638 research outputs found
Towards the Theory of Non--Abelian Tensor Fields I
We present a triangulation--independent area--ordering prescription which
naturally generalizes the well known path ordering one. For such a prescription
it is natural that the two--form ``connection'' should carry three ``color''
indices rather than two as it is in the case of the ordinary one--form gauge
connection. To define the prescription in question we have to define how to
{\it exponentiate} a matrix with three indices. The definition uses the fusion
rule structure constants.Comment: 22 pages, 18 figure
Oscillations of high energy neutrinos in matter: Precise formalism and parametric resonance
We present a formalism for precise description of oscillation phenomena in
matter at high energies or high densities, V > \Delta m^2/2E, where V is the
matter-induced potential of neutrinos. The accuracy of the approximation is
determined by the quantity \sin^2 2\theta_m \Delta V/2\pi V, where \theta_m is
the mixing angle in matter and \Delta V is a typical change of the potential
over the oscillation length (l \sim 2\pi/V). We derive simple and physically
transparent formulas for the oscillation probabilities, which are valid for
arbitrary matter density profiles. They can be applied to oscillations of high
energy (E > 10 GeV) accelerator, atmospheric and cosmic neutrinos in the matter
of the Earth, substantially simplifying numerical calculations and providing an
insight into the physics of neutrino oscillations in matter. The effect of
parametric enhancement of the oscillations of high energy neutrinos is
considered. Future high statistics experiments can provide an unambiguous
evidence for this effect.Comment: LaTeX, 5 pages, 1 figure. Linestyles in the figure corrected to match
their description in the caption; improved discussion of the accuracy of the
results; references added. Results and conclusions unchange
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
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
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
Reheat temperature in supersymmetric hybrid inflation models
The allowed range of parameters for supersymmetric hybrid inflation and its
extensions are investigated. The lower bound on the reheat temperature T_r in
these models with hierarchical right handed neutrinos is found to be 3*10^7
GeV. (T_r as low as 100 GeV is possible for quasi degenerate right handed
neutrinos.) We also present revised estimates for the scalar spectral index and
the symmetry breaking scale associated with inflation.Comment: 15 pages, 8 figures, revtex4. v2: minor changes, matches published
versio
Two Detector Reactor Neutrino Oscillation Experiment Kr2Det at Krasnoyarsk. Status Report
We consider status of the Kr2Det project aimed at sensitive searches for
neutrino oscillations in the atmospheric neutrino mass parameter region around
Dm2 ~ 3x10-3 eV2and at obtaining new information on the electron neutrino mass
structure (Ue3).Comment: 4 pages in pdf file. Talk presented at NANP-2001 International
Conference in Dubna, Russia, June 200
Stimulated Neutrino Transformation with Sinusoidal Density Profiles
Large amplitude oscillations between the states of a quantum system can be
stimulated by sinusoidal external potentials with frequencies that are similar
to the energy level splitting of the states or a fraction thereof. Situations
when the applied frequency is equal to an integer fraction of the energy level
splittings are known as parametric resonances. We investigate this effect for
neutrinos both analytically and numerically for the case of arbitrary numbers
of neutrino flavors. We look for environments where the effect may be observed
and find that supernova are the one realistic possibility due to the necessity
of both large densities and large amplitude fluctuations. The comparison of
numerical and analytic results of neutrino propagation through a model
supernova reveals it is possible to predict the locations and strengths of the
stimulated transitions that occur.Comment: 14 pages, 6 figure
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
- …