6533b833fe1ef96bd129c0de

RESEARCH PRODUCT

η′-Nucleus optical potential and possible η′ bound states

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Abstract Starting from a recent model of the η ′ N interaction, we evaluate the η ′ -nucleus optical potential, including the contribution of lowest order in density, t ρ / 2 m η ′ , together with the second-order terms accounting for η ′ absorption by two nucleons. We also calculate the formation cross section of the η ′ bound states from ( π + , p ) reactions on nuclei. The η ′ -nucleus potential suffers from uncertainties tied to the poorly known η ′ N interaction, which can be partially constrained by the experimental modulus of the η ′ N scattering length and/or the recently measured transparency ratios in η ′ nuclear photoproduction. Assuming an attractive interaction and taking the claimed experimental value | a η ′ N | = 0.1 fm , we obtain an η ′ optical potential in nuclear matter at saturation density of V η ′ = − ( 8.7 + 1.8 i ) MeV , not attractive enough to produce η ′ bound states in light nuclei. Larger values of the scattering length give rise to deeper optical potentials, with moderate enough imaginary parts. For a value | a η ′ N | = 0.3 fm , which can still be considered to lie within the uncertainties of the experimental constraints, the spectra of light and medium nuclei show clear structures associated to η ′ -nuclear bound states and to threshold enhancements in the unbound region.