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

This presentation summarizes recent results on heavy and exotic baryons from the CDF experiment at the Tevatron collider. It covers topics such as the mass and lifetime of Lb baryons, Lb decays to Lcp, pK, and pp, as well as the search for pentaquark states.

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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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