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Publications récentes


Lee-Yang–inspired functional with a density-dependent neutron-neutron scattering length

M. Grasso, D. Lacroix, and C. J. Yang

Inspired by the low-density Lee-Yang expansion for the energy of a dilute Fermi gas of density ρ and momentum kF, we introduce here a Skyrme-type functional that contains only s-wave terms and provides, at the mean-field level, (i) a satisfactory equation of state for neutron matter from extremely low densities up to densities close to the equilibrium point, and (ii) a good-quality equation of state for symmetric matter at density scales around (...)

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Renormalizability of the nuclear many-body problem with the Skyrme interaction beyond mean field

C. J. Yang, M. Grasso, K. Moghrabi, and U. van Kolck

Phenomenological effective interactions like Skyrme forces are currently used in mean-field calculations in nuclear physics. Mean-field models have strong analogies with the first order of the perturbative many-body problem and the currently used effective interactions are adjusted at the mean-field level. In this work, we analyze the renormalizability of the nuclear many-body problem in the case where the effective Skyrme interaction is employed in (...)

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Power counting in peripheral partial waves : The singlet channels

M. Pavón Valderrama, M. Sánchez Sánchez, C.-J. Yang, Bingwei Long, J. Carbonell, and U. van Kolck

We analyze the power counting of the peripheral singlet partial waves in nucleon-nucleon scattering. In agreement with conventional wisdom, we find that pion exchanges are perturbative in the peripheral singlets. We quantify from the effective field theory perspective the well-known suppression induced by the centrifugal barrier in the pion-exchange interactions. By exploring perturbation theory up to fourth order, we find that the one-pion-exchange (...)

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From bare interactions, low-energy constants, and unitary gas to nuclear density functionals without free parameters : Application to neutron matter

Denis Lacroix, Antoine Boulet, Marcella Grasso, and C.-J. Yang

We further progress along the line of Ref. [D. Lacroix, Phys. Rev. A 94, 043614 (2016)] where a functional for Fermi systems with anomalously large s-wave scattering length as was proposed that has no free parameters. The functional is designed to correctly reproduce the unitary limit in Fermi gases together with the leading-order contributions in the s- and p-wave channels at low density. The functional is shown to be predictive up (...)

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Pygmy Gamow-Teller resonance in the N=50 region : New evidence from staggering of β-delayed neutron-emission probabilities

D. Verney, D. Testov, F. Ibrahim, B. Roussière, S. Franchoo, R. Li, I. Matea, I. Stefan, and D. Suzuki

Abstract We report on the β-delayed neutron emission probability (P1n) measurements of the 82,83,84Ga (N=51,52,53) precursors performed in one single experiment using the 3He neutron-counter TETRA at the ALTO facility in Orsay. Altogether our results for the three A=82,83, and 84 Ga precursors point towards a sizable P1n staggering in the N=50 region, similar to the one already observed just after the N=28 shell closure in the K isotopes chain, hinting at a similar mechanism. We will (...)

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