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Recent CDF results on heavy and exotic baryons in p-pbar collisions at  s=1.96TeV

Recent CDF results on heavy and exotic baryons in p-pbar collisions at  s=1.96TeV. Francesca Curbis, Università di Roma “La Sapienza” for CDF Collaboration. Baryons 04, 25-29 Oct, Palaiseau, France. Outline. L b mass L b lifetime L b → L c p L b → pK,p p. CDF detector

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Recent CDF results on heavy and exotic baryons in p-pbar collisions at  s=1.96TeV

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  1. Recent CDF results on heavy and exotic baryons in p-pbar collisions at s=1.96TeV Francesca Curbis, Università di Roma “La Sapienza” for CDF Collaboration Baryons 04, 25-29 Oct, Palaiseau, France Francesca Curbis - Università di Roma “La Sapienza” & INFN

  2. Outline • Lb mass • Lb lifetime • Lb→Lcp • Lb→pK,pp • CDF detector • Bottom baryons • Pentaquark searches • Conclusions • theta plus • exotic cascade • theta c Francesca Curbis - Università di Roma “La Sapienza” & INFN

  3. CDF detector @Tevatron solenoid 1.4 T • solenoid 1.4 T • TRACKING system: • SILICON TRACKER • (L00+SVX+ISL) • (up to ||~2) • DRIFT CHAMBER • (96 layers) (||<1) • → particle ID with dE/dx • TIME OF FLIGHT→particle ID large radius tracking wire chamber time of flight High mass resolution with CDF tracking system Francesca Curbis - Università di Roma “La Sapienza” & INFN

  4. PID with TOF and dE/dx TOF complementary dE/dx K/pseparation 1.16s resolution 150ps for 150cm Low momentum < 1.6 GeV high momentum > 2 GeV Francesca Curbis - Università di Roma “La Sapienza” & INFN

  5. Bottom baryons Francesca Curbis - Università di Roma “La Sapienza” & INFN

  6. B mesons masses world best B+ B0 B0s Lb Measurement using several exclusive decay modes Use J/y trigger for detector calibration: Momentum scale, B-field correction and energy loss m(Lb)=5619±1.2±1.2 MeV/c2 compare to PDG 5624±9 MeV/c2 Francesca Curbis - Università di Roma “La Sapienza” & INFN

  7. Lb Lifetime in Lb→J/yL t(Lb) = 0.87±0.05 t(B0) (Hep-ph 0407004) Lb only @Tevatron Heavy Quark Expansion prediction @NLO World’s most precise measure in exclusive mode • decay asymmetrically p very soft Control sample: B0 →J/y K0s K0s long lived like L Francesca Curbis - Università di Roma “La Sapienza” & INFN

  8. B0 →J/y K0s high statistics t (B0)= 1.38±0.10ps Lb→J/yL Lb→J/yL t (Lb)= 1.25±0.26±0.10ps compare to PDG value t (Lb)= 1.229±0.08ps Francesca Curbis - Università di Roma “La Sapienza” & INFN

  9. Measurement of Lb →Lcp fbaryonxBr(Lb→L+cp) eB0 x NLb x Br(D- →Kpp) = = 0.66±0.11±0.09±0.18(Br) fd x Br(B0 →D+p) eLb x NB0 x Br(L+c →pKp) FIRST OBSERVATION! MC: 1.20±0.02±0.11 Data: 0.30±0.05 ±0.13 PDG: 1.82±0.49 B0 →D-p+ B reflections Francesca Curbis - Università di Roma “La Sapienza” & INFN

  10. Search for Lb→pK and pp decays eLx fLx Br(Lb→hh) N(Lb→hh) = eB x fB x Br(B0→Kp) N(B0→Kp) Previous best limit from ALEPH Br(Lb→pK+pp)<50×10-6 @90%C.L. Prediction:Mohanta, Giri, Khanna 2001 Br(Lb→pK)=(1.4-1.9)×10-6 Br(Lb→pp)=(0.8-1.2)×10-6 compare to Br(B0→K+p)= 18×10-6 Br(Lb→hh) < 22 10-6 @90%C.L. Fully exclusive decay N(Lb→hh) <75 @90%C.L. Br(Lb→pK+pp)<22× 10-6 @90%C.L. possibility for first observation of CP asymmetry in baryons Francesca Curbis - Università di Roma “La Sapienza” & INFN

  11. Pentaquark searches at CDF Francesca Curbis - Università di Roma “La Sapienza” & INFN

  12. Motivation qqqqq states prediction from Chiral Soliton Model (1997 Diakonov, Petrov, Polyakov) new searches for 5-quark states nK+ or pK0S narrow resonances seen in several experiment 1530 MeV 1710 MeV 1890 MeV 2070 MeV Francesca Curbis - Università di Roma “La Sapienza” & INFN

  13. Some pentaquark claims LEPS 8 GeV Synchrotrong n→K+K-n reaction NA49 pp collision at Ecm=17.2GeV H1e-p collision at Ecm=300GeV Q+→ n K+ Exotic cascade m=1862±2 MeV/c2 G < 18 MeV Qc →D*+pm=3099±3±5MeV/c2 G =12±3 MeV m=1540±10±5 MeV/c2 G < 25 MeV Q+ signal was confirmed by about 10 other experiments (CLAS, SAPHIR, ZEUS, HERMES, COSY-TOF,DIANA, SVD) many observations, can CDF see these resonance? Francesca Curbis - Università di Roma “La Sapienza” & INFN

  14. Q+→p K0S→pp+p- Q+decays strongly → zero lifetime →use prompt tracks + prompt K0S 2 energy ranges → 2 production mechanisms Minbias Unbiased inelastic collisions Jet20 Fragmentation from a 20 GeV jet 22.2M events Higher yield 14.2M events Lower BG to removeL→pp- contamination: m(pp) andm(pp) > 1.13 GeV Francesca Curbis - Università di Roma “La Sapienza” & INFN

  15. Selection of protons with TOF • Measure: • Momentum p • Time-of-flight t • Pathlength L calculate Separation powerful at low momenta Good PID in relevant momentum range high purity selection protons0.5<pT<2.1 GeV kaons0.5<pT <1.3 GeV pions 0.5<pT <1.3 GeV Resolution 150ps @ 150 cm Francesca Curbis - Università di Roma “La Sapienza” & INFN

  16. Known resonances Combine two tracks (or track+KS) → Calculate invariant mass f →K+K- L(1520)→ pK- K*+→ K0Sp+ Opp charge Same charge Reference mode Two tracks with PID Same topology Acceptance limited by TOF cuts: (determined with MC) Q+ →K0Spacceptance: 1.5<pT<4.5 GeV Francesca Curbis - Università di Roma “La Sapienza” & INFN

  17. Mass resolution Data/MC agree on KS MC resolution validated with K0S s(Q+)=2.6MeV from MC compare with 15MeV expected width Detector resolution better than expected intrinsic width Francesca Curbis - Università di Roma “La Sapienza” & INFN

  18. pK0S invariant mass spectrum Yields S=1856 S<89 @90%CL Yields S=-56103 S<76 @90%CL Francesca Curbis - Università di Roma “La Sapienza” & INFN

  19. Table of yields Minbias data Jet20 data f K+K- L(1520) pK- K*+ K0Sp+ Q+ pK0S limit on+ @90%CL 19,721273 3,276327 15,695775 1856 <89 26,658385 4,915702 35,7691,390 -56103 <76 Not corrected for acceptance-efficiency Resonance statistics higher than any of the Q+→pK0S reports High statistics reference signals , K*+, (1520) No evidence of narrow resonanceQ+→ pK0S Francesca Curbis - Università di Roma “La Sapienza” & INFN

  20. Exotic cascadeX0,--3/2 Lp- X- long lived ct=4.91 cm leaves hits in SVX Hyperons tracked in silicon X0,--3/2→X-p+,- Francesca Curbis - Università di Roma “La Sapienza” & INFN

  21. 2-track trigger sample Fit X0(1530) with BWxgaussian mass=1532±4 MeV/c2 Fit X(1860) yield=2182±92 events yield=47±70 events No signal Francesca Curbis - Università di Roma “La Sapienza” & INFN

  22. Jet20 data Fit X0(1530) with BWxG mass=1532±0.8 MeV/c2 Fit X(1860) yield=387±34 events yield=-16±27 events No signal Francesca Curbis - Università di Roma “La Sapienza” & INFN

  23. Q0c→ D(*)p Reference channels: D*+(2460) D*0 (2460) D** → D*+ p D** → D*0p+ → D+p0 D** → D*+p- → D0p0 Francesca Curbis - Università di Roma “La Sapienza” & INFN

  24. PID with TOF and dE/dx PID cut optimized on independent calibration sample Francesca Curbis - Università di Roma “La Sapienza” & INFN

  25. Results Qc→D*-p Qc→D-p Qc→D0p Qc→D0p No narrow resonances Francesca Curbis - Università di Roma “La Sapienza” & INFN

  26. Conclusions • B-baryons : • Best measurement of LB mass • Most precise LB lifetime in exclusive mode • First observation of LB→J/yL • Pentaquarks : • Despite good mass resolution, good particle identification and high statistic reference signals • CDF do not see evidences for pentaquarks • Plan to publish soon • →5Q needs high-statistics confirmation Francesca Curbis - Università di Roma “La Sapienza” & INFN

  27. Backup slides Francesca Curbis - Università di Roma “La Sapienza” & INFN

  28. Experimental signals All signals in the3-6srange Francesca Curbis - Università di Roma “La Sapienza” & INFN

  29. Reported signal peaks in nK+ CLAS hep-ex0307018 SAPHIR hep-ex0307083 DIANA (hep-ex0304040) CLAS-2 (hep-ex0402005) LEPS (hep-ex0402005) Francesca Curbis - Università di Roma “La Sapienza” & INFN

  30. Reported signal peaks in pK0S COSY-TOF hep-ex0403011 Asratyan et al.hep-ex0309042 SVD hep-ex0401024 HERMES hep-ex0312044 ZEUS hep-ex0403051 Francesca Curbis - Università di Roma “La Sapienza” & INFN

  31. Negative evidences HERA-B (hep-ex0403020) BES (hep-ex0402012) PHENIX (nucl-ex0404001) Francesca Curbis - Università di Roma “La Sapienza” & INFN

  32. Reference modes from other experiments for Q+ search HERA-B HERMES SVD-2 Francesca Curbis - Università di Roma “La Sapienza” & INFN

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