Penn CDF Group Overview & B Physics Activities Joseph Kroll

23 August 2004J. Kroll - Penn DOE review2 Contributions to the Experiment COT read out electronics and operation –includes dE/dx calibration – Eiko Yu (GS), Dave Ambrose (PD), Joel Heinrich (staff) –contributions to tracking software – Peter Wittich (PD) –Dave Ambrose is COT co-subproject leader –anticipate placing Aafke Kraan (PD) here TOF electronics and operation –includes extensive work on calibration, reconstruction, physics –Denys Usynin (GS) redid simulation and carries pager –Matthew Jones (PD) moved to tenure track faculty position at Purdue Calorimeter calibration electronics –Andrew Kovalev (GS) and Brig Williams

23 August 2004J. Kroll - Penn DOE review3 Contributions to the Experiment (cont) Trigger Level 2 decision crate upgrade – see talk –responsible for back-end of system including trigger decision –initial leadership from Peter Wittich –Daniel Whiteson (PD) & Kristian Hahn (GS) now driving back-end effort – help from Paul Keener (staff) here –Chris Neu (PD) shares responsibility for reCES part of system Trigger system –P. Wittich L2 software coordinator & then trigger subproject co-leader On-line beam profile monitoring with SVT – see talk –Chris Neu working with Luciano Ristori (CDF co-spokesperson)

23 August 2004J. Kroll - Penn DOE review4 Contributions to the Experiment (cont) Leadership in operations –Nigel Lockyer was operations department co-head from –D. Ambrose & M. Jones served 6 month terms as operations managers –P. Wittich was Trigger subproject co-leader –M. Jones is TOF subproject co-leader –D. Ambrose is COT subproject co-leader –Evelyn Thomson chaired the Run IIb XFT upgrade review –aside: all post-docs and grad. students serving as ACEs. Penn Group has made major contributions to operations of the experiment.

23 August 2004J. Kroll - Penn DOE review5 Physics CDF physics effort organized in 5 groups –top, electroweak, exotics, bottom, & QCD Penn CDF group involved in several key areas: –top physics – dilepton & lepton + jets channels cross section analysis mass measurement study of top decays for new physics –Electroweak physics WW production measurement –Exotic physics SUSY searches with dileptons –B physics B s flavor oscillations  b branching fractions

23 August 2004J. Kroll - Penn DOE review6 Physics (continued) Leadership roles –Nigel Lockyer was co-spokesperson from June’02 to June’04 –Evelyn Thomson is top group co-convener –Dave Ambrose co-led the Jet Simulation Task Force –Daniel Whiteson is Monte Carlo coordinator for the top group –Peter Wittich is Exotics group SUSY subgroup co-convener –Joseph Kroll is Mixing Analysis co-coordinator for the B group –J. Kroll was co-chair of the Higgs Sensitivity Committee –Joel Heinrich is a member of the CDF statistics committee –We are chairs of several godparent committees (internal review committees for publications)

23 August 2004J. Kroll - Penn DOE review7 Physics Publications The Penn CDF group has been the primary author or has made major contributions to several Run II publications: Charm meson production cross-section: 1 st Tevatron Run II PRL (published) top cross-section from dilepton events: 1 st CDF high p T paper (accepted by PRL) top cross-section lepton + jets with kinematics: PRD in preparation WW cross-section: PRL in preparation

23 August 2004J. Kroll - Penn DOE review8 The Beauty Unitary Triangle  of Chau & Keung parametrization is 

23 August 2004J. Kroll - Penn DOE review9 Neutral B Meson Flavor Oscillations Flavor oscillations occur through 2 nd order weak interactions e.g. Same diagrams and formula for  m s for B s except replace “d” with “s” All factors known well except “bag factor” £ “decay constant”  m d = § ps -1 (2%) (PDG 2002) from Lattice QCD calculations – see hep-ph/ From measurement of  m d derive |V * tb V td | 2

23 August 2004J. Kroll - Penn DOE review10 B Meson Flavor Oscillations (cont) If we measure  m s then we would know the ratio  m s /  m d Many theoretical quantities cancel in this ratio, we are left with from Lattice QCD calculations – see hep-ph/ Since V ts ¼ V cb this gives us our side R t This is why  m s is high priority in Run II

23 August 2004J. Kroll - Penn DOE review11 Experimental Steps for Measuring B s Mixing 1. Extract B 0 s signal – decay mode must identify b-flavor at decay (TTT) Examples: 2. Measure decay time (t) in B rest frame (L = distance travelled) (L00) 3. Determine b-flavor at production “flavor tagging” (TOF) “unmixed” means production and decay flavor are the same “mixed” means flavor at production opposite flavor at decay Flavor tag quantified by dilution D = 1 – 2w, w = mistag probability

23 August 2004J. Kroll - Penn DOE review12 Measuring B s Mixing (cont.) 4. Measure asymmetry these formulas assume perfect resolution for t Asymmetry is conceptual: actually perform likelihood fit to expected “unmixed” and “mixed” distributions Measure  m d to validate procedure

23 August 2004J. Kroll - Penn DOE review13 B Flavor Tagging We quantify performance with efficiency  and dilution D  = fraction of signal with flavor tag D = 1-2w, w = probability that tag is incorrect (mistag) Statistical error  A on asymmetry A (N is number of signal) statistical error scales with  D 2

23 August 2004J. Kroll - Penn DOE review14 Two Types of Flavor Tags Opposite side Same sideBased on fragmentation tracks or B ** + Applicable to both B 0 and B 0 s − other b not always in the acceptance − Results for B + and B 0 not applicable to B 0 s + better acceptance for frag. tracks than opp. side b Reminder: for limit on  m s must know D Produce bb pairs: find 2 nd b, determine flavor, infer flavor of 1 st b

23 August 2004J. Kroll - Penn DOE review15 Same Side Flavor Tags Based on correlation between charge of fragmentation particle and flavor of b in B meson Decay of P-wave mesons B ** also contributes to B 0, B + (not B 0 s ) Expected correlations different for B +, B 0, B 0 s TOF

23 August 2004J. Kroll - Penn DOE review16 Penn Contribution to CDF B Mixing Effort We are focusing our activities in 2 areas B flavor identification –developed 1 st Run II flavor tag (opposite side muons from b !  ) –required understanding sample composition of “lepton+SVT” data, used by all members of the B group studying opposite side flavor tags –currently pursuing understanding same-side kaon tagging –1 st step is to measure rate of kaons around B +, B 0, B 0 s (thesis of D.Usynin) – using both dE/dx and TOF for kaon identification –crucial for reliable prediction of dilution – need for limit on  m s B Mixing coordination expect Aart Heijboer to join this analysis effort

23 August 2004J. Kroll - Penn DOE review17 Soft Muon B Flavor Tag Based on b !  of  2 nd B hadron B  p T rel Larger p T rel increases b !  suppresses b ! c ! , fakes

23 August 2004J. Kroll - Penn DOE review18  K p Measure Kaon Multiplicity around B’s Example: B s ! D s  candidates dE/dxTOF  K p Can we see a difference in K multiplicity around B 0, B +, B 0 s ?

23 August 2004J. Kroll - Penn DOE review19 Need Reliable Simulation of TOF Example: TOF resolution – agreement between data and MC DataMC

23 August 2004J. Kroll - Penn DOE review20 B Baryon Branching Fractions Compare semileptonic rates to hadronic rates for  b At present Tevatron is the unique accelerator to study B Baryons Current World average  b lifetime lower than expected vs. Use same trigger (two track hadronic) to cancel trigger efficiencies Check with topologically similar B meson decays Thesis: Shin Shan Yu

23 August 2004J. Kroll - Penn DOE review21 B Baryon Signals Semileptonic decay modeHadronic decay mode  c signal Unknown B baryon production fraction cancels in ratio  B ! D  ) =  b !  c  )  can determine absolute BFs