12/15/06 B. Casey 1  s and  s at the Tevatron Gernot Weber Mainz University On behalf of Brendan Casey Brown University and the DØ and CDF collaborations CKM workshop, December Nagoya, Japan

12/15/06 B. Casey 2 Mixing in the B s System Time Evolution of neutral B mesons Three observables:  m   : dominated by b→ccs decays so don’t expect new physics Interesting because it defines the phenomenology and experimental program. Order 10%  → CPV studies without tagging b c c s  s : small in SM but succeptible to new physics phase in the B s mixing box diagrams ? BsBs BsBs

12/15/06 B. Casey 3 B physics at the Tevatron Large cross sections, all hadrons Many strengths to both but most important features: –DØ: muon system. CDF: displaced track trigger. Explore regions of parameter space inaccessible to B factories The secret to CDF The secret to DØ

12/15/06 B. Casey 4Signatures Flavor specific B s lifetime in D s  –CDF and DØ   s = 0 & pure CPB s →D s ( * ) D s ( * )   so far assuming  s = 0 & pure CP  –DØ: (  )(  ). CDF: (  )(  )   s = 0 CDF  L (B s →K + K    so far assuming  s = 0    sDØ Integrated semileptonic asymmetries   s –inclusive like-sign dimuons, exclusive D s  ±  and  sB s → J/  and  s –CDF: first measurement,  s set to zero –DØ: first measurement with  s as a free parameter

12/15/06 B. Casey 5 B s →D s  Lifetime PRL 97, (2006) Flavor specific decays carry equal amounts of B H and B L

12/15/06 B. Casey 6 B s →D s ( * ) D s ( * ) Current assumption: ~all CP even  saturates  –Can be verified with more data. DØ: partial reconstruction D s →  D s →  –Includes D s * →D s  direct measure of  CDF: full reconstruction 2×D s →  –Doesn’t include D s *, lower limit on  Both: error (and central value) dominated by D s →  BF

12/15/06 B. Casey 7 B s →D s ( * ) D s ( * )    

12/15/06 B. Casey 8 B s →K + K  Most straight forward measurement –Pure CP final state –Analog of K S →     –No CPV: direct measure of  L –Future: any indication of K + K  on  H path  unambiguous CPV Straight forward to understand, hard to do. –Large and complicated h + h  sample –Lifetime biasing trigger Possible at CDF due to displaced track trigger

12/15/06 B. Casey 9 B s →K + K   m(m( cc

12/15/06 B. Casey 10 A SL Measurements BsBs  DsDs  BsBs Direct measure of indirect CPV in B s mixing BsBs  DsDs  BsBs B  B  ↕ this versus this ↕ Two samples Exclusive untagged D s  Inclusive like-sign 

12/15/06 B. Casey 11 Main Systematics Detector related asymmetries: –Main asymmetry due to spectrometer geometry –Controlled by looking at charge asymmetry for different magnet polarities and different  regions. Kaon decay in flight: –Asymmetric due to hadronic interactions –Measured directly in data using kaons tagged from D* decay

12/15/06 B. Casey 12 A SL Results Inclusive dimuon Exclusive D s  m(  )        pol  pol Using WA A SL (B d ):

12/15/06 B. Casey 13 B s →J/   Analog to B 0 →J/  K S but VV instead of VP BsBs J/   S,D waves P wave J/   odd even

12/15/06 B. Casey 14 B s →J/   Time evolution: pure even case

12/15/06 B. Casey 15 B s →J/   Time evolution: even plus odd components CP conserving interference CP states = heavy, light states

12/15/06 B. Casey 16 B s →J/   Time evolution: even plus odd plus CPV CP conserving interference Heavy and light states are mixed CP CP violating interference between two paths

12/15/06 B. Casey 17 B s →J/   Time evolution: even plus odd plus CPV CP conserving interference Heavy and light states are mixed CP CP violating interference between two paths Same as seeing K L →    

12/15/06 B. Casey 18 B s →J/   Results Light Heavy

12/15/06 B. Casey 19 B s →J/   Results odd even DØ:

12/15/06 B. Casey 20  Results (Only DØ J/   allows  s ≠0 in his plot)   ps   Average  SM calculation (K+K-(K+K- BF(D s ( * ) D s ( * ) ) (Ds(Ds J/  

12/15/06 B. Casey 21  s Results   ps   ss

12/15/06 B. Casey 22Conclusions Now have information on all B s mixing parameters from the Tevatron experiments. –Very diverse program giving consistent results:  m s consistent with SM/CKM expectations  consistent with SM calculations Interesting  s parameter space accessible at the Tevatron Excellent example of the complementary aspects of the DØ and CDF programs Expect rapid improvements in precision on  s –Doubling data set –Results from both experiments based on full data set –New modes and new techniques

12/15/06 B. Casey 23Backup

12/15/06 B. Casey 24 B s →K + K  More details: –K + K  is always CP even –No indirect CPV: even state = light state –Also need to worry about direct CPV in the b→u tree Tree pollution complicates the translation to 

12/15/06 B. Casey 25 Detector Systematics Main detector related systematic is due to geometry in muon spectrometer One charge preferentially goes into gaps at edge of spectrometer

12/15/06 B. Casey 26 Detector Systematics Main detector related systematic is due to geometry in muon spectrometer One charge preferentially goes into gaps at edge of spectrometer Solve by flipping toroid polarity regularly and analyzing forward and backward data separately

12/15/06 B. Casey 27 Physics Systematics: Kaon Decay IP silicon fiber tracker solenoid uranium calorimeter muon chambers toroid Transverse flight path

12/15/06 B. Casey 28 Physics Systematics: Kaon Decay IP silicon fiber tracker solenoid uranium calorimeter muon chambers toroid Transverse flight path K  produce    from weak decay     

12/15/06 B. Casey 29 Physics Systematics: Kaon Decay IP silicon fiber tracker solenoid uranium calorimeter muon chambers toroid Transverse flight path K  produce    from weak decay K  stop more frequently in calorimeter from K  + N →Y +  nuclear interactions. (No K + analog)       

12/15/06 B. Casey 30 Physics Systematics: Kaon Decay IP silicon fiber tracker solenoid uranium calorimeter muon chambers toroid Transverse flight path K  produce    from weak decay K  stop more frequently in calorimeter from K  + N →Y +  nuclear interactions. (No K + analog)        Measured directly in data using kaons tagged from D* decay