Study of KStudy of Kp→p→,, and γn and γn → K→ K++Σ*Σ*
JiaJun WU JiaJun WU IHEPIHEP
In collaboration with Pu Ze Gao, S. Dulat, B. S. ZOU and A. Sibirtsev
OutlineOutline
IntroductionIntroductionThe research of KThe research of Kp→p→
The research of γn → KThe research of γn → K++Σ*Σ* The research of KThe research of Kp→ p→ SummarySummary
IntroductionIntroduction resonances in PDG
(1189)1/2+ *(1385)3/2+*(1670)3/2-
*(1775)5/2-*(1915)5/2+ *(2030)7/2+
These information are all from 1970-1985. The data are very OLD!!
****
****(1660)1/2+*(1750)1/2-
*(1940)3/2-*(2250)??*(1620)1/2- *(1690)??*(1880)1/2+*(2080)3/2*(2455)?? *(2620)??
***(1480)?? *(1560)??*(1580)3/2-
*(1770)1/2*(1840)3/2+ *(2000)3/2-
*(2070)5/2+ *(2100)7/2- *(3000)??*(3170)??
*
IntroductionIntroductionExperimental:
The limited data and knowledge of background
Large uncertainties for both established and unestablished *.
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 *(1405)
The Large strange components in N*(1535)
The prediction of 5-quark model
* [us][ds]s ~ 1575 MeV
* [us][du]d ~ 1360 MeV
* [us][ds]u ~ 1520 MeV
Capstick 3q model
IntroductionIntroduction We should re-examine old data, to find some new We should re-examine old data, to find some new
information about information about *.*.
Fortunately, there are 3 new experiments for Fortunately, there are 3 new experiments for *.*.
K p
*n K
CLAS 2005: *0p K
LEPS 2009:
E=1.5-4 GeV
E=1.5-2.4 GeV
2009:Crystal Ball
T. S. Mast, and R. D. Tripp et al. PRD 7, 5 (1973). Pk=0.3—0.6GeV
D. O. Huwe, Phys. Rev. 181, 1824 (1969). Pk=1.0—1.8GeV
0K p Pk=514-750 MeV
We use Effective Lagrange method to analysis these reactions.
Research of KResearch of Kp→p→
Pk=1.0-1.8 GeV
1 2
2 2 2 2 21 ( )
ni
i i i i
dNp p
dm
a
m m m
p1 is module of 3-momentum of in the C.M..
p2 is module of 3-momentum of in the rest system of *.
D. O. Huwe, Phys. Rev. 181, 1824 (1969).
93% *(3/2+)+7% background
ndf=10.1 / 9)
58% *(3/2)+ 37% *(1/2)+ 5% background
(2/ndf=3.2 / 9)
J. J. Wu, S. Dulat and B. S. ZouPRD 80, 017503 (2009)
Pk=0.3-0.6 GeV
100% *(3/2+)
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.
J. J. Wu, S. Dulat and B. S. Zou PRC 81,045210
59% *(3/2)+ 41% *(1/2)59% *(3/2+)
12.5% *(1/2-)
Interference
γn → Kγn → K++Σ*Σ*
*0p K
//
• Total cross section of CLAS well described.
• differential cross section of LEPS data also be described, but not for the beam asymmetry Abeam .
*n K
Hicks, et.al. (LEPS), PRL102,012501(2009)
Two Methods to Solve this Problem.
//
//beamA
and denote the cross sections for beam polarization vertical and parallel to reaction plane, respectively.
K
K
*(3/2)*(1/2)
K
a. Including
K
K
+
b. Tuning parameter h in contact term for
• h=1 for to describe the total cross section.
• Free h for without .
*0p K *n K
h is the parameters of contact term
Puze Gao, J. J. Wu, B. S. Zou, PRC81:055203
Include
h=1.11
ddcosc.mfor n K compared with LEPS data
h=1.0
*0p K
KKp→ p→
Crystal Ball 2009: 0K p pK=514-750 MeVPrakhov et al., PRC 80,025204
The 4-star resonances as follows are always included
With only t-, u- and the above 4 s-channels, the best fit of 17 parameters gives =763 for the 248 data points, including
(1189)1/2+ *(1385)3/2+*(1670)3/2-*(1775)5/2-
*(1915)5/2+ *(2030)7/2+
Differential cross
sections
polarization
is the angle of 0 and K- in the C.M. frame.
with inclusion of (1660)1/2+, =223 for 248 data points with 21 free parameters.
Best results with (1660)1/2+, fitted parameters for resonances
KKp→ p→ 00
Puze Gao, B.S. Zou, A. Sibirtsev arXiv:1011.2387 [nucl-th]
For (1380)1/2-, the present data is insensitive to it, and it is neither supported nor excluded.
Differential cross sections
SummarySummary
With the analysis of three reactions:With the analysis of three reactions:
K p→ ππΛK p→ ππΛ
γn → KΣ*γn → KΣ*
K p→πΛK p→πΛ
The evidence of *(1/2-) predicted by the penta-quark models.
Existence of (1660)1/2 +(***), with mass near 1635MeV, width 121MeV.
Need More experiment data to confirm them!!
Thank you!Thank you!