124 research outputs found
Flavor constraints on two-Higgs-doublet models with general diagonal Yukawa couplings
We consider constraints from flavor physics on two-Higgs-doublet models
(2HDM) with general, flavor-diagonal, Yukawa couplings. Analyzing the charged
Higgs contribution to different observables, we find that
transitions and restrict the coupling of the
top quark (corresponding to in models with a symmetry) to
for GeV. Stringent constraints from
meson decays are obtained also on the other third generation couplings
and , but with stronger dependence on
. For the second generation, we obtain constraints on combinations of
, , and from leptonic and
decays. The limits on the general couplings are translated to the common
2HDM types I -- IV with a symmetry, and presented on the
plane. The flavor constraints are most excluding in the
type II model which lacks a decoupling limit in . We obtain a lower
limit GeV in models of type II and III, while no lower
bound on is found for types I and IV.Comment: 24 pages, 11 figures. v2: Minor changes to text and numerics, results
and conclusions unchanged. References adde
Charged Higgs bosons in Minimal Supersymmetry: Updated constraints and experimental prospects
We discuss the phenomenology of charged Higgs bosons in the MSSM with minimal
flavor violation. In addition to the constrained MSSM (CMSSM) with universal
soft supersymmetry breaking mass parameters at the GUT scale, we explore
non-universal Higgs mass models (NUHM) where this universality condition is
relaxed. To identify the allowed parameter space regions, we apply constraints
from direct searches, low energy observables, and cosmology. We find that
values of the charged Higgs mass as low as GeV can be
accommodated in the NUHM models, but that several flavor physics observables
disfavor large contributions, associated with high , quite
independently of MSSM scenario. We confront the constrained scenarios with the
discovery potentials reported by ATLAS and CMS, and find that the current
exclusion by indirect constraints is similar to the expected LHC discovery
reach with 30 fb of data. Finally, we evaluate the sensitivity of the
presented discovery potential to the choice of MSSM benchmark scenario. This
sensitivity is found to be higher in the case of a light ()
charged Higgs.Comment: 33 pages, 17 figures, v2: Minor revision, agrees with published
versio
ELVIS - ELectromagnetic Vector Information Sensor
The ELVIS instrument was recently proposed by the authors for the Indian
Chandrayaan-1 mission to the Moon and is presently under consideration by the
Indian Space Research Organisation (ISRO). The scientific objective of ELVIS is
to explore the electromagnetic environment of the moon. ELVIS samples the full
three-dimensional (3D) electric field vector, E(x,t), up to 18 MHz, with
selective Nyqvist frequency bandwidths down to 5 kHz, and one component of the
magnetic field vector, B(x,t), from a few Hz up to 100 kHz.As a transient
detector, ELVIS is capable of detecting pulses with a minimum pulse width of 5
ns. The instrument comprises three orthogonal electric dipole antennas, one
magnetic search coil antenna and a four-channel digital sampling system,
utilising flexible digital down conversion and filtering together with
state-of-the-art onboard digital signal processing.Comment: 8 pages, 3 figures. Submitted to the DGLR Int. Symposium "To Moon and
Beyond", Bremen, Germany, 2005. Companion paper to arXiv:astro-ph/050921
Prospects for Lunar Satellite Detection of Radio Pulses from Ultrahigh Energy Neutrinos Interacting with the Moon
The Moon provides a huge effective detector volume for ultrahigh energy
cosmic neutrinos, which generate coherent radio pulses in the lunar surface
layer due to the Askaryan effect. In light of presently considered lunar
missions, we propose radio measurements from a Moon-orbiting satellite. First
systematic Monte Carlo simulations demonstrate the detectability of Askaryan
pulses from neutrinos with energies above 10^{20} eV, i.e. near and above the
interesting GZK limit, at the very low fluxes predicted in different scenarios.Comment: RevTeX (4 pages, 2 figures). v2 includes updated results and extended
discussio
Prospects for GMRT to Observe Radio Waves from UHE Particles Interacting with the Moon
Ultra high energy (UHE) particles of cosmic origin impact the lunar regolith
and produce radio signals through Askaryan effect, signals that can be detected
by Earth based radio telescopes. We calculate the expected sensitivity for
observation of such events at the Giant Metrewave Radio Telescope (GMRT), both
for UHE cosmic rays (CR) and UHE neutrino interactions. We find that for 30
days of observation time a significant number of detectable events is expected
above eV for UHECR or neutrino fluxes close to the current limits.
Null detection over a period of 30 days will lower the experimental bounds on
UHE particle fluxes by magnitudes competitive to both present and future
experiments at the very highest energies.Comment: 21 pages, 9 figure
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