Top Electroweak and Bottom Physics at CDF Top
Top, Electroweak and Bottom Physics at CDF • Top quark production x-section, mass • W boson mass, gauge boson pair production • Bs oscillations, B → PP Fumihiko UKEGAWA CDF Collaboration University of Tsukuba, Japan KEK Theory Meeting on Particle Physics Phenomenology, KEKPH 2007 March 1 - 3, 2007
Top Quark • Observed by CDF and DØ in Run-I data, 100 pb-1. • Tens of events reconstructed, measurements limited by statistics. • Run-II data now allow more detailed studies.
Top quark pair production Lepton + jet channel Jet multiplicity distribution
Top quark production cross section Di-lepton channel All-hadronic channel
Top quark production cross section All channels, techniques Good agreement with theory
Top Quark Mass Combine with W mass, probe Higgs indirectly. Run-I measurements Run-II expectations, ~3 Ge. V CDF/DØ 2 fb-1 goal hep-ex/0404010
Top mass measurement techniques Template method Reconstruct top “mass” from observed quantities (lepton, jets). Compare to MC distributions Lepton + jet channel Matrix element method Utilize maxima information of the event, such as • Parton level cross section • parton distribution function Evaluate a probability density as a function of true mtop, multiply prob. for all events In any method, understanding the jet energy scale is crucial and a dominant systematic uncertainty.
Top mass measurement : jet energy scale (JES) In situ calibration : Adjust the jet energy scale so as to get the correct W mass Effectively treated as a stat error. Matrix element method sample Stat + JES Similarly, with the template method :
Top mass measurements : dilepton and all-hadronic channels Di-lepton channel Matrix element method All-hadronic channel Template method Similarly, with the templete method :
CDF / DØ 2 fb-1 goal, ~3 Ge. V Top Quark Mass Past Present Future Aiming at <1% precision
Understanding the detector Bremsstrahlung tail
W-boson Mass Measurement m. T fit Electrons p. T fit m. T fit Muons ET fit
W boson mass uncertainties / result CDF RUN II PRELIMINARY
Higgs Mass? CDF/D Ø 2 fb-1 goal SM Higgs mass Or, SUSY Higgs favored?
Gauge boson pair production t Unified electroweak theory : Non-Abelian gauge structure. self-coupling among gauge bosons.
W + Photon Production Photons detected > 7 Ge. V Check 3 -body mass (l n g) for Brems. More direct test : angular distributions radiation amplitude zero
First observation
B Physics
Crucial information on the unitarity triangle of the CKM matrix, length of one of the sides
One of the challenges : resolving very quick oscillations Proper time resolution Real data, hadromic mode Roughly 20 times better than Belle/Ba. Bar
Impact on the triangle Summer 2005 Fall 2006
Penguin Tree
Expectation from MC Combinatorial background Partially Reconstructed Statistical separation using mass, kinematics, d. E/d. X
Rarer modes MC Three new modes observed
Mode 1 Gronau, PL B 492, 297 (2000) Agree, though errors are large Mode 2
Summary
Backup slides
260 pb-1 Future : look for CP-violation, ~0 expected in SM, arg(Vts).
1 fb-1
• • FCNC Vtd for B 0 d, Vts for B 0 s Helicity suppressed. B. F. very small. SM predictions for B. F. b d, s w t b d, s t w l+ l- w l+ w Z/g l-
Two and one candidates in the B 0 d and B 0 s mass windows. B. R. < 3. 0 x 10 -8 for B 0 d B. R. < 1. 0 x 10 -7 for B 0 s @ 95% C. L. Preliminary. CDF Run-I limits : B. R. < 8. 6 x 10 -7 for B 0 d B. R. < 2. 6 x 10 -6 for B 0 s PRD 57, 3811 (1998)
either left-handed (WL) or longitudinally polarized (W 0) Lepton angular distribution in W rest frame : Backward peak for left-handed W. smaller momentum in lab. DØ reconstructs cos = -cosq* ~160 pb-1 Entries W helicity in top decays F+ = 0. 3 cos( )
- Slides: 36
