ＣＤＦの最新結果 筑波大学数理物質研究科 佐藤構二 「フレーバー物理の新展開」研究会 2010 年 2 月 23 日

Tevatron Run II p – p collisions at  s = 1.96 TeV (1.8 TeV in Run I). Run II started in Summer Particle physics at the highest energy!

CDF Collaboration ~600 people from 14 Countries. Japanese collaboration –KEK –Osaka City University –Okayama University –University of Tsukuba –Waseda University

Tevatron Run II — Luminosity Status Typical Peak Luminosity : 3  cm 2 s -1. Delivers pb -1 /week. Integrated Luminosity –Delivered: 7.9 fb -1,Recorded: 6.7 fb -1. Recent analyses typically use up to 5 fb -1. Running in Possible running in Run II since Summer 2001

Collider Detector at Fermilab Multi-purpose detector Tracking in magnetic field.  Coverage |  |<~1. Precision tracking with silicon.  7 layers of silicon detectors. EM and Hadron Calorimeters.   E /E ~ 14%/  E (EM).   E /E ~ 84%/  E (HAD). Muon chambers.

Contents Top physics –Pair production cross section –Mass measurement –Property measurements –Single top observation Direct search for Higgs Boson –Standard Model Higgs

Top Physics

Top Physics at Tevatron Top quark was observed at TEVATRON in Top is still the least studied observed particle. Any deviation from SM might suggest new physics!! Top mass is unexpectedly heavy ~35  m b. –Special role in EWSB? p p t b WW q q’ t b W+W+ ll X Production cross-section Resonance production Production kinematics ttbar Spin correlation Top Mass W helicity |V tb | Branching Ratios Rare/non SM Decays Anomalous Couplings CP violation Top lifetime Top Charge Top Width _ _ _ _ BR (%)Bkgd. Di-lep.5Low L+jets30Moderate All had.44High  +X 21  -ID hard ttbar decay modes:

Top Pair Cross Section (L+jets) ~85% ~15% Top quark is mostly produced in pairs at Tevatron. Event selection: 1 lepton Pt>20, |  |<2.0 MET>25 ≥3 jets with Pt>20, |  |<2.0 ≥ 1 jet b-tagged  tt = 7.14 ± 0.34 (stat.) ± 0.58 (syst.) ± 0.14 (theory) pb (4.3 fb -1 )  tt = 7.04 ± 0.34 (stat.) ± 0.55 (syst.) ± 0.43 (lumi.) pb The dominant luminosity systematic can be canceled out by measuring ratio  tt /  Z.  (NLO) = pb

Top Pair Cross Section Cross section is sensitive to both production and decay anomaly. The difference between different decay modes might indicate new physics. CDF measures xs with various decay modes/methods, and the results are consistent with SM.

L+jets Top Mass Measurement with Matrix Element Method Construct likelihood for M t and Jet Energy Scale (JES) with Signal Matrix Element calculation. –JES had been the dominant systematic source. Simultaneously fit M top and JES. –JES constrained by hadronically decaying W→qq ’ in candidate events. t t q q g g b b W+W+ W-W- l+l+ q’ q 15%85%  100% Constrain Dijet mass To M W m t = 172.6±0.9 (stat.)±0.7 (JES)±1.1 (syst.) GeV/c 2 = ± 1.6 (total) GeV/c 2

Top Mass Tevatron Combination Use only best analyses from each decay mode, each experiment. M higgs < 157 GeV/c 2 (95% CL). M higgs < 186 GeV/c 2 w/ LEP direct search limit. Before Run II results (Spring 2004): M top =  4.3 GeV/c 2 m higgs  251 GeV/c 2 (95% CL) M top = 173.1±1.3 GeV/c 2 (winter 2009)

Search for tt Resonance Cross section limit on neutral vector resonance. Top color assisted technicolor predicts leptophobic Z’ with strong coupling to 3 rd generation quarks. Limit on Z’ with G=1.2%xM Z’ M Z’ > 805 GeV (2.8 fb -1 ) t t q q b b W+W+ W-W- q’’’ q’’ q’ q ? Analysis in all hadronic channel. No significant excess

Forward Backward Assymmetry L+jets analysis. Measure rapidity y had of hadronically decayed top. SM predicts at NLO: A fb pred. = 0.05  t t q q g g b b W+W+ W-W- l+l+ q’ q y had QlQl A fb = (stat) (syst) (3.2fb -1 ) ~2  effect! y<0 y>0

Spin Correlation Top does NOT hadronize (unique about top quark ). –SM prediction :  top ~0.4x s << 1/  QCD  s Spin information will be inherited by decay products. Signal: SM predicts  ~0.8. Bkgd:  = 1  = <κ<0.865 (68% C.L.) 2.8 fb -1

Single Top Production Top quark is sometimes singly produced Tevatron ±0.11 pb (NLO) 1.98±0.25 pb (NLO) 1 lepton, MET, 2 or 3 jets S/B separation by Matrix Element (ME) Event selection: 1 lepton, Pt>20 MET>25 2 or 3 jets, Pt>20, |  |<2.8 ≥1 jet b-tagged Signal ME bkgd ME  t+s-chan = pb (3.2 fb -1 ) 4.3  effect t-channel V tb V tb * s-channel V tb V tb *

5.0  observation!! t-channel V tb V tb * Single Top Combined Result  t+s-chan = pb  t-chan = 0.8±0.4 pb  s-chan = pb |V tb | = 0.91 ± 0.11 (exp.) ± 0.07 (theory) s-channel V tb V tb * 0.884±0.11 pb (NLO) 1.98±0.25 pb (NLO)

Direct Search for SM Higgs Boson

Production Cross Sections recently observed by CDF!

SM Higgs Properties at Tevatron bbWW mH<135 GeV (low mass): –gg→H→bb is difficult to see. –Look for WH/ZH with leptonic vector boson decays. mH>135 GeV (high mass): –Easiest to look for H→WW with one or two W decaying to lepton.

WH  l bb (low mass) S/B separation by NN. Four tagging categories, using 3 algorithms (including NN tagger). New NN b-jet energy correction See Nagai’s presentation!

3 b-tag categories with 2 algorithms. S/B separation by NN. Improved lepton coverage with forward EM clusters. Dominant backgrounds: –Z+jets, top, diboson ZH  ll+bb (low mass) l l tight 2 b-tag 1 b-tag (m H =120 GeV)

WH/ZH  MET+bb (low mass) Target process: ZH  bb –Also complementary to WH  l bb and ZH  llbb searches. 3 b-tag categories with 2 algorithms. S/B separation by NN. Dominant backgrounds: –QCD with MET miscalculation –W/Z+jets, top, diboson (m H =115 GeV) tight 2 b-tag + loose 2 b-tag

H  WW*  l + l - (high mass) Opposite sign 2 leptons. –Lepton acceptance improved by using isolated tracks. S/B separation by NN. –Matrix element calculation result input to NN. Newly including low M ll channel. Dominant background –DY, Diboson, top (m H =165 GeV)

Summary of Higgs Search Elaborate analyses are already there for most promising channels. Striving for further improvement. New channels are being explored.

CDF Combination m H (GeV)CDF x  SM x  SM

Tevatron Combination m H (GeV)CDFCDF+D x  SM 2.19 x  SM x  SM GeV excluded

B Physics See Miyake’s presentation!

Summary TEVATRON and CDF Run II are operating pretty well! –CDF has already collected ~6.7 fb -1 of data. Possible running in CDF keeps producing impressive physics results. –Top properties are studied closely. Top pair cross section precision is 6.5% (better than theory). Single top production has been observed. Top mass precision is 0.7 %. –Higgs boson is intensively searched for, with increasing sensitivity. 163<M H <166 GeV mass region has been excluded. No obvious signs of new physics so far, but stay tuned! –CDF is keeping a heavy challenge on SM.

TEV status Backup

Tevatron Status

Tevatron FY2011 Projection FY11 start Real data for FY02-FY fb fb -1 Highest Int. Lum Lowest Int. Lum FY10 start

Higgs Backup

WH  WWW*  l ± l ± +jets (high mass) Same sign 2 leptons. –Lepton acceptance improved by using isolated tracks. S/B separation by NN. Dominant background –DY, Diboson, W+jets

CDF Higgs Sensitivity Projections

S/B separation by NN. 3 b-tag categories with 2 algorithms. Improved lepton coverage with forward EM clusters. Dominant backgrounds: –Z+jets, top, diboson ZH  ll+bb (low mass) l l tight 2 b-tag loose 2 b-tag 1 b-tag (m H =120 GeV)

WH/ZH  MET+bb (low mass) Target process: ZH  bb –Also complementary to WH  l bb and ZH  llbb searches. S/B separation by NN. 3 b-tag categories with 2 algorithms. Dominant backgrounds: –QCD with MET miscalculation –W/Z+jets, top, diboson (m H =115 GeV) tight 2 b-tagloose 2 b-tag1 b-tag

H  WW*  l + l - (high mass) Opposite sign 2 leptons. –Lepton acceptance improved by using isolated tracks. S/B separation by NN. –Matrix element calculation result input to NN. Newly including low M ll events. Dominant background –DY, Diboson, top (m H =165 GeV) M ll <16 GeV channel

Tools Backup

Ttbar diagram t t q q g g b b W+W+ W-W- l +,, q’ q 15%85%  100% l -,, q’’’ q’’

B-Tagging B-jet tagging by secondary vertex displacement from the primary vertex. B-tagging reduces wrong jet- parton assignment as well as background events.

B-tag 2

Jet Probability Algorithm (1)

Jet Probability Algorithm (2)

Top Mass Backup

L+jets Top Mass Measurement with Matrix Element Method Construct likelihood for M t and Jet Energy Scale (JES) with Signal Matrix Element calculation. –JES had been the dominant systematic source. Simultaneously fit M top and JES. –JES constrained by hadronically decaying W→qq ’ in candidate events. t t q q g g b b W+W+ W-W- l+l+ q’ q 15%85%  100% Constrain Dijet mass To M W m t = 172.6±0.9 (stat.)±0.7 (JES)±1.1 (syst.) GeV/c 2 = ± 1.6 (total) GeV/c 2

CDF Top Mass Measurements

TEVATRON Top Mass Comb.

Top Mass Tevatron Combination Use only best analyses from each decay mode, each experiment. M higgs < 157 GeV/c 2 (95% CL). M higgs < 186 GeV/c 2 w/ LEP direct search limit. M top = 173.1±1.3 GeV/c 2 (winter 2009)

Top Mass Tevatron Combination Use only best analyses from each decay mode, each experiment. M higgs < 157 GeV/c 2 (95% CL). M higgs < 186 GeV/c 2 w/ LEP direct search limit. Before Run II results (Spring 2004): M top =  4.3 GeV/c 2 m higgs  251 GeV/c 2 (95% CL) M top = 173.1±1.3 GeV/c 2 (winter 2009)

L+jets Top Mass Measurement with Matrix Element Method Construct likelihood for M t and Jet Energy Scale (JES) with Signal Matrix Element calculation. Signal Matrix Element detector response function x: parton level quantities y: observed quantities Incoming parton PDFs normalizationacceptance 24 permutations of parton↔jet assumption

L+jets Top Mass Measurement with Matrix Element Method Systematic source Systematic uncertainty (GeV/c 2 ) Calibration0.1 MC generator0.6 ISR and FSR0.3 Residual JES0.5 b-JES0.4 Lepton P T 0.2 Multiple hadron interactions0.1 PDFs0.2 Background modeling0.5 Color reconnection0.3 Total1.1

CDF L+jets Template Method (3) JES syst 2.5 compared to 3.1 wo/ in situ calibration Likelihood fit looks for top mass, JES and background fraction that describes the data M top distribution best (template fit). L = 318 pb -1 M top distributions : 2tag1tagT 1tagL0tag m top = /-2.6 (stat)  3.0 (syst) GeV/c 2 A slide from summer Effect of in-situ calibration!!

Others

Single Top Combined Result 5 different L+jets analyses (3.2 fb -1 ) combine MET+jets analyses (2.1 fb -1 ) combine  t+s-chan = pb  t-chan = 0.8±0.4 pb  s-chan = pb |V tb | = 0.91 ± 0.11 (exp.) ± 0.07 (theory)

Spin correlation frame ttbar rest frame Measured in top/tbar rest frame

MSSM Higgs with bbb final state