1 / 21

Rare Charm and B decays at CDF

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 D 0 decays Search for D 0 → mm Search for B 0 s,d → mm. Chicago . Booster. CDF. DØ. Tevatron. p sou rce.

oriole
Download Presentation

Rare Charm and B decays at CDF

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 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 EPS 2003 Aachen

  2. Chicago  Booster CDF DØ Tevatron p source Main Injector (new) The Tevatron Tevatron Upgrade: Higher Bunch Crossing Rate: 396 ns 5-10 higher target lumi than RunI Higher C.o.M Energy RunI:1.8 TeV RunII:1.96 TeV EPS 2003 Aachen

  3. Tevatron Performance • Record lumi.: 4.5 1031 cm-2s-1 • (~factor 2 better than RunI) • Improving slowly • 4-7 pb-1 per week • For CDF: • Current:~200 pb-1 to tape • For this talk: • ~65pb-1 w/all important • Systems on (Feb.2002-Feb2003) Delivered delivered To tape To tape EPS 2003 Aachen

  4. 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 EPS 2003 Aachen

  5. 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 • 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 Online IP resolution from SVT Includes ~33mm beamspot s=47mm EPS 2003 Aachen

  6. Decay Rate Ratios ofCabibbo Suppressed D0 Decays • TH: R(KK/pp)<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 EPS 2003 Aachen

  7. D*/D0 Signal Extraction • Selection cuts: • D0 Impact Parameter<100mm, pt>5.5 GeV • D0 Lxy>350 mm • m(D*)-m(D0) 3s around expexted value • Use triggered track pairs • Combine D0 with soft p for D* • No particle ID Extract number of signal&bkg events from fits: 3697 D*→D0p →[pp]p 93560 D*→D0p →[Kp]p 8320 D*→D0p →[KK]p EPS 2003 Aachen

  8. Monte Carlo Input Relative Acceptance Corrections from MC • Different efficiencies due to: • Nuclear Interactions of K/p, K+/K- • p,K decay length • trigger bias (due to different • opening angle) • Using realistic detector simulation: EPS 2003 Aachen

  9. Decay Ratios: Results G(D0KK)/G(D0 Kp) = 9.38  0.18(stat)  0.10(syst) % G(D0pp)/G(D0 Kp) = 3.686 0.076(stat)  0.036(syst) % Competitive with FOCUS 2003: G(D0KK)/G(D0 Kp) = 9.93  0.14  0.14 % G(D0pp)/G(D0 Kp) = 3.53 0.12 0.06 % EPS 2003 Aachen

  10. CP asymmetries of Cabibbo Suppressed D0 decays • TH: O(10-310-2) • NP can enhance • the CP-violation rate Soft p charge tags D0 flavor: q(psoft)>0: D0 q(psoft)<0:D0bar • Need to correct observed asymmetries • for intrinsic charge asymmetry of CDF detector (soft tracks) • Study charge asymmetry as a function of • soft p pt EPS 2003 Aachen

  11. Charge Asymmetry in the CDF Detector Study asymmetry using unbiased tracks and correct • Residual asymmetry syst.error (same track quality cuts generic track sample) (Expect no CP asymmetry) EPS 2003 Aachen

  12. CPV: Results ACP(D0KK) = 2.0  1.7 (stat)  0.6 (syst) % ACP(D0pp) = 3.0  1.9 (stat)  0.6 (syst) % CLEO results: Plan: redo analysis for 8-10 times statistics EPS 2003 Aachen

  13. 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→ppto cancel acceptance and trigger effects • Only relative efficiency needed EPS 2003 Aachen

  14. Normalization Mode: D0→pp Search window: 1.84<m<1.884 GeV Selection: intersect D0 with soft p 0.144<m(D*)-m(D0)<0.147 Optimized cuts: Lxy<0.45 cm, |dxy|<0.015cm, Angle cut between track and muon stub, Track quality cuts N(pp) = 1371+-53 Kp Relative efficiency from Monte Carlo: ( muon reconstruction and p decay in flight efficiency) EPS 2003 Aachen

  15. Background Estimate combinatorics from high mass sideband where both tracks are muons Fakes from p misidentification: N(D0→pp) in mass window times (misid probability)2: p misid probability From D* tagged D0→Kp Combinatorics:1.5+-0.7 events Fakes: 0.22+-0.02 events EPS 2003 Aachen

  16. 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+→pmm, D+→Kmm, D0→me, Ds EPS 2003 Aachen

  17. Search for FCNCBs,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 EPS 2003 Aachen

  18. Bs→ mmsearchmethod • 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) EPS 2003 Aachen

  19. Background If correlations between cut variables small Factorize background estimate Estimate background from sideband (Heavy flavor contr. <10-9) Background: 0.57 +- 0.22 events EPS 2003 Aachen

  20. Bs→ mmSensitivity 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 10-7 not opened the box yet, will include 2-3 times the data and full muon coverage soon EPS 2003 Aachen

  21. 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! EPS 2003 Aachen

More Related