Pantheon SEMPARIS Le serveur des séminaires parisiens Paris

Statut Confirmé
Domaines nucl-th
Date Mercredi 4 Avril 2018
Heure 11:30
Institut IPN
Salle Bâtiment 100, Salle A015
Nom de l'orateur Urban
Prenom de l'orateur M.
Addresse email de l'orateur
Institution de l'orateur IPNO
Titre Screening and antiscreening of the pairing interaction in neutron matter
Résumé There are still large uncertainties about the density dependence of the critical temperature $T_c$ for the onset of superfluidity in neutron matter. In this talk, I will revisit the effect of particle-hole (screening) corrections on the S-wave pairing at densities prevailing in the inner crust of neutron stars. At low densities, the repulsive effect of spin fluctuations leads to a strong reduction of $T_c$ ompared to the BCS result, also seen in quantum Monte-Carlo calculations. However, I will show that at densities above 0.01-0.02 fm$^{-3}$, the attractive density fluctuations win against the repulsive spin fluctuations if realistic values for the Landau parameters are employed, leading to antiscreening rather than screening, i.e., to an enhancement of $T_c$. Then I will discuss the limit of low densities. In this limit, the celebrated Gorkov-Melik-Barkhudarov result, based on a weak-coupling formula, predicts a reduction of $T_c$ by a factor of 0.45. However, if one wants to reproduce this result by solving the gap equation with the screened pairing interaction, it turns out to be necessary to use renormalization-group evolved interactions with cutoffs that scale with the Fermi momentum $k_F$. Finally, I will briefly discuss the reduction of $T_c$ that one obtains by including, in addition to screening, the effect of pairing fluctuations in the framework of the Nozières-Schmitt-Rink theory.
Numéro de preprint arXiv
Commentaires $ $
Fichiers attachés
  • 2018_04_04_M_Urban.pdf (215938 bytes) OPEN

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