2,398 research outputs found
Supernova Neutrino Oscillations
Observing a high-statistics neutrino signal from a galactic supernova (SN)
would allow one to test the standard delayed explosion scenario and may allow
one to distinguish between the normal and inverted neutrino mass ordering due
to the effects of flavor oscillations in the SN envelope. One may even observe
a signature of SN shock-wave propagation in the detailed time-evolution of the
neutrino spectra. A clear identification of flavor oscillation effects in a
water Cherenkov detector probably requires a megatonne-class experiment.Comment: Proc. 129 Nobel Symposium "Neutrino Physics", 19-24 Aug 2004, Swede
Synchronisation and MSW sharpening of neutrinos propagating in a flavour blind medium
We consider neutrino oscillations in a medium in which scattering processes
are blind to the neutrino flavour. We present an analytical derivation of the
synchronised behaviour obtained in the limit where the average scattering rate
is much larger than the oscillation frequency. We also examine MSW transitions
in these circumstances, and show that a sharpening of the transition can
result.Comment: 8 pages, 3 figures, accepted for publication in Phys. Lett.
Lepton-Flavour Violation in Ordinary and Supersymmetric Grand Unified Theories
By an explicit calculation we show that in ordinary SU(5) logarithmic
divergence in the amplitude of cancels among diagrams and
remaining finite part is suppressed by at least . In SUSY SU(5),
when the effect of flavour changing wave function renormalization is taken into
account such logarithmic correction disappears, provided a condition is met
among SUSY breaking masses. In SUGRA-inspired SUSY GUT the remaining
logarithmic effect is argued not to be taken as a prediction of the theory.Comment: 8 pages, LaTeX209 file, using axodraw.st
Dynamics of a map with power-law tail
We analyze a one-dimensional piecewise continuous discrete model proposed
originally in studies on population ecology. The map is composed of a linear
part and a power-law decreasing piece, and has three parameters. The system
presents both regular and chaotic behavior. We study numerically and, in part,
analytically different bifurcation structures. Particularly interesting is the
description of the abrupt transition order-to-chaos mediated by an attractor
made of an infinite number of limit cycles with only a finite number of
different periods. It is shown that the power-law piece in the map is at the
origin of this type of bifurcation. The system exhibits interior crises and
crisis-induced intermittency.Comment: 28 pages, 17 figure
Effects of 4-Week training intervention with unknown loads on power output performance and throwing velocity in junior team handball players
PURPOSE:To compare the effect of 4-week unknown vs known loads strength training intervention on power output performance and throwing velocity in junior team handball players. METHODS:Twenty-eight junior team-handball players (17.2 ± 0.6 years, 1.79 ± 0.07 m, 75.6 ± 9.4 kg)were divided into two groups (unknown loads: UL; known loads: KL). Both groups performed two sessions weekly consisting of four sets of six repetitions of the bench press throw exercise, using the 30%, 50% and 70% of subjects' individual 1 repetition maximum (1RM). In each set, two repetitions with each load were performed, but the order of the loads was randomised. In the KL group, researchers told the subjects the load to mobilise prior each repetition, while in the UL group, researchers did not provide any information. Maximal dynamic strength (1RM bench press), power output (with 30, 50 and 70% of 1RM) and throwing velocity (7 m standing throw and 9 m jumping throw) were assessed pre- and post-training intervention. RESULTS:Both UL and KL group improved similarly their 1RM bench press as well as mean and peak power with all loads. There were significant improvements in power developed in all the early time intervals measured (150 ms) with the three loads (30, 50, 70% 1RM) in the UL group, while KL only improved with 30% 1RM (all the time intervals) and with 70% 1RM (at certain time intervals). Only the UL group improved throwing velocity in both standing (4.7%) and jumping (5.3%) throw (p > 0.05). CONCLUSIONS:The use of unknown loads has led to greater gains in power output in the early time intervals as well as to increases in throwing velocity compared with known loads. Therefore unknown loads are of significant practical use to increase both strength and in-field performance in a short period of training
Re-Examination of Generation of Baryon and Lepton Number Asymmetries by Heavy Particle Decay
It is shown that wave function renormalization can introduce an important
contribution to the generation of baryon and lepton number asymmetries by heavy
particle decay. These terms, omitted in previous analyses, are of the same
order of magnitude as the standard terms. A complete cancellation of leading
terms can result in some interesting cases.Comment: 12 pages, 2 Feynman graphs (not included), UPR-055
The Full Range of Predictions for B Physics From Iso-singlet Down Quark Mixing
We extend the range of predictions of the isosinglet (or vector) down quark
model to the fully allowed physical ranges, and also update this with the
effect of new physics constraints. We constrain the present allowed ranges of
sin(2*beta) and sin(2*alpha), gamma, x_s, and A_{B_s}. In models allowing
mixing to a new isosinglet down quark (as in E_6) flavor changing neutral
currents are induced that allow a Z^0 mediated contribution to B-Bbar mixing
and which bring in new phases. In (rho, eta), (x_s, sin(gamma)), and (x_s,
A_{B_s}) plots for the extra isosinglet down quark model which are herein
extended to the full physical range, we find new allowed regions that will
require experiments on sin(gamma) and/or x_s to verify or to rule out an extra
down quark contribution.Comment: 13 pages in RevTeX, 7 postscript figure
Exploiting the neutronization burst of a galactic supernova
One of the robust features found in simulations of core-collapse supernovae
(SNe) is the prompt neutronization burst, i.e. the first milliseconds
after bounce when the SN emits with very high luminosity mainly
neutrinos. We examine the dependence of this burst on variations in the input
of current SN models and find that recent improvements of the electron capture
rates as well as uncertainties in the nuclear equation of state or a variation
of the progenitor mass have only little effect on the signature of the
neutronization peak in a megaton water Cherenkov detector for different
neutrino mixing schemes. We show that exploiting the time-structure of the
neutronization peak allows one to identify the case of a normal mass hierarchy
and large 13-mixing angle , where the peak is absent. The
robustness of the predicted total event number in the neutronization burst
makes a measurement of the distance to the SN feasible with a precision of
about 5%, even in the likely case that the SN is optically obscured.Comment: 14 pages, 17 eps figures, revtex4 style, minor comments adde
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