413 research outputs found
Radiatively Generated Oscillations: General Analysis, Textures and Models
We study the consequences of assuming that the mass scale
corresponding to the solar neutrino oscillations and mixing angle
corresponding to the electron neutrino oscillation at CHOOZ are radiatively
generated through the standard electroweak gauge interactions. All the leptonic
mass matrices having zero and at a high scale lead to
a unique low energy value for the which is determined by the
(known) size of the radiative corrections, solar and the atmospheric mixing
angle and the Majorana mass of the neutrino observed in neutrinoless double
beta decay. This prediction leads to the following consequences: () The MSSM
radiative corrections generate only the dark side of the solar neutrino
solutions. () The inverted mass hierarchy () at the high scale
fails in generating the LMA solution but it can lead to the LOW or vacuum
solutions. () The generated in models with maximal solar
mixing at a high scale is zero to the lowest order in the radiative parameter.
It tends to get suppressed as a result of this and lies in the vacuum region.
We discuss specific textures which can lead to the LMA solution in the present
framework and provide a gauge theoretical realization of this in the context of
the seesaw model.Comment: 19 pages, LATE
Neutrino Anomalies in an Extended Zee Model
We discuss an extended model which naturally leads to mass
scales and mixing angles relevant for understanding both the solar and
atmospheric neutrino anomalies. No right-handed neutrinos are introduced in the
model.The model uses a softly broken symmetry. Neutrino
masses arise only at the loop level. The one-loop neutrino masses which arise
as in the Zee model solve the atmospheric neutrino anomaly while breaking of
generates at two-loop order a mass splitting needed for
the vacuum solution of the solar neutrino problem. A somewhat different model
is possible which accommodates the large-angle MSW resolution of the solar
neutrino problem.Comment: 11 pages including 2 figures; a reference added and text changed
accordingl
Floating Phase in 1D Transverse ANNNI Model
To study the ground state of ANNNI chain under transverse field as a function
of frustration parameter and field strength , we present here
two different perturbative analyses. In one, we consider the (known) ground
state at and as the unperturbed state and treat an
increase of the field from 0 to coupled with an increase of
from 0.5 to as perturbation. The first order perturbation
correction to eigenvalue can be calculated exactly and we could conclude that
there are only two phase transition lines emanating from the point
, . In the second perturbation scheme, we consider the
number of domains of length 1 as the perturbation and obtain the zero-th order
eigenfunction for the perturbed ground state. From the longitudinal spin-spin
correlation, we conclude that floating phase exists for small values of
transverse field over the entire region intermediate between the ferromagnetic
phase and antiphase.Comment: 11 pages, 11 figure
Algebraic approach in unifying quantum integrable models
A novel algebra underlying integrable systems is shown to generate and unify
a large class of quantum integrable models with given -matrix, through
reductions of an ancestor Lax operator and its different realizations. Along
with known discrete and field models a new class of inhomogeneous and impurity
models are obtained.Comment: Revtex, 6 pages, no figure, revised version to be published in Phys.
Rev. Lett., 199
Optical investigation of thermoelectric topological crystalline insulator PbSnSe
PbSnSe is a novel alloy of two promising thermoelectric
materials PbSe and SnSe that exhibits a temperature dependent band inversion
below 300 K. Recent work has shown that this band inversion also coincides with
a trivial to nontrivial topological phase transition. To understand how the
properties critical to thermoelectric efficiency are affected by the band
inversion, we measured the broadband optical response of
PbSnSe as a function of temperature. We find clear optical
evidence of the band inversion at K, and use the extended Drude
model to accurately determine a dependence of the bulk carrier
lifetime, associated with electron-acoustic phonon scattering. Due to the high
bulk carrier doping level, no discriminating signatures of the topological
surface states are found, although their presence cannot be excluded from our
data.Comment: 11 pages, 6 figure
Validation of Thermal Resistance Extracted From Measurements on Stripe Geometry SiGe HBTs
International audienceIn this article, we present a straightforward methodology to validate the consistency of thermal resistance (RTH) measurements for a set of stripe geometry silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs). The proposed approach is based on the behavior of frequency-dependent thermal impedance (ZTH) of HBTs. The key advantage of this method is its simplicity and ease of applicability because it requires no additional measurements than the conventional approaches to extract the electrothermal parameters. First, we provide a physics-based formulation to extract ZTH as a function of RTH. As a next step, we propose different normalization methods for ZTH in stripe emitter SiGe HBTs to validate the RTH used in our ZTH formulation. Finally, we substantiate our validation technique across stripe emitter SiGe HBTs having different emitter dimensions corresponding to STMicroelectronics B55 technology
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