We report on the prospective study of the rare B decays in ATLAS and CMS experiments, which will start from the end of 2007. In this talk, we focus on the study of the B to di-muon and b to s plus dimuon transition, which are sensitive to the new physics

Makoto Tomoto, Nagoya University

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Rare B decays in ATLAS and CMSCKM2006 at Nagoya UniversityDec. 14th 2006Makoto TomotoNagoya Universityon behalf of CMS and ATLAS collaborationsMakoto Tomoto (Nagoya University) CKM2006 at NagoyaOutlineB physics in ATLAS and CMSATLAS and CMS detectorsB?µµB?XµµConclusionMakoto Tomoto (Nagoya University) CKM2006 at NagoyaB physics in ATLAS and CMS• ATLAS and CMS – p-p collision at √s = 14TeV• σ(bb) = 500 µb– BdBd : B+B- : BsBs : b-barions = 4:4:1:1– 105 bb pairs/s  @ L=1033 cm-2s-1• “B-factory” as well as “New particle-factory”• Detector design is dedicated high-pTphysics– Majority of B-events is low-pTparticles• Trigger and analysis are a challenge? B-decays to µ’s are promising• Strategy on B-physics in ATLAS and CMS– CP violation (Low luminosity run)– Bs oscillation (Low luminosity run)– Rare B decay (Even in High lumi.)(B?µµ, B?K*µµ, Λb?Λµµ)Makoto Tomoto (Nagoya University) CKM2006 at Nagoya• B?µ+µ− and b?sll– Sensitive to new physics• SUSY, Higgs etc.– FCNC transition• Forbidden at tree diagram– SM: Br(b?sll) ~ 10-6 ~ 10-7– |Vts| and |Vtd| determination– Wilson coefficient C7, C9, C10B?sllBs?µ+µ−Br(B?µµ) Bs → µµ Bd → µµSM 3.5×10-9 0.9×10-103.0×10-7 95%CL11.1×10-7 95%CL1.6×10-7 90% CL0.6×10-7 90% CLCDF (780 pb-1) 1.0×10-7 95%CL DØ (700 pb-1) 2.0×10-7 95%CL Belle 78 fb-1 -BaBar 111 fb-1 -tanβ=5010-910-8Bd?µµBs?µµBelle  : 1.33 +0.42-0.37 ?0.10 x 10-6Br(Bd?K*µµ) measurementsBabar : 0.86 ?0.16 x 10-6+0.79-0.58Rare B decaysMakoto Tomoto (Nagoya University) CKM2006 at NagoyaLHCATLASCMSLHC 27Km tunnel• 27Km ring, proton-proton collider, √s=14TeV• 4 experiments in LHCLHCb dedicated  B-physicsALICE dedicated heavy ion Two general purpose detectors: CMS and ATLAS• Operation plan- End of 2007:900 GeVcommissioning run- After summer 2008:14TeV, Low luminosity run(L = 1033cm-2s-1)- Design:14TeV, High luminosity run(L = 1034cm-2s-1)DetectorsMakoto Tomoto (Nagoya University) CKM2006 at NagoyaCompact Muon Solenoid A Toroidal LHC ApparatuSTotal weight        : 12500 TOverall diameter : 15.0 m Overall length     : 21.5 mMagnetic Field    : 4 TeslaTotal weight        : 7000 TOverall diameter : 22.0 m Overall length     : 46.0 mMagnetic Field    : 2 Tesla (solenoid)0.5 Tesla (toroid)Inner DetectorsTo reconstruct vertex of B decaysUsed in HLT, better ID of B events? Impact parameter significanceATLAS:Pixel, SCT, TRT in 2 T solenoid fieldMakoto Tomoto (Nagoya University) CKM2006 at NagoyaCMS:Pixel, Silicon tracker in 4 T solenoid fieldMakoto Tomoto (Nagoya University) CKM2006 at NagoyaImpact Parameter Resolution0501001502002501 10 10 2pT (GeV)σ(d0) (µm)Impact par resol Final Detector LayoutImpact par resol TDR Detector Layout B-decay tracks in Bs-DsπB-decay trakcs in B-µµpT- range for muonsform B →µµIP resolution for ATLAS Final detectorCMS ATLASη< 0.25Impact parameter Mµµ Mass ResolutionCMSATLASATLAS pT>6GeV 25-70µmCMS pT>3-6GeV 50-90µm σ=36MeV(4Tesla)σ=84MeV(2Tesla)All η|η|<0.7|η|>1.2Muon detectorsFor trigger and offline selection to get pure rare B-decay samples Makoto Tomoto (Nagoya University) CKM2006 at NagoyaATLAS:• RPC (barrel) and TGC (endcap)for LVL1 trigger• CSC and MDT for precisetracking in 0.5 T toroid fieldCMS:• RPC (barrel) for LVL1 trigger• CSC and DT for precise tracking in 2 T solenoid fieldlow pThigh pT5 10 15 m0RPC 3RPC 2RPC 1low pThigh pTMDTMDTMDTMDTTGC 1TGC 2TGC 3MDTMDTTGC EITGC FIXX-LL01V04Tile CalorimeterMakoto Tomoto (Nagoya University) CKM2006 at NagoyaMuon detectorsATLAS Barrel muonATLAS Endcap muonCMS Endcap muonCMS Barrel muonATLAS CMSCosmic ray run with real muon detectors!ATLAS/CMS Trigger System<2.5 µs~10 ms~1 sHLT~1-2 kHz out~100 Hz outHardwareSoftware40MHz~100kHz~150HzFor rare B-decays, di-muon trigger is used Region of Interest (RoI ):HLT reconstruct b-decays using partial reconstructionin RoI around L1 muonMakoto Tomoto (Nagoya University) CKM2006 at NagoyaMakoto Tomoto (Nagoya University) CKM2006 at Nagoya10GeV6GeVATLAS LVL2:Confirm each m RoI from LVL1Mass cut   B?µµ : 4 GeV < M(µµ)< 6 GeVATLAS EF:Refit ID tracks in Level-2 RoIDecay vertex reconstructionTransverse Decay length cut:Lxy > 200µmdi-muon triggerATLAS LVL1: CMS LVL1:LVL1: 2µ RoIpT (µ) > 6GeV(~500 Hz @ L=1033cm-2s-1) ATLASOnline di-µ mass, (MeV)B? K* µ+ µ-B?µ+ µ-Not  normalizedpT>3GeV1/2singleµ diµpT (GeV)CMS HLT:Primary vertex reconstruction- use three most probable verticesRegional track reconstruction- partial reconstruction with ≤ 6hits- Pt > 4 GeVTrack pairs- mass windows for signal - (un)like sign chargeVertex fit- χ2 <20 & Decay flight length > 150µmMakoto Tomoto (Nagoya University) CKM2006 at NagoyaCMS offline analysis : B?µµχ2COSαisolationlxy/σxyATLAS offline analysis : Bs?µµMakoto Tomoto (Nagoya University) CKM2006 at Nagoya• Mmm = MBs+140-70 MeV • isolation: no charged tracks with pT > 0.8 GeV in cone θ < 15 degrees• vertex fit with pointing to primary vertex constraint• transverse decay length Lxy/s(Lxy) > 11B0s signal BG (bb?µµX)pT>6 GeV, ?Rµµ<0.9 50 events 6.0?106 eventsMµµcut 0.77 2?10-2Isolation cut 0.36 5?10-2Lxy/σ>11, χ2<15 0.4 < 0.7?10-4All cuts 7 20?20Exected signal v.s. inclusive bb?µµX bkgProjected upper limits : Bs?µµMakoto Tomoto (Nagoya University) CKM2006 at Nagoya( ) ( )totalBsbgsnnNBBr αεσµµ ?2,0 ≤→ −+7 signals and 20 backgrounds can expect upper limit on Br(Bs?µµ)• Single experiment expects to reachthe sensitivity of SM prediction3 years of data taking : L=30fb-1Still factor of 10 aboveBoth ATLAS and CMS has proven to continue measurement of  Bs?µµ at nominal LHC luminosity 1034. This will mean 100 fb-1 just in one year.Tevatron projectionATLAS/CMS expectationMakoto Tomoto (Nagoya University) CKM2006 at NagoyaSpecific background study : Bs?µµNumber of eventsFake events from B0d?? -?+??B0s?µ+ µ-Number of eventsMµµ µµB+?µµlνBG process Br Effective Br in B??? signal region~10-4 ~ 5 ? 10-8< 5 ?10-8< 10-8~ 10-10~ 10-10< 10-9B+ ? µ+µ- ?+?? < 5 ?10-6Bd? K? Bs ?KK 2 ? 10-5< 10-4~ 2 ? 10-8~ 2  ?10-8B0 ?? - µ+ ?µBc? µ+µ- ?+??B0d??0 µ+µ-B0s?µ+ µ-?B0d?µ+ µ-Much high branching ratiocompared to Br(Bs?µµ)=10-9Taking into account1. π/K?µ fake rate ~ 0.1-0.5%2. soft ν phase space ~ 10%Generator level studyNeeds further study with full simulationMakoto Tomoto (Nagoya University) CKM2006 at NagoyaB?Xµµexperimetal points <AFB>simulated events with SMsimulated events withpositive MSSM C7γeffSignature after trigger + offline reconstruction 30 fb-1BR used in the MCModels used in MC or to confront experimental sensitivities.Signal BkgBd?K0*µµB+?Κ+ µµBs ? φ µµ25001500 900 800<50000<10000<10000Melikhov, Nikitin, Simula, PRD57,98; Melikhov, Stech, PRD62, 2000 WC: SM Buras, Munz, PRD52, 95;MSSM Cho, Misiak,Wyller, PRD54,96.Λb? ΛµµBr.fractionµµ-massAFB< 40001.3 ×10-63.5 ×10-71.0 ×10-62.0 ×10-6 NP: Chen, Geng, PRD64,2001 Aliev NPB649,2003ATLAS statistical error<5%Entries  58025RMS     42.42    1N  1252± 1.634e+004   1µ 0.1±  5638  1σ  0.53± 14.47     2N  1148± 3.774e+004  2σ  0.73± 34.73 Mass, (MeV)5450 5500 5550 5600 5650 5700 5750 5800 5850Events0500100015002000250030003500 mass bΛ Λb massε = 25% σ= 21.5 MeVMass (MeV)M. Bigli tti et al. (ATLA  Coll.) Nucl. Phys B 156 (2006)B Λµ+µ−Forward-backward Asymmetry (AFB)Makoto Tomoto (Nagoya University) CKM2006 at NagoyaConclusion• ATLAS and CMS sensitivity to rare B-decay is expected to reach the level of SM prediction after 3 years of data taking– b?µµs and B?µµ promising for new physics– We will directly and indirectly be able to search for new physics at the same place and time• At LHC nominal luminosity 1034cm-2s-1, ATLAS and CMS can make a measurement of Bs->µµ branching ratio just after one year. • More study using full simulation/reconstruction is under way• The installation and commissioning of the detectors are in good progress• Everyone is waiting for the data taking …Makoto Tomoto (Nagoya University) CKM2006 at NagoyaBackup or Old slidesMakoto Tomoto (Nagoya University) CKM2006 at NagoyaBobeth et. al., PRD66 074021 (2002)          Rare B-decaysBs → µµ Bd → µµSM 3.5×10-9 0.9×10-103.0×10-7 95%CL11.1×10-7 95%CL1.6×10-7 90% CL0.6×10-7 90% CLCDF (780 pb-1) 1.0×10-7 95%CL DØ (700 pb-1) 2.0×10-7 95%CL Belle 78 fb-1 -BaBar 111 fb-1 -Bs?µ+µ−FCNC transition?Forbidden at tree levelBr(b?sll) ~ 10-6 ~ 10-7Br(B?µµ) ~ 10-9 ~ 10-10Indirect search for new physicsSUSY, Higgs etcFor b?sµµ transitions|Vts| and |Vtd| determinationWilson coefficient C7, C9, C10tanβ=50B?sll10-910-8Belle   : 1.33 +0.42-0.37?0.10 x 10-6Br(Bd?K*µµ)Babar : 0.86 ?0.16 x 10-6+0.79-0.58Bd?µµBs?µµ

Rare B decays in ATLAS and CMS

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