22,625 research outputs found
Probing minimal supergravity in the type-I seesaw mechanism with lepton flavour violation at the CERN LHC
The most general supersymmetric seesaw mechanism has too many parameters to
be predictive and thus can not be excluded by any measurements of lepton
flavour violating (LFV) processes. We focus on the simplest version of the
type-I seesaw mechanism assuming minimal supergravity boundary conditions. We
compute branching ratios for the LFV scalar tau decays, , as well as loop-induced LFV decays at low energy, such as
and , exploring their sensitivity to the
unknown seesaw parameters. We find some simple, extreme scenarios for the
unknown right-handed parameters, where ratios of LFV branching ratios correlate
with neutrino oscillation parameters. If the overall mass scale of the left
neutrinos and the value of the reactor angle were known, the study of LFV
allows, in principle, to extract information about the so far unknown
right-handed neutrino parameters.Comment: 29 pages, 27 figures; added explanatory comments, corrected typos,
final version for publicatio
Mixing of 1/2^- Octets under SU(3) Symmetry
We investigate the J^p=1/2^- baryons in the octets based on flavor SU(3)
symmetry. Since baryons with same quantum numbers can mix with each other, we
consider the mixing between two octets before their mixing with the singlet.
Most predicted decay widths are consistent with the experimental data, and
meanwhile we predict two possible mass ranges of the two octets.Comment: 8 latex page
They are Small Worlds After All: Revised Properties of Kepler M Dwarf Stars and their Planets
We classified the reddest () stars observed by the NASA
mission into main sequence dwarf or evolved giant stars and determined the
properties of 4216 M dwarfs based on a comparison of available photometry with
that of nearby calibrator stars, as well as available proper motions and
spectra. We revised the properties of candidate transiting planets using the
stellar parameters, high-resolution imaging to identify companion stars, and,
in the case of binaries, fitting light curves to identify the likely planet
host. In 49 of 54 systems we validated the primary as the host star. We
inferred the intrinsic distribution of M dwarf planets using the method of
iterative Monte Carlo simulation. We compared several models of planet orbital
geometry and clustering and found that one where planets are exponentially
distributed and almost precisely coplanar best describes the distribution of
multi-planet systems. We determined that M dwarfs host an average of
planets with radii of 1-4 and orbital periods of
1.5-180 d. The radius distribution peaks at and is
essentially zero at , although we identify three giant planet
candidates other than the previously confirmed Kepler-45b. There is suggestive
but not significant evidence that the radius distribution varies with orbital
period. The distribution with logarithmic orbital period is flat except for a
decline for orbits less than a few days. Twelve candidate planets, including
two Jupiter-size objects, experience an irradiance below the threshold level
for a runaway greenhouse on an Earth-like planet and are thus in a "habitable
zone".Comment: MNRAS, in press. Tables 1, 3, and 4 are available in electronic form
in the "anc" director
Quasiclassical Equations of Motion for Nonlinear Brownian Systems
Following the formalism of Gell-Mann and Hartle, phenomenological equations
of motion are derived from the decoherence functional formalism of quantum
mechanics, using a path-integral description. This is done explicitly for the
case of a system interacting with a ``bath'' of harmonic oscillators whose
individual motions are neglected. The results are compared to the equations
derived from the purely classical theory. The case of linear interactions is
treated exactly, and nonlinear interactions are compared using classical and
quantum perturbation theory.Comment: 24 pages, CALT-68-1848 (RevTeX 2.0 macros
On the Definition of Decoherence
We examine the relationship between the decoherence of quantum-mechanical
histories of a closed system (as discussed by Gell-Mann and Hartle) and
environmentally-induced diagonalization of the density operator for an open
system. We study a definition of decoherence which incorporates both of these
ideas, and show that it leads to a consistent probabilistic interpretation of
the reduced density operator.Comment: 10 pages, LaTeX, SJSU/TP-93-1
Generalized entropy and Noether charge
We find an expression for the generalized gravitational entropy of Hawking in
terms of Noether charge. As an example, the entropy of the Taub-Bolt spacetime
is calculated.Comment: 6 pages, revtex, reference correcte
Study of a soft lander/support module for Mars missions. Volume 3 - Appendixes Final summary report
Soft lander support module for Mars missions - lunar module radar evaluation and vernier phase simulatio
Supersymmetric seesaw type II: CERN LHC and lepton flavour violating phenomenology
We study the supersymmetric version of the type-II seesaw mechanism assuming
minimal supergravity boundary conditions. We calculate branching ratios for
lepton flavour violating (LFV) scalar tau decays, potentially observable at the
LHC, as well as LFV decays at low energy, such as and
compare their sensitivity to the unknown seesaw parameters. In the minimal case
of only one triplet coupling to the standard model lepton doublets, ratios of
LFV branching ratios can be related unambigously to neutrino oscillation
parameters. We also discuss how measurements of soft SUSY breaking parameters
at the LHC can be used to indirectly extract information of the seesaw scale.Comment: 25 pages, 14 figures, references and appendix added, minor
corrections; final version published in Phys.Rev.
- …