35,934 research outputs found
Radiative Neutrino Mass, Dark Matter and Leptogenesis
We propose an extension of the standard model, in which neutrinos are Dirac
particles and their tiny masses originate from a one-loop radiative diagram.
The new fields required by the neutrino mass-generation also accommodate the
explanation for the matter-antimatter asymmetry and dark matter in the
universe.Comment: 4 pages, 3 figures. Revised version with improved model. Accepted by
PR
Neutrino masses, leptogenesis and dark matter in hybrid seesaw
We suggest a hybrid seesaw model where relatively ``light''right-handed
neutrinos give no contribution to the neutrino mass matrix due to a special
symmetry. This allows their Yukawa couplings to the standard model particles to
be relatively strong, so that the standard model Higgs boson can decay
dominantly to a left and a right-handed neutrino, leaving another stable
right-handed neutrino as cold dark matter. In our model neutrino masses arise
via the type-II seesaw mechanism, the Higgs triplet scalars being also
responsible for the generation of the matter-antimatter asymmetry via the
leptogenesis mechanism.Comment: 4 page
Non-parametric models in the monitoring of engine performance and condition: Part 2: non-intrusive estimation of diesel engine cylinder pressure and its use in fault detection
An application of the radial basis function model, described in Part 1, is demonstrated on a four-cylinder DI diesel engine with data from a wide range of speed and load settings. The prediction capabilities of the trained model are validated against measured data and an example is given of the application of this model to the detection of a slight fault in one of the cylinders
Risk, cohabitation and marriage
This paper introduces imperfect information,learning,and risk aversion in a two sided matching model.The modelprovides a theoreticalframework for the com- monly occurring phenomenon of cohabitation followed by marriage,and is con- sistent with empirical findings on these institutions.The paper has three major results.First,individuals set higher standards for marriage than for cohabitation. When the true worth of a cohabiting partner is revealed,some cohabiting unions are converted into marriage while others are not.Second,individuals cohabit within classes.Third,the premium that compensates individuals for the higher risk involved in marriage over a cohabiting partnership is derived.This premium can be decomposed into two parts.The first part is a function of the individual ’s level of risk aversion,while the second part is a function of the di difference in risk between marriage and cohabitation.
Ground-State Entanglement in Interacting Bosonic Graphs
We consider a collection of bosonic modes corresponding to the vertices of a
graph Quantum tunneling can occur only along the edges of
and a local self-interaction term is present. Quantum entanglement of one
vertex with respect the rest of the graph is analyzed in the ground-state of
the system as a function of the tunneling amplitude The topology of
plays a major role in determining the tunneling amplitude
which leads to the maximum ground-state entanglement. Whereas in most of the
cases one finds the intuitively expected result we show that it
there exists a family of graphs for which the optimal value of is pushed
down to a finite value. We also show that, for complete graphs, our bi-partite
entanglement provides useful insights in the analysis of the cross-over between
insulating and superfluid ground statesComment: 5 pages (LaTeX) 5 eps figures include
Signature of Inverse Compton emission from blazars
Blazars are classified into high, intermediate and low energy peaked sources
based on the location of their synchrotron peak. This lies in infra-red/optical
to ultra-violet bands for low and intermediate peaked blazars. The transition
from synchrotron to inverse Compton emission falls in the X-ray bands for such
sources. We present the spectral and timing analysis of 14 low and intermediate
energy peaked blazars ob- served with XMMNewton spanning 31 epochs. Parametric
fits to X-ray spectra helps constrain the possible location of transition from
the high energy end of the syn- chrotron to the low energy end of the inverse
Compton emission. In seven sources in our sample, we infer such a transition
and constrain the break energy in the range 0.6 10 keV. The Lomb-Scargle
periodogram is used to estimate the power spectral density (PSD) shape. It is
well described by a power law in a majority of light curves, the index being
flatter compared to general expectation from AGN, ranging here between 0.01 and
1.12, possibly due to short observation durations resulting in an absence of
long term trends. A toy model involving synchrotron self-Compton (SSC) and
exter- nal Compton (EC; disk, broad line region, torus) mechanisms are used to
estimate magnetic field strength 6 0.03 - 0.88 G in sources displaying the
energy break and infer a prominent EC contribution. The timescale for
variability being shorter than synchrotron cooling implies steeper PSD slopes
which are inferred in these sources.Comment: 24 pages, 6 Tables, 13 figures, Accepted for MNRA
Dirac neutrinos and anomaly-free discrete gauge symmetries
Relying on Dirac neutrinos allows an infinity of anomaly-free discrete gauge
symmetries to be imposed on the Supersymmetric Standard Model, some of which
are GUT-compatible.Comment: 24 pages, minor changes, existence of flipped discrete gauge
symmetries is pointed ou
- …