1. June 16-20, 2005 北京 1 Atsushi Hosaka (RCNP, Osaka Univ) Decay and production of  + hep-ph/0409102, PRD71: 074021 (2005) A. H., M. Oka and T. Shinozaki hep-ph/0502093, PRD71: 054017 (2005) T. Hyodo and A. H. hep-ph/0505134, hep-ph/0503149 to appear PRD S.I. Nam, A.H. and H.-Ch. Kim Decay and production mechanism for  + (J P ) with renewed interest in  (1520)

2. June 16-20, 2005 北京 2 Facts ~ very narrow width ・ In production experiments,  << 20 MeV ・ In KN scattering 1 MeV or less T. Nakano et al. PRL, 91, 012002 (2003) A.Sibirtsev et al, PLB599 (2004) 230-235  = 1, 5, 10, 20 MeV More data from Nakano in this conference

3. June 16-20, 2005 北京 3 Outline 1. Decay of  + General remark Fall-apart in the quark model 2. Possibility of spin 3/2 - Phenomenological analysis 3. Photoproduction reconsidered pn asymmetry  n -> K -  + vs.  p -> K 0  + [  + or  (1520)]

4. June 16-20, 2005 北京 4 1. Decay of  +

5. June 16-20, 2005 北京 5 1/2 + P-wave coupling M* = 1540 MeV, g KN  ~ 10 1/2 – S-wave coupling  = 5 GeV Effect of entrifugal barrier ~ 50 ! Empirical fact: g mNN* < 10 (  NN or  NN)  = 100 MeV Simple estimate

6. June 16-20, 2005 北京 6 Fall apart decay Expected to be a dominant process in a constituent QM Fall apart, or diossociate 5q 4q 3q ~ 5q 2q 5q ~ Other mechanisms? N i = N f N i < N f

7. June 16-20, 2005 北京 7 Amplitude Rearranged ++ K N S-factor Intereaction N-like K-like V T ~ V fi We consider fall apart in the quark model

8. June 16-20, 2005 北京 8 Mqq of Yukawa type Interaction ~ V fi for Useful as a reference for further studies

9. June 16-20, 2005 北京 9 Negative parity ground state (0s) 5 Unique ~ AS KN state g KN  ~ 3 =>  ~ 0.5 - 1 GeV S-factor S-factor ~ p s (0s) 5 Carlson et al, PLB 573, 101 (2003) AH et al,

10. June 16-20, 2005 北京 10 Positive parity More complicated than s-wave due to p-wave excitation (1) Minimize Spin-Flavor interaction (2) Minimize Spin-Color (3) Diquark correlation of JW p s (0s) 4 0p We consider

11. June 16-20, 2005 北京 11 Spectroscopic factors SF SC JW > > Carlson et al, PRD70, 037501 (2004), hep-ph/0312325, Jennings-Maltman, PRD 69, 094020 (2004), hep-ph/0308286

12. June 16-20, 2005 北京 12 Results  (1/2 - ) >>  (1/2 + )

13. June 16-20, 2005 北京 13 We have seen: ・ Natural width of Pentaquarks 1/2 − ~ GeV 1/2 ＋ < 100 MeV <= Centrifugal force ・ Quark model values are consistent with them (0s) 5 1/2 – : as dominated by KN => can not be a narrow resonance 1/2 ＋ with JW-diquark correlation -> 10 MeV (or could be less) Spatial correlation can reduce ~ 1 MeV? dynamical question

14. June 16-20, 2005 北京 14 Other possibility Could it be (0s) 5 3/2 ー Decay into KN is suppressed due to d-wave K * (1 ー )N dominant but no decay into this channel No spin partner of 1/2 – …. Too broad to see

15. June 16-20, 2005 北京 15 2. Phenomenology of 3/2 - baryons Hyodo-Hosaka, hep-ph/0502093, PRD71:054017 (2005)

16. June 16-20, 2005 北京 16 with 8-10 mixing N  SU(3) description  +, N 1, N 2,         6 parameters

17. June 16-20, 2005 北京 17 Choose suitable baryons of J P = 1/2 + -, 3/2 + -, adding  + -> 6 baryons are enough Fitting into the SU(3) scheme with 8-10 mixing 1/2 + 3/2 - We can fix the mixing angle 

18. June 16-20, 2005 北京 18 Coupling constants g 8 and g 10  N can be fixed by masses Two nucleon decay widths determine g 8 and g 10 The resulting g 10 determines     (MeV) Decay widths

19. June 16-20, 2005 北京 19 3. Photoproductions

20. June 16-20, 2005 北京 20 This is serious, but showing absence of  + ?  p -> n K + K 0 New data from J-Lab  p n K+K+ K0K0 ++ Teken from DeVita’s talk at spring APS meeting

21. June 16-20, 2005 北京 21 Theoretical study Effective Lagrangian method hep-ph/0505134 Nam-Hosaka-Kim appears only for n-target

22. June 16-20, 2005 北京 22 Prior to this  n -> K -  (1520) and  p -> K 0  (1520) was studied and large pn asymmetry was found Nam-Hosaka-Kim, hep-ph/0503149 to appear PRD The role of the contact term (Kroll-Ruderman type) was emphasized

23. June 16-20, 2005 北京 23 Total  Angular dist Log-scale Theta production, J P = 3/2 -

24. June 16-20, 2005 北京 24 The role of the contact term is more important for J P = 3/2 - than 1/2 +

25. June 16-20, 2005 北京 25 Predictions We see a large asymmetry between pn targets Cross section for proton ~ few nb is consistent with the upper limit estimated by CLAS

26. June 16-20, 2005 北京 26 Summary Fall-apart decay in the quark model 1/2 – ~ GeV 1/2 + Several tens MeV could be 10 MeV or less for JW 3/2 – ~ zero or strongly suppressed SU(3) analysis 3/2 – is a natural candidate Photoproduction, revised There is a large pn asymmetry, especially for J = 3/2 No signal from the CLAS does not lead immediately to the absence of  + For  (1520), consistent with recent observation of LEPS New data from LEPS is interesting and important => Talk by Takashi Nakano

27. June 16-20, 2005 北京 27 Comments (1) A related work Melokov, Simula and Stech, PLB 594 (2004) 265 Claimed that  ~ 150 MeV for the JW wf In the quark model, there is no pole (h A ) term ==> Can not be applied to the quark model Assumption

28. June 16-20, 2005 北京 28 (2) 5-body calculation Confined state KN Scattering state + +... Recent calculation by Hiyama Gaussian Expansion Method Coupling to other channels including KN changes the nature of the confined state drastically Fall apart when R→∞

29. June 16-20, 2005 北京 29 1/2 – 1/2 + KN-like JW-type (0s) 5 1/2 –, (0s) 4 0p 1/2 + can no longer survive