Summary of Workshop? K.Imai (Kyoto) It is impossible to summarize all talks More and more data of the peak for  + We still don’t know what is  + Other exotics are also observed? We need more data and calculations Lets encourage exotics hunters K.Imai: Exotics 04/2/19 (Kyoto) K.Imai: Exotics 04/2/19 (Kyoto)

Sad story of old exotics Z* (old pentaquark) magic 15 years cycle Baryonium disappearence of beautiful peak Sextuquark (NN dibaryon) no more phase shift analysis no more stable H-dibaryon Motivation of KEK-PS K2,K3 beamlines

Exotic S=+1 Baryon NOTE ON THE S = + 1 BARYON SYSTEM (PDG 1986; Phys. Lett. B170, 289) The evidence for strangeness +1 baryon resonances was reviewed in our 1976 edition, 1 and more recently by Kelly 2 and by Oades. 3 Two new partial-wave anaIyses 4 have appeared since our 1984 edition. Both claim that the P 13 and perhaps other waves resonate. However, the results permit no definite conclusion- the same story heard for 15 years. The standards of proof must simply be much more severe here than in a channel in which many resonances are already known to exist. The general prejudice against baryons not made of three quarks and the lack of any experimental activity in this area make it likely that it will be another 15 years before the issue is decided. References 1. Particle Data Group, Rev. Mod. Phys. 48, SI88 ( 1976). 2. R.L. Kelly, in Proceedings of the Meeting on Exotic Resonances (Hiroshima, 1978), ed. I. Endo et al. 3. G.C. Oades, in Low and Intermediate Energy Kaon-Nucleon Physics (1981), ed. E. Ferrari and G. Violini. 4. K. Hashimoto, Phys. Rev. C29, 1377 (1984); and R.A. Arndt and L.D. Roper, Phys. Rev. D31, 2230 (1985).

Discovery of Lambpha Phys. Rev. Lett. 87 (2001)

 Invariant mass J.K.Ahn et al., (E224) Phys. Lett. B444 (98) 267 C.J.Yoon: new experiment

Happy story (hopefully) of  +  1540  10 MeV  < 25 MeV Gaussian significance 4.6  background T. Nakano et al., Phys.Rev.Lett. 91 (2003) Renaissance of hadron spectroscopy !

Summary of positive results Experiment LEPS/SPring-8 DIANA CLAS(d) SAPHIR ITEP( ) CLAS(p) HERMES ITEP(p) ZEUS : 1540  10  5 : 1539  2  few : 1542  2  5 : 1540  4  2 : 1533  5 : 1555  1  10 : 1528  2.6  2.1 : 1526  3  3 : : 25 : 9 : 21 : 25 : 20 : 26  7 : 19  5  2 : 24 : 23    Mass (MeV)  (MeV) Y. Mao S.Chekanov

Yajun Mao for HERMES Collaboration, YITP Multi-quark Workshop, Feb , 2004 Comparison With Other Experiments For a better comparison, take result from simply BG fitting Left panel: mass average = 1532±2.4MeV ( take ±3MeV of syst. error for ITEP, DIANA ) Right panel: width FWHM ( include detector resolution )

Increasing number of papers

What is  + ? Theorest ’ s answer Chiral Soliton Quark model conventional correlated diquark Hadronic bound state Others Jaffe, Lutz, Oka, Ko Hosaka, Kim, Ma, Gerasyuta

What is  + ? Experimentalists should answer Mass MeV 1 or 2 resonance Width Upper limit ? 1MeV from KN PSA ? Spin-parity 1/2 + 1/2 - 3/2 + 3/2 - ? Other member of anti-decuplet ? we need dedicated experiment at  + factory high statistics high resolution Jlab, SP8, KEK,,, H.Gao, K.I

To establish anti-decuplet  - - n K - -> K +  - -, p K - -> K +  +  - -  + p K - -> K 0  -  + S=-2 S=0 Diakonov MeV Jaffe, Wilczek MeV If M(  -- ) ~ 1750 MeV (Jaffe & Wilczek, hep-ph/ ) >2GeV/c K- beam (BNL or KEK or (J-PARC)) !

S=-2 Penta-quark  -- IK Yoo （ NA49 collaboration ） M=1862 MeV  <18 MeV hep-ex/

“ Experimental ” data from Lattice QCD A.Nakamura, S.Sasaki, N.Mathur 1/2- is lower than 1/2+ ?  + was found ? Yes and No -> need more “ L-QCD experiments”

Quartet quark ? New data from B-factories Yamamoto / Terasaki, Ko D sJ D** J/  Scalar meson Jaffe, Kunihiro, Harada, Nakamura revisit to long standing problem Chiral symmetry diquark correlation Why precise cancellation of attractive and repulsive NN force occur to create human being? Degree of chiral symmetry breaking or diquark correlation or God ?

 (1405) and Kaonic-nuclei Nemoto, Ahn, Hyodo, Akaishi, Yamazaki, Dote  (1405) another longstanding problem 3 quark or “pentaquark” ? Kaonic-nuclei may open new aspect of manybody problem with strangeness New data is coming (after 30 years) Experimental and theoretical works are accelerated by  + effect!

Conclusion Exciting period for exotic hadron physics has come. We have many thing to do in next 15 years until exotics becomes nonexotic physics.

謝辞 Thank you very much for joining this workshop ! A lot of thanks to supporting staffs, Ms. Tsuruhara, Takami, Yagi, Okada, Arimoto, Endo Mr. Takimi, Nawa Kojo, Tsumura, Kitazawa