1. K*Λ(1116) Photoproduction and Nucleon resonances K*Λ(1116) Photoproduction and Nucleon resonances Sang-Ho Kim( 金相鎬 ) (NTG, Inha University, Korea) In collaboration with Hyun-Chul Kim (Inha University), Yong-Seok Oh (Kyungpook National University), Seung-il Nam (Korea Aerospace University) BARYONS’2010,7-11 Dec, Osaka, Japan

2. 1. Introduction & Motivation 2. Theoretical framework ※ Tree-level Born approximation ※ Effective Lagrangian ※ Amplitude and Form factor 3. Numerical results 4. Conclusion 5. Outlook Outline

3. 1. Introduction ◈ It has been a very useful experimental tool to investigate QCD as a hadronic degrees of freedom. ◈ In theoretical sides, there have been various tools developed to investigate the photoproductions. ◈ Around the world, there are many experimental facilities and collaborations for this purpose, such as the CLAS at JLAB, LEPS at SPring-8, Bonn-ELSA, Tohoku LNS, etc. The meson photoproduction off the nucleon target

4. 1. Motivation Although the K* production rate is smaller than that for the K, it is still sizable. L. Guo et al. [CLAS collaboration], hep-ex/0601010

5. 1. Motivation ◈ It would be a right subject to study the heavy mass hadron productions, according to the recent experimental progesses. ◈ Nucleon resonances in strangeness production will give more information on microscopic hadron studies. ◈ It is interesting to study additional polarization observables together with the photon, target nucleon, and K* polarizations (future works). ◈ Since we do not have much experimental data for this channel, it would be a highly prospective subject for the possible future experiments. Vector strangeness meson, K* photoproduction

6. 2. Theoretical framework ◆ ◆ Effective Lagrangians for interaction vertices. ◆ ◆ Born approximation at tree level. ◆ ◆ Gauge invariant form factor prescription. ◆ ◆ Nucleon resonances in a full relativistic way.

7. Tree diagrams 2. Born approximation

8. 2. Effective Lagrangian t-channel K* exchange K exchange κ exchange

9. 2. Effective Lagrangian u-channel and contact term ● This contact diagram is essential to satisfy the gauge-invariance condition.

10. 2. Effective Lagrangian s-channel

11. 2. Amplitude and Form factor t-channel s-, u-channel Amplitude Form factor common form factor

12. 3. Total Cross section K-meson exchange dominates remarkably. There is considerable discrepancy between the theory and experiment. Therefore, to cure the problem, we are motivated to include the nucleon resonances near the threshold. there is considerable discrepancy between the theory and experiment. Therefore, to cure this γp ―› K*Λ(K*,K,κ,N,Λ,Σ,Σ*)

13. 3. Total Cross section γp ―› K*Λ(K*,K,κ,N,Λ,Σ,Σ*)

14. 3. Nucleon Resonances ◈ Among the nucleon resonances reported in PDG, we take into account only three- or four-star resonances. ◈ The threshold energy of K*Λ is 2008 MeV. 1) Mass(N*) 2008 MeV N* = P11(1440, 1/2+)**** N*= G17(2190, 7/2- )**** D13(1520, 3/2 -)**** H19(2220, 9/2+)**** S11(1535, 1/2 - )**** G19(2250, 9/2- )**** S11(1650, 1/2 - )**** I 11(2600,11/2- )*** D15(1675, 5/2 -)**** F15(1680, 5/2+)**** D13(1700, 3/2 -)*** P11(1710, 1/2+)*** P13(1720, 3/2+)**** ? ?

15. 1) Mass(N*) < 2008 MeV ◆ ◆ All values of the helicity amplitudes are given experimentally, so so the transition magnetic moments are calculated easily. 3. Nucleon Resonances

16. g K*N*Λ ◆ The coupling strength of g K*N*Λ is unknown. ▶ We treat it as a free parameter, and by varying the value g K*N*Λ of g K*N*Λ, we can know which nucleon resonance would dominate the process. Assumption : Considering the Nijmegen potential, g K*NΛ = -4.26, k K*NΛ =2.66, we assume that the ratio of g K*N*Λ and k K*N*Λ can be similar, ~1.6.

17. 1. P 11 (1440,1/2+) 2. P 11 (1710,1/2+) 3. Total Cross section Spin 1/2+ N* resonances are negligible.

18. 3. S 11 (1535,1/2-) 3. Total Cross section |g K*N*Λ | = 7.0~9.0 For |g K*N*Λ | = 7.0~9.0, it’s in a good agreement with the data.

19. 4. S 11 (1650,1/2-) 3. Total Cross section |g K*N*Λ | = 5.0~6.0 For |g K*N*Λ | = 5.0~6.0, it’s in a good agreement with the data.

20. 6. D 13 (1700,3/2-) 5. D 13 (1520,3/2-) 3. Total Cross section Spin 3/2- N* resonances are relatively small.

21. 7. P 13 (1720,3/2+) 3. Total Cross section Spin 3/2+ N* resonance is relatively small.

22. 3. Total Cross section 8. F 15 (1680,5/2+) 9. D 15 (1675,5/2-) Spin 5/2 N* resonances are negligible.

23. 3. Total Cross section Among the nucleon resonances less than 2008 MeV, P 11 (1440), P 11 (1710), D 15 (1675), and F 15 (1680) are almost negligible. D 13 (1520), D 13 (1700), and P 13 (1720) contribute slightly. S 11 (1535) and S 11 (1650) are most responsible for reproducing the data, when their values of the coupling constants are |g K*N*Λ (1535)| = 7.0~9.0 and |g K*N*Λ (1650)| = 5.0~6.0. |g K*N*Λ (1650)| = 5.0~6.0. |g KN*Λ (1535)| = 1.0~2.0 from the chiral unitary model

24. 3. Nucleon Resonances ◆ Except for N*(2190), the helicity amplitudes are not known experimentally. Moreover, only the ratio of the N*(2190)’s helicity amplitude is given. 2) Mass(N*) > 2008 MeV g K*N*Λ ◆ The coupling strength of g K*N*Λ is obtained by the SU(6) quark model. ▶ As a trial, we will take into account only G 17 (2190). Related works are under progress.

25. 4. Conclusion ◈ We investigated the K* photoproduction off the nucleon, γN ―›K*Λ(1116) γN ―›K*Λ(1116), within the tree level approximation. more ◈ In addition to K*, K, κ, N, Λ, Σ, Σ* contributions, we considered more nucleon resonances to explain the discrepancy between the previous nucleon resonances to explain the discrepancy between the previous theoretical result and experimental data in the near threshold region. theoretical result and experimental data in the near threshold region. Among them, S 11 (1535) and S 11 (1650) are responsible for ◈ Among them, S 11 (1535) and S 11 (1650) are responsible for rthe data, when their values for the coupling constant reproducing the data, when their values for the coupling constant are |g K*N*Λ (1535)| = 7.0~9.0 and |g K*N*Λ (1650)| = 5.0~6.0. are |g K*N*Λ (1535)| = 7.0~9.0 and |g K*N*Λ (1650)| = 5.0~6.0.

26. 5. Outlook 1. We will include more higher-spin resonances using experimental and theoretical information. and theoretical information. 2. Chi-square fitting will be taken into account. 3. Differential cross section, Double polarization observables. Double polarization observables. 4. Extending present framework into general vector meson-baryon photoproduction. photoproduction.

27. Thank you very much