10,444 research outputs found
Effects of Decays of Tau Neutrinos Near A Supernova
We revisit the constraints implied by SN 1987 A observations on the decay
rate of a multi-MeV decaying into the visible channel , if its lifetime is more than 10 {\it sec.}. We
discuss its implication for the minimal left-right symmetric model with see-saw
mechanism for neutrino masses. We also speculate on the possible formation of a
``giant Capacitor" in intergalactic space due to the decay of "neutronization"
's and spin allignment possibility in the supernova.Comment: 29 Pages, Tex file, UMDHEP 94-4
On Neutrino Masses and Family Replication
The old issue of why there are more than one family of quarks and leptons is
reinvestigated with an eye towards the use of anomaly as a tool for
constraining the number of families. It is found that, by assuming the
existence of right-handed neutrinos (which would imply that neutrinos will have
a mass) and a new chiral SU(2) gauge theory, strong constraints on the number
of families can be obtained. In addition, a model, based on that extra SU(2),
is constructed where it is natural to have one "very heavy" fourth neutrino and
three almost degenerate light neutrinos whose masses are all of the Dirac type.Comment: RevTex, 12 pages with 1 figure, minor changes to the text and added
acknowledgment
Searching for Strongly Interacting Massive Particles (SIMPs)
We consider laboratory experiments that can detect stable, neutral strongly
interacting massive particles (SIMPs). We explore the SIMP annihilation cross
section from its minimum value (restricted by cosmological bounds) to the barn
range, and vary the mass values from a GeV to a TeV. We calculate, as a
function of the SIMP-nucleon cross section, the minimum nucleon number A for
which there should be binding in a nucleus. We consider accelerator mass
spectrometry with a gold (A=200) target, and compute the likely abundance of
anomalous gold nuclei if stable neutral SIMPs exist. We also consider the
prospects and problems of detecting such particles at the Tevatron. We estimate
optimistically that such detection might be possible for SIMPs with
SIMP-nucleon cross sections larger than 0.1 millibarn and masses between 25 and
50 GeV.Comment: RevTeX, 10 pages, 3 figures; Minor updates to match published versio
SIMP (Strongly Interacting Massive Particle) Search
We consider laboratory experiments that can detect stable, neutral strongly
interacting massive particles (SIMPs). We explore the SIMP annihilation cross
section from its minimum value (restricted by cosmological bounds) to the barn
range, and vary the mass values from a GeV to a TeV. We also consider the
prospects and problems of detecting such particles at the Tevatron.Comment: Latex. 7 pages, 1 eps figure. Proceedings to the 4th UCLA Symposium
on Dark Matter DM2000, Marina del Rey, CA, USA, Feb. 23-25, 200
Possible Implications of Asymmetric Fermionic Dark Matter for Neutron Stars
We consider the implications of fermionic asymmetric dark matter for a "mixed
neutron star" composed of ordinary baryons and dark fermions. We find examples,
where for a certain range of dark fermion mass -- when it is less than that of
ordinary baryons -- such systems can reach higher masses than the maximal
values allowed for ordinary ("pure") neutron stars. This is shown both within a
simplified, heuristic Newtonian analytic framework with non-interacting
particles and via a general relativistic numerical calculation, under certain
assumptions for the dark matter equation of state. Our work applies to various
dark fermion models such as mirror matter models and to other models where the
dark fermions have self interactions.Comment: 20 pages, 6 figure
Global Topology and Local Violation of Discrete Symmetries
Cosmological models that are locally consistent with general relativity and
the standard model in which an object transported around the universe undergoes
P, C and CP transformations, are constructed. This leads to generalization of
the gauge fields that describe electro-weak and strong interactions by
enlarging the gauge groups to include anti-unitary transformations. Gedanken
experiments show that if all interactions obey Einstein causality then P, C and
CP cannot be violated in these models. But another model, which would violate
charge superselection rule even for an isolated system, is allowed. It is
suggested that the fundamental physical laws must have these discrete
symmetries which are broken spontaneously, or they must be non causal.Comment: 12 pages, 1 figure, latex, Revtex. Charge conjugation which is
physically implemented in a cosmology with the appropriate topology is
described in more detail. Some minor errors are corrected. Shortened to meet
the page limit of Physical Review Letters to which this paper was submitte
Geometric CP Violation with Extra Dimensions
We discuss how CP symmetry can be broken geometrically through orbifold
projections in hidden extra dimensions in the context of D-brane models for
particle unifications. We present a few toy models to illustrate the idea and
suggest ways to incorporate this technique in the context of realistic models.Comment: 6 pages, one figure; references updated and a new model adde
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