3,613 research outputs found
Left-Right Symmetry and Lepton Number Violation at the Large Hadron Electron Collider
We show that the proposed Large Hadron electron Collider (LHeC) will provide
an opportunity to search for left-right symmetry and establish lepton number
violation, complementing current and planned searches based on LHC data and
neutrinoless double beta decay. We consider several plausible configurations
for the LHeC -- including different electron energies and polarizations, as
well as distinct values for the charge misidentification rate. Within
left-right symmetric theories we determine the values of right-handed neutrino
and gauge boson masses that could be tested at the LHeC after one, five and ten
years of operation. Our results indicate that this collider might probe, via
the signal , Majorana neutrino masses up to 1 TeV
and masses up to 6.5 TeV. Interestingly, part of this parameter space is
beyond the expected reach of the LHC and of future neutrinoless double beta
decay experiments.Comment: 22 pages, 6 figures. Matches version published in JHE
Scaling treatment of the random field Ising model
Analytic phenomenological scaling is carried out for the random field Ising
model in general dimensions using a bar geometry. Domain wall configurations
and their decorated profiles and associated wandering and other exponents
are obtained by free energy minimization. Scaling
between different bar widths provides the renormalization group (RG)
transformation. Its consequences are (1) criticality at in
with correlation length diverging like for and
for , where is a decoration constant; (2) criticality in dimensions at , , where
, .
Finite temperature generalizations are outlined. Numerical transfer matrix
calculations and results from a ground state algorithm adapted for strips in
confirm the ingredients which provide the RG description.Comment: RevTex v3.0, 5 pages, plus 4 figures uuencode
Sterile neutrino dark matter, CDMS-II and a light Higgs boson
We add a singlet right handed neutrino plus a charged and a neutral singlet
scalars to the standard model. This extension includes a discrete symmetry such
that we obtain a heavy sterile neutrino which couples only to the electron and
the new scalars. In this sense the singlet neutrino does not mix with ordinary
ones and thus has no effect on Big Bang Nucleosynthesis. However, such sterile
neutrino can be in equilibrium with electroweak particles in the early Universe
due to its couplings to electrons and also because the Higgs boson mixes with
the singlet scalars. We obtain that the sterile neutrino constitutes a dark
matter candidate and analyze its direct detection in the light of current
experiments. Our results show that if such a sterile neutrino is realized in
nature, and CDMS-II experiment confirms its positive signal, dark matter
demands a rather light Higgs boson with new Physics at some 500 GeV scale.Comment: 16 pages, 13 figures, uses axodraw.st
Dark Matter from Late Invisible Decays to/of Gravitinos
In this work, we sift a simple supersymmetric framework of late invisible
decays to/of the gravitino. We investigate two cases where the gravitino is the
lightest supersymmetric particle or the next-to-lightest supersymmetric
particle. The next-to-lightest supersymmetric particle decays into two dark
matter candidates and has a long lifetime due to gravitationally suppressed
interactions. However, because of the absence of any hadronic or
electromagnetic products, it satisfies the tight bounds set by big bang
nucleosynthesis and cosmic microwaved background. One or both of the dark
matter candidates produced in invisible decays can contribute to the amount of
dark radiation and suppress perturbations at scales that are being probed by
the galaxy power spectrum and the Lyman-alpha forest data. We show that these
constraints are satisfied in large regions of the parameter space and, as a
result, the late invisible decays to/of the gravitino can be responsible for
the entire dark matter relic abundance.Comment: 9 pages, 6 figures. Submitted to PR
Surface crossover exponent for branched polymers in two dimensions
Transfer-matrix methods on finite-width strips with free boundary conditions
are applied to lattice site animals, which provide a model for randomly
branched polymers in a good solvent. By assigning a distinct fugacity to sites
along the strip edges, critical properties at the special (adsorption) and
ordinary transitions are assessed. The crossover exponent at the adsorption
point is estimated as , consistent with recent
predictions that exactly for all space dimensionalities.Comment: 10 pages, LaTeX with Institute of Physics macros, to appear in
Journal of Physics
Genomic islands of divergence in the Yellow Tang and the Brushtail Tang Surgeonfishes.
The current ease of obtaining thousands of molecular markers challenges the notion that full phylogenetic concordance, as proposed by phylogenetic species concepts, is a requirement for defining species delimitations. Indeed, the presence of genomic islands of divergence, which may be the cause, or in some cases the consequence, of speciation, precludes concordance. Here, we explore this issue using thousands of RAD markers on two sister species of surgeonfishes (Teleostei: Acanthuridae), Zebrasoma flavescens and Z. scopas, and several populations within each species. Species are readily distinguished based on their colors (solid yellow and solid brown, respectively), yet populations and species are neither distinguishable using mitochondrial markers (cytochrome c oxidase 1), nor using 5193 SNPs (pairwise Φst = 0.034). In contrast, when using outlier loci, some of them presumably under selection, species delimitations, and strong population structure follow recognized taxonomic positions (pairwise Φst = 0.326). Species and population delimitation differences based on neutral and selected markers are likely due to local adaptation, thus being consistent with the idea that these genomic islands of divergence arose as a consequence of isolation. These findings, which are not unique, raise the question of a potentially important pathway of divergence based on local adaptation that is only evident when looking at thousands of loci
Pair of Heavy-Exotic-Quarks at LHC
We study the production and signatures of heavy exotic quarks pairs at LHC in
the framework of the vector singlet model (VSM), vector doublet model (VDM) and
fermion-mirror-fermion (FMF) model. The pair production cross sections for the
electroweak and strong sector are computed.Comment: 7 pages, 6 figures. accept at Int. Jour. of Mod. Phy
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