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Pentaquarks : 五夸克态

Pentaquarks : 五夸克态. Bo-Qiang Ma ( 马伯强 ) PKU ( 北京大学物理学院 ) August 14, 200 4 talk at CCAST Wokshop on QCD and RHIC Physics. ?. In Collaboration with B. Wu Hep-ph/0312041, PRD69(2004)077501 Hep-ph/0312326, PLB586 （ 2004 ） 62

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Pentaquarks : 五夸克态

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  1. Pentaquarks: 五夸克态 Bo-Qiang Ma (马伯强) PKU (北京大学物理学院) August 14, 2004 talk at CCAST Wokshop on QCD and RHIC Physics ? In Collaboration with B. Wu Hep-ph/0312041, PRD69(2004)077501 Hep-ph/0312326, PLB586（2004）62 Hep-ph/0311331, Hep-ph/0402244 Hep-ph/0408121 all to appear in PRD Also HERMES Collaborators (Y.Mao et al.): PLB585(2004)213.

  2. A Break Through of Hadron Physics in 2003：Pentaquark五夸克态 • Second Item of Top 10 Physics News in 2003 In News: • Nature Science Update: “…could have important implications for understanding of the early universe” • BBC News: “should have far-reaching consequences for understanding the structureof matter” • MSN: “a new classification of matter…”

  3. Search for Exotic Baryon States

  4. Baryon States Y 0 I Z

  5. Previous Searches for Exotic Baryons

  6. L(1405) as 5-quark state Jue-Ping Liu, Z.Phys.C 22(1984)171 • Using QCD sum rule method to calculate the 5-quark component of L(1405) • But cannot rule out miminal uds component in the state

  7. Pentaquark States • Predictions of pentaquark states with both strange and charm (by Lipkin et al.), no evidence found in experimental searchesformore than ten years.

  8. Prediction in Chiral Soliton Model pK0 or nK+

  9. Suggestion for the existence of higher multipletsM.-L.Yan and X.-H.Meng,Commun. Theor. Phys. 24 (1995) 435 • The corrections to the Gell-Mann-Okubo relations of baryons masses in SU(3) Skyrmen model are considered. • The results could be regarded as a signal for the existence of the SU(3) rotation excitation states of baryons: 27-plet, 10*-let, and 35-let.

  10. Nothing is “Exotic” in the Chiral Solition Picture • Baryons are “solitons” in the chiral fields. • No baryon is “exotic” except that it has different quantum numbers compared to other baryons.

  11. “Exotic”-baryon (Pentaquark) DefinationH.Gao and B.-Q. MaMod. Phys. Lett. A 14 (1999) 2313 • A pentaquark qqqqq state can be clearly distinguished from the conventional qqq-baryon state or their hybrids if the flavor of q is different from any of the other four quarks: minimal Fock state of pentaquark • Possible existence of uudds and uuuds states are suggested. -

  12. Suggestion for search of pentaquark uudds statein physics processH.Gao and B.-Q. MaMod. Phys. Lett. A 14 (1999) 2313 • Suggested: *n K-Θ+ missing mass method to construct Θ+ • SPring8 and CLAS experiments: sub-process n K-(K+n) an additional K+ is detected to reduce background for the missing mass spectrum and real photon is used instead of virtual photon.

  13. What is a Pentaquark

  14. HERMES Result: Talk by Yajun Mao at Tokyo Resonance is observed at 1528  2.6  2.1 MeV Width is FWHM = 19  5  2 MeV Naïve significance in ±2s ~ 4.7s True significance 59/16 ~ 3.7s Unbinned fit is used: result doesn’t depend on bin size and starting point Yajun Mao for HERMES Collaboration, YITP Multi-quark Workshop, Feb. 17-19, 2004

  15. Where else to look for Q+ Production

  16. world-average: M(Q+): 15322.4 MeV Summary of recent experiments

  17. Summary of recent Evidence for

  18. Summary of Null Results

  19. no evidence forQ++  K+p in HERMES Suggesting Q+Being Isosinglet I=0 is likely I=2 is ruled out I=1 is unlikely, but cannot be ruled out X.Chen, Y.Mao, and B.Q.Ma, hep-ph/0407381

  20. Pentaquark States from Theory:anti-decuplet in chiral soliton models-1st version

  21. S Prediction of Diquark model R.L. Jaffe and F. Wilczek, PRL91 (2003) 232003 [ud]2s +(1530) 1 I3 -1 1 *0 -1 *- *0 3/2(1750) [ds]2u [us]2d

  22. Evidence for New Pentaquark? pp *--X, *0X,  - -  -+ NA49 at CERN C. Alt et al., hep-ex/0310014 s = 17,2 GeV SM:M(*--) = 2070 MeV [qiqj]2q:M(*--) = 1750 MeV But: It is not what theory predicted ! D. Diakonov et al., hep-ph/0310212 1,862  0,002 GeV

  23. Anti-Decuplet in Chiral Soliton Model - Version 2 D. Diakonov andV. Petrov hep-ph/0310212 B. Wu and Ma, hep-ph/0311331, PRD S uud ds +(1539) 1 I3 sdu.. duu(dd+ss) N(1647) -1 1 *0 108 MeV sdd.. sdu.. suu(dd+ss) (1754) -1 *- *0 3/2(1862) ssu.. ssd (uu+dd) ssd du ssu ud

  24. Where are the missing members of antidecuplet? • For baryons with spin ½ and + parity, there is no N around, and a weak evidence for S(1770), so Diakonov and Petro (hep-ph/0310212) suggeted a missing N around 1650-1690 MeV; the position of N(1710) is not at M=1710 MeV, but some where around M=1650 to 1690 MeV, suggested by Arndt et al(nucl-th/0312126) . • We noticed ( hep-ph/9311331) that there are candidates of N(1650) and S(1750) with spin ½ and negative (–) parity, in PDG This maysuggest a negative parity for antidecuplet members in the chiral soliton model: parity in chiral solition has two parts: quantized part with positive parity and classical part with unknown parity; the collective coordinate quantization can not inevitably fix the parity of the corresponding baryons.

  25. The width formula and the widths in the case of negative parity decay width is excellent for S(1750), but poor for N(1650) , possible solution: SU(3) breaking for baryons with strangeness, or there is a missing N resonance around 1650 with narrow width.

  26. Theories of positive parity forQ+ • Chiral Soliton Models (old version) Diakonov-Petrov-Polyakov, ZPA359(1997)305 • Analysis in Quark Model Stancu-Riska, PLB575(2003)242 • Diquark Cluster Model Jaffe-Wilczek, PRL91(2003)232003 • Diquark-Triquark Model Karliner-Lipkin, PLB575(2003)249 • Inherent Nodal Structure Analysis Y.-x.Liu, J.-s.Li, and C.-g. Bao, hep-ph/0401197

  27. Theories of negative parity forQ+ • Naive Quark Model Jaffe (1976) • Some Quark Models Capstick-Page-Roberts, PLB570(2003)185 Huang-Zhang-Yu-Zhou, hep-ph/0310040，PLB • QCD Sum Rules Zhu, PRL91(2003)232002, Sugiyama-Doi-Oka, hep-ph/0309271 • Lattice QCD Sasaki, hep-ph/0310014, Csikor et al, hep-ph/0309090, but we heard difference voices recently

  28. Where is the answer? Experiment! • Many suggestions on detecting the parity Oh-Kim-Lee, hep-ph/0310019 Zhao, hep-ph/0310350 Liu-Ko-Kubarovsky, nucl-th/0310087 Nakayama-Tsushima, hep-ph/0311112 Thomas-Hicks-Hosaka, hep-ph/0312083 …… • Measurement of parity is crucial to test theories

  29. What else if I=0 or S=1/2 / / • Answer: Most theories would need revision! Would be a new surprise!

  30. Predictions of New Pentaquarks-27-plet Figure from Wu & Ma, PRD69(2004)077501.

  31. The mass splitting of the 27-plet from chiral solitons

  32. The widths of the 27-plet baryons SU(3) Symmetric Case

  33. The picture of the 27-plet baryons:non-exotic members are well established We suggest that the quantum numbers ofX(1950) is JP=(3/2)+

  34. Many new pentaquarksto be discovered

  35. Predictions ofQ* • Walliser-Kopeliovich, hep-ph/0304058 mass=1650/1690 MeV • Borisyuk-Faber-Kobushkin, hep-ph/0307370 mass=1595 MeV, width=80 MeV • Wu-Ma, PLB586(2004)62 mass=1600 MeV, width less than 43 MeV

  36. Predictions of New Pentaquarks-35-plet Figure from Wu & Ma, PRD, to appear .

  37. Mass splitting of 35-plet from chiral solitons

  38. The widths of the 35-plet baryons SU(3) Symmetric Case

  39. Prediction of Pentaquarks in SU(4) Chiral Solition Model B.Wu and B.-Q.Ma, hep-ph/0402244, PRD to appear

  40. Experiment Evidence at H1 hep-ex/0403017

  41. The pentaquark uuddc _ • Prediction of the mass of the ground uuddcbar: m=2704 MeV, as pD state Wu-Ma, hep-ph/0402244 • Observation by H1 Collaboration: m=3099 MeV hep-ex/0403017 can be considered as pD* state • From M(D*-D)~300 MeV, the observed uuddcbar can be considered as an excited state (chiral partner) of the predicted ground pentaquark state M. Nowak et al, TPJU-4/2004, BNL-NTBNL-NT-04/10

  42. Conclusions • The discovery of pentaquark Q+，if confirmed, opens a new window to understand the basic structure of matter. • Measurement of the parity, isospin and spin of Q+is crucial to test different theories • There could be new pentaquark states waiting for discovery

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