV
B-hadron = 230 b
L = 1-2 x 1033 cm-2 s-1
1034 cm-2 s-1 for rare decays
L = 2 x 1032 cm-2 s-1
Exclusive channels ~ 2.8 106
Dominated by bb J/Hadronic channels: < 105
(however all with muon tag)
Exclusive channels ~ 3.4 106
1.7 106 bb J/Hadronic channels ~ 1.7 106
Overview of the B physics potential
FPCP 2003 : 3-6 June 2003 Ecole Polytechnique, Paris
Status and Prospects of ATLAS and CMS for B Physics and CP Violation
Fairouz Ohlsson-MalekLPSC-Grenoble/IN2P3/ATLAS 6
Trigger Strategies
ATLAS CMSLevel 1 1 pT> 6 GeV, ||
<2.4
26 GeV
1 pT> 14 GeV, || <2.4
23 GeV
Level 2 Lepton reconstruction and Identification
Track reconstruction either in full ID volume or in ROI followed by mass cuts on track combinations
Event Filter
Offline algorithms, Decay vertices cuts ….
FPCP 2003 : 3-6 June 2003 Ecole Polytechnique, Paris
Status and Prospects of ATLAS and CMS for B Physics and CP Violation
Fairouz Ohlsson-MalekLPSC-Grenoble/IN2P3/ATLAS 7
Trigger Strategies
2 trigger:LVL1: 2 , LVL2: track in spectrometer+InnerBd J/ () Ks, Bs J/() ,b J/ () , B , B K*0 , B
-e() trigger:LVL1: eGeV, LVL2: tracking in regionBd J/ (ee) Ks + B b J/ (ee) + B d…-hadron trigger:LVL1: + jet (ET> 5 GeV), LVL2 tracking in regionB + B , Bs Ds + B , ….
ATLAS as an example
FPCP 2003 : 3-6 June 2003 Ecole Polytechnique, Paris
Status and Prospects of ATLAS and CMS for B Physics and CP Violation
Fairouz Ohlsson-MalekLPSC-Grenoble/IN2P3/ATLAS 8
B Tagging strategies
l
B0
B0D
K-
b
b
d
u
d
u
B0
+
Opposite side lepton tag:
ATLAS CMS
Efficiency 4% (e+) 4%
D 0.52(), 0.46 e 0.44
ATLAS CMS
Efficiency 82% () 21%
D 0.16() 0.32
Same side pion (B** + fragmentation):
ATLAS CMS
Efficiency 64% () 65%
D 0.17() 0.18
Jet charge – same (ATLAS) and opposite (CMS) side:
FPCP 2003 : 3-6 June 2003 Ecole Polytechnique, Paris
Status and Prospects of ATLAS and CMS for B Physics and CP Violation
Fairouz Ohlsson-MalekLPSC-Grenoble/IN2P3/ATLAS 9
Precision measurements
Benchmark channels:Bd J/ Ks sin2 Bd +- sensitivityBsJ/ weak phase s, s BsDs (a1) ms B+ K+ K+ - Br
Upper limit on Br= 5.3 10-7 for 3 years @ 1033 cm-2 s-1
FPCP 2003 : 3-6 June 2003 Ecole Polytechnique, Paris
Status and Prospects of ATLAS and CMS for B Physics and CP Violation
Fairouz Ohlsson-MalekLPSC-Grenoble/IN2P3/ATLAS 10
Precision measurements
1 year @ 1033 cm-2 s-1 ATLAS CMS
N Triggered events
N Offline events
S/B
800 000 ev
170 000 ev
31
4400 000 ev
430 000 ev
8
sin2
Lepton tags
Jet/charge tags
Total
0.039
0.026
0.017
0.031
0.021
0.015
ATLAS+CMS
3 years @ 1033 cm-2 s-1
ATLAS+CMS
3 years @ 1033 cm-2 s-1
+ LHCb, 5 years @ 1032 cm-2 s-1
0.007 0.005
The case of Bd J/ Ks sin2
Systematics can be controlled with very high statistics using control samples such as B+ J/ K+
FPCP 2003 : 3-6 June 2003 Ecole Polytechnique, Paris
Status and Prospects of ATLAS and CMS for B Physics and CP Violation
Fairouz Ohlsson-MalekLPSC-Grenoble/IN2P3/ATLAS 11
Physics of Bs mesonsCP violation weak phase s= 2= 22
Bs oscillation parameterms
Precision ons ~ 8-12%, s
Benchmark channels:Bs J/ Bs Ds Bs Ds a1
ATLAS CMS
Proper time resolution
51 fs (60%)
107 fs (40%)
70 fs
ms 5 meas. up to
36 ps-1 30 ps-1
Measurable values up to ms
22.5 ps-1 26 ps-1
1 year @ 1033 cm-2 s-1
FPCP 2003 : 3-6 June 2003 Ecole Polytechnique, Paris
Status and Prospects of ATLAS and CMS for B Physics and CP Violation
Fairouz Ohlsson-MalekLPSC-Grenoble/IN2P3/ATLAS 12
Physics of Bs mesonsBs J/
BR(BsJ/ )=(9.3±3.3)x10-4
J/ℓ+ℓ- (BR≈6%), K+K (BR≈49%)
HLT mass resolutions HLT mass resolutions
= 22.4 = 22.4 MeVMeV
= 2.2 = 2.2 MeVMeV
= 46.5 = 46.5 MeVMeV
J/J/ BBss
CMS studies
Lvl-1 Lvl-1 Lvl-2 Lvl-2 Lvl-2 Rate Lvl-2 Rate Lvl-3 Lvl-3 Lvl-3 RateLvl-3 Rate Events/ 10fbEvents/ 10fb-1-1
16.5%16.5% 13.7%13.7% 14.5 Hz14.5 Hz 8.7%8.7% <1.7Hz<1.7Hz 8380083800
FPCP 2003 : 3-6 June 2003 Ecole Polytechnique, Paris
Status and Prospects of ATLAS and CMS for B Physics and CP Violation
Fairouz Ohlsson-MalekLPSC-Grenoble/IN2P3/ATLAS 13
Physics of Bs mesons
Benchmark channels:Bs J/ Bs J/
s= 2= 22SM predicts s ~O(0.03) New Physics
S/B >~1.
.30,33.0)(sin
.19,17.0)(sin
sM
sM
x
x
models some in %40 toup and %10 BSMCP
SMCP aa
Experimental lower limit
Theory:
ATLAS studies
Bs J/
FPCP 2003 : 3-6 June 2003 Ecole Polytechnique, Paris
Status and Prospects of ATLAS and CMS for B Physics and CP Violation
Fairouz Ohlsson-MalekLPSC-Grenoble/IN2P3/ATLAS 14
Potential for studying rare decays
FCNC bs or bd only at loop-level in SM Br < O(10-5)
B K* , B , B , B K* , ….
b s,d
W-
u,c,t
b s,d
?
Sensitive to new physics:New diagrams appearing :charged Higgs, chargino, squark contributions|Vtd| |Vts| in SMComplementary determination from ms
FPCP 2003 : 3-6 June 2003 Ecole Polytechnique, Paris
Status and Prospects of ATLAS and CMS for B Physics and CP Violation
Fairouz Ohlsson-MalekLPSC-Grenoble/IN2P3/ATLAS 15
Potential for studying rare decaysThe case of B K*
B K*
ATLAS 1995
CMS 4200
5% precision on AFB after 3 years @ low lumi
)cos(
0
1 )cos()cos(
1
0 )cos(
1)(
22
ddsd
dd
dsd
d
dsdsAFB
SM
MSSM C7 >0
MSSM C7 <0
Three points: mean values of AFB in three q2/MB
2 experimental regions with error bars
FPCP 2003 : 3-6 June 2003 Ecole Polytechnique, Paris
Status and Prospects of ATLAS and CMS for B Physics and CP Violation
Fairouz Ohlsson-MalekLPSC-Grenoble/IN2P3/ATLAS 16
Potential for studying rare decaysThe case of B
Mass resolution Mass resolution
HLTHLTFull Full
TrackerTracker
= 46 = 46 MeVMeV
= 74 = 74 MeVMeV
CMS studies for Bs
Offline analysis results Offline analysis results (hep-ph/9907256), (hep-ph/9907256), using SM BR=using SM BR=3.5x103.5x10-9-9
(Lvl-1 trigger in |(Lvl-1 trigger in ||<2.4 |<2.4 instead of |instead of ||< 2.1)|< 2.1)10 fb10 fb-1 -1 => 7 signal events => 7 signal events with <1 backgroundwith <1 background 55 observation with 30 fb observation with 30 fb-1-1
and analysis could be and analysis could be perfomed perfomed at high lumi tooat high lumi too
Bs Bd Background
ATLAS 92 14 660
CMS 26 4.1 < 6.4
1 year @1034 cm-2 s-1
FPCP 2003 : 3-6 June 2003 Ecole Polytechnique, Paris
Status and Prospects of ATLAS and CMS for B Physics and CP Violation
Fairouz Ohlsson-MalekLPSC-Grenoble/IN2P3/ATLAS 17
Potential for studying rare decaysexploring more difficult modes: Bd K*
ATLAS studies
S
B~ 19
Level 1: 6
Level 2: cluster candidate is selected if
Cluster Et > 4 GeV
0.5 strips cluster width 3.5 strips
Energy leakage in direction 9 %
Energy leakage in direction 9 %
Energy proportion of strips 2nd maximum 6%
2nd maximum physical meaning 1.5%
Shower shape
/0 rejection
Very preliminary
FPCP 2003 : 3-6 June 2003 Ecole Polytechnique, Paris
Status and Prospects of ATLAS and CMS for B Physics and CP Violation
Fairouz Ohlsson-MalekLPSC-Grenoble/IN2P3/ATLAS 18
B hadron production at LHC
QCD
Semihard
PYTHIA
CDF measurement of b-b correlation using - b-jet data and comparison to models
QCD - NLO describe the shape of differential cross section however underestimates absolute value of cross section by factor ~2.4
The case with Fermilab
FPCP 2003 : 3-6 June 2003 Ecole Polytechnique, Paris
Status and Prospects of ATLAS and CMS for B Physics and CP Violation
Fairouz Ohlsson-MalekLPSC-Grenoble/IN2P3/ATLAS 19
B hadron production at LHC
ATLAS - proposal for measurement of b-b production correlations using exlusive B-decay and semi leptonic decay to muon:
B Bd J/Ks0, B Bs J/
No degradation of efficiency as b-b close in space.
=J/ -
FPCP 2003 : 3-6 June 2003 Ecole Polytechnique, Paris
Status and Prospects of ATLAS and CMS for B Physics and CP Violation
Fairouz Ohlsson-MalekLPSC-Grenoble/IN2P3/ATLAS 20
Conclusions
General purpose central LHC detectors ATLAS and CMS are well equipped for multi thematic B-physics program - including B-decays and B-production.
1. In CP violation the main emphasis will be on underlying mechanisms and evidence of New physics. ATLAS and CMS are especially precise in measurement of . LHC ‘gold-plated’ mode is also Bs J/
2. Bs mixing studies make clear that there is sensitivity to ms far beyond SM expectations. The width difference s can be measured best in Bs J/ with relative precision 8%.
3. Rare decays B have the most favorable experimental signature allowing to measure also at nominal LHC luminosity 1034 cm-2 s-1. Will measure branching ration of Bs which is in SM of order Br<(10-9). Precision measurements will be done for B K*.
4. Beauty production and correlations at central LHC collisions will be measured for QCD tests. The program includes baryon production polarization
5. ATLAS and CMS beauty trigger strategies will be adapted according to luminosity conditions at initial LHC period.
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