Measurement of Spin-Density Matrix Elements for $\varphi$-Meson Photoproduction from Protons and Deuterons Near Threshold

Abstract

The LEPS/SPring-8 experiment made a comprehensive measurement of the spin-density matrix elements for $\gamma p\to \varphi p$, $\gamma d\to \varphi pn$ and $\gamma d\to \varphi d$ at forward production angles. A linearly polarized photon beam at $E_{\gamma }$=1.6-2.4 GeV was used for the production of $\varphi$ mesons. The natural-parity Pomeron exchange processes remains dominant nearthreshold. The unnatural-parity processes of pseudoscalar exchange is visible in the production from nucleons but is greatly reduced in the coherent production from deuterons. There is no strong $E_{\gamma }$-dependence, but some dependence on momentum-transfer. A small but finite value of the spin-density matrix elements reflecting helicity-nonconserving amplitudes in the $t$-channel is observed.

25 pages, 14 figures

References in corpus (17)

• The gamma + p to K+ + Lambda and gamma + p to K+ + Sigma0 reactions at forward angles with photon energies from 1.5 to 2.4 GeV
• phi photo-production from Li, C, Al, and Cu nuclei at Egamma=1.5 - 2.4 GeV
• Diffractive $\varphi$-meson photoproduction on proton near threshold
• Photoproduction of Vector Mesons at Large Transfer
• Photoproduction of phi(1020) mesons on the proton at large momentum transfer
• Photoproduction of phi mesons from the proton: Polarization observables and strangeness in the nucleon
• Spin effects and baryon resonance dynamics in phi-meson photoproduction at few GeV
• Forward coherent $\varphi$-meson photoproduction from deuterons near threshold
• Is the nonmonotonic behavior in the cross section of phi photoproduction near threshold a signature of a resonance?
• The extraction of $\varphi -N$ total cross section from $d(\gamma ,p{K}^{+}{K}^{-})n$
• First measurement of coherent $\varphi$-meson photoproduction on deuteron at low energies
• Measurement of the incoherent $\gamma d\to \varphi pn$ photoproduction near threshold
• A coupled-channel analysis for phi-photoproduction with Lambda(1520)
• Photoproduction of phi meson off deuteron near threshold
• Non-diffractive mechanisms in the $\varphi$ meson photoproduction on nucleons
• Coherent phi and omega meson photoproduction from deuteron and non-diffractive channels
• An isotopic effect in phi photoproduction at a few GeV

Cited by in corpus (17)

• Data analysis techniques, differential cross sections, and spin density matrix elements for the reaction $\gamma p\to \varphi p$
• Nucleon resonances $N(1875)$ and $N(2100)$ as strange partners of LHCb pentaquarks
• $\varphi$ photoprodution with coupled-channel effects
• $\varphi$-meson lepto-production near threshold and the strangeness $D$-term
• Vector Meson Photoproduction with a Linearly Polarized Beam
• On the near-threshold peak structure in the differential cross section of ϕ-meson photoproduction: indication of a missing resonance with non-negligible strangeness content
• Interference effect between $\varphi$ and $\Lambda (1520)$ production channels in the $\gamma p\to K^{+}{K}^{-}p$ reaction near threshold
• $P_c$-like pentaquarks in hidden strange sector
• $\varphi$ photoproduction on the proton at $E_{\gamma }$ = 1.5 - 2.9 GeV
• First measurement of coherent $\varphi$-meson photoproduction from helium-4 near threshold
• Differential cross section and photon beam asymmetry for the gamma p -> pi+ n reaction at forward pi+ angles at Egamma=1.5-2.95 GeV
• Pomeron, nucleon-resonance, and $(0^{+},0^{-},1^{+})$-meson contributions in $\varphi$-meson photoproduction
• Testing the $\varphi$-nuclear potential in pion-induced $\varphi$ meson production on nuclei near threshold
• On the near-threshold incoherent $\varphi$ photoproduction on the deuteron: any trace of a resonance?
• Incoherent photoproduction of $\varphi$-meson from deuteron at low energies
• Measurement of Spin-Density Matrix Elements in $\varphi (1020)\to K_S^0{K}_L^0$ Photoproduction with a Linearly Polarized Photon Beam at $E_{\gamma }=8.2-8.8$ GeV
• Dynamical model of $\varphi$ meson photoproduction on the nucleon and ${}^{4}He$