4,862 research outputs found
A New Class of Supersymmetric Theories
We construct a class of quantum mechanical theories which are invariant under
fermionic transformations similar to supersymmetry transformations. The
generators of the transformations in this case, however, satisfy a BRST-like
algebra.Comment: 9 page
On the Higher Order Corrections to Heavy Quark Effective Theory
We show that the different ways of deriving the Heavy Quark Effective Theory
(HQET) lead to equivalent theories. The equivalence can be established through
a careful redefinition of the field variables. We demonstrate the equivalence
to order in the presence of a constant electric field.Comment: 17 pages, UR-1325, ER-40685-77
Finite Temperature and Large Gauge Invariance
We discuss the problem of large gauge invariance at finite temperature.Comment: Talk presented at the Second School on Field Theory and Gravitation
in Vitoria, to be published in the proceeding
A Key Establishment Scheme for Mobile Wireless Sensor Networks Using Post-Deployment Knowledge
Establishment of pairwise keys between sensor nodes in a sensor network is a
difficult problem due to resource limitations of sensor nodes as well as
vulnerability to physical captures of sensor nodes by the enemy. Public-key
cryptosystems are not much suited for most resource-constrained sensor
networks. Recently, elliptic curve cryptographic techniques show that public
key cryptosystem is also feasible for resource-constrained sensor networks.
However, most researchers accept that the symmetric key cryptosystems are
viable options for resource-constrained sensor networks. In this paper, we
first develop a basic principle to address the key pre-distribution problem in
mobile sensor networks. Then, using this developed basic principle, we propose
a scheme which takes the advantage of the post-deployment knowledge. Our scheme
is a modified version of the key prioritization technique proposed by Liu and
Ning. Our improved scheme provides reasonable network connectivity and
security. Moreover, the proposed scheme works for any deployment topology.Comment: Published in International Journal of Computer Networks &
Communications (IJCNC) Vol.3, No.4, July 201
Giant number fluctuations in microbial ecologies
Statistical fluctuations in population sizes of microbes may be quite large
depending on the nature of their underlying stochastic dynamics. For example,
the variance of the population size of a microbe undergoing a pure birth
process with unlimited resources is proportional to the square of its mean. We
refer to such large fluctuations, with the variance growing as square of the
mean, as Giant Number Fluctuations (GNF). Luria and Delbruck showed that
spontaneous mutation processes in microbial populations exhibit GNF. We explore
whether GNF can arise in other microbial ecologies. We study certain simple
ecological models evolving via stochastic processes: (i) bi-directional
mutation, (ii) lysis-lysogeny of bacteria by bacteriophage, and (iii)
horizontal gene transfer (HGT). For the case of bi-directional mutation
process, we show analytically exactly that the GNF relationship holds at large
times. For the ecological model of bacteria undergoing lysis or lysogeny under
viral infection, we show that if the viral population can be experimentally
manipulated to stay quasi-stationary, the process of lysogeny maps essentially
to one-way mutation process and hence the GNF property of the lysogens follows.
Finally, we show that even the process of HGT may map to the mutation process
at large times, and thereby exhibits GNF.Comment: 18 pages, 5 figure
Nonleptonic Decays of Charmed Mesons into two Pseudoscalar Mesons
We investigate the nonleptonic decay of charmed meson into two pseudoscalar
mesons using the vector--dominance model, and compare the results with those
obtained from the factorization model. In particular, we discuss the role of
the annihilation diagrams in the two models.Comment: 10 pages, UR-1235, ER40685-687, (figures not included
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