150 research outputs found
Surface charge algebra in gauge theories and thermodynamic integrability
Surface charges and their algebra in interacting Lagrangian gauge field
theories are investigated by using techniques from the variational calculus. In
the case of exact solutions and symmetries, the surface charges are interpreted
as a Pfaff system. Integrability is governed by Frobenius' theorem and the
charges associated with the derived symmetry algebra are shown to vanish. In
the asymptotic context, we provide a generalized covariant derivation of the
result that the representation of the asymptotic symmetry algebra through
charges may be centrally extended. Finally, we make contact with Hamiltonian
and with covariant phase space methods.Comment: 40 pages Latex file, published versio
Irreversible thermodynamics of open chemical networks I: Emergent cycles and broken conservation laws
In this and a companion paper we outline a general framework for the
thermodynamic description of open chemical reaction networks, with special
regard to metabolic networks regulating cellular physiology and biochemical
functions. We first introduce closed networks "in a box", whose thermodynamics
is subjected to strict physical constraints: the mass-action law, elementarity
of processes, and detailed balance. We further digress on the role of solvents
and on the seemingly unacknowledged property of network independence of free
energy landscapes. We then open the system by assuming that the concentrations
of certain substrate species (the chemostats) are fixed, whether because
promptly regulated by the environment via contact with reservoirs, or because
nearly constant in a time window. As a result, the system is driven out of
equilibrium. A rich algebraic and topological structure ensues in the network
of internal species: Emergent irreversible cycles are associated to
nonvanishing affinities, whose symmetries are dictated by the breakage of
conservation laws. These central results are resumed in the relation between the number of fundamental affinities , that of broken
conservation laws and the number of chemostats . We decompose the
steady state entropy production rate in terms of fundamental fluxes and
affinities in the spirit of Schnakenberg's theory of network thermodynamics,
paving the way for the forthcoming treatment of the linear regime, of
efficiency and tight coupling, of free energy transduction and of thermodynamic
constraints for network reconstruction.Comment: 18 page
Converting Classical Theories to Quantum Theories by Solutions of the Hamilton-Jacobi Equation
By employing special solutions of the Hamilton-Jacobi equation and tools from
lattice theories, we suggest an approach to convert classical theories to
quantum theories for mechanics and field theories. Some nontrivial results are
obtained for a gauge field and a fermion field. For a topologically massive
gauge theory, we can obtain a first order Lagrangian with mass term. For the
fermion field, in order to make our approach feasible, we supplement the
conventional Lagrangian with a surface term. This surface term can also produce
the massive term for the fermion.Comment: 30 pages, no figures, v2: discussions and references added, published
version matche
Matched Asymptotic Expansion for Caged Black Holes - Regularization of the Post-Newtonian Order
The "dialogue of multipoles" matched asymptotic expansion for small black
holes in the presence of compact dimensions is extended to the Post-Newtonian
order for arbitrary dimensions. Divergences are identified and are regularized
through the matching constants, a method valid to all orders and known as
Hadamard's partie finie. It is closely related to "subtraction of
self-interaction" and shows similarities with the regularization of quantum
field theories. The black hole's mass and tension (and the "black hole
Archimedes effect") are obtained explicitly at this order, and a Newtonian
derivation for the leading term in the tension is demonstrated. Implications
for the phase diagram are analyzed, finding agreement with numerical results
and extrapolation shows hints for Sorkin's critical dimension - a dimension
where the transition turns second order.Comment: 28 pages, 5 figures. v2:published versio
Fluctuation theorem and large deviation function for a solvable model of a molecular motor
We study a discrete stochastic model of a molecular motor. This discrete
model can be viewed as a \emph{minimal} ratchet model. We extend our previous
work on this model, by further investigating the constraints imposed by the
Fluctuation Theorem on the operation of a molecular motor far from equilibrium.
In this work, we show the connections between different formulations of the
Fluctuation Theorem. One formulation concerns the generating function of the
currents while another one concerns the corresponding large deviation function,
which we have calculated exactly for this model. A third formulation of FT
concerns the ratio of the probability of making one forward step to the
probability of making one backward step. The predictions of this last
formulation of the Fluctuation Theorem adapted to our model are in very good
agreement with the data of Carter and Cross [Nature, {\bf 435}, 308 (2005)] on
single molecule measurements with kinesin. Finally, we show that all the
formulations of FT can be understood from the notion of entropy production.Comment: 15 pages, 9 figure
A fluctuation theorem for currents and non-linear response coefficients
We use a recently proved fluctuation theorem for the currents to develop the
response theory of nonequilibrium phenomena. In this framework, expressions for
the response coefficients of the currents at arbitrary orders in the
thermodynamic forces or affinities are obtained in terms of the fluctuations of
the cumulative currents and remarkable relations are obtained which are the
consequences of microreversibility beyond Onsager reciprocity relations
Random paths and current fluctuations in nonequilibrium statistical mechanics
An overview is given of recent advances in nonequilibrium statistical
mechanics about the statistics of random paths and current fluctuations.
Although statistics is carried out in space for equilibrium statistical
mechanics, statistics is considered in time or spacetime for nonequilibrium
systems. In this approach, relationships have been established between
nonequilibrium properties such as the transport coefficients, the thermodynamic
entropy production, or the affinities, and quantities characterizing the
microscopic Hamiltonian dynamics and the chaos or fluctuations it may generate.
This overview presents results for classical systems in the escape-rate
formalism, stochastic processes, and open quantum systems
Gallavotti-Cohen-Type symmetry related to cycle decompositions for Markov chains and biochemical applications
We slightly extend the fluctuation theorem obtained in \cite{LS} for sums of
generators, considering continuous-time Markov chains on a finite state space
whose underlying graph has multiple edges and no loop. This extended frame is
suited when analyzing chemical systems. As simple corollary we derive in a
different method the fluctuation theorem of D. Andrieux and P. Gaspard for the
fluxes along the chords associated to a fundamental set of oriented cycles
\cite{AG2}.
We associate to each random trajectory an oriented cycle on the graph and we
decompose it in terms of a basis of oriented cycles. We prove a fluctuation
theorem for the coefficients in this decomposition. The resulting fluctuation
theorem involves the cycle affinities, which in many real systems correspond to
the macroscopic forces. In addition, the above decomposition is useful when
analyzing the large deviations of additive functionals of the Markov chain. As
example of application, in a very general context we derive a fluctuation
relation for the mechanical and chemical currents of a molecular motor moving
along a periodic filament.Comment: 23 pages, 5 figures. Correction
Testing numerical relativity with the shifted gauge wave
Computational methods are essential to provide waveforms from coalescing
black holes, which are expected to produce strong signals for the gravitational
wave observatories being developed. Although partial simulations of the
coalescence have been reported, scientifically useful waveforms have so far not
been delivered. The goal of the AppleswithApples (AwA) Alliance is to design,
coordinate and document standardized code tests for comparing numerical
relativity codes. The first round of AwA tests have now being completed and the
results are being analyzed. These initial tests are based upon periodic
boundary conditions designed to isolate performance of the main evolution code.
Here we describe and carry out an additional test with periodic boundary
conditions which deals with an essential feature of the black hole excision
problem, namely a non-vanishing shift. The test is a shifted version of the
existing AwA gauge wave test. We show how a shift introduces an exponentially
growing instability which violates the constraints of a standard harmonic
formulation of Einstein's equations. We analyze the Cauchy problem in a
harmonic gauge and discuss particular options for suppressing instabilities in
the gauge wave tests. We implement these techniques in a finite difference
evolution algorithm and present test results. Although our application here is
limited to a model problem, the techniques should benefit the simulation of
black holes using harmonic evolution codes.Comment: Submitted to special numerical relativity issue of Classical and
Quantum Gravit
A Dialogue of Multipoles: Matched Asymptotic Expansion for Caged Black Holes
No analytic solution is known to date for a black hole in a compact
dimension. We develop an analytic perturbation theory where the small parameter
is the size of the black hole relative to the size of the compact dimension. We
set up a general procedure for an arbitrary order in the perturbation series
based on an asymptotic matched expansion between two coordinate patches: the
near horizon zone and the asymptotic zone. The procedure is ordinary
perturbation expansion in each zone, where additionally some boundary data
comes from the other zone, and so the procedure alternates between the zones.
It can be viewed as a dialogue of multipoles where the black hole changes its
shape (mass multipoles) in response to the field (multipoles) created by its
periodic "mirrors", and that in turn changes its field and so on. We present
the leading correction to the full metric including the first correction to the
area-temperature relation, the leading term for black hole eccentricity and the
"Archimedes effect". The next order corrections will appear in a sequel. On the
way we determine independently the static perturbations of the Schwarzschild
black hole in dimension d>=5, where the system of equations can be reduced to
"a master equation" - a single ordinary differential equation. The solutions
are hypergeometric functions which in some cases reduce to polynomials.Comment: 47 pages, 12 figures, minor corrections described at the end of the
introductio
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