7/7/06Jason Rieger BEACH 2006 Rare B Decays at the Tevatron Jason Rieger, Indiana University On behalf of the DØ and CDF collaborations BEACH 2006

7/7/06Jason Rieger BEACH 2006 A Myriad of Rare Decays Those which require large data sets –Measurement of Br(B s  D s1 (2536)  X) at D  Those which are Cabibo suppressed –Br(B  D K)/Br(B  D π) at CDF FCNC at the Tevatron, still room for factor 10+ SUSY effects –B s   +  -

7/7/06Jason Rieger BEACH 2006 The DØ Detector 2 Tesla Magnetic Field Excellent Coverage –Muon system: |  |<2 –Tracking System: |  |<3 Robust Muon triggers High semi-leptonic yields

7/7/06Jason Rieger BEACH 2006 The CDF Detector New Silicon vertex detecor –Inner layer at 1.35 cm New central tracker –Excellent mass resolution Extended  coverage TOF and dE/dx particle ID Second level impact parameter trigger –Allows all hadronic B decay triggers

7/7/06Jason Rieger BEACH 2006 Medium Rare Br(B s  D s1 (2536)  X) Important for testing HQET –Semileptonic decay to heavy excited state, mostly in phase space close to zero recoil, where most of the correction action is! The B 0 s  D s1 (2536)  is a significant fraction of B 0 s semileptonic decays making it important for: –Comparing inclusive/exclusive decay rates –Extracting CKM matrix elements –Using semileptonic decays in B 0 s mixing More info on D s ** doublets

7/7/06Jason Rieger BEACH 2006 B s  D s1 (2536)  X Decay K K  It all Starts Here! BsBs D s **  D*KsD*Ks +-+- D 0  our guy of interest

7/7/06Jason Rieger BEACH 2006 Data Sample and Signal D* Candidates 82130±463 D* Candidates D s ** Candidates 43.8±8.3 D s ** signal events ~5  significance DØ RunII Preliminary

7/7/06Jason Rieger BEACH 2006 The Measurement Normalize to the known branching ratio: We can use the equation Giving a final result of First Measurement!!!

7/7/06Jason Rieger BEACH 2006 Comparison With Theory Using And assuming Br(D s1 (2536)  D * K s 0 )=0.25 –D s1 (2536) decays half the time into D * K 0 by isospin arguments –K 0 decays half the time in K s 0 We get the following Source Br(B s 0  D s1 (2536)  X This Result(0.86±0.16(stat)±0.13(syst)±0.09(prod.frac))% ISGW20.53% RQM0.39% HQET & QCD sum rules0.195% H.B. Mayorga,A.Moreno Briceno and J.H.Munoz J.Phys G 29(2003) 2059 from PDG

7/7/06Jason Rieger BEACH 2006 Rare Br(B  DK)/Br(B  D  ) Can use partial widths of B  D 0 K to Obtain measurement of Belle, Babar and CLEO have advanced measurements in this channel Before the Tevatron can contribute with the B s channel we first have to understand B + This is the Tevatron’s first step in the measurement of gamma See talk by A. Garmash for a more detailed discussion

7/7/06Jason Rieger BEACH 2006 The Data Sample Use : – small kinematic differences between modes –Particle ID (dE/dx) to differentiate between the two modes Calibrate dE/dx using sample of kaons and pions from : –D *  D 0  K  –1.5 sigma separation Unbinned Likelihood fit was used, combining kinematic information & dE/dx

7/7/06Jason Rieger BEACH 2006 Br(B  DK)/Br(B  D  ) results World Average for this measurement: –0.0830± Coming from combined results of Belle, Babar and Cleo Br(B  DK)/Br(B  D  ) = 0.065±0.007 (stat.)±0.004(syst.) Mass fit projection PID fit projection

7/7/06Jason Rieger BEACH 2006 (Very) Rare Flavor Changing Neutral Currents FCNC’s are forbidden at tree level. B  l + l - decays are also helicity supressed Standard Model –BR(B s  +  - )~3.4 x10 -9 –Depends only on one SM operator in effective Hamiltonian, –hadronic uncertainties are small

7/7/06Jason Rieger BEACH 2006 New Physics in Flavor Physics? b  s penguins –b  s , b  s l + l -, b  s sbar rate, and asymmetry measurements at Belle, Babar, and Cleo are all consistent with theory B  –Measured at Belle and again, consistent with theory B s mixing –First double-sided limit by D  limited hope for new physics, the later measurement by CDF confirmed that  m s within theory errors, no new physics there All great measurements, but…

7/7/06Jason Rieger BEACH 2006 Annihilation Topologies Initial state: –q=s better than q=d since V ts >>V td : factor ~40 gain Final state : –Rate proportional to m l 2 –l=  versus l=e : factor ~40000 gain –l=  versus l=  : factor ~200 gain b q l+l+ V tq Internal SM is the same regardless of q or l l-l- Much harder to do experimentally This is why we use B s  +  -

7/7/06Jason Rieger BEACH 2006 Annihilation Topologies Pick up several powers of tan , once you introduce SUSY Higgs M. Carena et al. hep-ph/

7/7/06Jason Rieger BEACH 2006 Annihilation Topologies Pick up several powers of tan , once you introduce SUSY Higgs M. Carena et al. hep-ph/ Given agreement between Tevatron  m s and CKM fit on order of 5 ps -1 B s  +  - still unbounded!

7/7/06Jason Rieger BEACH 2006 B s  +  - analysis variables used Isolation Fraction of momentum in jet carried by B meson Expect majority of momentum from b to be carried by B s meson Pointing angle Angle between dimuon momentum vector and decay length vector Angle should be small between these two vectors Decay Length Significance Since the B meson has lifetime one can require decay length to be greater than error on decay length

7/7/06Jason Rieger BEACH 2006 B   +  - experimental search CDF –780 pb -1 di-muon triggered data –Two separate seach channels central/central muons central/forward muons –Extract B s & B d limit D  –300 pb -1 di-muon triggered data –Study done for sensitivity out to 700 pb -1 –B d & B s overlap Both Experiments Blind analysis Side bands for background determination Use B +  J/  K + as normalization mode

7/7/06Jason Rieger BEACH 2006 Normalization Normalization done to B  J/  K + Advantages: –  +  - selection efficiency the same –High statistics –Well known branching ratio Disadvantages: –b  B s and b  B d fragmentations both needed

7/7/06Jason Rieger BEACH 2006 B  +  - Cut Optimization at D  Optimize cuts on three Discriminating variables: Pointing angle Decay length significance Isolation

7/7/06Jason Rieger BEACH 2006 B  +  - Cut Optimization at CDF Discriminating Variables Pointing Angle Proper Decay Length Isolation

7/7/06Jason Rieger BEACH 2006 B s  +  - at D  D  waiting for full RunIIa dataset to open the box Preliminary sensitivity for 700pb -1 : 2.3x10 -7 Expect 2.2 ±0.7 background events

7/7/06Jason Rieger BEACH 2006 Latest B s  +  - Results Effect of old ~0.4fb -1 Tev. Limit on a favorable corner Of parameter space Minimal SO(10)

7/7/06Jason Rieger BEACH 2006 Latest B s  +  - Results One less corner of Parameter space! Minimal SO(10) BF(B s  +  - ) < 1x10 95% CL

7/7/06Jason Rieger BEACH 2006 Conclusions B physics at the Tevatron is great for exploring many different types of rare decays B s  +  - remains the best current probe for SUSY effects in B physics –One of the last places to find order 10 SUSY effects!