Vector meson photoproduction 2018-06-26 Vector meson photoproduction Electromagnetic structure of spin-1 vector boson 2014 8. 28 CLAS WORKSHOP@KNU B. G. Yu & K.-J. Kong (Korea Aerospace Univ.)

2018-06-26

2018-06-26

Photoproduction of charged

Charged process

Reggeization: charged case

Observables

Reggeization: neutral case

Photoproduction of

Reggeization

2018-06-26 Summary & Perspective

Back up

EM structure of charged vector meson

Motivation Why vector meson photoproduction ? 2018-06-26 Motivation Why vector meson photoproduction ? Study electromagnetic structure of spin-1 vector boson Charge + magnetic dipole moment + electric quadrupole moment Study N* resonances associated with strangeness production rho(770) thres. energy W ~ 1.7 GeV ; nucleon poles are far below the threshold & N* resonances apparent from PDG. K*(892) thres. energy W ~ 2 GeV ; no N* resonances from PDG. Charged process is special ; dominated by t-ch. vector meson exch. Neutral process is special ; dominated by t-ch. Pomeron exch. Effective Lagrangian approach with cpl.const. within physical range Production mechanism of charged process not understood yet due to a difficulty in gauge prescription for spin-1 vector boson exch.

Summary & Perspective Why K* Lambda photoproduction ? 2018-06-26 Summary & Perspective Why K* Lambda photoproduction ? =A good place to study K* meson properties Decisive role of the vector meson with magnetic dipole moment + electric quadrupole moment - sign & magnitude of magnetic dipole - gauge prescription = on-shell + transversality Clean background to investigate EM properties of vector meson - dominating t-ch. meson exchange ; K*(892) + K(494) - Rho + (Delta + N*) ---- K* + (… ) Extraction of EM form factor of K* from electroproduction Reggeized meson exchanges at forward angle ====================

K*Lambda cross section @CLAS/JLab (hep-ex/0601010) 2018-06-26 K*Lambda cross section @CLAS/JLab (hep-ex/0601010)

K*Sigma+ cross section @CLAS/JLab PRC75,042201(2007)

K*Sigma+ cross section @CBELSA/TAPS EPJA35,333(2009) 2018-06-26 K*Sigma+ cross section @CBELSA/TAPS EPJA35,333(2009)

Photoproduction amplitude

2018-06-26 Model calculation Q. Zhao et al., PRC64 052201(2001)

K*Sigma+ cross section 2018-06-26 K*Sigma+ cross section

Model calculation Oh & Kim PRC73,065202 (2006)

2018-06-26 Model calculation S. Ozaki et al., PRC81 035206 (2010)

Effective Lagrangians 2018-06-26 Effective Lagrangians

Photon-V-V vertex

2018-06-26 Pole model Photoproduction current

2018-06-26 Gauge invariance I

2018-06-26 Gauge invariance II

Coupling constants

Rho+

Rho+ model II

Rho-

Rho- model II

K* model I

K* model II

Cutoff-dependence model II

K+K*+contact term model II

Differential cross sections model II

Photoproduction amplitude 2018-06-26 Photoproduction amplitude

2018-06-26 Gauge invariance

2018-06-26 Regge model

Photoproduction amplitude

Angular Distrib. K*Lambda Numerical results Angular Distrib. K*Lambda

Angular distrib. & Total cross section

Angular distrib. & Photon polarization

Summary & perspective gamma p  K* Lambda ~ t-ch. meson exch. 2018-06-26 Summary & perspective gamma p  K* Lambda ~ t-ch. meson exch. Pole model + Reggeized t-ch. Pole  complementary to each other to investigate production mechanism. 3. Magnetic dipole moment of K* meson  crucial to explain experiment. 4. Y* resonance in the u-ch.  base for studying Y* in the backward region. 5. Extension to electroproduction  advantageous to extract EM form factors of the spin-1 K* vector meson. -------------

K*

K*

Rho+

Rho-

Exchange Degeneracy Duality of s-ch. resonance to t-ch. Regge pole 2018-06-26 Exchange Degeneracy Duality of s-ch. resonance to t-ch. Regge pole