533 research outputs found
A Functional and Lagrangian Formulation of Two-Dimensional Topological Gravity
We reconsider two-dimensional topological gravity in a functional and
lagrangian framework. We derive its Slavnov-Taylor identities and discuss its
(in)dependence on the background gauge. Correlators of reparamerization
invariant observables are shown to be globally defined forms on moduli space.
The potential obstruction to their gauge-independence is the non-triviality of
the line bundle on moduli space , whose first Chern-class is
associated to the topological invariants of Mumford, Morita and Miller. Based
on talks given at the Fubini Fest, Torino, 24-26 February 1994, and at the
Workshop on String Theory, Trieste, 20-22 April 1994.Comment: 11 pages, harvmac, CERN-TH-7302/94, GEF-Th-6/199
A nilpotent symmetry of quantum gauge theories
For the Becchi-Rouet-Stora-Tyutin (BRST) invariant extended action for any
gauge theory, there exists another off-shell nilpotent symmetry. For linear
gauges, it can be elevated to a symmetry of the quantum theory and used in the
construction of the quantum effective action. Generalizations for nonlinear
gauges and actions with higher order ghost terms are also possible.Comment: RevTeX, 9 pages, several changes to include generalizations to
quartic and higher ghost terms and non-linear gauges. Abstract changed. Final
version to be publishe
BRS "Symmetry", prehistory and history
Prehistory - Starting from 't Hooft's (1971) we have a short look at Taylor's
and Slavnov's works (1971-72) and at the lectures given by Rouet and Stora in
Lausanne-1973 which determine the transition from pre-history to history.
History - We give a brief account of the main analyses and results of the BRS
collaboration concerning the renormalized gauge theories, in particular the
method of the regularization independent, algebraic renormalization, the
algebraic proof of S-matrix unitarity and that of gauge choice independence of
the renormalized physics. We conclude this report with a suggestion to the
crucial question: what could remain of BRS invariance beyond perturbation
theory.Comment: Talk given at: A Special day in honour of Raymond Stora, Annecy, July
8, 201
The Complexity of Vector Spin Glasses
We study the annealed complexity of the m-vector spin glasses in the
Sherrington-Kirkpatrick limit. The eigenvalue spectrum of the Hessian matrix of
the Thouless-Anderson-Palmer (TAP) free energy is found to consist of a
continuous band of positive eigenvalues in addition to an isolated eigenvalue
and (m-1) null eigenvalues due to rotational invariance. Rather surprisingly,
the band does not extend to zero at any finite temperature. The isolated
eigenvalue becomes zero in the thermodynamic limit, as in the Ising case (m=1),
indicating that the same supersymmetry breaking recently found in Ising spin
glasses occurs in vector spin glasses.Comment: 4 pages, 2 figure
Numerical study of the scaling properties of SU(2) lattice gauge theory in Palumbo non-compact regularization
In the framework of a non-compact lattice regularization of nonabelian gauge
theories we look, in the SU(2) case, for the scaling window through the
analysis of the ratio of two masses of hadronic states. In the two-dimensional
parameter space of the theory we find the region where the ratio is constant,
and equal to the one in the Wilson regularization. In the scaling region we
calculate the lattice spacing, finding it at least 20% larger than in the
Wilson case; therefore the simulated physical volume is larger.Comment: 24 pages, 7 figure
Non-Uniqueness of Quantized Yang-Mills Theories
We consider quantized Yang-Mills theories in the framework of causal
perturbation theory which goes back to Epstein and Glaser. In this approach
gauge invariance is expressed by a simple commutator relation for the S-matrix.
The most general coupling which is gauge invariant in first order contains a
two-parametric ambiguity in the ghost sector - a divergence- and a
coboundary-coupling may be added. We prove (not completely) that the higher
orders with these two additional couplings are gauge invariant, too. Moreover
we show that the ambiguities of the n-point distributions restricted to the
physical subspace are only a sum of divergences (in the sense of vector
analysis). It turns out that the theory without divergence- and
coboundary-coupling is the most simple one in a quite technical sense. The
proofs for the n-point distributions containing coboundary-couplings are given
up to third or fourth order only, whereas the statements about the
divergence-coupling are proven in all orders.Comment: 22 pages. The paper is written in TEX. The necessary macros are
include
Modular Invariance on the Torus and Abelian Chern-Simons Theory
The implementation of modular invariance on the torus as a phase space at the
quantum level is discussed in a group-theoretical framework. Unlike the
classical case, at the quantum level some restrictions on the parameters of the
theory should be imposed to ensure modular invariance. Two cases must be
considered, depending on the cohomology class of the symplectic form on the
torus. If it is of integer cohomology class , then full modular invariance
is achieved at the quantum level only for those wave functions on the torus
which are periodic if is even, or antiperiodic if is odd. If the
symplectic form is of rational cohomology class , a similar result
holds --the wave functions must be either periodic or antiperiodic on a torus
times larger in both direccions, depending on the parity of .
Application of these results to the Abelian Chern-Simons is discussed.Comment: 24 pages, latex, no figures; title changed; last version published in
JM
From Koszul duality to Poincar\'e duality
We discuss the notion of Poincar\'e duality for graded algebras and its
connections with the Koszul duality for quadratic Koszul algebras. The
relevance of the Poincar\'e duality is pointed out for the existence of twisted
potentials associated to Koszul algebras as well as for the extraction of a
good generalization of Lie algebras among the quadratic-linear algebras.Comment: Dedicated to Raymond Stora. 27 page
RNA Pore Translocation with Static and Periodic Forces: Effect of Secondary and Tertiary Elements on Process Activation and Duration
We use MD simulations to study the pore translocation properties of a pseudoknotted viral RNA. We consider the 71-nucleotide-long xrRNA from the Zika virus and establish how it responds when driven through a narrow pore by static or periodic forces applied to either of the two termini. Unlike the case of fluctuating homopolymers, the onset of translocation is significantly delayed with respect to the application of static driving forces. Because of the peculiar xrRNA architecture, activation times can differ by orders of magnitude at the two ends. Instead, translocation duration is much smaller than activation times and occurs on time scales comparable at the two ends. Periodic forces amplify significantly the differences at the two ends, for both activation times and translocation duration. Finally, we use a waiting-times analysis to examine the systematic slowing downs in xrRNA translocations and associate them to the hindrance of specific secondary and tertiary elements of xrRNA. The findings provide a useful reference to interpret and design future theoretical and experimental studies of RNA translocation
The Complexity of Ising Spin Glasses
We compute the complexity (logarithm of the number of TAP states) associated
with minima and index-one saddle points of the TAP free energy. Higher-index
saddles have smaller complexities. The two leading complexities are equal,
consistent with the Morse theorem on the total number of turning points, and
have the value given in [A. J. Bray and M. A. Moore, J. Phys. C 13, L469
(1980)]. In the thermodynamic limit, TAP states of all free energies become
marginally stable.Comment: Typos correcte
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