2008/02/22 特定領域「フレーバーの物理の新展開」研究会 CDF での Top Flavor の物理 戸村 友宣 ( 筑波大学 )

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 Introduction Top quark is the heaviest known fundamental particle. Is this large mass related to electroweak symmetry breaking? Relationship between m t, m W, and m H Top quark has very short lifetime Decay before hadronization Momentum and spin are transferred to decay products

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 Tevatron Run II Proton-Antiproton Collider with CM energy of 1.96 TeV Peak luminosity: 2.9  cm -2 s -1 Delivered luminosity: > 3.5 fb -1

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 CDF II Detector General Purpose solenoidal detector Efficiency: ~85% Recorded >2.9 fb -1

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 Top Pair Production Top pair production through strong interaction ~85% ~15%

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 Top Pair Production Cross Section Measured using many different techniques Good agreement Between measurements Between data and theory dileptonl+jetsall hadronic

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 Forward Backward Asymmetry Forward-backward asymmetry arises from interference between LO and higher order diagrams (NLO Theory: A fb = 0.04±0.01)(NLO Theory: A fb = 0.04—0.07) Lab (ppbar-rest) frame ttbar (parton) rest frame 1.9 fb -1

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 ttbar Production Mechanism Measure fraction of gg vs. qq top production SM prediction: ~85% qq, ~15% gg Large theoretical uncertainty (~10%) Two complementary approaches NN with production and decay kinematics Track multiplicity distributions Combine two methods: ~6% improvement 1 fb -1

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 ttbar Differential Cross Section Measure d  /dM tt and test consistency with SM Spectrum is sensitive to many BSM resonances (Z ′, coloron, etc.) ttbar invariant mass is reconstructed for l+jets events Subtract background and correct the distribution using a regularized unfolding technique Data is consistent with SM p-value = fb -1

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 Search for Massive Gluon Search for heavy gluon-like particle, G  ttbar (color-octet model, etc.) 3 parameters Mass(M), Width(  ), coupling( ) Event-by-event ttbar invariant mass reconstruction for l+jets with a Matrix Element technique (DLM) Data is consistent with SM (<1.7  ) within 400  M  800, 0.05  /M  0.5 Set upper/lower limit for massive gluon coupling Coloron model ( =  1,  /M  0.2) is excluded in the range,  /M  0.5 and M  800 q Q g + G gsgs gsgs q g s Q g s SM  interfere  MG 1.9 fb -1

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 Top Quark Mass Many techniques were deployed for top mass measurements Tevatron combination calculated 1 year ago

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 New Mass Measurements (1) Template Method Reconstruct top mass event-by-event and generate templates Use dijet mass from W daughters for in-situ jet energy calibration Combined for dilepton and l+jets all-hadronic Apply NN event- selection to improve S/B 1.9 fb -1

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 New Mass Measurement (2) Matrix Element Method Calculate event-probability from the kinematics of decay products using Matrix Element dilepton lepton+jets Apply NN event- selection to optimize S/B Cut lower tail of log-likelihood distribution 1.9 fb -1

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 Top Quark Width Measure width of top quark directly using template method Use 1-tag and 2-tag l+jets data Calculate upper limit using Feldman-Cousin prescription 1 fb -1

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 Top Quark Charge Measure the charge of “ top ” quark SM top charge: +2/3 XM top charge: −4/3 D. Chang et. al. Phys. Rev. D59 (1999) t  W + b or t  W − b Charge of W (lepton charge) Pairing between W and b Flavor of b-jet Use dilepton and l+jets data Measured f + =0.87 p-value=0.31 Exclude CL 1.5 fb -1

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 W Helicity V−A character of the top decay makes the helicity of W only F 0 =0.70, F − =0.30, F + =0.00 (longitudinal, left-handed, right-handed) l l+l+ W+W+ b ** cos   Method Matrix Element Technique 1.9 fb -1 If F + fixed to 0: If F 0 fixed to 0.7:

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 Search for FCNC Decay t  Zq Top FCNC is extremely rare In SM, BR(t  Zq)=O( ) BSM, up to O(10 -4 ) Calculate  2 for FCNC top decay 1.9 fb -1

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 Single Top Production Single top production through weak interaction  single top  |V tb | 2 Sensitive to: 4-th generation H + W ′ FCNC Etc. Background for WH  l bb s-channel  NLO = 0.88±0.07 pb t-channel  NLO = 1.98±0.21 pb ? W,H+W,H+ Z c t

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 Evidence for Single Top Multivariate Likelihood Function 7 input variables (kinematics, kinematic solver and ANN b-tag outputs) Matrix Element Technique Ratio of event probability densities for signal and bkg 2.7  significance (2.9  expected)3.1  significance (3.0  expected) 1.5 fb -1

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 Direct Measurement of |V tb | CKM Matrix Element |V tb | Describes strength of Wtb vertex  single top  |V tb | 2 Assumes |V tb | 2 +|V tb | 2  <<|V tb | 2 Measured with Matrix Element Technique Theory uncertainty arises from the cross-section dependence on Top quark mass Factorization and renormalization scales PDFs and  s (Z. Sullivan, Phys. Rev. D70 (2004) ) 1.5 fb -1

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 Search for W ′ Resonance Search for resonance in tb channel using M WJJ Many theories include new gauge boson Extensions to the SM (GUT) Extra Dimensions (Kaluza-Klein) Use massive W boson with SM-like couplings Z. Sullivan, arXiv:hep-ph/ Large branching fraction to 1.9 fb -1

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 Summary CDF entered era of precision top measurements. Mass and cross section No longer stat. dominant. Need revisit syst. Uncertainty. New measurements for the properties of top quark. Some of them are measurable only at Tevatron. Many improvements in analysis techniques. Top is a good probe for new physics. Good agreement with Standard Model, so far. New results will be coming! CDF/Tevatron combination for top mass, including recent 2 /fb results. Single top: 4~5 sigma w/ >2 /fb

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 Backups

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 Background fb -1 Dilepton Lepton+Jets

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 Example of Syst. Err. for M top Combined Template Method for dilepton and lepton+jets

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 b-jet Flavor Tagging Jet Charge Performance Dil  =87%, P=61%,  D 2 =0.10 L+J:  =98%, P=61%,  D 2 =0.13 (x=0.5) Jet axis b tagged Soft  P Trel Away Jet b tagged

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 W Helicity

2008/02/22 特定領域「フレーバーの物理の新展開」研究会 Forward-Backward Asymmetry Interference between LO and NLO diagrams