13,164 research outputs found
Fluctuation theorems and orbital magnetism in nonequilibrium state
We study Langevin dynamics of a driven charged particle in the presence as
well as in the absence of magnetic field. We discuss the validity of various
work fluctuation theorems using different model potentials and external drives.
We also show that one can generate an orbital magnetic moment in a
nonequilibrium state which is absent in equilibrium.Comment: Based on a talk by A. M. J at international workshop MESODIS'06 (IIT
Kanpur,Dec-2006
A Regulatory approach to financial product advice and distribution
Financial distribution, where the distributor is the agent of both the product provider and the customer has been found to inherently work against the interests of customers, in the form of high service fees and perverse incentives in sales practices. This paper proposes segregation of financial advice from financial distribution. It proposes a Financial Advisers Bill, 2012, to promote the development of a market for advice. The Bill suggests that financial advisers be recognised as professionals and be regulated under a new statutory body called the Institute of Financial Advisers of India. The paper suggests that regulation of distributors continue to remain under the purview of product regulators. It outlines alternative models in which the distribution market may be organised. It also points out that the Ministry of Finance and the Financial Stability and Development Council need to play an active role in co-ordinating the setting of common standards for distribution across all product regulators.Consumer Protection; distribution regulation; mutual funds; insurance; pensions; investment advice
Neutrino Mass, Coupling Unification, Verifiable Proton Decay, Vacuum Stability and WIMP Dark Matter in SU(5)
Nonsupersymmetric minimal SU(5) with Higgs representations and
and standard fermions in is well known for its
failure in unification of gauge couplings and lack of predicting neutrino
masses. Like standard model, it is also affected by the instability of the
Higgs scalar potential. We note that extending the Higgs sector by and
not only leads to the popular type-II seesaw ansatz for neutrino
masses with a lower bound on the triplet mass GeV,
but also achieves precision unification of gauge couplings without
proliferation of non-standard light Higgs scalars or fermions near the TeV
scale. Consistent with recent LUX-2016 lower bound, the model easily
accommodates a singlet scalar WIMP dark matter near the TeV scale which
resolves the vacuum stability issue even after inclusion of heavy triplet
threshold effect. We estimate proton lifetime predictions for
including uncertainties due to input parameters and threshold effects due to
superheavy Higgs scalars and superheavy gauge bosons.
The predicted lifetime is noted to be verifiable at Super Kamiokande and Hyper
Kamiokande experiments.Comment: 36 pages, 9 figures (Accepted for publication in Advances in High
Energy Physics
Quantum Stochastic Absorption
We report a detailed and systematic study of wave propagation through a
stochastic absorbing random medium. Stochastic absorption is modeled by
introducing an attenuation constant per unit length in the free
propagation region of the one-dimensional disordered chain of delta function
scatterers. The average value of the logarithm of transmission coefficient
decreases linearly with the length of the sample. The localization length is
given by , where and
are the localization lengths in the presence of only disorder and
of only absorption respectively. Absorption does not introduce any additional
reflection in the limit of large , i.e., reflection shows a monotonic
decrease with and tends to zero in the limit of , in
contrast to the behavior observed in case of coherent absorption. The
stationary distribution of reflection coefficient agrees well with the
analytical results obtained within random phase approximation (RPA) in a larger
parameter space. We also emphasize the major differences between the results of
stochastic and coherent absorption.Comment: RevTex, 6 pages,2 column format, 9 .eps figures include
Dephasing of Aharonov-Bohm oscillations in a mesoscopic ring with a magnetic impurity
We present a detailed analysis of the Aharonov-Bohm interference oscillations
manifested through transmission of an electron in a mesoscopic ring with a
magnetic impurity atom inserted in one of its arms. The electron interacts with
the impurity through the exchange interaction leading to exchange spin-flip
scattering. Transmission in the spin-flipped and spin-unflipped channels are
explicitly calculated. We show that the spin-flipper acts as a dephasor in
spite of absence of any inelastic scattering. The spin-conductance (related to
spin-polarized transmission coefficient) is asymmetric in the flux reversal as
opposed to the two probe conductance which is symmetric under flux reversal.Comment: 4 pages RevTex, 6 figures, brief repor
Modelling of Stochastic Absorption in a Random Medium
We report a detailed and systematic study of wave propagation through a
stochastic absorbing random medium. Stochastic absorption is modeled by
introducing an attenuation constant per unit length in the free
propagation region of the one-dimensional disordered chain of delta function
scatterers. The average value of the logarithm of transmission coefficient
decreases linearly with the length of the sample. The localization length is
given by , where and
are the localization lengths in the presence of only disorder and
of only absorption respectively. Absorption does not introduce any additional
reflection in the limit of large , i.e., reflection shows a monotonic
decrease with and tends to zero in the limit of , in
contrast to the behavior observed in case of coherent absorption. The
stationary distribution of reflection coefficient agrees well with the
analytical results obtained within random phase approximation (RPA) in a larger
parameter space. We also emphasize the major differences between the results of
stochastic and coherent absorption.Comment: 7 pages RevTex, 9 eps figures included, modified version of
cond-mat/9909327, to appear in PRB, mpeg simulations at
http://www.iopb.res.in/~joshi/mpg.htm
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