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Rare Charm and B decays at CDF Julia Thom FNAL EPS 7/18/2003 •Tevatron/CDF Experiment •Decay Rate Ratios and CP Asymmetries of Cabibbo suppressed D0 decays •Search for D0→mm •Search for B0s,d → mm Julia Thom, FNAL EPS 2003 Aachen The Tevatron Chicago Booster CDF DØ Tevatron p source Main Injector (new) Tevatron Upgrade: Higher Bunch Crossing Rate: 396 ns 5-10 higher target lumi than RunI Higher C.o.M Energy RunI:1.8 TeV Julia Thom, FNAL EPS 2003 Aachen RunII:1.96 TeV Tevatron Performance •Record lumi.: 4.5 1031 cm-2s-1 (~factor 2 better than RunI) •Improving slowly •4-7 pb-1 per week Delivered delivered For CDF: Current:~200 pb-1 to tape To tape To tape For this talk: ~65pb-1 w/all important Systems on (Feb.2002-Feb2003) Julia Thom, FNAL EPS 2003 Aachen The CDF Run II Detector • New DAQ Track based trigger at L1 (XFT) Impact parameter trigger at L2 (SVT) (by far most important upgrade for B and charm) • New Silicon system – 7-8 layer silicon detector (up to ||~2) Improved b-tagging Extended muon systems (to ||~1.5) • Time of flight detector(particle ID) • New central drift chamber –Detector upgrades give new charm and bottom physics program –Charm Results already competitive with world’s best Julia Thom, FNAL EPS 2003 Aachen Silicon Vertex Trigger Level 1 track trigger: high pt Level 2 track trigger: large d0 Improves RunI sensitivity by 4-5 orders of magnitude CDF as “Charm Factory” ~million D0’s per 100 pb-1 Online IP resolution from SVT s=47mm Triggers used in this talk: •Two track trigger 2 tracks pt>2GeV, d0>120mm, Spt>5.5 GeV •Rare B trigger 2 muons with momentum/vertexing requirements Julia Thom, FNAL EPS 2003 Aachen Includes ~33mm beamspot Decay Rate Ratios of Cabibbo Suppressed D0 Decays D 0 K ( D 0 ( KK )) N D 0 ( KK ) 0 ( D K ) N D 0 K D 0 ( KK ) TH: R(KK/)<1.4 Ex: ~2.5 (world average) (difference prob. due to FSI) •Many systematics (trigger, reconstruction..) cancel in ratio •Relative acceptance estimated from MC + realistic simulation Julia Thom, FNAL EPS 2003 Aachen D*/D0 Signal Extraction •Use triggered track pairs •Combine D0 with soft for D* •No particle ID Selection cuts: •D0 Impact Parameter<100mm, pt>5.5 GeV •D0 Lxy>350 mm •m(D*)-m(D0) 3s around expexted value Extract number of signal&bkg events from fits: 93560 D*→D0 →[K] Julia Thom, FNAL 8320 D*→D0 →[KK] EPS 2003 Aachen 3697 D*→D0 →[] Monte Carlo Input Relative Acceptance Corrections from MC Different efficiencies due to: • Nuclear Interactions of K/, K+/K• ,K decay length • trigger bias (due to different opening angle) Using realistic detector simulation: Julia Thom, FNAL EPS 2003 Aachen Decay Ratios: Results (D0KK)/(D0 K) = 9.38 0.18(stat) 0.10(syst) % (D0)/(D0 K) = 3.686 0.076(stat) 0.036(syst) % Competitive with FOCUS 2003: (D0KK)/(D0 K) = 9.93 0.14 0.14 % (D0)/(D0 K) = 3.53 0.12 0.06 % Julia Thom, FNAL EPS 2003 Aachen CP asymmetries of Cabibbo Suppressed D0 decays TH: O(10-310-2) NP can enhance the CP-violation rate N D 0 ( KK ) ACP D N D 0 ( KK ) D N D 0 ( KK ) 0 N D 0 ( KK ) 0 Soft charge tags D0 flavor: q(soft)>0: D0 D D 0 0 q(soft)<0:D0bar •Need to correct observed asymmetries for intrinsic charge asymmetry of CDF detector (soft tracks) •Study charge asymmetry as a function of soft pt Julia Thom, FNAL EPS 2003 Aachen Charge Asymmetry in the CDF Detector Study asymmetry using unbiased tracks and correct Residual asymmetry (same track quality cuts generic track sample) (Expect no CP asymmetry) N N AQ ( pt ) N N Acorr ( D 0 f ) ( D f ) ( D 0 f ) ( D f ) Julia Thom, FNAL 1 AQ 1 AQ EPS 2003 Aachen syst.error CPV: Results ACP(D0KK) = 2.0 1.7 (stat) 0.6 (syst) % ACP(D0) = 3.0 1.9 (stat) 0.6 (syst) % CLEO results: Acp ( D 0 KK ) 0 2.2 0.8% Acp ( D 0 ) 1.9 3.2 0.8% Plan: redo analysis for 8-10 times statistics Julia Thom, FNAL EPS 2003 Aachen Search for FCNC D0→mm •SM expectation BR~ 3*10-13 •Best limit: <4.1x10-6 (90% CL) (Beatrice/WA92, E771) •BR significantly enhanced with New Physics (e.g. R-Parity Violation Susy: ~3.5*10-6) • Events from two-track trigger use first 63pb-1 of data •Normalize to D0→ to cancel acceptance and trigger effects •Only relative efficiency needed upper N ( m m ) ( ) 0 90%CL BR90%CL ( D m m ) BR ( ) ( mm ) N ( ) Julia Thom, FNAL EPS 2003 Aachen Normalization Mode: D0→ Search window: 1.84<m<1.884 GeV Selection: intersect D0 with soft 0.144<m(D*)-m(D0)<0.147 Optimized cuts: K Lxy<0.45 cm, |dxy|<0.015cm, Angle cut between track and muon stub, Track quality cuts N() = 137153 Relative efficiency from Monte Carlo: ( ) 1.14 0.04 ( mm ) ( muon reconstruction and decay in flight efficiency) Julia Thom, FNAL EPS 2003 Aachen Background Fakes from misidentification: N(D0→) in mass window times (misid probability)2: Estimate combinatorics from high mass sideband where both tracks are muons misid probability From D* tagged D0→K Combinatorics:1.50.7 events Julia Thom, FNAL Fakes: 0.220.02 events EPS 2003 Aachen FCNC D0→mm: Results M(mm) with D* tag and 2 muons 1.7 expected events, 0 observed events: Ncl=2.3 BR(D0→mm)<2.4x10-6 (90% CL) Factor 2 improvement over best limit Next: use full muon coverage and 2-3 times more data (~1year) also look at D+→mm, D+→Kmm, D0→me, Ds Julia Thom, FNAL EPS 2003 Aachen Search for FCNC Bs,d → mm •BR(Bs0→mm)~10E-9 in SM •Best published limit:2.6 10E-6 at 90% C.L.(CDF) •Can be enhanced by >2 orders of magnitude in SUSY scenarios •Particular interest: hand in hand with deviations of (g-2)m (hep-ph/0108037) Relevant part predicts 10-7:10-8 Observable in Run II If true, m(h)~120 GeV Lots of theoretical interest Julia Thom, FNAL EPS 2003 Aachen Bs → mm search method obs N 90 %CL BR ( Bs m m ) s Bs Ldt •Acceptance estimated from MC (|y(B)|<1.0 and pt(b)>6 GeV), •Trigger and reconstruction efficiency from data •Analysis cut efficiency from MC (x-check with B+ →J/Psi data) •Bs cross-section: assume Bd:Bs 3:1 Discriminating variables: •Dimuon Inv.mass (mmm3 s around PDG) •Lifetime (ct>200mm) •Pointing angle (Dphi<0.1 rad) •Isolation of Bs candidate (iso>0.65) Julia Thom, FNAL EPS 2003 Aachen Background Estimate background from sideband (Heavy flavor contr. <10-9) If correlations between cut variables small Factorize background estimate N (bkg) N ( sb | ct , D ) (iso) R(mmm ) Background: 0.57 +- 0.22 events Julia Thom, FNAL EPS 2003 Aachen Bs → mm Sensitivity Current estimated sensitivity optimized cuts and 65 pb-1 of data: BR(Bs → mm) < 2.4 10-6 RunI limit:2.6 10-6 BR(Bd → mm)<8.0 107 not opened the box yet, will include 2-3 times the data and full muon coverage soon Julia Thom, FNAL EPS 2003 Aachen Conclusions First Results on Rare Charm (and B) decays at CDF Decay ratios and CPV of Cabibbo suppressed D0 decays already competitive/best sensitivity FCNC searches: best limits D0 → mm: factor 2 improvement over best publ. limit Bs → mm: expect to improve RunI limits soon! Julia Thom, FNAL EPS 2003 Aachen