meson photoproduction with
hadron rescattering
Hyun-Chul Kim
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.
Motivation
This bump structure cannot
be explained by the pomeron
and one meson-exchange
picture!
텍스트
Motivation
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 coupledchannel 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
Production Mechanism
Conventional approach
A. Titov et al. PRC 60, 035205 (1999)
t-channel
hadron exchange
Pomeron
Present approach
Rescattering amplitudes
Rescattering equation
Hadronic part
Blankenbecler-Sugar type scattering equation
Rescattering equation
Rescattering part in a coupled-channel formalism
Rescattering equation
Rescattering part in a coupled-channel formalism
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
Spin-density matrices
In general, spin-density matrices
near the threshold region are well
described.
Decay angular distributions
Definition of angles
C.M. system
Gottfried-Jackson
system
Decay angular distributions
Decay angular distributions
T. Mibe et al. [LEPS Collaboration],
PRL 95, 182001 (2005)
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.
23
Though this be madness,
yet there is method in it.
Hamlet Act 2, Scene 2
Thank you very much!