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Nuclear Theory·nucl-th

Friday·May 19, 2017

6 papers—5 primary·1 cross-listed

All6Primary5Cross-lists1
  1. 01

    Two-step nuclear reactions: The Surrogate Method, the Trojan Horse Method and their common foundations

    Mahir S. Hussein

    In this Letter I argue that the Surrogate Method, used to extract the fast neutron capture cross section on actinide target nuclei, which has important practical application for the next generation of breeder reactors, and the Trojan Horse Method employed to extract reactions of importance to nuclear astrophysics, have a common foundation, the Inclusive Non-Elastic Breakup (INEB)Theory. Whereas the Surrogate Method relies on the premise that the extracted neutron cross section in a (d,p) reaction is predominantly a compound nucleus one, the Trojan Horse Method, assumes a predominantly direct process for the secondary reaction induced by the surrogate fragment. In general, both methods contain both direct and compound contributions, and I show how theses seemingly distinct methods are in fact the same but at different energies and different kinematic regions. The unifying theory is the rather well developed INEB theory.

    nucl-thnucl-exEPJA(2017)·8 citations
  2. 02

    Fluctuations in non-ideal pion gas with dynamically fixed particle number

    E.E. Kolomeitsev🇸🇰 · D.N. Voskresensky🇷🇺

    We consider a non-ideal hot pion gas with the dynamically fixed number of particles in the model with the interaction. The effective Lagrangian for the description of such a system is obtained after dropping the terms responsible for the change of the total particle number. Reactions , which determine the isospin balance of the medium, are permitted. Within the self-consistent Hartree approximation we compute the effective pion mass, thermodynamic characteristics of the system and the variance of the particle number at temperatures above the critical point of the induced Bose-Einstein condensation when the pion chemical potential reaches the value of the effective pion mass. We analyze conditions for the condensate formation in the process of thermalization of an initially non-equilibrium pion gas. The normalized variance of the particle number increases with a temperature decrease but remains finite in the critical point of the Bose-Einstein condensation. This is due to the non-perturbative account of the interaction and is in contrast to the ideal-gas case. In the kinetic regime of the condensate formation the variance is shown to stay finite also.

    nucl-thNPA(2018)·10 citations
  3. 03

    Low energy peripheral scaling in Nucleon-Nucleon Scattering and uncertainty quantification

    I. Ruiz Simo🇪🇸 · J.E. Amaro🇪🇸 · E. Ruiz Arriola🇪🇸 · R. Navarro Perez🇺🇸

    We analyze the peripheral structure of the nucleon-nucleon interaction for LAB energies below 350 MeV. To this end we transform the scattering matrix into the impact parameter representation by analyzing the scaled phase shifts and the scaled mixing parameters in terms of the impact parameter . According to the eikonal approximation, at large angular momentum these functions should become an universal function of , {\it independent} on . This allows to discuss in a rather transparent way the role of statistical and systematic uncertainties in the different long range components of the two-body potential. Implications for peripheral waves obtained in chiral perturbation theory interactions to fifth order (N5LO) or from the large body of NN data considered in the SAID partial wave analysis are also drawn from comparing them with other phenomenological high-quality interactions, constructed to fit scattering data as well. We find that both N5LO and SAID peripheral waves disagree more than with the Granada-2013 statistical analysis, more than with the 6 statistically equivalent potentials fitting the Granada-2013 database and about with the historical set of 13 high-quality potentials developed since the 1993 Nijmegen analysis.

    nucl-thhep-phJ.Phys.G(2018)·9 citations
  4. 04

    Superfluid Gap in Neutron Matter from a Microscopic Effective Interaction

    Omar Benhar · Giulia De Rosi

    Correlated Basis Function (CBF) perturbation theory and the formalism of cluster expansions have been recently employed to obtain an effective interaction from a nuclear Hamiltonian strongly constrained by phenomenology. We report the results of a study of the superfluid gap in pure neutron matter, associated with the formation of Cooper pairs in the channel. The calculations have been carried out using an improved version of the CBF effective interaction, in which three-nucleon forces are taken into account using a microscopic model. Our results show that a non-vanishing superfluid gap develops at densities in the range , where g cm is the equilibrium density of isospin-symmetric nuclear matter, corresponding mainly to the neutron star inner crust.

    nucl-thJ.Low Temp.Phys.(2017)·13 citations
  5. 05

    -meson--nucleus bound states

    J. J. Cobos-Martínez🇧🇷 · K. Tsushima🇧🇷 · G. Krein🇧🇷 · A. W. Thomas🇦🇺

    -meson--nucleus bound state energies and absorption widths are calculated for seven selected nuclei by solving the Klein-Gordon equation with complex optical potentials. Essential input for the calculations, namely the medium-modified and meson masses, as well as the density distributions in nuclei, are obtained from the quark-meson coupling model. The attractive potential for the -meson in the nuclear medium originates from the in-medium enhanced loop in the -meson self-energy. The results suggest that the -meson should form bound states with all the nuclei considered. However, the identification of the signal for these predicted bound states will need careful investigation because of their sizable absorption widths.

    nucl-thhep-exhep-phnucl-exPRC(2017)·42 citations

Affiliations

first authorsco-authorsvia INSPIRE