Formation of Possible \(\eta '\)(958)-Nucleus Bound States and \(\eta '\)N Interaction

Abstract

The formation cross sections of η ′ (958)-nucleus systems by missing mass spectroscopies are discussed for the study of in-medium modification of the mass of the η ′ (958) meson. We conclude that the evidence of a possible mass reduction of η ′ can be observed as a peak structure around the η ′ threshold. The spectroscopy of the (p, d) reaction has been performed at GSI. The bound state formations by the (γ, p) reaction can be done at SPring-8.

Comment on "Search for $η'$ Bound Nuclei in the $^{12}\mathrm{C}(γ,p)$ Reaction with Simultaneous Detection of Decay Products"

“…1 of Ref. [4], exhibiting scatteringangle dependence of the formation spectrum). Therefore, it requires justification to apply a common F (2) factor to the whole kinematical region.…”

“…2 of Ref. [4]. The accuracy of W 0 , which is responsible for the absorption process, is essentially important for the estimation of both (dσ/dΩ) η ′ abs theory and (dσ/dΩ) η ′ esc theory , which appear explicitly in Eqs.…”

Search for $η'$ bound nuclei in the $^{12}{\rm C}(γ,p)$ reaction with simultaneous detection of decay products

“…The obtained dσ dΩ η+ps exp was compared with theoretical cross sections, dσ dΩ η+ps theory , expected in different V 0 cases. For this purpose, we calculated the expected excitation energy of the η ′ + 11 B system E ex , relative to the production threshold E 0 , in the framework of a distorted wave impulse approximation (DWIA) [17,28]. The DWIA is the standard technique used for describing bound states such as in hypernuclei and pionic atoms [29][30][31][32][33][34].…”

“…We calculated the excitation spectra for η ′ angular momenta up to 7, which is large enough to have convergence for E ex − E 0 50 MeV [17,28]. Because the η ′ escape process contributes only in E ex − E 0 > 0 MeV, we evaluate F from experimental and theoretical cross sections of the η ′ escape process, dσ We discuss V 0 as a function of the branching fraction of the η ′ N → ηN absorption process, Br η ′ N →ηN .…”

“…We calculated R(E) by Green's function as in Ref. [28]. The calculation is decomposed into the η ′ escape and absorption processes as…”