Study of K-p→Lp+p-, Lp0 and γn → K+Σ*- JiaJun WU IHEP In collaboration with Pu Ze Gao, S. Dulat, B. S. ZOU and A. Sibirtsev

Outline Introduction The research of K-p→Lp+p- The research of γn → K+Σ*- The research of K-p→ Lp0 Summary

Introduction S resonances in PDG S (1189)1/2+ S*(1385)3/2+ S*(1670)3/2- S*(1775)5/2- S*(1915)5/2+ S*(2030)7/2+ **** S*(1660)1/2+ S*(1750)1/2- S*(1940)3/2- S*(2250)?? *** S*(1620)1/2- S*(1690)?? S*(1880)1/2+ S*(2080)3/2+ S*(2455)?? S*(2620)?? ** S*(1480)?? S*(1560)?? S*(1580)3/2- S*(1770)1/2+ S*(1840)3/2+ S*(2000)3/2- S*(2070)5/2+ S*(2100)7/2- S*(3000)?? S*(3170)?? * These information are all from 1970-1985. The data are very OLD!!

Introduction Experimental: Theoretical: Large uncertainties for both established and unestablished S*. The limited data and knowledge of background New resonances have not been discovered. Theoretical: There are many new models for baryon compared to the 30 years ago : penta-quark models and meson cloud models `u /`d asymmetry in the proton The mass order reverse problem between N*(1535) and L*(1405) The Large strange components in N*(1535)

The prediction of 5-quark model L* [us][ds]`s ~ 1575 MeV S* [us][du]`d ~ 1360 MeV X* [us][ds]`u ~ 1520 MeV Capstick 3q model

Introduction We should re-examine old data, to find some new information about S*. Fortunately, there are 3 new experiments for S*. D. O. Huwe, Phys. Rev. 181, 1824 (1969). Pk=1.0—1.8GeV T. S. Mast, and R. D. Tripp et al. PRD 7, 5 (1973). Pk=0.3—0.6GeV CLAS 2005： Eg=1.5-4 GeV LEPS 2009： Eg=1.5-2.4 GeV Crystal Ball 2009： Pk=514-750 MeV We use Effective Lagrange method to analysis these reactions.

Research of K-p→Lp+p- Pk=1.0-1.8 GeV 93% S*(3/2+)+7% background (c2/ndf=10.1 / 9) D. O. Huwe, Phys. Rev. 181, 1824 (1969). J. J. Wu, S. Dulat and B. S. Zou PRD 80, 017503 (2009) p1 is module of 3-momentum of p+ in the C.M.. p2 is module of 3-momentum of p- in the rest system of S*. 58% S*(3/2+)+ 37% S*(1/2-)+ 5% background (c2/ndf=3.2 / 9)

Pk=0.3-0.6 GeV

59% S*(3/2+)+ 41% S*(1/2-) 59% S*(3/2+) 100% S*(3/2+) Interference Phase space 12.5% S*(1/2-) J. J. Wu, S. Dulat and B. S. Zou PRC 81,045210 First reason: S-wave between the S*-(3/2+) and p+ ; but P-wave between the S*-(1/2-) and p+ . Second reason: the width of S*-(3/2+) is 35.5MeV; but that of S*-(1/2-) is 118.6MeV from fit before.

γn → K+Σ*- g N KpL Total cross section of CLAS well described. differential cross section of LEPS data also be described, but not for the beam asymmetry Abeam . and denote the cross sections for beam polarization vertical and parallel to reaction plane, respectively. K g N KpL N,D S*(3/2) S*(1/2) L,S* Hicks, et.al. (LEPS), PRL102,012501(2009) Two Methods to Solve this Problem.

g N KpL + a. Including S(1380)1/2- N,D N + S(1/2-),(L) L,S* K b. Tuning parameter h in contact term for h=1 for to describe the total cross section. Free h for without S(1380)1/2-. h is the parameters of contact term Puze Gao, J. J. Wu, B. S. Zou, PRC81:055203

ds/dcosqc.m. for gn ->KS* compared with LEPS data Include S(1380)1/2- h=1.11 ds/dcosqc.m. for gn ->KS* compared with LEPS data

K-p→ Lp0 Crystal Ball 2009： pK=514-750 MeV Prakhov et al., PRC 80,025204 With only t-, u- and the above 4 s-channels, the best fit of 17 parameters gives c2 =763 for the 248 data points, including Differential cross sections The 4-star S resonances as follows are always included S (1189)1/2+ S*(1385)3/2+ S*(1670)3/2- S*(1775)5/2- S*(1915)5/2+ S*(2030)7/2+ L polarization q is the angle of p0 and K- in the C.M. frame.

K-p→ Lp0 Best results with S(1660)1/2+, fitted parameters for S resonances with inclusion of S(1660)1/2+, c2 =223 for 248 data points with 21 free parameters. Puze Gao, B.S. Zou, A. Sibirtsev arXiv:1011.2387 [nucl-th]

Differential cross sections For S(1380)1/2-, the present data is insensitive to it, and it is neither supported nor excluded. Differential cross sections

Summary With the analysis of three reactions: K p→ ππΛ γn → KΣ* K p→πΛ The evidence of S*(1/2-) predicted by the penta-quark models. Existence of S(1660)1/2 +(***), with mass near 1635MeV, width 121MeV. Need More experiment data to confirm them!!

Thank you!