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

Reminder on Heavy Quark Baryons Total space-flavor-spin wave function must be symmetric  similar multiplets if c quark is exchanged by b quark S-wave  8 S-wave isospin multiplets, 35 P-wave, 85 D-wave,.. Baryons made from u,d,s,c quarks  One heavy quark – symmetric 6 F antisymmetric 3 F 3F3F 6F6F s light =0s light =1 J P =1/2+J P =1/2+ or 3/2+ Heavy Quark Symmetry  j light decouples  excitation spectra are independent of heavy quark flavor Simplification: Heavy quark - light diquark picture. Laboratory to test QCD. example exact for m Q → 

Charmed baryonsBeauty baryons Experimental Status 2 years ago 

Experimental Status Charmed baryonsBeauty baryons Many new states observed recently at B-factoriesTEVATRON Important ingredients PID, high momentumdetached vertex

ΛcΛc c[ud]

Observation of Λ c (2940) + by BaBar Σ c (2455)π→ Λ c + π + π - Λ c (2880) Λ c (2940) Λ c (2765) BaBar: no isospin partners in D + p  2880, 2940 are isoscalars PRL98, D0pD0p Λ c (2880) Λ c (2940) NEW PRL98, D 0 sidebands wrong-sign combinations New decay mechanism: heavy quark → meson. Belle confirmed Λ c (2940) + mass is 5MeV below D*p threshold  molecule? He, Li, Liu, Zeng, hep-ph/ CLEO Λ c π + π - Measurements of M and Γ are consistent Exotics? (  mass, decay pattern) Chen, Chua, PRD75, (2007) Garcilazo, Vijande, Valcarce, JPG34, 961 (2007) Chen, Chen, Liu, Deng, Zhu, PRD75, (2007) More experimental studies to discriminate. Conventional baryon?  J P =5/2-, 1/2 +, 3/2 +,.. Γ(Σ c * π): Γ(Σ c π):Γ(D 0 p), …

Λ c (2880) + spin-parity from Belle helicity angle J=5/2 is favored over 3/2 (4.5σ) or 1/2 leading Regge trajectory with Λ c + 1/2+ and Λ c (2625) + 3/2- m(Λ c π) Σ c (2520) evidence Σ c (2455) PRL98, Angular analysis of Λ c (2880)→Σ c (2455)π Heavy Quark Symmetry: 5/2-  R=1.4 5/2+  R~0.3 Capstick, Isgur PRD34,2809 (1986) Quark Model: 5/ / / / Resonant structure of Λ c (2880)→ Λ c + π + π - Chen, Chua, PRD75, (2007) Selem, Wilczek, hep-ph/ predicted in string theory  5/2+ is favored over 5/2-  Λ c (2880) + is likely 5/2+

ΣcΣc cdd, c{ud}, cuu

Observation of Σ c (2800) isotriplet by Belle Mass, width  Σ c (2800) can be 3/2- (?) Mass of Σ c (2800) is at D 0 p threshold. Pirjol,PRD56,5487 (1997) PRL94, Λc+π-Λc+π- Λc+π0Λc+π0 Λc+π+Λc+π+ Σ c (2800) + NEW Σ c (2800) ++ NEW Σ c (2800) 0 NEW  Feed-down from Λ c (2880) + → Σ c π→Λ c + π + π - feed-down Measurements of M, Γ and σ are consistent Capstick, Isgur, PRD34,2809 (1986) More experimental studies to confirm J P.

ΞcΞc csd, csu

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

Evidence for Ξ c (3055) and Ξ c (3123) from BaBar Ξ c (3080) + Ξ c (2980) + Σ c (2455) ++ K - →Λ c + K - π + Σ c (2520) ++ K - →Λ c + K - π + Ξ c (3055) + NEW Ξ c (3123) + evidence hep-ex/... (preliminary) More experimental studies to assign J P. Presented at EPS-HEP 2007

Study of B + →Λ c + Λ c - K + by BaBar B + → Λ c + Λ c - K + decay has been observed by Belle BaBar: confirmation, resonant structure. Λc+K-Λc+K- BaBar  “More data are needed before firm conclusions can be drawn.” Excited Ξ c ? not seen in continuum Λ c + Λ c - K - m bc (GeV/c 2 ) B - meson NEW confirmed NEW PRL97, (2006) phase-space sidebands

ΩcΩc css

Observation of Ω c * by BaBar significance 5.2σ Ωc0 Ωc0  Ω c * NEW Last unobserved ground state charmed baryon. m(Ω c *) – m(Ω c ) = (70.8 ± 1.0 ± 1.1) MeV/c 2 PRL97, Comparison with predictions data Rosner, PRD52, 6461 (1995) Spin-flavor wave-functions Ebert et al, PRD72, (2005) QM with heavy-quark-light-diquark Burakovsky et al, PRD56, 7124 (1997) Regge framework Lichtenberg et al, PRD53, 6678 (1996) Mass sum rules Martin et al, PLB355, 345 (1995) potential model m(Ω c *) – m(Ω c ) Result Mathur et al, PRD66, (2002) Lattice NRQCD (quenched) Roncaglia et al, PRD52,1722 (1995) Feynman-Hellman theorem Jenkins, PRD54, 4515 (1996) 1/M Q and 1/Nc expansion Savage, PLB359, 189 (1995) Chiral Perturbation Theory  Good agreement

ΣbΣb bdd, b{ud}, buu

Blind signal region arXiv: Λb0π+Λb0π+ Λb0π-Λb0π- Λb0→Λc+π-Λb0→Λc+π- Observation of Σ b and Σ b * by CDF arXiv:

blind BG fixed arXiv: Λb0π+Λb0π+ Λb0π-Λb0π- Λb0→Λc+π-Λb0→Λc+π- Observation of Σ b and Σ b * by CDF arXiv:

blind BG fixed arXiv: Fix all widths: Λb0π+Λb0π+ Λb0π-Λb0π- Σ b *- NEW Σ b - NEW Σ b *+ NEW Σ b + NEW Results (MeV/c 2 ): Korner et al, PPNP33,787 Λb0π+Λb0π+ Λb0π-Λb0π- Λb0→Λc+π-Λb0→Λc+π- Observation of Σ b and Σ b * by CDF Fix shape and normalization of bg. Significance >5.2σ (4 peaks vs. BG only) Each peak >3 σ (except Σ b + ) arXiv:

blind BG fixed arXiv: Fix all widths: Λb0π+Λb0π+ Λb0π-Λb0π- Σ b *- NEW Σ b - NEW Σ b *+ NEW Σ b + NEW Results (MeV/c 2 ): Korner et al, PPNP33,787 Λb0π+Λb0π+ Λb0π-Λb0π- Λb0→Λc+π-Λb0→Λc+π- Observation of Σ b and Σ b * by CDF Fix shape and normalization of bg. Significance >5.2σ (4 peaks vs. BG only) Each peak >3 σ (except Σ b + ) Comparison with predictions Mathur et al, PRD66, (2002) Lattice NRQCD (quenched) Karliner, Lipkin, PLB575,249 (2003) QM Roncaglia et al, PRD52,1722 (1995) Feynman-Hellman theorem Capstick, Isgur, PRD34,2809 (1986) relativised QM m(Σ b )–m(Λ b )m(Σ b *)–m(Σ b ) data Jenkins, PRD54, 4515 (1996) 1/M Q and 1/Nc expansion Ebert et al, PRD72, (2005) QM with heavy-quark-light-diquark  Good agreement m(Σ b – ) – m(Σ b + ) = 5-7 MeV expect arXiv:

ΞbΞb bsd, bsu

Observation of Ξ b - by D0 and CDF arXiv: J/ ψ Ξ - Ξ b - NEW arXiv: Ξ b - NEW Lattice QCDQMHQET Comparison with predictions Mass measurements are consistent Ξ b - → J/ ψ Ξ -  Good agreement PRL99, PRL99, Proper decay time distribution consistent with expected Ξ b lifetime

 Ground state SU(3) multiplets of charmed baryons are complete.  Flood of highly excited charmed baryons. Charmed baryonsBeauty baryons Summary on Heavy Quark Baryons Λ c (2880) Σb*Σb* ΣbΣb ΞbΞb Σ c (2800) Ξ c (3080) Ξ c (2980) Ωc*Ωc* Ξ c (3055) Λ c (2940) CLEO Belle BaBar D0 CDF  New era in beauty baryon spectroscopy.

Reminder on Pentaquarks  Repeat measurements with high statistics + LEPS – CLAS – Belle + SVD-2 GroupReactionσ’s LEPS  C  K + K - X 4.6 DIANA K + Xe  K 0 p Xe’ 4.4 CLAS-d  d  K + K - p(n) 5.2 SAPHIR  p  K + K 0 (n) 4.8 ITEP- A  K 0 p X 6.7 CLAS-p  p   + K - K + (n) 7.8 HERMES e + d  K 0 p X ~5 ZEUS e + p  e’K 0 p X ~5 SVD-2 pA  K 0 pX 5.5 TOF pp  K 0 p  Θ(1540) + predicted in Chiral Soliton Model Observed in γn→Θ + K - → (K + n)K - and K + n→Θ + →pK S M ~ 1540 MeV/c 2 Γ < 1 MeV Low Γ and M are difficult to explain Θ(1540) + |uudds> Initial evidence: Also many null results, not easily comparable.

Introduction to Pentaquarks  Repeat measurements with high statistics + LEPS – CLAS – Belle + SVD-2 GroupReactionσ’s LEPS  C  K + K - X 4.6 DIANA K + Xe  K 0 p Xe’ 4.4 CLAS-d  d  K + K - p(n) 5.2 SAPHIR  p  K + K 0 (n) 4.8 ITEP- A  K 0 p X 6.7 CLAS-p  p   + K - K + (n) 7.8 HERMES e + d  K 0 p X ~5 ZEUS e + p  e’K 0 p X ~5 SVD-2 pA  K 0 pX 5.5 TOF pp  K 0 p  PDG2006 NEW? Θ(1540) + predicted in Chiral Soliton Model Observed in γn→Θ + K - → (K + n)K - and K + n→Θ + →pK S M ~ 1540 MeV/c 2 Γ < 1 MeV Low Γ and M are difficult to explain Θ(1540) + |uudds> Initial evidence: Also many null results, not easily comparable.

Statistics x1.6  Θ(1540) + signal confirmed, significance increased from 4.4 to 5.3σ  MC verified on tagged kaon data at Belle New DIANA result NEW estimation of Θ(1540) + width K + Xe → p K S Xe’ Assumption Γ, MeV DIANABelle Nuclear suppression is the same for Θ + and nonresonant K 0 p 0.9 ± 0.3<0.64 No nuclear suppression for Θ ± 0.11<0.28 ? my estimate  Contradiction with Belle persists (2.2σ, 2.4%) Inelastic Θ(1540) + production will decrease Belle upper limit M(pK S ) DIANA finds no Θ + signal for p K+ >525MeV 445<p K+ <525MeV p K+ >525MeV  2.9σ fluctuation, decreases significance of DIANA signal 17 events expected -3 found  Evidence for Θ(1540) + from DIANA is weak. PAN70,35 (2007)

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

New COSY-TOF results In previous analysis background was underestimated  significance lower than claimed. PLB649,252 (2007) Statistics x10, improved detection capability  Θ(1540) + signal not confirmed pp → pK 0 Σ +  Evidence for Θ(1540) + from COSY-TOF is negated. NEW PreviousComparison Background shape from new data. Θ+Θ+

New H1 result ep → pK S X No Θ + signal H1 result can be compared with ZEUS result  ZEUS H1  H1 and ZEUS results are in conflict. Extrapolated to ZEUS y-region. (preliminary) Q 2 >20GeV 2, 0.04<y<0.95 ZEUS M(pK S ) PLB639,202 (2006)

Statistics x8  Θ(1540) + signal confirmed, significance increased from 5.5 to ~8σ SVD-2 result: the most significant Θ + signal pA → K S pX K S decays inside / outside Vertex Detector M(pK S )  SVD-2 result strongly contradicts HERA-B, CDF. Θ(1540) + is produced with small x F Group σ[Θ(1540) + ] / σ[ Λ(1520)]  s, GeV SVD-28-12%12 HERA-B<2% at 95% C.L.40 CDF<3% at 90% C.L.2000 For central production difference in energy should not be important. M(pK S ) M = 1523 MeV = 12 MeV Nevnt = 165 M = 1522 MeV = 12 MeV Nevnt = 205 hep-ex/

Other new results on pentaquarks KEK-PS E522 PLB635,72(2006) “ Search for Θ + via π-p→K-X reaction near threshold” OBELIX (LEAR,CERN) NPA779,116(2006) “Search for the Θ + pentaquark in antiproton 4 He annihilation at rest”. CLAS PRL97,032001(2006) “Search for the Θ + pentaquark in the γd→ ΛnK + reaction measured at CLAS ” CLAS PRD74,032001(2006) “Search for the Θ + pentaquark in the reactions γp→K 0 K + n and γp→K 0 K 0 p ” FOCUS PLB639,604(2006) “Search for a pentaquark decaying to pK S ” DELPHI arXiv: Search for Pentaquarks in the Hadronic Decays of the Z Boson with the DELPHI Detector” 2.5σ signal at M=1530MeV No new positive results for doubly strange pentaquark Φ(1860) or charmed pentaquark Θ c (3100) 0. “No stars” in PDG2006  not discussed here.  No significant Θ + signals.

Summary on Θ(1540) +  For  experiment with positive result  experiment with similar conditions but null result. GroupReactionσ’s LEPS  C  K + K - X 4.6 LEPS  d  p K - X DIANA K + Xe  K 0 p Xe’ 4.4 CLAS-d  d  K + K - p(n) 5.2 SAPHIR  p  K + K 0 (n) 4.8 ITEP- A  K 0 p X 6.7 CLAS-p  p   + K - K + (n) 7.8 HERMES e + d  K 0 p X ~5 ZEUS e + p  e’K 0 p X ~5 SVD-2 pA  K 0 pX 5.5 TOF pp  K 0 p  Evidence for Θ(1540) + pentaquark is weak  Not a single convincing evidence for Θ(1540) + unpublished ~5σ New data are taken (2007). Statistics x3. ~5σ In conflict with NOMAD. Not accessible in new data (energy too low). Contradicts BaBar eBe → pK S X ( statistics x100 larger). In conflict with H1. ~8σ~8σContradicts HERA-B, CDF. 5.4σContradiction with Belle persists. unpublished

Conclusions 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 from LEPS, HERA-II. Impressive progress in heavy flavor baryons # charmed baryons 12 → 18 # beauty baryons 1 → 4 Λ c (2880) +, Ω c *, Σ b, Σ b *, Ξ b provide important constraints for theory. To use other new states: Λ c (2940), Σ c (2800), Ξ c (2980), Ξ c (3055), Ξ c (3080), we need symbiosis between theory and experiment. Experiments are consistent and experimental results are robust. over last 2 years New challenges for theory?

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Doubly charmed baryons Λc+K-π+Λc+K-π+ Ξc+π+π-Ξc+π+π- Ξ cc + SELEX New decay channel.  cc +   c + K -  + Selex’s  cc (3520) + is found neither in  c + K -  + nor in  c 0  +  cc +   c + K -  +  cc +   cc 0  + also not seen in photo production (FOCUS) hep-ex/ Not confirmed by BaBar and Belle.