6,231 research outputs found
Hard Thermal Loops in the n-Dimensional phi3 Theory
We derive a closed-form result for the leading thermal contributions which
appear in the n-dimensional phi3 theory at high temperature. These
contributions become local only in the long wavelength and in the static
limits, being given by different expressions in these two limits.Comment: 3 pages, one figure. To be published in the Brazilian Journal of
Physic
The 3-graviton vertex function in thermal quantum gravity
The high temperature limit of the 3-graviton vertex function is studied in
thermal quantum gravity, to one loop order. The leading () contributions
arising from internal gravitons are calculated and shown to be twice the ones
associated with internal scalar particles, in correspondence with the two
helicity states of the graviton. The gauge invariance of this result follows in
consequence of the Ward and Weyl identities obeyed by the thermal loops, which
are verified explicitly.Comment: 19 pages, plain TeX, IFUSP/P-100
Dressing Symmetries of Holomorphic BF Theories
We consider holomorphic BF theories, their solutions and symmetries. The
equivalence of Cech and Dolbeault descriptions of holomorphic bundles is used
to develop a method for calculating hidden (nonlocal) symmetries of holomorphic
BF theories. A special cohomological symmetry group and its action on the
solution space are described.Comment: 14 pages, LaTeX2
Vertex-algebraic structure of the principal subspaces of certain A_1^(1)-modules, I: level one case
This is the first in a series of papers in which we study vertex-algebraic
structure of Feigin-Stoyanovsky's principal subspaces associated to standard
modules for both untwisted and twisted affine Lie algebras. A key idea is to
prove suitable presentations of principal subspaces, without using bases or
even ``small'' spanning sets of these spaces. In this paper we prove
presentations of the principal subspaces of the basic A_1^(1)-modules. These
convenient presentations were previously used in work of
Capparelli-Lepowsky-Milas for the purpose of obtaining the classical
Rogers-Ramanujan recursion for the graded dimensions of the principal
subspaces.Comment: 20 pages. To appear in International J. of Mat
Hard thermal effective action in QCD through the thermal operator
Through the application of the thermal operator to the zero temperature
retarded Green's functions, we derive in a simple way the well known hard
thermal effective action in QCD. By relating these functions to forward
scattering amplitudes for on-shell particles, this derivation also clarifies
the origin of important properties of the hard thermal effective action, such
as the manifest Lorentz and gauge invariance of its integrand.Comment: 6 pages, contribution of the quarks to the effective action included
and one reference added, version to be published in Phys. Rev.
General structure of the graviton self-energy
The graviton self-energy at finite temperature depends on fourteen structure
functions. We show that, in the absence of tadpoles, the gauge invariance of
the effective action imposes three non-linear relations among these functions.
The consequences of such constraints, which must be satisfied by the thermal
graviton self-energy to all orders, are explicitly verified in general linear
gauges to one loop order.Comment: 4 pages, minor corrections of typo
Non-linear electromagnetic interactions in thermal QED
We examine the behavior of the non-linear interactions between
electromagnetic fields at high temperature. It is shown that, in general, the
log(T) dependence on the temperature of the Green functions is simply related
to their UV behavior at zero-temperature. We argue that the effective action
describing the nonlinear thermal electromagnetic interactions has a finite
limit as T tends to infinity. This thermal action approaches, in the long
wavelength limit, the negative of the corresponding zero-temperature action.Comment: 7 pages, IFUSP/P-111
Effective actions at finite temperature
This is a more detailed version of our recent paper where we proposed, from
first principles, a direct method for evaluating the exact fermion propagator
in the presence of a general background field at finite temperature. This can,
in turn, be used to determine the finite temperature effective action for the
system. As applications, we discuss the complete one loop finite temperature
effective actions for 0+1 dimensional QED as well as for the Schwinger model in
detail. These effective actions, which are derived in the real time (closed
time path) formalism, generate systematically all the Feynman amplitudes
calculated in thermal perturbation theory and also show that the retarded
(advanced) amplitudes vanish in these theories. Various other aspects of the
problem are also discussed in detail.Comment: 9 pages, revtex, 1 figure, references adde
On the Infrared Behavior of the Pressure in Thermal Field Theories
We study non-perturbatively, via the Schwinger-Dyson equations, the leading
infrared behavior of the pressure in the ladder approximation. This problem is
discussed firstly in the context of a thermal scalar field theory, and the
analysis is then extended to the Yang-Mills theory at high temperatures. Using
the Feynman gauge, we find a system of two coupled integral equations for the
gluon and ghost self-energies, which is solved analytically. The solutions of
these equations show that the contributions to the pressure, when calculated in
the ladder approximation, are finite in the infrared domain.Comment: 20 pages plus 4 figures available by request, IFUSP/P-100
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