23 research outputs found
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Pump Probe Spectroscopy of Quasiparticle Dynamics in Cuprate Superconductors
Neutrino transport: no asymmetry in equilibrium
A small asymmetry in the flux of neutrinos emitted by a hot newly-born
neutron star could explain the observed motions of pulsars. However, even in
the presence of parity-violating processes with anisotropic scattering
amplitudes, no asymmetry is generated in thermal equilibrium. We explain why
this no-go theorem stymies some of the proposed explanations for the pulsar
``kick'' velocities.Comment: 4 pages, late
Reply to Comment on "Pulsar velocities and neutrino oscillations"
We have recently proposed an explanation for the birth velocities of pulsars
based on neutrino oscillations (hep-ph/9606428). One of the quantities, dN/dT,
was evaluated in the approximation of constant chemical potential for the
electrons. An alternative approximation based on the assumption Ye=const, used
by Qian (astro-ph/9705055), yields a somewhat higher prediction for the
magnetic field inside a neutron star. If the same input parameters are used,
the two approximations are in reasonable agreement, given the uncertainty in
the geometry of the magnetic field and the simplified picture of neutrino
emission that comes with the notion of a neutrinosphere.Comment: 2 pages, no figure
Neutral current induced neutrino oscillations in a supernova
Neutral currents induced matter oscillations of electroweak-active
(anti-)neutrinos to sterile neutrinos can explain the observed motion of
pulsars. In contrast to a recently proposed explanation of the pulsar birth
velocities based on the electron to tau (muon) neutrino oscillations
[hep-ph/9606428], the heaviest neutrino (either active or sterile) would have
to have mass of order several keV.Comment: 6 pages, latex, postscript file is also available at
ftp://dept.physics.upenn.edu/pub/Kusenko/UPR729T.p
Implications of Gauge Unification for Time Variation of the Fine Structure Constant
Unification of the gauge couplings would imply that time variations of the
fine structure constant are accompanied by calculable and very significant time
variations in the QCD scale parameter . Since is
the dominant factor in setting the hadron masses, estimates made by simple
variations of the fine structure constant may not provide meaningful limits.
There may also be related variations in Yukawa couplings and the electroweak
scale. Implications for the 21 cm hyperfine transition, big bang
nucleosynthesis, and the triple alpha process are discussed. We find that the
first of these already provides strong constraints on the underlying theory. It
is emphasized more generally that time (and space) variations of fundamental
couplings and their correlations may be a significant probe of
ultra-high-energy physics.Comment: 13 pages, uses JHEP.cl
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
Pulsar kicks from neutrino oscillations
Neutrino oscillations can explain the observed motion of pulsars. We show
that two different models of neutrino emission from a cooling neutron star are
in good quantitative agreement and predict the same order of magnitude for the
pulsar kick velocity, consistent with the data.Comment: revtex; 4 page
Phase Transitions and Vacuum Tunneling Into Charge and Color Breaking Minima in the MSSM
The scalar potential of the MSSM may have local and global minima
characterized by non-zero expectation values of charged and colored bosons.
Even if the true vacuum is not color and charge conserving, the early Universe
is likely to occupy the minimum of the potential in which only the neutral
Higgs fields have non-zero vev's. The stability of this false vacuum with
respect to quantum tunneling imposes important constraints on the values of the
MSSM parameters. We analyze these constraints using some novel methods for
calculating the false vacuum decay rate. Some regions of the MSSM parameter
space are ruled out because the lifetime of the corresponding physically
acceptable false vacuum is small in comparison to the present age of the
Universe. However, there is a significant fraction of the parameter space that
is consistent with the hypothesis that the Universe rests in the false vacuum
that is stable on a cosmological time scale.Comment: 30 pages, latex, epsf, 6 figures included, complete postscript file
is available at ftp://dept.physics.upenn.edu/pub/Kusenko/UPR677T.p