TY - JOUR

T1 - S-pairing in neutron matter

T2 - I. Correlated basis function theory

AU - Fabrocini, Adelchi

AU - Fantoni, Stefano

AU - Illarionov, Alexey Yu

AU - Schmidt, Kevin

N1 - Funding Information:
This work has been partially supported by the Italian MIUR through the PRIN: Fisica Teorica del Nucleo Atomico e dei Sistemi a Molti Corpi. K.E.S. acknowledges partial support by the US National Science Foundation via grant PHY-0456609. A.Yu.I. is grateful to INFN and to the Dipartimento di Fisica “E. Fermi” of the University of Pisa.

PY - 2008/5/1

Y1 - 2008/5/1

N2 - S-wave pairing in neutron matter is studied within an extension of correlated basis function (CBF) theory to include the strong, short range spatial correlations due to realistic nuclear forces and the pairing correlations of the Bardeen, Cooper and Schrieffer (BCS) approach. The correlation operator contains central as well as tensor components. The correlated BCS scheme of [S. Fantoni, Nucl. Phys. A 363 (1981) 381], developed for simple scalar correlations, is generalized to this more realistic case. The energy of the correlated pair condensed phase of neutron matter is evaluated at the two-body order of the cluster expansion, but considering the one-body density and the corresponding energy vertex corrections at the first order of the Power Series expansion. Based on these approximations, we have derived a system of Euler equations for the correlation factors and for the BCS amplitudes, resulting in correlated nonlinear gap equations, formally close to the standard BCS ones. These equations have been solved for the momentum independent part of several realistic potentials (Reid, Argonne v14 and Argonne v8′) to stress the role of the tensor correlations and of the many-body effects. Simple Jastrow correlations and/or the lack of the density corrections enhance the gap with respect to uncorrelated BCS, whereas it is reduced according to the strength of the tensor interaction and following the inclusion of many-body contributions.

AB - S-wave pairing in neutron matter is studied within an extension of correlated basis function (CBF) theory to include the strong, short range spatial correlations due to realistic nuclear forces and the pairing correlations of the Bardeen, Cooper and Schrieffer (BCS) approach. The correlation operator contains central as well as tensor components. The correlated BCS scheme of [S. Fantoni, Nucl. Phys. A 363 (1981) 381], developed for simple scalar correlations, is generalized to this more realistic case. The energy of the correlated pair condensed phase of neutron matter is evaluated at the two-body order of the cluster expansion, but considering the one-body density and the corresponding energy vertex corrections at the first order of the Power Series expansion. Based on these approximations, we have derived a system of Euler equations for the correlation factors and for the BCS amplitudes, resulting in correlated nonlinear gap equations, formally close to the standard BCS ones. These equations have been solved for the momentum independent part of several realistic potentials (Reid, Argonne v14 and Argonne v8′) to stress the role of the tensor correlations and of the many-body effects. Simple Jastrow correlations and/or the lack of the density corrections enhance the gap with respect to uncorrelated BCS, whereas it is reduced according to the strength of the tensor interaction and following the inclusion of many-body contributions.

KW - Nuclear cluster models

KW - Nuclear forces

KW - Nuclear matter

KW - Nuclear pairing

KW - Superfluidity

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U2 - 10.1016/j.nuclphysa.2008.01.024

DO - 10.1016/j.nuclphysa.2008.01.024

M3 - Article

AN - SCOPUS:41349121963

SN - 0375-9474

VL - 803

SP - 137

EP - 158

JO - Nuclear Physics A

JF - Nuclear Physics A

IS - 3-4

ER -