1,489 research outputs found
Sensitivity to the Higgs sector of SUSY-seesaw models via LFV tau decays
Here we study and compare the sensitivity to the Higgs sector of the
SUSY-seesaw models via the LFV tau decays: tau-> 3 mu, tau->K^{+}K^{-}, tau->mu
eta and tau-> mu f_{0}. We emphasize that, at present, the two later channels
are the most efficient ones to test indirectly the Higgs particles.Comment: 4 pages, 3 figures, conference SUSY09 Boston (M.Herrero
Higgs Boson Masses in the MSSM with Heavy Majorana Neutrinos
We present a full diagrammatic computation of the one-loop corrections from
the neutrino/sneutrino sector to the renormalized neutral CP-even Higgs boson
self-energies and the lightest Higgs boson mass, Mh, within the context of the
so-called MSSM-seesaw scenario. This consists of the Minimal Supersymmetric
Standard Model with the addition of massive right handed Majorana neutrinos and
their supersymmetric partners, and where the seesaw mechanism is used for the
lightest neutrino mass generation. We explore the dependence on all the
parameters involved, with particular emphasis in the role played by the heavy
Majorana scale. We restrict ourselves to the case of one generation of
neutrinos/sneutrinos. For the numerical part of the study, we consider a very
wide range of values for all the parameters involved. We find sizeable
corrections to Mh, which are negative in the region where the Majorana scale is
large (10^{13}-10^{15} GeV) and the lightest neutrino mass is within a range
inspired by data (0.1-1 eV). For some regions of the MSSM-seesaw parameter
space, the corrections to Mh are substantially larger than the anticipated
Large Hadron Collider precision.Comment: Latex, 50 pages, 15 figures, 6 tables. Discussion improved. Comments
and some new approximate formulae have been added. Published version on JHE
Radiative corrections to from three generations of Majorana neutrinos and sneutrinos
In this work we study the radiative corrections to the mass of the lightest
Higgs boson of the MSSM from three generations of Majorana neutrinos and
sneutrinos. The spectrum of the MSSM is augmented by three right handed
neutrinos and their supersymmetric partners. A seesaw mechanism of type I is
used to generate the physical neutrino masses and oscillations that we require
to be in agreement with present neutrino data. We present a full one-loop
computation of these Higgs mass corrections, and analyze in full detail their
numerical size in terms of both the MSSM and the new (s)neutrino parameters. A
critical discussion on the different possible renormalization schemes and their
implications is included.Comment: 42 pages, 39 figures, 1 appendix, version published in AHE
Long wavelength local density of states oscillations near graphene step edges
Using scanning tunneling microscopy and spectroscopy, we have studied the
local density of states (LDOS) of graphene over step edges in boron nitride.
Long wavelength oscillations in the LDOS are observed with maxima parallel to
the step edge. Their wavelength and amplitude are controlled by the energy of
the quasiparticles allowing a direct probe of the graphene dispersion relation.
We also observe a faster decay of the LDOS oscillations away from the step edge
than in conventional metals. This is due to the chiral nature of the Dirac
fermions in graphene.Comment: 5 pages, 4 figures, to appear in Phys. Rev. Let
Quantum Hall Effect, Screening and Layer-Polarized Insulating States in Twisted Bilayer Graphene
We investigate electronic transport in dual-gated twisted bilayer graphene.
Despite the sub-nanometer proximity between the layers, we identify independent
contributions to the magnetoresistance from the graphene Landau level spectrum
of each layer. We demonstrate that the filling factor of each layer can be
independently controlled via the dual gates, which we use to induce Landau
level crossings between the layers. By analyzing the gate dependence of the
Landau level crossings, we characterize the finite inter-layer screening and
extract the capacitance between the atomically-spaced layers. At zero filling
factor, we observe magnetic and displacement field dependent insulating states,
which indicate the presence of counter-propagating edge states with inter-layer
coupling.Comment: 4 pages, 3 figure
Tunneling in graphene-topological insulator hybrid devices
Hybrid graphene-topological insulator (TI) devices were fabricated using a
mechanical transfer method and studied via electronic transport. Devices
consisting of bilayer graphene (BLG) under the TI BiSe exhibit
differential conductance characteristics which appear to be dominated by
tunneling, roughly reproducing the BiSe density of states. Similar
results were obtained for BLG on top of BiSe, with 10-fold greater
conductance consistent with a larger contact area due to better surface
conformity. The devices further show evidence of inelastic phonon-assisted
tunneling processes involving both BiSe and graphene phonons. These
processes favor phonons which compensate for momentum mismatch between the TI
and graphene points. Finally, the utility of these tunnel
junctions is demonstrated on a density-tunable BLG device, where the
charge-neutrality point is traced along the energy-density trajectory. This
trajectory is used as a measure of the ground-state density of states
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