Penn CDF Group Overview & B Physics Activities Joseph Kroll.

Penn CDF Group Overview & B Physics Activities

Joseph Kroll

23 August 2004 J. Kroll - Penn DOE review 2

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


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)


Contributions to the Experiment (cont)

• Leadership in operations– Nigel Lockyer was operations department co-head from 2000-2002

– 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.


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• Bs flavor oscillations• b branching fractions


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)


Physics Publications

The Penn CDF group has been the primary author or has mademajor contributions to several Run II publications:

Charm meson production cross-section: 1st Tevatron Run II PRL (published)

top cross-section from dilepton events: 1st CDF high pT paper (accepted by PRL)

top cross-section lepton + jets with kinematics: PRD in preparation

WW cross-section: PRL in preparation


The Beauty Unitary Triangle

of Chau & Keungparametrization is


Neutral B Meson Flavor Oscillations

Flavor oscillations occur through2nd order weak interactions

e.g.

Same diagrams and formula for ms for Bs except replace “d” with “s”

All factors known well except “bag factor” £ “decay constant”

md = 0.489 § 0.008 ps-1 (2%) (PDG 2002) from Lattice QCD calculations – see hep-ph/0406184

From measurement of md derive |V*tbVtd|2


B Meson Flavor Oscillations (cont)

If we measure ms then we would know the ratio ms/md

Many theoretical quantities cancel in this ratio, we are left with

from Lattice QCD calculations – see hep-ph/0406184

Since Vts ¼ Vcb this gives us our side Rt

This is why ms ishigh priority in Run II


Experimental Steps for Measuring Bs Mixing

1. Extract B0s 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


Measuring Bs 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 md

to validate procedure


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 D2


Two Types of Flavor Tags

Opposite side

Same side Based on fragmentation tracks or B**

+ Applicable to both B0 and B0s

− other b not always in the acceptance

− Results for B+ and B0 not applicable to B0s

+ better acceptance for frag. tracks than opp. side b

Reminder: for limit on ms must know D

Produce bb pairs: find 2nd b, determine flavor,infer flavor of 1st b


Same Side Flavor Tags

Based on correlation betweencharge of fragmentation particleand flavor of b in B meson

Decay of P-wave mesonsB** also contributesto B0, B+ (not B0

s)

Expected correlationsdifferent for B+, B0, B0

sTOF


Penn Contribution to CDF B Mixing Effort

• We are focusing our activities in 2 areas

• B flavor identification– developed 1st 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

– 1st step is to measure rate of kaons around B+, B0, B0s (thesis of

D.Usynin) – using both dE/dx and TOF for kaon identification

– crucial for reliable prediction of dilution – need for limit on ms

• B Mixing coordination

• expect Aart Heijboer to join this analysis effort


Soft Muon B Flavor Tag

Based on b!of2nd B hadron

B

pTrel

pTrel

Larger pTrel increases b!

suppresses b! c!, fakes


Kp

Measure Kaon Multiplicity around B’s

Example: Bs! Ds candidates

dE/dx TOF

K

p

Can we see a difference in K multiplicity around B0, B+, B0s?


Need Reliable Simulation of TOF

Example: TOF resolution – agreement between data and MC

Data MC


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


B Baryon Signals

Semileptonic decay mode Hadronic decay mode

c signal

Unknown B baryon production fraction cancels in ratioB ! D) = b ! c) can determine absolute BFs

Penn CDF Group Overview & B Physics Activities Joseph Kroll.

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