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## Hyun-Chul Kim

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**Hyun-Chul Kim**meson photoproduction with hadron rescattering Department of Physics Inha University In collaboration with H.Y. Ryu, A. Hosaka, A. Titov EFB 22, Sept. 10, 2013@Kraków**Motivation**OZI rule violation - Gluonic dynamics (Pomeron) - Hidden strangeness • Usual vector-meson exchanges are forbidden by the charge conjugation. • Hybrid exotic vector mesons (C=+1) are allowed but not much data.**This bump structure cannot be explained by the pomeron and**one meson-exchange picture! Motivation 텍스트**Motivation**• How to explain the bump structure around the K Lambda(1520) threshold. • How to describe the production mechanism near the threshold in place of the pomeron. In the present talk, we propose possible coupled-channel effects that may explain the phi photoproduction mechanism near the threshold region.**Summary of previous works**Titov et al. PRC 60, 035205 (1999): Structure of the phi photoproduction • Ordinary vector-meson exchange is forbidden. • The pomeron governs the energy dependence of the differential cross section, though it is theoretically plausible only at higher energies.**Summary of previous works**• Mibe et al. PRL, 95, 182001 (2005): phi diffractive photoproduction near the threshold • Ozaki et al. PRC 80, 035201 (2009): K-matrix method (Coupled-channel) • Chang et al. PRC 82, 015205 (2010): Measurement of the spin-density matrices • Kiswandhi et al. PLB 691, 214 (2010): Possible N*(2080) resonance with large strangeness**Effective Lagrangian methods**Describe hadron processes in terms of effective degrees of freedom: Quark-gluon dynamics are encoded in the coupling constants and form factors. S.i. Nam, A. Hosaka, HChK, Phys. Rev. D 71, 114012 (2005) S.i. Nam, K.S. Choi, A. Hosaka, HChK, D 75, 014027 (2005)**Effective Lagrangian methods**Invariant amplitude**Conventional approach**Production Mechanism A. Titov et al. PRC 60, 035205 (1999) t-channel hadron exchange Pomeron Present approach Rescattering amplitudes**Hadronic part**Rescattering equation Blankenbecler-Sugar type scattering equation**Rescattering part in a coupled-channel formalism**Rescattering equation**Rescattering part in a coupled-channel formalism**Rescattering equation In this work, we will consider only the imaginary part for simplicity, to see the reliability of the present method. The full computation is under way.**Rescattering amplitudes**= Most important term +**Numerical results**Hadrons Hadrons + Pomeron**Differential Cross Sections**No Pomeron contribution (E = 2 GeV). Hadronic process can explain the angular distribution.**Differential cross sections**• Mibe et al. PRL, 95, 182001 (2005)**Spin-density matrices**In general, spin-density matrices near the threshold region are well described.**Definition of angles**C.M. system Gottfried-Jackson system Decay angular distributions**T. Mibe et al. [LEPS Collaboration], PRL 95, 182001 (2005)**Decay angular distributions**Summary and Outlook**• We investigated phi photoproduction, emphasizing the significance of the rescattering contributions, in particular, the K Lambda(1520) channel. • The K Lambda (1520) plays a dominant role. • However, we have considered here only the imaginary part of the rescattering amplitudes, to see their importance. • The real part of the rescattering amplitudes are under investigation, and it seems even more important. The corresponding work will soon appear.**Though this be madness,yet there is method in it.**Hamlet Act 2, Scene 2 Thank you very much!