38 research outputs found
Large Order Behavior of Quasiclassical Euclidean Gravity in Minisuperspace Models
We demonstrate in two minisuperspace models that a perturbation expansion of
quasiclassical Euclidean gravity has a factorial dependence on the order of the
term at large orders. This behavior indicates that the expansion is an
asymptotic series which is suggestive of an effective field theory. The series
may or may not be Borel summable depending on the classical solution expanded
around. We assume that only the positive action classical solution contributes
to path integrals. We close with some speculative discussion on possible
implications of the asymptotic nature of the expansion.Comment: 10 pages, Late
Energy Flow in Acoustic Black Holes
We present the results of an analysis of superradiant energy flow due to
scalar fields incident on an acoustic black hole. In addition to providing
independent confirmation of the recent results in [5], we determine in detail
the profile of energy flow everywhere outside the horizon. We confirm
explicitly that in a suitable frame the energy flow is inward at the horizon
and outward at infinity, as expected on physical grounds.Comment: 8 pages, 9 figures, Comments added to discussion of energy flow and
introductory section abbreviate
Can Induced Theta Vacua be Created in Heavy Ion Collisions?
The development of the early Universe is a remarkable laboratory for the
study of most nontrivial properties of particle physics. What is more
remarkable is the fact that these phenomena at the QCD scale can be, in
principle, experimentally tested in heavy ion collisions. We expect that, in
general, an arbitrary theta-state would be created in the heavy ion collisions,
similar to the creation of the disoriented chiral condensate with an arbitrary
isospin direction. It should be a large domain with a wrong
orientation. We test this idea numerically in a simple model where we study the
evolution of the phases of the chiral condensates in QCD with two quark flavors
with non-zero theta-parameter. We see the formation of a non-zero theta-vacuum
with the formation time of the order of seconds. This result will
have important implications for a possible axion search experiment at RHIC.Comment: 4 pages, 3 figures, Latex, Discussion of experimental signatures
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Real time statistical field theory
We have written a {\it Mathematica} program that calculates the integrand
corresponding to any amplitude in the closed-time-path formulation of real time
statistical field theory. The program is designed so that it can be used by
someone with no previous experience with {\it Mathematica}. It performs the
contractions over the tensor indices that appear in real time statistical field
theory and gives the result in the 1-2, Keldysh or RA basis. We have used the
program to calculate the ward identity for the QED 3-point function, the QED
4-point function for two photons and two fermions, and the QED 5-point function
for three photons and two fermions. In real time statistical field theory,
there are seven 3-point functions, 15 4-point functions and 31 5-point
functions. We produce a table that gives the results for all of these
functions. In addition, we give a simple general expression for the KMS
conditions between -point green functions and vertex functions, in both the
Keldysh and RA basesComment: 25 pages, 12 figure
The spectrum of multi-flavor QCD_2 and the non-Abelian Schwinger equation
Massless is dominated by classical configurations in the large
limit. We use this observation to study the theory by finding solutions to
equations of motion, which are the non-Abelian generalization of the Schwinger
equation. We find that the spectrum consists of massive mesons with which correspond to Abelian solutions. We generalize previously
discovered non-Abelian solutions and discuss their interpretation. We prove a
no-go theorem ruling out the existence of soliton solutions. Thus the
semi-classical approximation shows no baryons in the case of massless quarks, a
result derived before in the strong-coupling limit only.Comment: 17 pages, Latex. 1 figur
vacua states in heavy ion collisions in presence of dissipation and noise
We have studied possible formation of vacua states in heavy ion
collisions. Random phases of the chiral fields were evolved in a finite
temperature potential, incorporating the breaking of symmetry. Initial
random phases very quickly settle into oscillation around the values dictated
by the potential. The simulation study indicate that an initial =0
state do not evolve into a 0 state. However, an initial
0 state, if formed in heavy ion collision, can survive, as a
coherent superposition of a number of modes.Comment: 6 pages, 6 figure