JOINT ICTP/SISSA STATISTICAL PHYSICS SEMINAR: "Collective modes of trapped Fermi gases with in-medium interaction"

[statphys]

JOINT ICTP/SISSA STATISTICAL PHYSICS SEMINAR

Tuesday, 12 May 2009   -    12:30 hrs

Seminar Room
ICTP Leonardo Building - 1st floor

Silvia CHIACCHIERA

(Universidade de Coimbra)

"Collective modes of trapped Fermi gases
with in-medium interaction"



Abstract

Due to the Pauli blocking of the intermediate states, the scattering 
matrix (or T matrix) of two fermionic atoms in a Fermi gas becomes 
different from that of two atoms in free space. We calculate  the 
in-medium T matrix in ladder approximation and study its effects on the 
properties of the collective modes of a trapped gas in the normal-fluid 
phase. We introduce the in-medium interaction on both sides of the 
Boltzmann equation, namely in the calculation of the mean field and in 
the calculation of the collision rate. This allows us to explain the 
observed upward shift of the frequency of the quadrupole mode in the 
collisionless regime. By including the mean field, we also improve 
considerably the agreement with the measured temperature dependence of 
frequency and damping rate of the scissors mode, whereas the use of the 
in-medium cross section deteriorates the description, in agreement with 
previous work.