Navarra, F. S., Nielsen, M., Oset, E., & Sekihara, T. (2015). Testing the molecular nature of D-s0*(2317) and D-0*(2400) in semileptonic B-s and B decays. Phys. Rev. D, 92(1), 014031–14pp.
Abstract: We study the semileptonic B-s and B decays into the D-s0*(2317) and D-0*(2400) resonances, respectively. With the help of a chiral unitarity model in coupled channels we compute the ratio of the decay widths of both processes. Using current values of the width for the (B) over bar (0) -> D-0*(2400)(+)(v) over bar (l)l(-) we make predictions for the rate of the (B) over bar (0)(s) -> D-s0*(2317)(+)(v) over bar (l)l(-) decay and for the DK invariant mass distribution in the (B) over bar (0)(s) -> DK (v) over bar (l)l(-) decay.
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Nanova, M. et al, & Oset, E. (2012). Transparency ratio in gamma A -> eta ' A ' and the in-medium eta ' width. Phys. Lett. B, 710(4-5), 600–606.
Abstract: The photoproduction of eta'-mesons off different nuclei has been measured with the CBELSA/TAPS detector system for incident photon energies between 1500-2200 MeV. The transparency ratio has been deduced and compared to theoretical calculations describing the propagation of eta'-mesons in nuclei. The comparison indicates a width of the eta'-meson of the order of Gamma = 15-25 MeV at rho = rho(0) for an average momentum p(eta') = 1050 MeV/c, at which the eta'-meson is produced in the nuclear rest frame. The inelastic eta'N cross section is estimated to be 3-10 mb. Parameterizing the photoproduction cross section of eta'-mesons by sigma(A) = sigma(0)A(alpha), a value of alpha = 0.84 +/- 0.03 has been deduced.
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Nagahiro, H., Hirenzaki, S., Oset, E., & Ramos, A. (2012). eta '-Nucleus optical potential and possible eta ' bound states. Phys. Lett. B, 709(1-2), 87–92.
Abstract: Starting from a recent model of the eta'N interaction, we evaluate the eta'-nucleus optical potential, including the contribution of lowest order in density, t rho/2m(eta'), together with the second-order terms accounting for eta' absorption by two nucleons. We also calculate the formation cross section of the eta' bound states from (pi(+), p) reactions on nuclei. The eta'-nucleus potential suffers from uncertainties tied to the poorly known eta'N interaction, which can be partially constrained by the experimental modulus of the eta'N scattering length and/or the recently measured transparency ratios in eta' nuclear photoproduction. Assuming an attractive interaction and taking the claimed experimental value vertical bar a(eta'N)vertical bar = 0.1 fm, we obtain an eta' optical potential in nuclear matter at saturation density of V eta' = -(8.7 + 1.8i) MeV, not attractive enough to produce eta' 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 vertical bar a(eta'N)vertical bar = 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 eta'-nuclear bound states and to threshold enhancements in the unbound region.
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Molina, R., Xie, J. J., Liang, W. H., Geng, L. S., & Oset, E. (2020). Theoretical interpretation of the D-s(+) -> pi(+)pi(0)eta decay and the nature of a(0)(980). Phys. Lett. B, 803, 135279–4pp.
Abstract: In a recent paper [I], the BESIII Collaboration reported the so-called first observation of pure W-annihi- lation decays D-s(+) -> a(0)(+) (980)pi(0) and D-s(+) -> a(0)(0)(980)pi(+). The measured absolute branching fractions are, however, puzzlingly larger than those of other measured pure W-annihilation decays by at least one order of magnitude. In addition, the relative phase between the two decay modes is found to be about 0 degrees. In this letter, we show that all these can be easily understood if the a(0)(980) is a dynamically generated state from (K) over barK and pi eta interactions in coupled channels. In such a scenario, the D-s(+) decay proceeds via internal W emission instead of W-annihilation, which has a larger decay rate than W-annihilation. The proposed decay mechanism and the molecular nature of the a(0)(980) also provide a natural explanation to the measured negative interference between the two decay modes.
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Molina, R., Xiao, C. W., & Oset, E. (2012). J/psi reaction mechanisms and suppression in the nuclear medium. Phys. Rev. C, 86(1), 014604–9pp.
Abstract: Recent studies of the interaction of vector mesons with nuclei make possible and opportune the study of the interaction of the J/psi with nuclei and the investigation of the origin of the J/psi suppression in its propagation thorough a nuclear medium. We observe that the transition of J/psi N to VN with V being a light vector, rho, omega, phi, together with the inelastic channels, J/psi N -> (D) over bar Lambda(c) and J/psi N -> (D) over bar Sigma(c), leads to a particular shape of the inelastic cross section. Analogously, we consider the mechanisms where the exchanged D collides with a nucleon and gives pi Lambda(c) or pi Sigma(c). The cross section has a peak around root s = 4415 MeV, where the J/psi N couples to a resonance predicted recently. We study the transparency ratio for electron-induced J/psi production in nuclei at about 10 GeV and find that 30-35% of the J/psi produced in heavy nuclei are absorbed inside the nucleus. This ratio is in line with depletions of J/psi through matter observed in other reactions.
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