Mar. 1-3, 2007 特定領域研究会鳥羽 1

Photo-productions of Kaons and Hyperons

Atsushi Hosaka, RCNP, Osaka University

1. Chiral symmetry 1. Gauge inv.: Kroll-Ruderman term N –> K(1520), N –> K(1520) 2. Tomozawa-Weinberg

2. SU(3) symmetry violation? N –> Kg.s. and the use of polarization

Mar. 1-3, 2007 特定領域研究会鳥羽 2

Effective lagrangian method

Good physics intuitions if separated

NN Y, Q, …Y, Q, …

Higher order corrections are classified either one of them

Mar. 1-3, 2007 特定領域研究会鳥羽 3

StrategyUse fundamental symmetry relations as much as possible

Chiral, flavor, u-spin, KR-asymmetry and so on

(1) Kroll-Ruderman: Proton-neutron asymmetry(2) TW (gV=1)(3) Yukawa: F/D ratio, Decay pattern: (1405) –> KN, , etc(4) U-spin: 8 –> 10 process

Mar. 1-3, 2007 特定領域研究会鳥羽 4

Chiral symmetry 1: Gauge inv. Role of the Kroll-Ruderman term

Mar. 1-3, 2007 特定領域研究会鳥羽 5

present only for charge-exchangereactions

Particularly important for J = 3/2J = 1/2 の場合はそれほどでもない

p –> K(1520), n –> K

Mar. 1-3, 2007 特定領域研究会鳥羽 6

p –> K (1520) J = 3/2–

Nam-Hosaka-Kim, PRD 71:114012,2005

Energy dependence t or dependence

= 700 MeV <=> r ~ 0.8 fm

Mar. 1-3, 2007 特定領域研究会鳥羽 7

p p ++*, *, n n ++**

p p 00*, *, n n ––**

= 700 MeV <=> r ~ 0.8 fm

Mar. 1-3, 2007 特定領域研究会鳥羽 8

Chiral symmetry 2:Role of the Tomozawa-Weinberg

Mar. 1-3, 2007 特定領域研究会鳥羽 9

(, K) and (K, ) reactions KEK experiments

+

K K

Tomozawa-Weinberg term

TW

Forbidden due to offdiagnality

Tomozawa-Weinberg (gV=1)

Mar. 1-3, 2007 特定領域研究会鳥羽 10

Theoretical question

PS: Linear sigma model suited to dynamical description for chiral symmetry breaking BUT no convergence in perturbation better large k behavior

PV: Non-linear sigma model Good convergence at low momentum

At low energies, PV should be used with FFConsistent with the low energy theorem Some confusions

Mar. 1-3, 2007 特定領域研究会鳥羽 11

Estimation

PS

PSPV PV

T. Hyodo (YITP)

Mar. 1-3, 2007 特定領域研究会鳥羽 12

2. SU(3) symmetry violation?

Mar. 1-3, 2007 特定領域研究会鳥羽 13

SU(3) symmetry

Current masses: mu, md ~ 10 MeV, ms ~ 100 MeV BUTConstituent masses: mu*, md* ~ 300 MeV, ms* ~ 400 MeV

It is likely that SU(3) symmetry is good for basic interactions BUTmay break through dynamical effects m << mK

=> Strongly coupled meson-baryon dynamics Spontaneous breaking of chiral symmetry

Mar. 1-3, 2007 特定領域研究会鳥羽 14

Production of K and (1116)

Studied many years: BUT we can learn something essential now

• Can SU(3) relations be used?

• How strongly does the K* couple to N and Y?

Pion production: well knownKaon production: less understood Large ambiguities

Mar. 1-3, 2007 特定領域研究会鳥羽 15

Various couplingsBennhold Ozaki

~SU(3)Set1 Set2

– 3.09 –3.80 –4.091.23 1.20 0.78–0.19 –0.51 –0.07–0.12 0.67 0.16–0.08 –0.31 –0.11-0.08 –0.61 –0.37

€

gKΛN / 4π

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gKΣN / 4π

€

gKK*γ gK*ΛNV /4π

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gK*Kγ gK*ΛNT /4π

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gK*Kγ gK*ΣNV /4π

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gK*Kγ gK*ΣNT /4π

Wea

k

Stro

ng

Mar. 1-3, 2007 特定領域研究会鳥羽 16

p –> K+

Weak K* ~ SU(3)Strong K*

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TotalSAPHIA

W ~ 2.1 GeV

Mar. 1-3, 2007 特定領域研究会鳥羽 17

p –> K+

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E = 1.9 GeV, W ~ 2.1 GeV

dependence

SAPHIA

LEPS

CLAS

Weak K* ~ SU(3)Strong K*

Mar. 1-3, 2007 特定領域研究会鳥羽 18

p –> K+

Weak K* ~ SU(3)Strong K*

E = 1.9 GeV, W ~ 2.1 GeV

AsymmetryA

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0.5

- 0.5

LEPS

Asymmetry A

Mar. 1-3, 2007 特定領域研究会鳥羽 19

Role of K*

Strong K* => pn asymmetry is not so largeWeak => could be large due to contact term

Information of n-target is very important

Mar. 1-3, 2007 特定領域研究会鳥羽 20

Something is missing?

Meson clouds

Anomalous process

Magnetic

Spin 3/2

Mar. 1-3, 2007 特定領域研究会鳥羽 21

Summary

There are many important but not yet well understood physics

• Test of chiral symmetry: KR- and TW terms

• SU(3) relations holds? Vector meson couplings

Mar. 1-3, 2007 特定領域研究会鳥羽 22

LEPS data

-dependence

Asymmetry

+ : K* dominant– : K dominant

Mar. 1-3, 2007 特定領域研究会鳥羽 23

p –> K+

Weak K* ~ SU(3)Strong K*

E = 1.9 GeV, W ~ 2.1 GeV

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LEPS

CLAS

SAPHIA

dependence

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SAPHIATotal

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