1,284 research outputs found
Cold asymmetrical fermion superfluids in nonperturbative renormalisation group
The application of the nonperturbative renormalisation group approach to a
system with two fermion species is studied. Assuming a simple ansatz for the
effective action with effective bosons, describing pairing effects we derive a
set of approximate flow equations for the effective coupling including boson
and fermionic fluctuations. The case of two fermions with different masses but
coinciding Fermi surfaces is considered.
The phase transition to a phase with broken symmetry is found at a critical
value of the running scale. The large mass difference is found to disfavour the
formation of pairs.
The mean-field results are recovered if the effects of boson loops are
omitted. While the boson fluctuation effects were found to be negligible for
large values of they become increasingly important with decreasing
thus making the mean field description less accurate.Comment: 11 pages, 2 figures, revte
Superfluidity in many fermion systems: Exact renormalisation group treatment
The application of the exact renormalisation group to symmetric as well as
asymmetric many-fermion systems with a short-range attractive force is studied.
Assuming an ansatz for the effective action with effective bosons, describing
pairing effects a set of approximate flow equations for the effective coupling
including boson and fermionic fluctuations has been derived. The phase
transition to a phase with broken symmetry is found at a critical value of the
running scale. The mean-field results are recovered if boson-loop effects are
omitted. The calculations with two different forms of the regulator are shown
to lead to a similar results. We find that, being quite small in the case of
the symmetric many-fermion system the corrections to mean field approximation
becomes more important with increasing mass asymmetry.Comment: Talk given at the IVth International Conference on Quarks and Nuclear
Physics (QNP06), Madrid, 5-10 June 200
Reply to Comment on ``Determination of pion-baryon coupling constants from QCD sum rules''
In response to Kim's comment (nucl-th/9903040) on the sum rules for
pion-baryon coupling constants obtained in hep-ph/9512259 and hep-ph/9606471,
we point out that our treatment of the continuum is consistent with duality and
with the fact that the correlator in the presence of an external meson or field
should be represented by a double dispersion relation.Comment: 5 pages (RevTeX), reply to nucl-th/990304
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