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First measurement of coherent $\phi$-meson photoproduction from helium-4 near threshold
- Source :
- Phys. Rev. C 97, 035208 (2018)
- Publication Year :
- 2017
-
Abstract
- The differential cross sections and decay angular distributions for coherent $\phi$-meson photoproduction from helium-4 have been measured for the first time at forward angles with linearly polarized photons in the energy range $E_{\gamma} = \text{1.685-2.385 GeV}$. Thanks to the target with spin-parity $J^{P} = 0^{+}$, unnatural-parity exchanges are prohibited, 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 dominance ($> 94\%$) of natural-parity exchanges in this reaction. To evaluate the contribution from natural-parity exchanges to the forward cross section ($\theta = 0^\circ$) for the $\gamma p \rightarrow \phi p$ reaction near the threshold, the energy dependence of the forward cross section ($\theta = 0^\circ$) for the $\gamma {^{4}\text{He}} \rightarrow \phi {^{4}\text{He}}$ reaction was analyzed. The comparison to $\gamma p \rightarrow \phi p$ 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 $\gamma p \rightarrow \phi p$ reaction near the threshold.<br />Comment: 6 pages, 4 figures
- Subjects :
- Nuclear Experiment
Subjects
Details
- Database :
- arXiv
- Journal :
- Phys. Rev. C 97, 035208 (2018)
- Publication Type :
- Report
- Accession number :
- edsarx.1711.01095
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1103/PhysRevC.97.035208