https://doi.org/10.1140/epja/i2012-12148-8
Regular Article - Theoretical Physics
Resummation of in-medium ladder diagrams: s-wave effective range and p-wave interaction
Physik-Department T39, Technische Universität München, D-85747, Garching, Germany
* e-mail: nkaiser@ph.tum.de
Received:
31
July
2012
Revised:
27
September
2012
Accepted:
1
October
2012
Published online:
26
October
2012
A recent work on the resummation of fermionic in-medium ladder diagrams to all orders is extended by considering the effective range correction in the s-wave interaction and a (spin-independent) p-wave contact-interaction. A two-component recursion generates the in-medium T-matrix at any order when off-shell terms spoil the factorization of multi-loop diagrams. The resummation to all orders is achieved in the form of a geometrical series for the particle-particle ladders, and through an arctangent-function for the combined particle-particle and hole-hole ladders. One finds that the effective range correction changes the results in the limit of large scattering length considerably, with the effect that the Bertsch parameter ξ n nearly doubles. Applications to the equation of state of neutron matter at low density are also discussed. For the p-wave contact-interaction the resummation to all orders is facilitated by decomposing tensorial loop-integrals with a transversal and a longitudinal projector. The enhanced attraction provided by the p-wave ladder series has its origin mainly in the coherent sum of Hartree and Fock contributions.
© SIF, Springer-Verlag Berlin Heidelberg, 2012
