38,923 research outputs found
Electric Dipole Moments in the Generic Supersymmetric Standard Model
The generic supersymmetric standard model is a model built from a
supersymmetrized standard model field spectrum the gauge symmetries only. The
popular minimal supersymmetric standard model differs from the generic version
in having R-parity imposed by hand. We review an efficient formulation of the
model and some of the recently obtained interesting phenomenological features,
focusing on one-loop contributions to fermion electric dipole moments.Comment: 1+7 pages Revtex 3 figures incoporated; talk at NANP'0
Exact asymptotics of monomer-dimer model on rectangular semi-infinite lattices
By using the asymptotic theory of Pemantle and Wilson, exact asymptotic
expansions of the free energy of the monomer-dimer model on rectangular lattices in terms of dimer density are obtained for small values
of , at both high and low dimer density limits. In the high dimer density
limit, the theoretical results confirm the dependence of the free energy on the
parity of , a result obtained previously by computational methods. In the
low dimer density limit, the free energy on a cylinder
lattice strip has exactly the same first terms in the series expansion as
that of infinite lattice.Comment: 9 pages, 6 table
In an Attempt to Introduce Long-range Interactions into Small-world Networks
Distinguishing the long-range bonds with the regular ones, the critical
temperature of the spin-lattice Guassian model built on two typical Small-world
Networks (SWNs) is studied. The results show much difference from the classical
case, and thus may induce some more accurate discussion on the critical
properties of the spin-lattice systems combined with the SWNs.Comment: 4 pages, 3 figures, 18 referenc
Neutrino Oscillations from Supersymmetry without R-parity - Its Implications on the Flavor Structure of the Theory
We discuss here some flavor structure aspects of the complete theory of
supersymmetry without R-parity addressed from the perspective of fitting
neutrino oscillation data based on the recent Super-Kamiokande result. The
single-VEV parametrization of supersymmetry without R-parity is first reviewed,
illustrating some important features not generally appreciated. For the flavor
structure discussions, a naive, flavor model independent, analysis is
presented, from which a few interesting things can be learned.Comment: 1+10 pages latex, no figure; Invited talk at NANP 99 conference,
Dubna (Jun 28 - Jul 3) --- submission for the proceeding
Relativistic corrections to the Pionium Lifetime
Next to leading order contributions to the pionium lifetime are considered
within non-relativistic effective field theory. A more precise determination of
the coupling constants is then needed in order to be consistent with the
relativistic pion-pion scattering amplitude which can be obtained from chiral
perturbation theory. The relativistic correction is found to be 4.1% and
corresponds simply to a more accurate value for the non-relativistic decay
momentum.Comment: 5 pages, Latex. Includes corrections based on a more precise matching
to the pion-pion scattering amplitude from chiral perturbation theor
Efficient implementation of a van der Waals density functional: Application to double-wall carbon nanotubes
We present an efficient implementation of the van der Waals density
functional of Dion et al [Phys. Rev. Lett. 92, 246401 (2004)], which expresses
the nonlocal correlation energy as a double spacial integral. We factorize the
integration kernel and use fast Fourier transforms to evaluate the
selfconsistent potential, total energy, and atomic forces, in N log(N)
operations. The resulting overhead in total computational cost, over semilocal
functionals, is very moderate for medium and large systems. We apply the method
to calculate the binding energies and the barriers for relative translation and
rotation in double-wall carbon nanotubes.Comment: 4 pages, 1 figure, 1 tabl
Little Higgs Model Completed with a Chiral Fermionic Sector
The implementation of the little Higgs mechanism to solve the hierarchy
problem provides an interesting guiding principle to build particle physics
models beyond the electroweak scale. Most model building works, however, pay
not much attention to the fermionic sector. Through a case example, we
illustrate how a complete and consistent fermionic sector of the TeV effective
field theory may actually be largely dictated by the gauge structure of the
model. The completed fermionic sector has specific flavor physics structure,
and many phenomenological constraints on the model can thus be obtained beyond
gauge, Higgs, and top physics. We take a first look on some of the quark sector
constraints.Comment: 14 revtex pages with no figure, largely a re-written version of
hep-ph/0307250 with elaboration on flavor sector FCNC constraints; accepted
for publication in Phys.Rev.
Energy Relaxation of Hot Dirac Fermions in Graphene
We develop a theory for the energy relaxation of hot Dirac fermions in
graphene. We obtain a generic expression for the energy relaxation rate due to
electron-phonon interaction and calculate the power loss due to both optical
and acoustic phonon emission as a function of electron temperature
and density . We find an intrinsic power loss weakly
dependent on carrier density and non-vanishing at the Dirac point ,
originating from interband electron-optical phonon scattering by the intrinsic
electrons in the graphene valence band. We obtain the total power loss per
carrier within the range of electron
temperatures . We find optical (acoustic) phonon
emission to dominate the energy loss for in the density range .Comment: 5 page
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