62,930 research outputs found
Comment on "Light-front Schwinger model at finite temperature"
In a recent paper by A. Das and X. Zhou [Phys. Rev. D 68, 065017 (2003)] it
is claimed that explicit evaluation of the thermal photon self-energy in the
Schwinger model gives off-shell thermal Green functions that are different in
light-front and conventional quantizations. We show that the claimed difference
originates from an erroneous simplification of the fermion propagator used in
the light-front calculation.Comment: 8 pages, revtex4, added section refuting the massless limit proposed
in hep-th/031102
Nodal Quasiparticle Dispersion in Strongly Correlated d-wave Superconductors
We analyze the effects of a momentum-dependent self-energy on the
photoemission momentum distribution curve (MDC) lineshape, dispersion and
linewidth. We illustrate this general analysis by a detailed examination of
nodal quasiparticles in high Tc cuprates. We use variational results for the
nodal quasiparticle weight Z (which varies rapidly with hole doping x) and the
low energy Fermi velocity (which is independent of x), to show that
the high energy MDC dispersion , so that it is much
larger than the bare (band structure) velocity and also increases strongly with
underdoping. We also present arguments for why the low energy Fermi velocity
and the high energy dispersion are independent of the bare band structure at
small x. All of these results are in good agreement with earlier and recent
photoemission data [Zhou et al, Nature 423, 398 (2003)].Comment: 4 pages, 3 eps fig
The Gentlest Ascent Dynamics
Dynamical systems that describe the escape from the basins of attraction of
stable invariant sets are presented and analyzed. It is shown that the stable
fixed points of such dynamical systems are the index-1 saddle points.
Generalizations to high index saddle points are discussed. Both gradient and
non-gradient systems are considered. Preliminary results on the nature of the
dynamical behavior are presented
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