13,776 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
Implications of lepton nonuniversality in the beauty sector
The phenomenon of CP violation in the standard model (SM) framework and the
decay dynamics have been established from the data obtained from the B
factories and so far we have not seen anything new. Nevertheless, there have
been instances of deviations in many measured observables in the flavor sector,
as far as the data and predictions are concerned. Here we will mention some
deviations obtained in measurements related to lepton universality, as seen
from the data, and try to understand their implications. To accommodate the
observed data we will consider a leptoquark model, which seems to be one
interesting model beyond the SM.Comment: 6 pages, 4 figures, talk given at BEACH 2016, George Mason
University, Fairfax, Virginia, USA, June 201
Recommended from our members
Unbiased Boolean analysis of public gene expression data for cell cycle gene identification.
Cell proliferation is essential for the development and maintenance of all organisms and is dysregulated in cancer. Using synchronized cells progressing through the cell cycle, pioneering microarray studies defined cell cycle genes based on cyclic variation in their expression. However, the concordance of the small number of synchronized cell studies has been limited, leading to discrepancies in definition of the transcriptionally regulated set of cell cycle genes within and between species. Here we present an informatics approach based on Boolean logic to identify cell cycle genes. This approach used the vast array of publicly available gene expression data sets to query similarity to CCNB1, which encodes the cyclin subunit of the Cdk1-cyclin B complex that triggers the G2-to-M transition. In addition to highlighting conservation of cell cycle genes across large evolutionary distances, this approach identified contexts where well-studied genes known to act during the cell cycle are expressed and potentially acting in nondivision contexts. An accessible web platform enables a detailed exploration of the cell cycle gene lists generated using the Boolean logic approach. The methods employed are straightforward to extend to processes other than the cell cycle
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
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
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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