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Heavy flavor baryons

LP07, August 13-18, 2007, Daegu, Korea. Heavy flavor baryons. Roman Mizuk (ITEP, Moscow). Belle Collaboration. charm and beauty baryons pentaquark searches. Reminder on Heavy Quark Baryons. Baryons made from u,d,s,c quarks . similar multiplets if c quark is exchanged by b quark.

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Heavy flavor baryons

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  1. LP07, August 13-18, 2007, Daegu, Korea Heavy flavor baryons Roman Mizuk (ITEP, Moscow) Belle Collaboration charm and beauty baryons pentaquark searches

  2. Reminder on Heavy Quark Baryons Baryons made from u,d,s,c quarks  similar multiplets if c quark is exchanged by b quark antisymmetric 3F symmetric 6F Total space-flavor-spin wave functionmust be symmetric One heavy quark – example S-wave  8 S-wave isospin multiplets, 35 P-wave, 85 D-wave,.. Heavy Quark Symmetry jlight decouples  excitation spectra are independent of heavy quark flavor exact for mQ→  Simplification: Heavy quark - light diquark picture. Laboratory to test QCD.

  3. Experimental Status 2 years ago  Charmed baryons Beauty baryons

  4. Experimental Status Many new states observed recently at B-factories TEVATRON Important ingredients PID, high momentum detached vertex Charmed baryons Beauty baryons

  5. Λc c[ud]

  6. Observation of Λc(2940)+ by BaBar Conventional baryon? JP=5/2-, 1/2+, 3/2+,.. D0p PRL98,012001 Measurements of M and Γ are consistent Λc(2880) CLEOΛcπ+π- Λc(2940) NEW New decay mechanism: heavy quark → meson. wrong-sign combinations BaBar: no isospin partners in D+p 2880, 2940 are isoscalars D0 sidebands Exotics? Σc(2455)π→Λc+π+π- Λc(2940)+ mass is 5MeV below D*p threshold molecule? PRL98,262001 Λc(2880) He, Li, Liu, Zeng, hep-ph/0606015 Belle confirmed ( mass, decay pattern) Chen, Chua, PRD75, 094017 (2007) Garcilazo, Vijande, Valcarce, JPG34, 961 (2007) Chen, Chen, Liu, Deng, Zhu, PRD75, 094017 (2007) Λc(2940) Λc(2765) More experimental studies to discriminate. Γ(Σc*π):Γ(Σcπ):Γ(D0p), …

  7. Λc(2880)+ spin-parity from Belle m(Λcπ) Σc(2455) Σc(2520) evidence PRL98,262001 Angular analysis of Λc(2880)→Σc(2455)π Resonant structure of Λc(2880)→Λc+π+π- helicity angle J=5/2 is favored over 3/2(4.5σ) or 1/2(5.4σ) Capstick, Isgur PRD34,2809 (1986) Chen, Chua, PRD75, 094017 (2007) • Quark Model: • 5/2- 2900 3130 • 7/2- 3125 • 5/2+ 2910 3140 • 7/2+ 3175 • Heavy Quark Symmetry: • 5/2- R=1.4 • 5/2+ R~0.3  5/2+ is favored over 5/2- predicted in string theory Selem, Wilczek, hep-ph/0602128 @ leading Regge trajectory with Λc+1/2+ and Λc(2625)+3/2-  Λc(2880)+ is likely 5/2+

  8. Σc cdd, c{ud}, cuu

  9. Observation of Σc(2800) isotriplet by Belle PRL94,122002 Λc+π- Λc+π0 Λc+π+ Σc(2800)0 NEW Σc(2800)++ NEW feed-down Σc(2800)+ NEW feed-down  Feed-down from Λc(2880)+→Σcπ→Λc+π+π- Measurements of M, Γ and σ are consistent Mass, width Σc(2800) can be 3/2- (?) More experimental studies to confirm JP. Capstick, Isgur, PRD34,2809 (1986) Pirjol,PRD56,5487 (1997) Mass of Σc(2800) is at D0p threshold.

  10. Ξc csd, csu

  11. Observation of Ξc(2980) and Ξc(3080) by Belle PRL97,162001 hep-ex/0607042 Λc+K-π+ Λc+K-π+ Ξc(3080)+ NEW Ξc(3080)+ BaBar confirmed Ξc(2980)+ NEW Ξc(2980)+ New decay mechanism:s-quark → meson. resonant structure Λc+Ksπ- Ξc(3080)0 NEW BaBar confirmed also Ξc(3080)0 Measurements of M and Γ are consistent Mass D-wave excitations ? Ξc(2980)1/2+, 3/2+,.. Ξc(3080)5/2+,.. Rosner JPG34,S127 (2007) Chen, Chua, PRD75, 094017 (2007) Garcilazo, Vijande, Valcarce, JPG34, 961 (2007) Chen, Chen, Liu, Deng, Zhu, PRD75, 094017 (2007) Ebert, Faustov, Galkin, arXiv:0705.2957 More experimental studies to assign JP.

  12. Evidence for Ξc(3055) and Ξc(3123) from BaBar Presented at EPS-HEP 2007 Σc(2455)++K-→Λc+K-π+ Ξc(2980)+ Ξc(3055)+ NEW Ξc(3080)+ Σc(2520)++K-→Λc+K-π+ Ξc(3080)+ Ξc(3123)+ evidence hep-ex/... (preliminary) More experimental studies to assign JP.

  13. Study of B+→Λc+Λc-K+ by BaBar B+→Λc+Λc-K+ decay has been observed by Belle PRL97,202003 (2006) NEW BaBar: confirmation, resonant structure. Λc+ Λc- K- Λc+K- NEW B- meson phase-space confirmed sidebands mbc (GeV/c2) Excited Ξc? not seen in continuum BaBar “More data are needed before firm conclusions can be drawn.”

  14. Ωc css

  15. Observation of Ωc* by BaBar data Ebert et al, PRD72,034026 (2005) QM with heavy-quark-light-diquark Mathur et al, PRD66,014502 (2002) Lattice NRQCD (quenched) Burakovsky et al, PRD56, 7124 (1997) Regge framework Jenkins, PRD54, 4515 (1996) 1/MQ and 1/Nc expansion Lichtenberg et al, PRD53, 6678 (1996) Mass sum rules Savage, PLB359, 189 (1995) Chiral Perturbation Theory Rosner, PRD52, 6461 (1995) Spin-flavor wave-functions Roncaglia et al, PRD52,1722 (1995) Feynman-Hellman theorem Martin et al, PLB355, 345 (1995) potential model PRL97,232001 Ωc* NEW Ωc0g significance 5.2σ Result m(Ωc*) – m(Ωc) = (70.8 ± 1.0 ± 1.1) MeV/c2 Last unobserved ground state charmed baryon. Comparison with predictions m(Ωc*) – m(Ωc) Good agreement

  16. Σb bdd, b{ud}, buu

  17. Observation of Σb and Σb* by CDF arXiv:0706.3868 arXiv:0706.3868 Λb0→Λc+π- Λb0π- Λb0π+ Blind signal region

  18. Observation of Σb and Σb* by CDF arXiv:0706.3868 arXiv:0706.3868 Λb0→Λc+π- Λb0π- blind BG fixed Λb0π+ blind

  19. Observation of Σb and Σb* by CDF arXiv:0706.3868 arXiv:0706.3868 Λb0→Λc+π- Korner et al, PPNP33,787 Λb0π- Σb- NEW Σb*- NEW Fix all widths: Λb0π- blind Fix shape and normalization of bg. Results (MeV/c2): BG fixed Σb+ NEW Σb*+ NEW Λb0π+ Λb0π+ blind Significance >5.2σ (4 peaks vs. BG only) Each peak >3 σ (except Σb+)

  20. Observation of Σb and Σb* by CDF arXiv:0706.3868 arXiv:0706.3868 Λb0→Λc+π- Korner et al, PPNP33,787 Λb0π- Σb- NEW Σb*- NEW Fix all widths: Λb0π- blind Fix shape and normalization of bg. Results (MeV/c2): BG fixed Σb+ NEW Σb*+ NEW Λb0π+ Λb0π+ blind Significance >5.2σ (4 peaks vs. BG only) Each peak >3 σ (except Σb+) m(Σb)–m(Λb) m(Σb*)–m(Σb) Comparison with predictions Karliner, Lipkin, PLB575,249 (2003) QM data expect m(Σb–) – m(Σb+) = 5-7 MeV Mathur et al, PRD66,014502 (2002) Lattice NRQCD (quenched) Jenkins, PRD54, 4515 (1996) 1/MQ and 1/Nc expansion Ebert et al, PRD72,034026 (2005) QM with heavy-quark-light-diquark Roncaglia et al, PRD52,1722 (1995) Feynman-Hellman theorem Capstick, Isgur, PRD34,2809 (1986)relativised QM Good agreement

  21. Ξb bsd, bsu

  22. Observation of Ξb- by D0 and CDF arXiv:0707.0589 J/ψΞ- arXiv:0706.1690 J/ψΞ- Ξb-→ J/ψΞ- PRL99,052002 PRL99,052001 Ξb- NEW Ξb- NEW Comparison with predictions Mass measurements are consistent Lattice QCD QM HQET Proper decay time distribution consistent with expected Ξb lifetime Good agreement

  23. Summary on Heavy Quark Baryons Charmed baryons Beauty baryons Ξc(3080) CLEO Belle BaBar D0 CDF Ξc(3055) Ξc(2980) Λc(2940) Λc(2880) Σc(2800) Ωc* Σb* Ξb Σb  Ground state SU(3) multiplets of charmed baryons are complete.  Flood of highly excited charmed baryons. New era in beauty baryon spectroscopy.

  24. Reminder on Pentaquarks Θ(1540)+ |uudds> Θ(1540)+ predicted in Chiral Soliton Model Observed in γn→Θ+K-→ (K+n)K- and K+n→Θ+→pKS M ~ 1540 MeV/c2 Γ < 1 MeV Low Γ and M are difficult to explain Initial evidence: Also many null results, not easily comparable. Repeat measurements with high statistics + LEPS – CLAS – Belle + SVD-2

  25. Introduction to Pentaquarks Θ(1540)+ |uudds> Θ(1540)+ predicted in Chiral Soliton Model Observed in γn→Θ+K-→ (K+n)K- and K+n→Θ+→pKS M ~ 1540 MeV/c2 Γ < 1 MeV Low Γ and M are difficult to explain Initial evidence: Also many null results, not easily comparable. Repeat measurements with high statistics + LEPS – CLAS – Belle + SVD-2 PDG2006 NEW?

  26. New DIANA result PAN70,35 (2007) K+ Xe→ p KS Xe’ Statistics x1.6Θ(1540)+ signal confirmed, significance increased from 4.4 to 5.3σ M(pKS) NEW estimationof Θ(1540)+ width 445<pK+<525MeV my estimate  Contradiction with Belle persists (2.2σ, 2.4%) DIANA finds no Θ+ signal for pK+>525MeV Inelastic Θ(1540)+production will decrease Belle upper limit M(pKS) 17 events expected MC verified on tagged kaon data at Belle pK+>525MeV -3 found  2.9σ fluctuation, decreases significance of DIANA signal Evidence for Θ(1540)+from DIANA is weak.

  27. New NOMAD result EPJC49,499 (2007) NOMAD Preliminary Θ+ N → Θ+X Θ(1540)+ signal is not confirmed based on subsaple Upper Limit on Θ+production rate per  interactionvs. xF NOMAD result can be compared with ITEP- result  Θ+production rate ~10-3 Θ+  For large part of xFrange NOMAD and ITEP- results are in conflict.

  28. New COSY-TOF results PLB649,252 (2007) pp → pK0Σ+ Statistics x10, improved detection capability  Θ(1540)+ signal not confirmed NEW Previous Comparison Θ+ Background shape from new data. In previous analysis background was underestimated significance lower than claimed. Evidence for Θ(1540)+from COSY-TOF is negated.

  29. New H1 result PLB639,202 (2006) ep → pKSX No Θ+ signal H1 result can be compared with ZEUSresult  M(pKS) ZEUS ZEUS (preliminary) Q2>20GeV2, 0.04<y<0.95 H1 Extrapolated to ZEUS y-region. H1 and ZEUS results are in conflict.

  30. SVD-2 result: the most significant Θ+ signal hep-ex/0509033 pA → KSpX Statistics x8Θ(1540)+ signal confirmed, significance increased from 5.5 to ~8σ M(pKS) M(pKS) KS decays inside / outside Vertex Detector M = 1522 MeV s = 12 MeV Nevnt = 205 M = 1523 MeV s = 12 MeV Nevnt = 165 Θ(1540)+ is produced with small xF For central production difference in energy should not be important. SVD-2 result strongly contradicts HERA-B, CDF.

  31. Other new results on pentaquarks 2.5σ signal at M=1530MeV  No significant Θ+signals. No new positive results for doubly strange pentaquark Φ(1860) or charmed pentaquark Θc(3100)0. “No stars” in PDG2006  not discussed here.

  32. Summary on Θ(1540)+ ~5σ New data are taken (2007).Statistics x3. unpublished ~5σ 5.4σ Contradiction with Belle persists. In conflict with NOMAD. Not accessible in new data (energy too low). unpublished Contradicts BaBar eBe→pKSX(statistics x100 larger). In conflict with H1. ~8σ Contradicts HERA-B, CDF. Not a single convincing evidence for Θ(1540)+ For  experiment with positive result  experiment with similar conditions but null result. Evidence for Θ(1540)+pentaquark is weak

  33. Conclusions • Impressive progress in heavy flavor baryons • # charmed baryons 12 → 18 • # beauty baryons 1 → 4 • Λc(2880)+, Ωc*, Σb, Σb*, Ξb provide important constraints for theory. To use other new states: Λc(2940), Σc(2800), Ξc(2980), Ξc(3055), Ξc(3080),we need symbiosis between theory and experiment. • Experiments are consistent and experimental results are robust. over last 2 years • Experimental evidence for pentaquarks is weak • More null results since PDG2006: COSY-TOF, H1, NOMAD, ... • Very low Θ+width: DIANA Γ = (0.36 ± 0.11) MeV • New results are expected fromLEPS, HERA-II. New challenges for theory?

  34. Back-up

  35. Doubly charmed baryons hep-ex/0702001 SELEX Λc+K-π+ Ξc+π+π- Ξcc+ Ξcc+ New decay channel. cc+ c+ K- + Not confirmed by BaBar and Belle. cc+ c+ K- + cc+ cc0 + Selex’s cc(3520)+ is found neither in c+ K- + nor in c0 + also not seen in photo production (FOCUS)

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