52,755 research outputs found
Unconventional behavior of Dirac fermions in three-dimensional gauge theory
We study the unconventional behavior of massless Dirac fermions due to
interaction with a U(1) gauge field in two spatial dimensions. At zero chemical
potential, the longitudinal and transverse components of gauge interaction are
both long-ranged. There is no fermion velocity renormalization since the system
respects Lorentz invariance. At finite chemical potential, the Lorentz
invariance is explicitly broken by the finite Fermi surface. The longitudinal
gauge interaction is statically screened and becomes unimportant, whereas the
transverse gauge interaction remains long-ranged and leads to singular
renormalization of fermion velocity. The anomalous dimension of fermion
velocity is calculated by means of the renormalization group method. We then
examine the influence of singular velocity renormalization on several physical
quantities, and show that they exhibit different behavior at zero and finite
chemical potential.Comment: 9 pages, 4 figure
Dynamical chiral symmetry breaking in QED at finite density and impurity potential
We study the effects of finite chemical potential and impurity scattering on
dynamical fermion mass generation in (2+1)-dimensional quantum electrodynamics.
In any realistic systems, these effects usually can not be neglected. The
longitudinal component of gauge field develops a finite static length produced
by chemical potential and impurity scattering, while the transverse component
remains long-ranged because of the gauge invariance. Another important
consequence of impurity scattering is that the fermions have a finite damping
rate, which reduces their lifetime staying in a definite quantum state. By
solving the Dyson-Schwinger equation for fermion mass function, it is found
that these effects lead to strong suppression of the critical fermion flavor
and the dynamical fermion mass in the symmetry broken phase.Comment: 8 pages, 4 figure
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