3,877 research outputs found
Higher gauge theory -- differential versus integral formulation
The term higher gauge theory refers to the generalization of gauge theory to
a theory of connections at two levels, essentially given by 1- and 2-forms. So
far, there have been two approaches to this subject. The differential picture
uses non-Abelian 1- and 2-forms in order to generalize the connection 1-form of
a conventional gauge theory to the next level. The integral picture makes use
of curves and surfaces labeled with elements of non-Abelian groups and
generalizes the formulation of gauge theory in terms of parallel transports. We
recall how to circumvent the classic no-go theorems in order to define
non-Abelian surface ordered products in the integral picture. We then derive
the differential picture from the integral formulation under the assumption
that the curve and surface labels depend smoothly on the position of the curves
and surfaces. We show that some aspects of the no-go theorems are still present
in the differential (but not in the integral) picture. This implies a
substantial structural difference between non-perturbative and perturbative
approaches to higher gauge theory. We finally demonstrate that higher gauge
theory provides a geometrical explanation for the extended topological symmetry
of BF-theory in both pictures.Comment: 26 pages, LaTeX with XYPic diagrams; v2: typos corrected and
presentation improve
Fluctuation theorems for excess and housekeeping heats for underdamped systems
We present a simple derivation of the integral fluctuation theorems for
excess housekeeping heat for an underdamped Langevin system, without using the
concept of dual dynamics. In conformity with the earlier results, we find that
the fluctuation theorem for housekeeping heat holds when the steady state
distributions are symmetric in velocity, whereas there is no such requirement
for the excess heat. We first prove the integral fluctuation theorem for the
excess heat, and then show that it naturally leads to the integral fluctuation
theorem for housekeeping heat. We also derive the modified detailed fluctuation
theorems for the excess and housekeeping heats.Comment: 10 pages. Section 3 contains further generalization
Entropy production theorems and some consequences
The total entropy production fluctuations are studied in some exactly
solvable models. For these systems, the detailed fluctuation theorem holds even
in the transient state, provided initially the system is prepared in thermal
equilibrium. The nature of entropy production during the relaxation of a system
to equilibrium is analyzed. The averaged entropy production over a finite time
interval gives a better bound for the average work performed on the system than
that obtained from the well known Jarzynski equality. Moreover, the average
entropy production as a quantifier for information theoretic nature of
irreversibility for finite time nonequilibrium processes is discussed.Comment: 12 pages, 3 figure
Fluctuation theorems in presence of information gain and feedback
In this study, we rederive the fluctuation theorems in presence of feedback,
by assuming the known Jarzynski equality and detailed fluctuation theorems. We
first reproduce the already known work theorems for a classical system, and
then extend the treatment to the other classical theorems. For deriving the
extended quantum fluctuation theorems, we have considered open systems. No
assumption is made on the nature of environment and the strength of system-bath
coupling. However, it is assumed that the measurement process involves
classical errors.Comment: 8 pages, 1 figur
Relativistic Mean Field in 80 nuclei and low energy proton reactions
Relativistic Mean Field calculations have been performed for a number of
nuclei in mass 80 region. Ground state binding energy, charge radius
and charge density values have been compared with experiment. Optical potential
have been generated folding the nuclear density with the microscopic nuclear
interaction DDM3Y. S-factors for low energy () and () reactions
have been calculated and compared with experiment.Comment: To appear in Physical Review
Topologically Massive Non-Abelian Gauge Theories: Constraints and Deformations
We study the relationship between three non-Abelian topologically massive
gauge theories, viz. the naive non-Abelian generalization of the Abelian model,
Freedman-Townsend model and the dynamical 2-form theory, in the canonical
framework. Hamiltonian formulation of the naive non-Abelian theory is presented
first. The other two non-Abelian models are obtained by deforming the
constraints of this model. We study the role of the auxiliary vector field in
the dynamical 2-form theory in the canonical framework and show that the
dynamical 2-form theory cannot be considered as the embedded version of naive
non-Abelian model. The reducibility aspect and gauge algebra of the latter
models are also discussed.Comment: ReVTeX, 17 pp; one reference added, version published in Phys. Rev.
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