Photoproduction of K* �for the study of the

structure of Λ(1405)�

Tetsuo Hyodoa �

a RCNP, Osaka b IFIC, Valencia c Barcelona Univ.

2003, November 4th

A. Hosakaa, E. Osetb, A. Ramosc and M. J. Vicente Vacasb

1.  Introduction �1. Motivation : Two poles? �

2.  Chiral unitary model�1. Framework of the chiral unitary model"2. Example : K-p scatterings"3. Pole structure of Λ(1405)�4. Example : π-p -> K0πΣ�

3.  K*Λ(1405) production�1. Effective interactions �2. Numerical results�

Contents

Motivations : Two poles?

•  Cloudy bag model" (1990) J. Fink et al. PRC41, 2720 •  Chiral unitary model" (2001~) J. A. Oller et al. PLB500, 263 E. Oset et al. PLB527, 99 D. Jido et al. PRC66, 025203 T. Hyodo et al. PRC68, 018201

There are two poles of the scattering amplitude"around nominal Λ(1405) energy region."

Λ(1405) : JP=1/2-, I=0"

ChU model, T. Hyodo

Chiral unitary model

Unitarity of S-matrix"Chiral symmetry"Flavor SU(3) meson-baryon scatterings (s-wave)"

Resonances"

Low energy "behavior"

Non-perturbative"resummation"

Λ(1405), Λ(1670), N(1535), Σ(1620), Ξ(1620)

Dynamical"generation"

Chiral perturbation theory"

Unitarization

Framework of the chiral unitary model

Resonances"

Generated resonances are"expressed as poles of the "scattering amplitude."

Total cross sections of K-p scatterings

T. Hyodo, et al., Phys. Rev. C 68, 018201 (2003)

200

150

100

50

0

σ T [m

b]

300200100

K-p70

60

50

40

30

20

10

0300200100

π0Λ

200

150

100

50

0300200100

π+Σ−

60

50

40

30

20

10

0

σ T [m

b]

300200100Plab [MeV/c]

K0n60

50

40

30

20

10

0300200100

Plab [MeV/c]

π0Σ080

60

40

20

0300200100

Plab [MeV/c]

π−Σ+

Λ(1405) in the chiral unitary model

D. Jido, et al., Nucl. Phys. A 723, 205 (2003)

πΣ mass distribution"

1390 + 66i (πΣ)

1426 + 16i (KN)

Example : the π-p -> K0πΣ reaction

Chiral"term"

N(1710)"

Chiral unitary model"

Results for π-p -> K0πΣ

T. Hyodo, et al., nucl-th/0307005, Phys. Rev. C, in press

Total cross sections [mb] Mass distribution

�  There are two mechanisms in the initial" stage interaction, which filter each one" of the resonances."

Good agreement"Σ(1385) effect"

Photoproduction of K* Λ(1405)

Only K-p channel appears at the initial stage"

Higher pole ??"

Effective interactions for meson part

1.  γVP coupling"

2.  VPP coupling"

Effective interaction for Σ(1385)

3.  Σ(1385)MB coupling"

4.  K-P -> Σ(1385) -> MB amplitude"

SU(6) symmetry"

2.5x10-3

2.0

1.5

1.0

0.5

0.0

dσ/d

MI[µ

b]

1550150014501400135013001250MI [MeV]

π0Σ0 (~I=0) average of charged πΣ π0Λ (I=1)

Experiments : πΣ mass distribution

Plab = 2.5 GeV/c sqrt s ~ 2.35 GeV

Preliminary �

Summary and conclusions

We study the structure of Λ(1405) using "the chiral unitary model.�

 There are two poles of the scattering " amplitude around nominal Λ(1405)."Pole 1 (1426+16i) : strongly couples to KN state"Pole 2 (1390+66i) : strongly couples to πΣ state"

http://www.rcnp.osaka-u.ac.jp/~hyodo/index_e.html

" By observing the πΣ mass distribution in" the γp -> K*Λ(1405) reaction, it could be " possible to isolate higher energy pole."

Appendix : other processes

γp -> K-πΣ

Κ-p -> γπΣ J.C. Nacher, et al., PLB461, 299(1999) �

J.C. Nacher, et al., PLB445, 55(1999) �

Spring-8"

J-PARC?"