35,824 research outputs found
Radiative Neutrino Mass, Dark Matter and Leptogenesis
We propose an extension of the standard model, in which neutrinos are Dirac
particles and their tiny masses originate from a one-loop radiative diagram.
The new fields required by the neutrino mass-generation also accommodate the
explanation for the matter-antimatter asymmetry and dark matter in the
universe.Comment: 4 pages, 3 figures. Revised version with improved model. Accepted by
PR
Dirac neutrinos and anomaly-free discrete gauge symmetries
Relying on Dirac neutrinos allows an infinity of anomaly-free discrete gauge
symmetries to be imposed on the Supersymmetric Standard Model, some of which
are GUT-compatible.Comment: 24 pages, minor changes, existence of flipped discrete gauge
symmetries is pointed ou
Neutrino masses, leptogenesis and dark matter in hybrid seesaw
We suggest a hybrid seesaw model where relatively ``light''right-handed
neutrinos give no contribution to the neutrino mass matrix due to a special
symmetry. This allows their Yukawa couplings to the standard model particles to
be relatively strong, so that the standard model Higgs boson can decay
dominantly to a left and a right-handed neutrino, leaving another stable
right-handed neutrino as cold dark matter. In our model neutrino masses arise
via the type-II seesaw mechanism, the Higgs triplet scalars being also
responsible for the generation of the matter-antimatter asymmetry via the
leptogenesis mechanism.Comment: 4 page
Extremely Correlated Fermi Liquid Description of Normal State ARPES in Cuprates
The normal state single particle spectral function of the high temperature
superconducting cuprates, measured by the angle resolved photoelectron
spectroscopy (ARPES), has been considered both anomalous and crucial to
understand. Here we show that an unprecedentedly detailed description of the
data is provided by a spectral function arising from the Extremely Correlated
Fermi Liquid state of the t-J model proposed recently by Shastry. The
description encompasses both laser and conventional synchrotron ARPES data on
optimally doped BiSrCaCuO, and also conventional
synchrotron ARPES data on the LaSrCuO materials. {\em It
fits all data sets with the same physical parameter values}, satisfies the
particle sum rule and successfully addresses two widely discussed "kink"
anomalies in the dispersion.Comment: Published version, 5 figs; published 29 July (2011
Multiband effects on the conductivity for a multiband Hubbard model
The newly discovered iron-based superconductors have attracted lots of
interests, and the corresponding theoretical studies suggest that the system
should have six bands. In this paper, we study the multiband effects on the
conductivity based on the exact solutions of one-dimensional two-band Hubbard
model. We find that the orbital degree of freedom might enhance the critical
value of on-site interaction of the transition from a metal to an
insulator. This observation is helpful to understand why undoped High-
superconductors are usually insulators, while recently discovered iron-based
superconductors are metal. Our results imply that the orbital degree of freedom
in the latter cases might play an essential role.Comment: 4 pages, 5 figure
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