Accurate determination of the interaction betweenΛhyperons and nucleons from auxiliary field diffusion Monte Carlo calculations

Abstract

Background: An accurate assessment of the hyperon-nucleon interaction is of great interest in view of recent observations of very massive neutron stars. The challenge is to build a realistic interaction that can be used over a wide range of masses and in infinite matter starting from the available experimental data on the binding energy of light hypernuclei. To this end, accurate calculations of the hyperon binding energy in a hypernucleus are necessary.Purpose: We present a quantum Monte Carlo study of Λ and ΛΛ hypernuclei up to A = 91. We investigate the contribution of two-and three-body Λ-nucleon forces to the Λ binding energy.Method: Ground state energies are computed solving the Schrödinger equation for non-relativistic baryons by means of the auxiliary field diffusion Monte Carlo algorithm extended to the hypernuclear sector. Results:We show that a simple adjustment of the parameters of the ΛN N three-body force yields a very good agreement with available experimental data over a wide range of hypernuclear masses. In some cases no experiments have been performed yet, and we give new predictions.Conclusions: The newly fitted ΛN N force properly describes the physics of medium-heavy Λ hypernuclei, correctly reproducing the saturation property of the hyperon separation energy.

Dense baryonic matter: Constraints from recent neutron star observations

“…Advanced Monte Carlo calculations of hypernuclear matter [89][90][91] have recently focused on the role of repulsive three-body ΛN N forces. These computations use semi-phenomenological ΛN interactions fitted to the available two-body scattering data together with parametrized ΛN N potentials constrained by the systematics of Λ separation energies in a series of hypernuclei.…”

Anomalous Electromagnetic Transport in Compact Stars

“…The reason is that, while under terrestrial conditions, hyperons are unstable and decay into nucleons through weak interactions, in neutron stars, the equilibrium conditions at core densities of order 2 − 3ρ 0 (with ρ 0 0.16 fm −3 the nuclear saturation density) can make the inverse process possible [3][4][5][6][7][8][9][10][11][12]. Thus, at large enough baryon chemical potential, the conversion of nucleons into hyperons becomes energetically favorable.…”

The EOS of Neutron Matter and the Effect of Λ Hyperons to Neutron Star Structure

“…[19,20,24]. We solve the many-body ground-state using the auxiliary field diffusion Monte Carlo (AFDMC) originally introduced by Schmidt and Fantoni [25].…”

“…The AFDMC results have been obtained by including the two-body ΛN force alone (dashed red upper curve), and together with two models of the ΛNN interaction, ΛNN(I) initially proposed by Usmani [17], and ΛNN(II) of Ref. [24]. Hypernuclear three-body forces are crucial to qualitatively and quantitatively reproduce the binding energy of hypernuclei.…”