20,886 research outputs found
On the Form Factors of the $D_{s}^{+}\to \phi\mu^{+}\nu_{\mu} decay
We apply the infinite mass effective theory, when a heavy quark mass tends to
infinity, and Chiral perturbation theory at the quark level, based on the
extended Nambu -- Jona -- Lasinio model with linear realization of chiral
symmetry, to calculate the form factors of the
decay up to the first order in current
-- quark mass. The theoretical results are compared with experimental data
and found to be in good agreement.Comment: 7pages, latex, no figure
Gauging N=4 supersymmetric mechanics II: (1,4,3) models from the (4,4,0) ones
Exploiting the gauging procedure developed by us in hep-th/0605211, we study
the relationships between the models of N=4 mechanics based on the off-shell
multiplets (4,4,0) and (1,4,3). We make use of the off-shell N=4, d=1 harmonic
superspace approach as most adequate for treating this circle of problems. We
show that the most general sigma-model type superfield action of the multiplet
(1,4,3) can be obtained in a few non-equivalent ways from the (4,4,0) actions
invariant under certain three-parameter symmetries, through gauging the latter
by the appropriate non-propagating gauge multiplets. We discuss in detail the
gauging of both the Pauli-Gursey SU(2) symmetry and the abelian three-generator
shift symmetry. We reveal the (4,4,0) origin of the known mechanisms of
generating potential terms for the multiplet (1,4,3), as well as of its
superconformal properties. A new description of this multiplet in terms of
unconstrained harmonic analytic gauge superfield is proposed. It suggests, in
particular, a novel mechanism of generating the (1,4,3) potential terms via
coupling to the fermionic off-shell N=4 multiplet (0,4,4).Comment: 27 page
High harmonic generation in crystals using Maximally Localized Wannier functions
In this work, the nonlinear optical response, and in particular, the high
harmonic generation of semiconductors is addressed by using the Wannier gauge.
One of the main problems in the time evolution of the Semiconductor Bloch
equations resides in the fact that the dipole couplings between different bands
can diverge and have a random phase along the reciprocal space and this leads
to numerical instability. To address this problem, we propose the use of the
Maximally Localized Wannier functions that provide a framework to map ab-initio
calculations to an effective tight-binding Hamiltonian with great accuracy. We
show that working in the Wannier gauge, the basis set in which the Bloch
functions are constructed directly from the Wannier functions, the dipole
couplings become smooth along the reciprocal space thus avoiding the problem of
random phases. High harmonic generation spectrum is computed for a 2D monolayer
of hBN as a numerical demonstration
CP odd anomalous interactions of Higgs boson in its production at Photon Colliders
We discuss the potentialities of the study of CP-odd interactions of the
Higgs boson with photons via its production at gamma-gamma and e-gamma
colliders. Our treatment of H-gamma-gamma and H-Z-gamma anomalous interactions
includes a set of parameters, whose impact on physical observables has not been
considered before. We focus on two reactions - gamma+gamma-->H and e+gamma-->eH
- and introduce the polarization and/or azimuthal asymmetries that are
particularly sensitive to specific features of anomalies. We discuss the ways
of disentangling effects of physically different parameters of anomalies and
estimate what magnitude of CP violating phenomena can be seen in these
experiments.Comment: 17 pages, 9 figs; some modifications in the results presentation;
version to be published in Eur.Phys.J.
Inflation from Supersymmetric Quantum Cosmology
We derive a special scalar field potential using the anisotropic Bianchi type
I cosmological model from canonical quantum cosmology under determined
conditions in the evolution to anisotropic variables . In the
process, we obtain a family of potentials that has been introduced by hand in
the literature to explain cosmological data. Considering supersymmetric quantum
cosmology, this family is scanned, fixing the exponential potential as more
viable in the inflation scenario .Comment: 14 pages, latex2e, To appear in Phys. Rev.
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