1,282 research outputs found
Bound-state dark matter with Majorana neutrinos
We propose a simple scenario in which dark matter (DM) emerges as a stable
neutral hadronic thermal relics, its stability following from an exact
symmetry. Neutrinos pick up radiatively induced
Majorana masses from the exchange of colored DM constituents. There is a common
origin for both dark matter and neutrino mass, with a lower bound for
neutrinoless double beta decay. Direct DM searches at nuclear recoil
experiments will test the proposal, which may also lead to other
phenomenological signals at future hadron collider and lepton flavour violation
experiments.Comment: 9 pages, 4 figures. arXiv admin note: text overlap with
arXiv:1803.0852
The Spin-Orbit Evolution of GJ 667C System: The Effect of Composition and Other Planet's Perturbations
Potentially habitable planets within the habitable zone of M-dwarfs are
affected by tidal interaction. We studied the tidal evolution in GJ 667C using
a numerical code we call TIDEV. We reviewed the problem of the dynamical
evolution focusing on the effects that a rheological treatment, different
compositions and the inclusion of orbital perturbations, have on the spin-down
time and the probability to be trapped in a low spin-orbit resonance.
Composition have a strong effect on the spin-down time, changing, in some
cases, by almost a factor of 2 with respect to the value estimated for a
reference Earth-like model. We calculated the time to reach a low resonance
value (3:2) for the configuration of 6 planets. Capture probabilities are
affected when assuming different compositions and eccentricities variations. We
chose planets b and c to evaluate the probabilities of capture in resonances
below 5:2 for two compositions: Earth-like and Waterworld planets. We found
that perturbations, although having a secular effect on eccentricities, have a
low impact on capture probabilities and noth- ing on spin-down times. The
implications of the eccentricity variations and actual habitability of the GJ
667C system are discussed.Comment: 15 pages, 9 figures, 4 tables. Accepted for publication in MNRAS - V
Symmetrical Observability of Kinematic Parameters in Symmetrical Parallel Mechanisms
This article presents an application of symmetry group theory in kinematic identification of parallel mechanisms of nlegs legs -- Kinematic Identification implies the estimation of the actual geometrical parameters (as opposed to nominal ones) of a physical mechanism -- For a symmetric mechanism, KI requires configuring sets of leg positions with symmetrical observability – This article presents as main contributions: (i) a conjecture that allows mapping the symmetries of the mechanism into the active-joint workspace, (ii) a set of necessary conditions to express leg parameters in coordinate systems which allow symmetrical observability, and (iii) a procedure for exploiting symmetries in pose selection for kinematic identification of symmetrical parallel mechanisms -- For the kinematic identification itself, we adopt a divide-and-conquer (DC) identification protocol -discussed by us in another publication- in which each leg of the mechanism is independently identified by using the inverse calibration method -- In this article we emphasize how to exploit the symmetries existent in (nlegs − 1) legs of the parallel mechanism allowing to apply to other legs the symmetry-transformed sample protocol used for the kinematic identification of a reference leg -- The symmetrical observability of sets of leg parameters allows to reduce the costs of the pose selection procedure by a factor of (1/nlegs) compared to a complete DC procedure in which the poses of each leg are selected independently -- The pose selection is carried out only for the reference leg -- For the (nlegs−1) remaining legs the poses are dictated by symmetry operations performed onto the poses of the reference leg -- An application of the symmetrical observability is presented through the simulated kinematic identification of a 3RRR symmetrical parallel mechanismPolytechnic School of the University of São PauloSitio webIndicaciones, Associação Brasileira de Métodos Computacionais em Engenharia, International Association for Computational Mechanics, International Congress and Convention Association, Conheça o São Paulo é Tudo de Bom, Embratur, PETROBRA
Finding the Higgs Boson through Supersymmetry
The study of displaced vertices containing two b--jets may provide a double
discovery at the Large Hadron Collider (LHC): we show how it may not only
reveal evidence for supersymmetry, but also provide a way to uncover the Higgs
boson necessary in the formulation of the electroweak theory in a large region
of the parameter space. We quantify this explicitly using the simplest minimal
supergravity model with bilinear breaking of R-parity, which accounts for the
observed pattern of neutrino masses and mixings seen in neutrino oscillation
experiments.Comment: 7 pages, 7 figures. Final version to appear at PRD. Discussion and
results were enlarge
The onset of synchronization in large networks of coupled oscillators
We study the transition from incoherence to coherence in large networks of
coupled phase oscillators. We present various approximations that describe the
behavior of an appropriately defined order parameter past the transition, and
generalize recent results for the critical coupling strength. We find that,
under appropriate conditions, the coupling strength at which the transition
occurs is determined by the largest eigenvalue of the adjacency matrix. We show
how, with an additional assumption, a mean field approximation recently
proposed is recovered from our results. We test our theory with numerical
simulations, and find that it describes the transition when our assumptions are
satisfied. We find that our theory describes the transition well in situations
in which the mean field approximation fails. We study the finite size effects
caused by nodes with small degree and find that they cause the critical
coupling strength to increase.Comment: To appear in PRE; Added an Appendix, a reference, modified two
figures and improved the discussion of the range of validity of perturbative
approache
Probing Neutrino Oscillations in Supersymmetric Models at the Large Hadron Collider
The lightest supersymmetric particle may decay with branching ratios that
correlate with neutrino oscillation parameters. In this case the CERN Large
Hadron Collider (LHC) has the potential to probe the atmospheric neutrino
mixing angle with sensitivity competitive to its low-energy determination by
underground experiments. Under realistic detection assumptions, we identify the
necessary conditions for the experiments at CERN's LHC to probe the simplest
scenario for neutrino masses induced by minimal supergravity with bilinear R
parity violation.Comment: 11 pages, 6 figures. To appear in Physical Review
Probing neutrino mass with multilepton production at the Tevatron in the simplest R-parity violation model
We analyze the production of multileptons in the simplest supergravity model
with bilinear violation of R parity at the Fermilab Tevatron. Despite the small
R-parity violating couplings needed to generate the neutrino masses indicated
by current atmospheric neutrino data, the lightest supersymmetric particle is
unstable and can decay inside the detector. This leads to a phenomenology quite
distinct from that of the R-parity conserving scenario. We quantify by how much
the supersymmetric multilepton signals differ from the R-parity conserving
expectations, displaying our results in the plane. We
show that the presence of bilinear R-parity violating interactions enhances the
supersymmetric multilepton signals over most of the parameter space, specially
at moderate and large .Comment: 26 pages, 23 figures. Revised version with some results corrected and
references added. Conclusions remain the sam
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