1. CKM2006 at Nagoya University Dec. 14 th 2006 Makoto Tomoto Nagoya University on behalf of CMS and ATLAS collaborations Rare B decays in ATLAS and CMS

2. Makoto Tomoto (Nagoya University)CKM2006 at Nagoya Outline B physics in ATLAS and CMS ATLAS and CMS detectors B   b  X s  Conclusion

3. Makoto Tomoto (Nagoya University)CKM2006 at Nagoya B physics in ATLAS and CMS ATLAS and CMS –p-p collision at  s = 14TeV  (bb) = 500  b –B d B d : B + B - : B s B s : b-barions = 4:4:1:1 –10 5 bb pairs/s @ L=10 33 cm -2 s -1 “B-factory” as well as “New particle-factory” Detector design is dedicated to high-p T physics –Majority of B-events is low-p T particles Trigger and analysis are a challenge  B-decays to  ’s are promising Strategy on B-physics in ATLAS and CMS –CP violation (Low luminosity run) –B s oscillation (Low luminosity run) –Rare B decay (Even in High lumi.) (B   B  K* ,  b   )

4. Makoto Tomoto (Nagoya University)CKM2006 at Nagoya B      and b  sll –Sensitive to new physics SUSY etc. –FCNC transition Forbidden at tree diagram –SM: Br(b  sll) ~ 10 -6 ~ 10 -7 –|V ts | and |V td | determination –Wilson coefficient C 7, C 9, C 10 B  sll BsBs Br(B   ) B s   B d   SM3.5  10 -9 0.9  10 -10 CDF (780 pb -1 )1.0  10 -7 95%CL3.0  10 -7 95%CL DØ (700 pb -1 )2.0  10 -7 95%CL11.1  10 -7 95%CL Belle 78 fb -1 -1.6  10 -7 90% CL BaBar 111 fb -1 -0.6  10 -7 90% CL tan  =50 10 -9 10 -8 B d   B s   Belle : 1.33 +0.42 -0.37 ±0.10 x 10 -6 Br(B d  K*  ) measurements Babar : 0.86 ±0.16 x 10 -6 +0.79 -0.58 Rare B decays

5. Makoto Tomoto (Nagoya University)CKM2006 at Nagoya LHC ATLAS CMS 27Km ring, proton-proton collider,  s=14TeV 4 experiments in LHC LHCb dedicated B-physics ALICE dedicated heavy ion Two general purpose detectors: CMS and ATLAS Operation plan - End of 2007: 900 GeV commissioning run - After summer 2008: 14TeV, Low luminosity run (L = 10 33 cm -2 s -1 ) - Design: 14TeV, High luminosity run (L = 10 34 cm -2 s -1 ) LHC 27Km tunnel

6. Makoto Tomoto (Nagoya University)CKM2006 at Nagoya Detectors Compact Muon Solenoid A Toroidal LHC ApparatuS Total weight : 12500 T Overall diameter : 15.0 m Overall length : 21.5 m Magnetic Field : 4 Tesla Total weight : 7000 T Overall diameter : 22.0 m Overall length : 46.0 m Magnetic Field : 2 Tesla (solenoid) 0.5 Tesla (toroid)

7. Makoto Tomoto (Nagoya University)CKM2006 at Nagoya Inner Detectors To reconstruct vertex of B decays Used in HLT, better b-ID  Impact parameter significance  Di muon mass resolution ATLAS: Pixel, SCT, TRT in 2 T solenoid field CMS: Pixel, Silicon tracker in 4 T solenoid field

8. Makoto Tomoto (Nagoya University)CKM2006 at Nagoya p T - range for muons form B  IP resolution for ATLAS Final detector CMSATLAS  < 0.25 Tracker Performance Impact parameterM  Mass Resolution CMS ATLAS CMS pT>3-6GeV 50-90  m  =36MeV (4Tesla)  =84MeV (2Tesla) All  |  |<0.7 |  |>1.2 ATLAS pT>6GeV 25-70  m ||||||||

9. Makoto Tomoto (Nagoya University)CKM2006 at Nagoya Muon detectors For trigger and offline selection to get pure rare B-decay samples ATLAS: RPC (barrel) and TGC (endcap) for LVL1 trigger CSC and MDT for precise tracking in 0.5 T toroid field CMS: RPC (barrel) for LVL1 trigger CSC and DT for precise tracking in 2 T solenoid field

10. Makoto Tomoto (Nagoya University)CKM2006 at Nagoya Muon detectors ATLAS Barrel muon ATLAS Endcap muon CMS Endcap muon CMS Barrel muon ATLAS CMS Cosmic ray run with real muon detectors!

11. Makoto Tomoto (Nagoya University)CKM2006 at Nagoya ATLAS/CMS Trigger System <2.5  s ~10 ms ~1 s HLT ~1-2 kHz out ~100 Hz out Hardware Software 40MHz ~100kHz ~150Hz For rare B-decays, di-muon trigger is used Region of Interest (RoI ): HLT reconstruct b-decays using partial reconstruction in RoI around L1 muon

12. Makoto Tomoto (Nagoya University)CKM2006 at Nagoya 20GeV 6GeV ATLAS LVL1: Requiring di-  (6GeV), rate ~500Hz ATLAS LVL2: Confirm each m RoI from LVL1 Mass cut B   : 4 GeV < M(  )< 6 GeV ATLAS EF: Refit ID tracks in Level-2 RoI Decay vertex reconstruction Transverse Decay length cut: L xy > 200  m di-muon trigger p T >3GeV 1/2 single  di  rate ~900Hz p T (GeV) CMS HLT: Primary vertex reconstruction - use three most probable vertices Regional track reconstruction - partial reconstruction with ≤ 6hits - Pt > 4 GeV Track pairs - mass windows for signal - (un)like sign charge Vertex fit -  2 150  m CMS LVL1: LVL1: 2  RoI p T (  ) > 6GeV (~500 Hz @ L=10 33 cm -2 s -1 ) ATLAS Online di-  mass, (MeV) B  K *  +  - B   +  - Not normalized

13. Makoto Tomoto (Nagoya University)CKM2006 at Nagoya CMS offline analysis : B   22 COS  isolation l xy /  xy After selections … 6.1 events/10fb -1 v.s.  X background 13.8 +22.0 -13.8 l xy  p T (B s )  

14. Makoto Tomoto (Nagoya University)CKM2006 at Nagoya ATLAS offline analysis : B s   p T >6GeV, ΔR  <0.9 M  = M Bs +140 -70 MeV isolation: no charged tracks with p T > 0.8 GeV in cone  < 15 degrees vertex fit with pointing to primary vertex constraint transverse decay length L xy /  (L xy ) > 11 B 0 s signalBG (bb   X ) p T >6 GeV, ΔR  <0.950 events6.0×10 6 events M  cut0.772×10 -2 Isolation cut0.365×10 -2 L xy /  >11,  2 <15 0.4< 0.7×10 -4 All cuts720±20 Exected signal v.s. inclusive bb   X bkg L=10fb -1 (can be collected in a year) Br(Bs   ) = 3.5x10 -9

15. Makoto Tomoto (Nagoya University)CKM2006 at Nagoya Projected upper limits : B s   7 signals and 20 backgrounds can expect upper limit on Br(B s   ) Single experiment expects to reach the sensitivity of SM prediction 3 years of data taking : L=30fb -1 Still factor of ~10 above Both ATLAS and CMS has proven to continue measurement of B s   at nominal LHC luminosity 10 34 cm -2 s -1. This will mean 100 fb -1 just in one year. Tevatron projection ATLAS/CMS expectation

16. Makoto Tomoto (Nagoya University)CKM2006 at Nagoya Specific background study : B s   Number of events Fake events from B 0 d →π - μ + ν μ B 0 s →µ + µ - Number of events M µµ B +   l BG processBrEffective Br in B  μμ signal region B 0 → π - µ + ν µ ~10 -4 ~ 5 ∙ 10 -8 B + → µ + µ - ℓ + ν ℓ < 5 ∙10 -6 < 5 ∙10 -8 B c → µ + µ - ℓ + ν ℓ < 10 -4 < 10 -8 B 0 d → π 0 µ + µ - ~ 2 ∙ 10 - 8 ~ 10 -10 B 0 s → µ + µ - γ~ 2 ∙10 - 8 ~ 10 -10 B d → Kπ B s → KK2 ∙ 10 -5 < 10 -9 B 0 d →µ+ µ- Much high branching ratio compared to Br(B s   )=10 -9 Taking into account  /K   fake rate ~ 0.1-0.5% 2.soft phase space ~ 10% Generator level study Needs further study with full simulation

17. Makoto Tomoto (Nagoya University)CKM2006 at Nagoya b  X s  experimetal points simulated events with SM simulated events with positive MSSM C 7  eff BR used in the MC Signature after trigger + offline reconstruction 30 fb -1 Models used in MC or to confront experimental sensitivities. SignalBkg 1.3  10 -6 3.5  10 -7 1.0  10 -6 2.0  10 -6 B d → K 0*  B + →    B s →  Br.fraction  -mass A FB 2500 1500 900 <50000 <10000 Melikhov, Nikitin, Simula, PRD57,98; Melikhov, Stech, PRD62, 2000 WC: SM Buras, Munz, PRD52, 95; MSSM Cho, Misiak,Wyller, PRD54,96.  b →  800< 4000NP: Chen, Geng, PRD64,2001 Aliev NPB649,2003 ATLAS statistical error<5%  b mass  = 25%  = 21.5 MeV Mass (MeV) M. Biglietti et al. (ATLAS Coll.) Nucl. Phys B 156 (2006) B    Forward-backward Asymmetry (A FB )

18. Makoto Tomoto (Nagoya University)CKM2006 at Nagoya Conclusion ATLAS and CMS sensitivity to rare B-decay is expected to reach the level of SM prediction after 3 years of data taking –b   s and B   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 10 34 cm -2 s -1, ATLAS and CMS can make a measurement of B s ->  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 …

19. Makoto Tomoto (Nagoya University)CKM2006 at Nagoya Backup or Old slides

20. Makoto Tomoto (Nagoya University)CKM2006 at Nagoya Bobeth et. al., PRD66 074021 (2002) Rare B-decays B s   B d   SM3.5  10 -9 0.9  10 -10 CDF (780 pb-1)1.0  10 -7 95%CL3.0  10 -7 95%CL DØ (700 pb-1)2.0  10 -7 95%CL11.1  10 -7 95%CL Belle 78 fb-1-1.6  10 -7 90% CL BaBar 111 fb-1-0.6  10 -7 90% CL BsBs FCNC transition  Forbidden at tree level Br(b  sll) ~ 10 -6 ~ 10 -7 Br(B   ) ~ 10 -9 ~ 10 -10 Indirect search for new physics SUSY, Higgs etc For b  s  transitions |V ts | and |V td | determination Wilson coefficient C 7, C 9, C 10 tan  =50 B  sll 10 -9 10 -8 Belle : 1.33 +0.42 -0.37 ±0.10 x 10 -6 Br(B d  K*  ) Babar : 0.86 ±0.16 x 10 -6 +0.79 -0.58 B d   B s  