150 research outputs found
Diquark interaction and gaps for color superconductivity
Using flow equations, we derive an effective quark-quark interaction and
obtain the coupled set of gap equations for the condensates of the CFL phase of
massless dense QCD. The formalism developed here enables one to
consider more general case of nonzero -quark mass.Comment: 3 pages, Lattice2002(nonzerot), talk presented at 20th International
Symposium on Lattice Field Theory (LATTICE2002), Boston, Massachusetts, 24-29
June 200
Exotic superfluidity in cold atoms
We derived the low energy effective action for the collective modes in
asymmetric fermionic systems with attractive interaction. We obtained the phase
diagram in terms of the chemical potentials. It features a stable gapless
superfluidity with one Fermi surface on the BEC side of the resonance. Also we
predict a sharp increase in outer core of a vortex, i.e. vortex size, upon
entering into the gapless phase. This may serve as a signature of a gapless
phase.Comment: 12 pages, 6 figures, proceedings of the conference "Shifmania,
Crossing the Boundaries: Gauge Dynamics at Strong Coupling", May 14-17, 200
Exotic superfluids: Breached Pairing, Mixed Phases and Stability
We review properties of gapless states. We construct a model where a stable
breached pair (gapless) state is realized.Comment: 9 pages, talk presented at workshop "Continuous Advances in QCD
2004," Minneapolis, USA, May 13-16, 200
Stability Conditions in Gapless Superconductors
Gapless superconductivity can arise when pairing occurs between fermion
species with different Fermi surface sizes, provided there is a sufficiently
large mismatch between Fermi surfaces and/or at sufficiently large coupling
constant. In gapless states, secondary Fermi surfaces appear where
quasiparticle excitation energy vanishes. This work focuses on homogeneous and
isotropic superfluids in the s-wave channel, with either zero (conventional
superconductor), one, or two spherical Fermi surfaces. The stability conditions
for these candidate phases are analyzed. It is found that gapless states with
one Fermi surface are stable in the BEC region, while gapless states with two
Fermi surfaces are unstable in all parameter space. The results can be applied
to ultracold fermionic atom systems.Comment: 7 pages, 5 figures, Proceedings of 'Continuous Advances in QCD 2006',
May 11-14, 2006, Minneapolis, M
Color superconductivity from magnetic interaction induced by flow equations
Using flow equations, we derive an effective quark-quark interaction and
obtain the coupled set of gap equations for the condensates of the CFL phase of
massless N_f=3 dense QCD. We find two different sources of the infrared cutoff
in magnetic interaction. When the penetration depth of the magnetic field
inside the superconductor is less than the coherence length of quark-quark
bound state, our results for the gap agree with those of Son. In the other
case, we obtain parametric enhancement of the gap on the coupling constant.Comment: 14 pages, talk presented at workshop "Continuous Advances in QCD
2002/Arkadyfest," Minneapolis, USA, 17-23 May, 200
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