Publications

Order by: publication date number of citations

• Study of the hyperon-nucleon interaction via final-state interactions in exclusive reactions

  Nicholas Zachariou, Daniel Watts, Yordanka Ilieva

  SciPost Phys. Proc. 3, 026 (2020) · published 25 February 2020 | Toggle abstract · pdf

  A novel approach that allows access to long-sought information on the Hyperon-Nucleon (YN) interaction was developed by producing a hyperon beam within a few-body nuclear system, and studying final-state interactions. The determination of polarisation observables, and specifically the beam spin asymmetry, in exclusive reactions allows a detailed study of the various final-state interactions and provides us with the tools needed to isolate kinematic regimes where the YN interaction dominates. High-statistics data collected using the CLAS detector housed in Hall-B of the Thomas Jefferson laboratory allows us to obtain a large set of polarisation observables and place stringent constraints on the underlying dynamics of the YN interaction.

• Lattice phase shifts and mixing angles for an arbitrary number of coupled channels

  Lukas Bovermann, Evgeny Epelbaum, Hermann Krebs, Dean Lee

  SciPost Phys. Proc. 3, 052 (2020) · published 27 February 2020 | Toggle abstract · pdf

  We present a lattice method for determining scattering phase shifts and mixing angles for the case of an arbitrary number of coupled channels. The proposed method combines a spherical wall boundary condition and a channel-mixing auxiliary potential to extract the full-rank S-matrix from the radial wave functions. We consider the scattering problem of two spin-1 bosons interacting with a test potential involving up to four coupled channels. For this benchmark system, the phase shifts and mixing angles are shown to agree on the lattice and in the continuum. Our method should allow to extend previous two-channel nuclear lattice EFT simulations to mixing of more than two partial waves.

• Properties of heavy mesons at finite temperature

  Gloria Montaña, Angels Ramos, Laura Tolós

  SciPost Phys. Proc. 3, 038 (2020) · published 26 February 2020 | Toggle abstract · pdf

  We study the properties of heavy mesons using a unitarized approach in a hot pionic medium, based on an effective hadronic theory. The interaction between the heavy mesons and pseudoscalar Goldstone bosons is described by a chiral Lagrangian at next-to-leading order in the chiral expansion and leading order in the heavy-quark mass expansion so as to satisfy heavy-quark spin symmetry. The meson-meson scattering problem in coupled channels with finite-temperature corrections is solved in a self-consistent manner. Our results show that the masses of the ground-state charmed mesons $D(0^-)$ and $D_s(1^-)$ decrease in a pionic environment at $T\neq 0$ and they acquire a substantial width. As a consequence, the behaviour of excited mesonic states (i.e. $D_{s0}^*(2317)^\pm$ and $D_0^*(2300)^{0,\pm}$), generated dynamically in our heavy-light molecular model, is also modified at $T\neq 0$. The aim is to test our results against Lattice QCD calculations in the future.

• Roy Glauber and asymptotic diffraction theory

  Per Osland

  SciPost Phys. Proc. 3, 016 (2020) · published 25 February 2020 | Toggle abstract · pdf

  This is a review of Glauber's asymptotic diffraction theory, in which diffractive scattering is described in terms of interference between semiclassical amplitudes, resulting from a stationary-phase approximation. Typically two such amplitudes are sufficient to accurately describe elastic scattering, but the stationary points are located at complex values of the impact parameter. Their separation controls the interference pattern, and their offsets from the real axis determine the overall fall-off with momentum transfer. Asymptotically, at large momentum transfers, the stationary points move towards singularities of the profile function. I also include some reminiscences from our collaboration.

• Three-nucleon force effects in the FSI configuration of the d(n, nn)p breakup reaction

  Hiroyuki Kamada, Henryk Witała, Jacek Golak, Roman Skibiński

  SciPost Phys. Proc. 3, 046 (2020) · published 27 February 2020 | Toggle abstract · pdf

  We investigated three-nucleon (3N) force effects in the final state interaction (FSI) configuration of the d(n, nn)p breakup reaction at the incoming nucleon energy E n = 200 MeV. Although 3N force effects for the elastic nucleon-deuteron scattering cross section at comparable energies are located predominantly in the region of intermediate and backward angles, the corresponding 3N force effects for the integrated FSI configuration breakup cross section are found also at forward scattering angles.

• Beryllium-9 in cluster effective field theory

  Elena Filandri, Paolo Andreatta, Carlo A. Manzata, Chen Ji, W. Leidemann, G. Orlandini

  SciPost Phys. Proc. 3, 034 (2020) · published 26 February 2020 | Toggle abstract · pdf

  We study the 9 Be ground-state energy with non-local αn and αα potentials derived from Cluster Effective Field Theory. The short-distance dependence of the interaction is regulated with a momentum cutoff. The potential parameters are fitted to reproduce scattering length and effective range. We implement such potential models in a Non-Symmetrized Hyperspherical Harmonics (NSHH) code in momentum space. In addition we calculate ground-state energies of various alpha nuclei. Work is in progress in view of the calculation of the photodisintegration of 9 Be with the Lorentz Integral Transform (LIT) method.

• Influence of the Pauli principle on two-cluster potential energy

  Yuliya A. Lashko, Victor S. Vasilevsky, Gennady F. Filippov

  SciPost Phys. Proc. 3, 021 (2020) · published 25 February 2020 | Toggle abstract · pdf

  We study effects of the Pauli principle on the potential energy of two-cluster systems. The object of the investigation is the lightest nuclei of p-shell with a dominant $\alpha$-cluster channel. For this aim we construct matrix elements of two-cluster potential energy between cluster oscillator functions with and without full antisymmetrization. Eigenvalues and eigenfunctions of the potential energy matrix are studied in detail. Eigenfunctions of the potential energy operator are presented in oscillator, coordinate and momentum spaces. We demonstrate that the Pauli principle affects more strongly the eigenfunctions than the eigenvalues of the matrix and leads to the formation of resonance and trapped states.