502 research outputs found
TOPOLOGICAL OBJECTS AND CONFINEMENT ON THE LATTICE
First we discuss various topological objects (monopoles, ``minopoles'' and
``hybrids'') which may be important for the confinement mechanism in various
abelian projections. The second topic is the string between quark and
antiquark. The standard quantum string with the Nambu-Goto action exists only
in D=26. If we start from the field theory, in which the string excitations
exist, and change the variables in the path integral to the string variables,
then the Jacobian appears. This Jacobian generates the correction to the
Nambu-Goto action. For this effective action the conformal anomaly cancels in
D=4. Thus we get the quantum string theory in D=4.Comment: 9 pages, LaTeX, 2 uuencoded tar-compressed postscript figures, needs
psfig.tex; talk given by Polikarpov M.I. at International RCNP Workshop on
Color Confinement and Hadrons (Confinement 95), March 22--24, 1995, RCNP,
Osaka, Japan. (Revision: problems in figures fixed
Beta decay and other processes in strong electromagnetic fields
We consider effects of the fields of strong electromagnetic waves on various
characteristics of quantum processes. After a qualitative discussion of the
effects of external fields on the energy spectra and angular distributions of
the final-state particles as well as on the total probabilities of the
processes (such as decay rates and total cross sections), we present a simple
method of calculating the total probabilities of processes with production of
non-relativistic charged particles. Using nuclear beta-decay as an example, we
study the weak and strong field limits, as well as the field-induced beta-decay
of nuclei stable in the absence of the external fields, both in the tunneling
and multi-photon regimes. We also consider the possibility of accelerating
forbidden nuclear beta-decays by lifting the forbiddeness due to the
interaction of the parent or daughter nuclei with the field of a strong
electromagnetic wave. It is shown that for currently attainable electromagnetic
fields all effects on total beta-decay rates are unobservably small.Comment: LaTeX, 30 pages, 2 figures. Invited contribution to the special issue
of Yadernaya Fizika dedicated to the centennial anniversary of birthday of
A.B. Migdal. V2: references adde
Chizhov and Petcov Reply
We have found in [1] new conditions for a total neutrino conversion in the
case of neutrino oscillations taking place in a medium, consisting of n = 2 (or
3) alternating layers with constant densities and . It is claimed in
[4] that our results are particular case of enhancement of neutrino
oscillations, which was suggested earlier by other authors and was widely
discussed in the literature. We refute these claims, confirming the novelty of
our results.Comment: 2 pages, LATEX; concise (essentially 1 page) and somewhat modified
version of Ref. SISSA 5/2000/EP (hep-ph/0003110); reply on the ``Comment on
New Conditions for a Total Neutrino Conversion in a Medium'', Phys. Rev.
Lett. 85 (2000) 3978; published as ``Chizhov and Petcov Reply'' in Phys. Rev.
Lett. 85 (2000) 397
A continuum model for current distribution in Rutherford cables
An analysis of eddy currents induced in flat Rutherford-type cables by external time dependent magnetic fields has been performed. The induced currents generate in turn a secondary magnetic field which has a longitudinal periodicity (periodic pattern). The dependence of the amplitude of the pattern on the history of the cable excitation has been investigated. The study has been carried out with two different models for the simulation of current distribution in Rutherford cables, namely a network model, based on a lumped parameters circuit and a "continuum" model, based on a distributed parameters circuit. We show the results of simulations of the current distribution in the inner cable of a short LHC dipole model in different powering conditions and compare them to experimental data. (12 refs)
Floquet theory of neutrino oscillations in the earth
We review the Floquet theory of linear differential equations with periodic
coefficients and discuss its applications to neutrino oscillations in matter of
periodically varying density. In particular, we consider parametric resonance
in neutrino oscillations which can occur in such media, and discuss
implications for oscillations of neutrinos traversing the earth and passing
through the earth's core.Comment: LaTeX, 28 pages, 8 eps figures. Contribution to the special issue of
Yad. Fiz. dedicated to the memory of A.B. Migda
Exotic smooth structures on 4-manifolds with zero signature
For every integer , we construct infinite families of mutually
nondiffeomorphic irreducible smooth structures on the topological -manifolds
and (2k-1)(\CP#\CPb), the connected sums of
copies of and \CP#\CPb.Comment: 6 page
De Sitter space and perpetuum mobile
We give general arguments that any interacting non--conformal {\it classical}
field theory in de Sitter space leads to the possibility of constructing a
perpetuum mobile. The arguments are based on the observation that massive free
falling particles can radiate other massive particles on the classical level as
seen by the free falling observer. The intensity of the radiation process is
non-zero even for particles with any finite mass, i.e. with a wavelength which
is within the causal domain. Hence, we conclude that either de Sitter space can
not exist eternally or that one can build a perpetuum mobile.Comment: 11 pages revtex, no figures. Added discussion to strengthen
conclusio
Isometry invariance of exact correlation functions in various charts of Minkowski and de Sitter spaces
We consider quantum field theory with selfinteractions in various patches of
Minkowski and de Sitter space-times. Namely, in Minkowski space-time we
consider separately right (left) Rindler wedge, past wedge and future wedge. In
de Sitter space-time we consider expanding Poincare patch, static patch,
contracting Poincare patch and global de Sitter itself. In all cases we
restrict our considerations to the isometry invariant states leading to
maximally analytic propagators. We prove that loop corrections in right (left)
Rindler wedge, in the past wedge (of Minkowski space-time), in the static patch
and in the expanding Poincare patch (of de Sitter space-time) respect the
corresponding isometries of the corresponding symmetric space-times. All these
facts are related to the causality and analyticity properties of the
propagators for the states that we consider. At the same time in the future
wedge, in the contracting Poincare patch and in global de Sitter space-time
infrared effects violate the isometries.Comment: 35 pages, 6 figures Additional references and minor clarifications
added; version accepted to PR
- âŠ