2,082 research outputs found
Perturbation Theory for Antisymmetric Tensor Fields in Four Dimensions
Perturbation theory for a class of topological field theories containing
antisymmetric tensor fields is considered. These models are characterized by a
supersymmetric structure which allows to establish their perturbative
finiteness.Comment: 23 page
Instabilities of noncommutative two dimensional BF model
The noncommutative extension of two dimensional BF model is considered. It is
shown that the realization of the noncommutative map via the Groenewold-Moyal
star product leads to instabilities of the action, hence to a non
renormalizable theory.Comment: 9 page
Extended uncertainty principle and the geometry of (anti)-de Sitter space
It has been proposed that on (anti)-de Sitter background, the Heisenberg
uncertainty principle should be modified by the introduction of a term
proportional to the cosmological constant. We show that this modification of
the uncertainty principle can be derived straightforwardly from the geometric
properties of (anti)-de Sitter spacetime. We also discuss the connection
between the so-called extended generalized uncertainty principle and triply
special relativity.Comment: 8 pages, plain TeX, references adde
Strongly Scale-dependent Non-Gaussianity
We discuss models of primordial density perturbations where the
non-Gaussianity is strongly scale-dependent. In particular, the non-Gaussianity
may have a sharp cut-off and be very suppressed on large cosmological scales,
but sizeable on small scales. This may have an impact on probes of
non-Gaussianity in the large-scale structure and in the cosmic microwave
background radiation anisotropies.Comment: 4 page
Symmetry breaking aspects of the effective Lagrangian for quantum black holes
The physical excitations entering the effective Lagrangian for quantum black
holes are related to a Goldstone boson which is present in the Rindler limit
and is due to the spontaneous breaking of the translation symmetry of the
underlying Minkowski space. This physical interpretation, which closely
parallels similar well-known results for the effective stringlike description
of flux tubes in QCD, gives a physical insight into the problem of describing
the quantum degrees of freedom of black holes. It also suggests that the
recently suggested concept of 'black hole complementarity' emerges at the
effective Lagrangian level rather than at the fundamental level.Comment: 11 pages, Latex,1 figur
Non-Unitary and Unitary Transitions in Generalized Quantum Mechanics, New Small Parameter and Information Problem Solving
Quantum Mechanics of the Early Universe is considered as deformation of a
well-known Quantum Mechanics. Similar to previous works of the author, the
principal approach is based on deformation of the density matrix with
concurrent development of the wave function deformation in the respective
Schr{\"o}dinger picture, the associated deformation parameter being interpreted
as a new small parameter. It is demonstrated that the existence of black holes
in the suggested approach in the end twice causes nonunitary transitions
resulting in the unitarity. In parallel this problem is considered in other
terms: entropy density, Heisenberg algebra deformation terms, respective
deformations of Statistical Mechanics, - all showing the identity of the basic
results. From this an explicit solution for Hawking's informaion paradox has
been derived.Comment: 18 page
Wave Packets Propagation in Quantum Gravity
Wave packet broadening in usual quantum mechanics is a consequence of
dispersion behavior of the medium which the wave propagates in it. In this
paper, we consider the problem of wave packet broadening in the framework of
Generalized Uncertainty Principle(GUP) of quantum gravity. New dispersion
relations are derived in the context of GUP and it has been shown that there
exists a gravitational induced dispersion which leads to more broadening of the
wave packets. As a result of these dispersion relations, a generalized
Klein-Gordon equation is obtained and its interpretation is given.Comment: 9 pages, no figur
Algebraic renormalization of supersymmetric gauge theories with dimensionful parameters
It is usually believed that there are no perturbative anomalies in
supersymmetric gauge theories beyond the well-known chiral anomaly. In this
paper we revisit this issue, because previously given arguments are incomplete.
Specifically, we rule out the existence of soft anomalies, i.e., quantum
violations of supersymmetric Ward identities proportional to a mass parameter
in a classically supersymmetric theory. We do this by combining a previously
proven theorem on the absence of hard anomalies with a spurion analysis, using
the methods of Algebraic Renormalization. We work in the on-shell component
formalism throughout. In order to deal with the nonlinearity of on-shell
supersymmetry transformations, we take the spurions to be dynamical, and show
how they nevertheless can be decoupled.Comment: Final version, typoes fixed. Revtex, 48 page
Nonrenormalization theorems for N=2 Super Yang-Mills
The BRST algebraic proofs of the the nonrenormalization theorems for the beta
functions of N=2 and N=4 Super Yang-Mills theories are reviewed.Comment: 3 pages, contribution to SUSY 2000 Encyclopedi
Covariant Helicity-Coupling Amplitudes: A New Formulation
We have worked out covariant amplitudes for any two-body decay of a resonance
with an arbitrary non-zero mass, which involves arbitrary integer spins in the
initial and the final states. One key new ingredient for this work is the
application of the total intrinsic spin operator which is given
directly in terms of the generators of the Poincar\'e group.
Using the results of this study, we show how to explore the Lorentz factors
which appear naturally, if the momentum-space wave functions are used to form
the covariant decay amplitudes. We have devised a method of constructing our
covariant decay amplitudes, such that they lead to the Zemach amplitudes when
the Lorentz factors are set one
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