2,335 research outputs found
Inverting a Supernova: Neutrino Mixing, Temperatures and Binding Energy
We show that the temperatures of the emergent non-electron neutrinos and the
binding energy released by a galactic Type II supernova are determinable,
assuming the Large Mixing Angle (LMA) solution is correct, from observations at
the Sudbury Neutrino Observatory (SNO) and at Super-Kamiokande (SK). If the
neutrino mass hierarchy is inverted, either a lower or upper bound can be
placed on the neutrino mixing angle , and the hierarchy can be
deduced for adiabatic transitions. For the normal hierarchy, neither can
be constrained nor can the hierarchy be determined. Our
conclusions are qualitatively unchanged for the proposed Hyper-Kamiokande
detector.Comment: Following astro-ph/0208035, we adopt electron and non-electron
neutrino spectra with very small differences. Conclusions change
An Integrated Picture of Star Formation, Metallicity Evolution, and Galactic Stellar Mass Assembly
We present an integrated study of star formation and galactic stellar mass
assembly from z=0.05-1.5 and galactic metallicity evolution from z=0.05-0.9
using a very large and highly spectroscopically complete sample selected by
rest-frame NIR bolometric flux in the GOODS-N. We assume a Salpeter IMF and fit
Bruzual & Charlot (2003) models to compute the galactic stellar masses and
extinctions. We determine the expected formed stellar mass density growth rates
produced by star formation and compare them with the growth rates measured from
the formed stellar mass functions by mass interval. We show that the growth
rates match if the IMF is slightly increased from the Salpeter IMF at
intermediate masses (~10 solar masses). We investigate the evolution of galaxy
color, spectral type, and morphology with mass and redshift and the evolution
of mass with environment. We find that applying extinction corrections is
critical when analyzing galaxy colors; e.g., nearly all of the galaxies in the
green valley are 24um sources, but after correcting for extinction, the bulk of
the 24um sources lie in the blue cloud. We find an evolution of the
metallicity-mass relation corresponding to a decrease of 0.21+/-0.03 dex
between the local value and the value at z=0.77 in the 1e10-1e11 solar mass
range. We use the metallicity evolution to estimate the gas mass of the
galaxies, which we compare with the galactic stellar mass assembly and star
formation histories. Overall, our measurements are consistent with a galaxy
evolution process dominated by episodic bursts of star formation and where star
formation in the most massive galaxies (>1e11 solar masses) ceases at z<1.5
because of gas starvation. (Abstract abridged)Comment: 48 pages, Accepted by the Astrophysical Journa
New Constraints on Neutrino Oscillations in Vacuum as a Possible Solution of the Solar Neutrino Problem
Two-neutrino oscillations in vacuum are studied as a possible solution of the
solar neutrino problem. New constraints on the parameter sn2, characterizing
the mixing of the electron neutrino with another active or sterile neutrino, as
well as on the mass--squared difference, dm2, of their massive neutrino
components, are derived using the latest results from the four solar neutrino
experiments. Oscillations into a sterile neutrino are ruled out at 99 % C.L. by
the observed mean event rates even if one includes the uncertainties of the
standard solar model predictions in the analysis.Comment: 10 pages + 3 figures attached as postscript files, IFP-480-UNC and
Ref. SISSA 177/93/EP (Updated Version which takes into account the latest
GALLEX results from 30 runs
Progress in the physics of massive neutrinos
The current status of the physics of massive neutrinos is reviewed with a
forward-looking emphasis. The article begins with the general phenomenology of
neutrino oscillations in vacuum and matter and documents the experimental
evidence for oscillations of solar, reactor, atmospheric and accelerator
neutrinos. Both active and sterile oscillation possibilities are considered.
The impact of cosmology (BBN, CMB, leptogenesis) and astrophysics (supernovae,
highest energy cosmic rays) on neutrino observables and vice versa, is
evaluated. The predictions of grand unified, radiative and other models of
neutrino mass are discussed. Ways of determining the unknown parameters of
three-neutrino oscillations are assessed, taking into account eight-fold
degeneracies in parameters that yield the same oscillation probabilities, as
well as ways to determine the absolute neutrino mass scale (from beta-decay,
neutrinoless double-beta decay, large scale structure and Z-bursts). Critical
unknowns at present are the amplitude of \nu_\mu to \nu_e oscillations and the
hierarchy of the neutrino mass spectrum; the detection of CP violation in the
neutrino sector depends on these and on an unknown phase. The estimated
neutrino parameter sensitivities at future facilities (reactors, superbeams,
neutrino factories) are given. The overall agenda of a future neutrino physics
program to construct a bottom-up understanding of the lepton sector is
presented.Comment: 111 pages, 35 figures. Update
Signals of R-parity violating supersymmetry in neutrino scattering at muon storage rings
Neutrino oscillation signals at muon storage rings can be faked by
supersymmetric (SUSY) interactions in an R-parity violating scenario. We
investigate the -appearance signals for both long-baseline and near-site
experiments, and conclude that the latter is of great use in distinguishing
between oscillation and SUSY effects. On the other hand, SUSY can cause a
manifold increase in the event rate for wrong-sign muons at a long-baseline
setting, thereby providing us with signatures of new physics.Comment: 7 pages LaTeX, 4 ps figures, accepted for publication in Phys. Rev.
QCD Corrections to Electroweak Annihilation Decays of Superheavy Quarkonia
QCD corrections to all the allowed decays of superheavy groundstate quarkonia
into electroweak gauge and Higgs bosons are presented. For quick estimates,
approximations that reproduce the exact results within less than at worst two
percent are also given.Comment: 20 pages RevTeX, 9 figures. The complete paper, including figures, is
also available via anonymous ftp at (129.13.102.139) as
ftp://ttpux2.physik.uni-karlsruhe.de/ttp95-05/ttp95-05.ps, or via www at
http://ttpux2.physik.uni-karlsruhe.de/cgi-bin/preprints
High energy neutrinos from neutralino annihilations in the Sun
Neutralino annihilations in the Sun to weak boson and top quark pairs lead to
high-energy neutrinos that can be detected by the IceCube and KM3 experiments
in the search for neutralino dark matter. We calculate the neutrino signals
from real and virtual WW, ZZ, Zh, and production and decays,
accounting for the spin-dependences of the matrix elements, which can have
important influences on the neutrino energy spectra. We take into account
neutrino propagation including neutrino oscillations, matter-resonance,
absorption, and nu_tau regeneration effects in the Sun and evaluate the
neutrino flux at the Earth. We concentrate on the compelling Focus Point (FP)
region of the supergravity model that reproduces the observed dark matter relic
density. For the FP region, the lightest neutralino has a large bino-higgsino
mixture that leads to a high neutrino flux and the spin-dependent neutralino
capture rate in the Sun is enhanced by 10^3 over the spin-independent rate. For
the standard estimate of neutralino captures, the muon signal rates in IceCube
are identifiable over the atmospheric neutrino background for neutralino masses
above M_Z up to 400 GeV.Comment: 45 pages, 18 figures and 5 tables, PRD versio
Infrared Quasi Fixed Point Structure in Extended Yukawa Sectors and Application to R-parity Violation
We investigate one-loop renormalization group evolutions of extended sectors
of Yukawa type couplings. It is shown that Landau Poles which usually provide
necessary low energy upper bounds that saturate quickly with increasing initial
value conditions, lead in some cases to the opposite behaviour: some of the low
energy couplings decrease and become vanishingly small for increasingly large
initial conditions. We write down the general criteria for this to happen in
typical situations, highlighting a concept of {\sl repulsive} quasi-fixed
points, and illustrate the case both within a two-Yukawa toy model as well as
in the minimal supersymmetric standard model with R-parity violation. In the
latter case we consider the theoretical upper bounds on the various couplings,
identifying regimes where are
dynamically suppressed due to the Landau Pole. We stress the importance of
considering a large number of couplings simultaneously. This leads altogether
to a phenomenologically interesting seesaw effect in the magnitudes of the
various R-parity violating couplings, complementing and in some cases improving
the existing limits.Comment: Latex, 33 pages, 6 figure
Infrared quasi-fixed solutions in the NMSSM
The considerable part of the parameter space in the MSSM corresponding to the
infrared quasi fixed point scenario is almost excluded by LEP II bounds on the
lightest Higgs boson mass. In the NMSSM the mass of the lightest Higgs boson
reaches its maximum value in the strong Yukawa coupling limit when Yukawa
couplings are essentially larger than gauge ones at the Grand Unification
scale. In this limit the solutions of the renormalisation group equations are
attracted to the infrared and Hill type effective fixed lines or surfaces in
the Yukawa coupling parameter space. They are concentrated in the vicinity of
quasi fixed points for . However the solutions are attracted
to such points rather weakly. For this reason when all the
solutions of the renormalisation group equations are gathered near a line in
the Hill type effective surface. In the paper the approximate solutions for the
NMSSM Yukawa couplings are given. The possibility of --quark and
--lepton Yukawa coupling unification at the scale is also
discussed.Comment: 32 pages, 8 figures included, LaTeX 2
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