4,323 research outputs found
An Angular Correlation Test of Time Reversal Invariance
Gamma-ray angular correlation experiment of time reversal invarianc
Angular Correlation of Cascade Gamma Rays in 94nb
Angular correlation of cascade gamma rays in niobiu
Formation of Black Holes from Collapsed Cosmic String Loops
The fraction of cosmic string loops which collapse to form black holes is
estimated using a set of realistic loops generated by loop fragmentation. The
smallest radius sphere into which each cosmic string loop may fit is obtained
by monitoring the loop through one period of oscillation. For a loop with
invariant length which contracts to within a sphere of radius , the
minimum mass-per-unit length necessary for the cosmic string
loop to form a black hole according to the hoop conjecture is . Analyzing loops, we obtain the empirical estimate for the fraction of cosmic string
loops which collapse to form black holes as a function of the mass-per-unit
length in the range . We
use this power law to extrapolate to , obtaining the
fraction of physically interesting cosmic string loops which
collapse to form black holes within one oscillation period of formation.
Comparing this fraction with the observational bounds on a population of
evaporating black holes, we obtain the limit on the cosmic string mass-per-unit-length. This limit is consistent
with all other observational bounds.Comment: uuencoded, compressed postscript; 20 pages including 7 figure
Bounds on Dark Matter from the ``Atmospheric Neutrino Anomaly''
Bounds are derived on the cross section, flux and energy density of new
particles that may be responsible for the atmospheric neutrino anomaly. Decay of primordial
homogeneous dark matter can be excluded.Comment: 10 pages, TeX (revtex
Analytic Results for the Gravitational Radiation from a Class of Cosmic String Loops
Cosmic string loops are defined by a pair of periodic functions and
, which trace out unit-length closed curves in three-dimensional
space. We consider a particular class of loops, for which lies along
a line and lies in the plane orthogonal to that line. For this class
of cosmic string loops one may give a simple analytic expression for the power
radiated in gravitational waves. We evaluate exactly in
closed form for several special cases: (1) a circle traversed
times; (2) a regular polygon with sides and interior vertex angle
; (3) an isosceles triangle with semi-angle .
We prove that case (1) with is the absolute minimum of within
our special class of loops, and identify all the stationary points of
in this class.Comment: 15 pages, RevTex 3.0, 7 figures available via anonymous ftp from
directory pub/pcasper at alpha1.csd.uwm.edu, WISC-MILW-94-TH-1
Laboratory Evaluation of Egg White and Milk External Biomarkers for Wasmannia auropunctata (Hymenoptera: Formicidae)
A Closed-Form Expression for the Gravitational Radiation Rate from Cosmic Strings
We present a new formula for the rate at which cosmic strings lose energy
into gravitational radiation, valid for all piecewise-linear cosmic string
loops. At any time, such a loop is composed of straight segments, each of
which has constant velocity. Any cosmic string loop can be arbitrarily-well
approximated by a piecewise-linear loop with sufficiently large. The
formula is a sum of polynomial and log terms, and is exact when the
effects of gravitational back-reaction are neglected. For a given loop, the
large number of terms makes evaluation ``by hand" impractical, but a computer
or symbolic manipulator yields accurate results. The formula is more accurate
and convenient than previous methods for finding the gravitational radiation
rate, which require numerical evaluation of a four-dimensional integral for
each term in an infinite sum. It also avoids the need to estimate the
contribution from the tail of the infinite sum. The formula has been tested
against all previously published radiation rates for different loop
configurations. In the cases where discrepancies were found, they were due to
errors in the published work. We have isolated and corrected both the analytic
and numerical errors in these cases. To assist future work in this area, a
small catalog of results for some simple loop shapes is provided.Comment: 29 pages TeX, 16 figures and computer C-code available via anonymous
ftp from directory pub/pcasper at alpha1.csd.uwm.edu, WISC-MILW-94-TH-10,
(section 7 has been expanded, two figures added, and minor grammatical
changes made.
(5S,6S)-4,5-Dimethyl-3-methylÂacryloyl-6-phenyl-1,3,4-oxadiazinan-2-one
The title compound, C15H18N2O3, is an example of an oxadiazinan-2-one with significant interÂaction between the N3-acyl and N4-methyl groups. These steric interÂactions result in a large torsion angle between the two carbonyl groups, not present with acyl substituents with less steric demand
Off-diagonal structure of neutrino mass matrix in see-saw mechanism and electron-muon-tau lepton universality
By a simple extension of the standard model in which ()
universality is not conserved, we present a scenario within the framework of
see-saw mechanism in which the neutrino mass matrix is strictly off-diagonal in
the flavor basis. We show that a version of this scenario can accomodate the
atmospheric neutrino oscillations and
oscillations claimed by the LSND collaboration.
PACS: 14.60.Pq; 14.60.St;13.15.+gComment: 5 pages, Revtex, 1 figure: The model accomodate another version which
explains atmospheric neutrino data and the observed solar neutrino
oscillations (large angle solution). In the previous version the value of
\lambda parameter is changed to the expected one. This version now
accomodates LSND result and solar neutrino oscillations (small angle MSW
solution
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