Statut  Confirmé 
Série  IPNTHEO 
Domaines  nuclth 
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 particlehole (screening) corrections on the Swave 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 MonteCarlo calculations. However, I will show that at densities above 0.010.02 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 GorkovMelikBarkhudarov result, based on a weakcoupling 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 renormalizationgroup 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 NozièresSchmittRink theory. 
Numéro de preprint arXiv  
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