2017/11/30 by LEPS Collaboration, T. Hiraiwa, M. Yosoi +48
Physics and Astronomy · #Atomic and Subatomic Physics Research #High-Energy Particle Collisions Research #Meson #Nuclear physics #Parity (physics) #Particle physics #Photon #Physics #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #nucl-ex
paper · pdf · doi:10.1103/physrevc.97.035208
published as Phys. Rev. C 97, 035208 (2018) · 6 pages, 4 figures
openalex created_date 2017/11/17 · arxiv created 2018/01/27 · openalex publication_date 2018/03/27 · arxiv updated 2018/04/04 · openalex updated_date 2026/08/05
The differential cross sections and decay angular distributions for coherent \ensuremathφ-meson photoproduction from helium-4 are measured for the first time at forward angles with linearly polarized photons in the energy range E_\ensuremathγ=1.685--2.385\phantom\rule4.pt0exGeV. Thanks to the target with spin-parity JP=0+, unnatural-parity exchanges are absent, and thus natural-parity exchanges can be investigated clearly. The decay asymmetry with respect to photon polarization is shown to be very close to the maximal value. This ensures the strong dominance (>94%) of natural-parity exchanges in this reaction. To evaluate the contribution from natural-parity exchanges to the forward cross section (\ensuremathθ=0^\ensuremath∘) for the \ensuremathγp\ensuremath→\ensuremathφp reaction near threshold, the energy dependence of the forward cross section (\ensuremathθ=0^\ensuremath∘) for the \ensuremathγ4He\ensuremath→\ensuremathφ4He reaction is analyzed. The comparison to \ensuremathγp\ensuremath→\ensuremathφp data suggests that enhancement of the forward cross section arising from natural-parity exchanges and/or destructive interference between natural-parity and unnatural-parity exchanges is needed in the \ensuremathγp\ensuremath→\ensuremathφp reaction near threshold.