1. 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

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

3. 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 The data are very OLD!!

4. 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)

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

6. 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= GeV
Crystal Ball
2009：
Pk= MeV
We use Effective Lagrange method to analysis these reactions.

7. 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, (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)

8. Pk= GeV

9. 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.

10. 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.

11. 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

12. 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

13. 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.

14. 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: [nucl-th]

15. 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

16. 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!!

17. Thank you!