The interaction of the low-lying pseudoscalar mesons with the ground-state baryons in the charm sector is studied within a coupled-channel approach using a t-channel vector-exchange driving force. The amplitudes describing the scattering of the pseudoscalar mesons off the ground-state baryons are obtained by solving the Lippmann-Schwinger equation. We analyze in detail the effects of going beyond the t = 0 approximation. Our model predicts the dynamical generation of several open-charm baryon resonances in different isospin and strangeness channels, some of which can be clearly identified with recently observed states.

Single-particle energies of the Λc chamed baryon are obtained in several nuclei from the relevant self-energy constructed within the framework of a perturbative many-body approach. Results are presented for a charmed baryon-nucleon (YcN ) potential based on a SU(4) extension of the mesonexchange hyperon-nucleon potentialà of the Jülich group. Three different models (A, B and C) of this interaction, that differ only on the values of the couplings of the scalar σ meson with the charmed baryons, are considered. Phase shifts, scattering lengths and effective ranges are computed for the three models and compared with those predicted by the YcN interaction derived in Eur. Phys. A 54, 199 (2018) from the extrapolation to the physical pion mass of recent results of the HAL QCD Collaboration. Qualitative agreement is found for two of the models (B and C) considered. Our results for Λc-nuclei are compatible with those obtained by other authors based on different models and methods. We find a small spin-orbit splitting of the p−, d− and f −wave states as in the case of single Λ-hypernuclei. The level spacing of Λc single-particle energies is found to be smaller than that of the corresponding one for hypernuclei. The role of the Coulomb potential and the effect of the coupling of the ΛcN and ΣcN channels on the single-particle properties of Λc−nuclei are also analyzed. Our results show that, despite the Coulomb repulsion between the Λc and the protons, even the less attractive one of our YcN models (model C) is able to bind the Λc in all the nuclei considered. The effect of the ΛcN − ΣcN coupling is found to be almost negligible due to the large mass difference of the Λc and Σc baryons.

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In this work we study the radiative decay of dynamically generated $J^P=\oh^-$ charm baryons into the ground state $J^P=\oh^+$ baryons. Since different theoretical interpretations of these baryonic resonances, and in particular of the $\Lambda_c(2595)$, give different predictions, a precise experimental measurement of these decays would be an important step for understanding their nature.Comment: 10 pages, 1 figur

Abstract. We present a high-resolution P-wave velocity model of the sedimentary cover and the uppermost basement to ∼3 km depth obtained by full-waveform inversion of multichannel seismic data acquired with a 6 km long streamer in the Alboran Sea (SE Iberia). The inherent non-linearity of the method, especially for short-offset, band-limited seismic data as this one, is circumvented by applying a data processing or modelling sequence consisting of three steps: (1) data re-datuming by back-propagation of the recorded seismograms to the seafloor; (2) joint refraction and reflection travel-time tomography combining the original and the re-datumed shot gathers; and (3) full-waveform inversion of the original shot gathers using the model obtained by travel-time tomography as initial reference. The final velocity model shows a number of geological structures that cannot be identified in the travel-time tomography models or easily interpreted from seismic reflection images alone. A sharp strong velocity contrast accurately defines the geometry of the top of the basement. Several low-velocity zones that may correspond to the abrupt velocity change across steeply dipping normal faults are observed at the flanks of the basin. A 200–300 m thick, high-velocity layer embedded within lower-velocity sediment may correspond to evaporites deposited during the Messinian crisis. The results confirm that the combination of data re-datuming and joint refraction and reflection travel-time inversion provides reference models that are accurate enough to apply full-waveform inversion to relatively short offset streamer data in deep-water settings starting at a field-data standard low-frequency content of 6 Hz.