/ nucl-ex arXiv:1711.01095


First measurement of coherent $\phi$-meson photoproduction from helium-4 near threshold


Hiraiwa, T. (Kyoto U.) ; Yosoi, M. (Osaka U., Res. Ctr. Nucl. Phys.) ; Niiyama, M. (Kyoto U.) ; Morino, Y. (KEK, Tsukuba) ; Nakatsugawa, Y. (Beijing, Inst. High Energy Phys.) ; Sumihama, M. (Gifu U.) ; Ahn, D.S. (Nishina Ctr., RIKEN) ; Ahn, J.K. (Korea U.) ; Chang, W.C. (Taiwan, Inst. Phys.) ; Chen, J.Y. (NSRRC, Taiwan) ; Daté, S. (Japan Synch. Radiation Res. Inst.) ; Fujimura, H. (Wakayama Medical U.) ; Fukui, S. (Osaka U., Res. Ctr. Nucl. Phys.) ; Hicks, K. (Ohio U.) ; Hotta, T. (Osaka U., Res. Ctr. Nucl. Phys.) ; Hwang, S.H. (KRISS, Taejon) ; Ishikawa, T. (Tohoku U., Sendai, ELPH) ; Kato, Y. (Nagoya U.) ; Kawai, H. (Chiba U.) ; Kohri, H. (Osaka U., Res. Ctr. Nucl. Phys.) ; Kon, Y. (Osaka U., Res. Ctr. Nucl. Phys.) ; Lin, P.J. (Taiwan, Inst. Phys.) ; Maeda, Y. (Shin-Etsu Chem., Fukui) ; Miyabe, M. (Tohoku U., Sendai, ELPH) ; Mizutani, K. (Kyoto U.) ; Muramatsu, N. (Tohoku U., Sendai, ELPH) ; Nakano, T. (Osaka U., Res. Ctr. Nucl. Phys.) ; Nozawa, Y. (Osaka U., Res. Ctr. Nucl. Phys.) ; Ohashi, Y. (Japan Synch. Radiation Res. Inst.) ; Ohta, T. (Tokyo U.) ; Oka, M. (Osaka U., Res. Ctr. Nucl. Phys.) ; Rangacharyulu, C. (Saskatchewan U.) ; Ryu, S.Y. (Osaka U., Res. Ctr. Nucl. Phys.) ; Saito, T. (Chiba U.) ; Sawada, T. (Michigan U.) ; Shimizu, H. (Tohoku U., Sendai, ELPH) ; Strokovsky, E.A. (Dubna, JINR) ; Sugaya, Y. (Osaka U., Res. Ctr. Nucl. Phys.) ; Suzuki, K. (Osaka U., Inst. Phys.) ; Tokiyasu, A.O. (Tohoku U., Sendai, ELPH) ; Tomioka, T. (Chiba U.) ; Tsunemi, T. (Kyoto U.) ; Uchida, M. (Tokyo Inst. Tech.) ; Yorita, T. (Osaka U., Res. Ctr. Nucl. Phys.)

Pages: 6

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.

Web-Page: http://inspirehep.net/record/1634470/files/mkk_mmkk.png; http://inspirehep.net/record/1634470/files/comp_dsdt0.png; http://inspirehep.net/record/1634470/files/dsdtall.png; http://inspirehep.net/record/1634470/files/decayangle.png; http://inspirehep.net/record/1634470/files/arXiv:1711.01095.pdf


Note: 6 pages, 4 figures

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 Record created 2017-12-04, last modified 2017-12-04


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