1. Evidence for a new resonance S *(1380) with J P =1/2  JiaJun WU In collaboration with S. Dulat and B. S. ZOU

2.  Introduction.  First evidence from   p      at Plab   GeV.  Second evidence from   p      at Plab   GeV.  Summary.

3. Introduction  The classical constituent quark models are based on the assumption of three constituent quarks inside each baryon.  The lowest excitation of baryons is the orbital angular momentum L =1 excitation of a quark, resulting to spin parity 1/2 .  There are many problems of these quark models. Next we will give two examples.

4.  u /  d asymmetry in the proton The number of  d is more than  u:  d  u =0.12 This result demands its 5-quark components to be at least 12%. meson cloudpenta-quark u du SS SS SS u u SS d G. T. Garvey and J. C. Peng, Prog. Part. Nucl. Phys. 47,203 (2001), N. Kaiser, P. B. Siegel, and W. Weise, PLB 362,23 (1995). D. Jido, J. A. Oller, E. Oset, A. Ramos, and U. G.Meissner, NPA725, 181 (2003). C. Helminen and D. O. Riska, NPA699, 624(2002). S. L. Zhu, etc. High Energy Phys. Nucl. Phys. 29, 250(2005). B. S. Zou, EPJA35, 325 (2008).

5. N*(1535) ~ [ud][us]  s  *(1405) ~ [ud][su]  u The mass order reverse problem In the constituent quark models N*(1535) ~ uud (L=1)  *(1405) ~ uds (L=1) In the penta-quark models N*(1535) ~   *(1405) ~ KN  In the meson cloud models

6. The prediction of 5-quak model  * [us][ds]  s ~ 1575 MeV  * [us][du]  d ~ 1360 MeV  * [us][ds]  u ~ 1520 MeV Capstick 3q model

7. First evidence from   p      at Plab    GeV. D. O. Huwe, Phys. Rev. 181, 1824 (1969).           p 1 is module of 3-momentum of   in the C.M.. p 2 is module of 3-momentum of   in the rest system of  *.

8. Jia-Jun Wu, S. Dulat and B. S. Zou PHYSICAL REVIEW D 80, 017503 (2009)

9. 93% S *(3/2 + )+7% background     ndf=10.1 / 9) 58% S *(3/2  )+ 37% S *(1/2  )+ 5% background (  2 / ndf=3.2 / 9) 1.For M  in the range of 1340- 1430 MeV. 2.The range of beam momen-tum is 1–1.45 GeV. 3.Cos( . K) > 0.95 For  *(3/2 + ): (1+ 3cos2  )/2 For  *(1/2 - ) and background: 1 Robert K. Adair, Phys. Rev. 100, 1540 (1955). D. O. Huwe, PR 181, 1824 (1969).

10. Second evidence from   p      at Plab    GeV. T. S. Mast, and R. D. Tripp et al., PRD 7, 5 (1973). M. B. Watson and R. D. Tripp et al., PR 131, 2248 (1963). R. Armenteros et al., Nucl. Phys. B 21, 15 (1970). The theoretical mechanisms

11. From the picture, the result of our calculation is very close to the experiment points at the range of  *(1520). Jia-Jun Wu, S. Dulat and B. S. Zou arXiv: 0909, 1380

12. 100%  *(3/2 + ) 60%  *(3/2  )+ 40%  *(1/2  ) Phase space First reason: S-wave between the  *   3/2 + ) and    but P-wave between the  *  (1/2  ) and  . Second reason: the width of  *   3/2 + ) is 35.5MeV;  but that of  *  (1/2  ) is 118.6MeV from fit before. T. S. Mast, and R. D. Tripp et al. PRD 7, 5 (1973).

13. Summary  We find some evidence that a new resonance  *(1/2  ) exists in the K-p reaction.  Higher statistic data experiments are necessary to establish this new resonance and to understand its property.

14. Thank you