7,664 research outputs found
Leptogenic Supersymmetry at the LHC
Leptogenic Supersymmetry is a scenario characterized by copious lepton
production in cascade decays. Due to the high lepton multiplicity and the lack
of significant missing energy, leptogenic supersymmetry provides very clean
channels which can be probed already with the early LHC data. Furthermore, the
Higgs may be discovered in the h->b bbar mode because the leptons accompanying
Higgs production efficiently suppress the background.Comment: 4 pages, 2 figures. Contribution to the proceedings of SUSY 09,
Northeastern University, Boston, M
On Resonant Leptogenesis
It has been recently shown that the quantum Boltzmann equations may be
relevant for the leptogenesis scenario. In particular, they lead to a
time-dependent CP asymmetry which depends upon the previous dynamics of the
system. This memory effect in the CP asymmetry is particularly important in
resonant leptogenesis where the asymmetry is generated by the decays of nearly
mass-degenerate right-handed neutrinos. We study the impact of the nontrivial
time evolution of the CP asymmetry in resonant leptogenesis, both in the
one-flavour case and with flavour effects included. We show that significant
qualitative and quantitative differences arise with respect to the case in
which the time dependence of the CP asymmetry is neglected.Comment: 16 pages, 7 figures. IOP LaTeX class used. Minor corrections and
references added. Matches the version published in JCA
On the Impact of Flavour Oscillations in Leptogenesis
When lepton flavour effects in thermal leptogenesis are active, they
introduce important differences with respect to the case in which they are
neglected, the so-called one-flavour approximation. We investigate analytically
and numerically the transition from the one-flavour to the two-flavour case
when the -lepton flavour becomes distinguishable from the other two
flavours. We study the impact of the oscillations of the asymmetries in lepton
flavour space on the final lepton asymmetries, for the hierarchical
right-handed neutrino mass spectrum. Flavour oscillations project the lepton
state on the flavour basis very efficiently. We conclude that flavour effects
are relevant typically for M_1\lsim 10^{12} GeV, where is the mass of
the lightest right-handed neutrino.Comment: 24 pages, 9 figures. Minor corrections; version published in JCA
Quantum Boltzmann Equations and Leptogenesis
The closed time-path formalism is a powerful Green's function formulation to
describe non-equilibrium phenomena in field theory and it leads to a complete
non-equilibrium quantum kinetic theory. We make use of this formalism to write
down the set of quantum Boltzmann equations relevant for leptogenesis. They
manifest memory effects and off-shell corrections. In particular, memory
effects lead to a time-dependent CP asymmetry whose value at a given instant of
time depends upon the previous history of the system. This result is
particularly relevant when the asymmetry is generated by the decays of nearly
mass-degenerate heavy states, as in resonant or soft leptogenesis.Comment: 21 pages, 5 figures. IOP LaTeX class used. Minor corrections and
references added. Matches the version published in JCA
A fast and robust hand-driven 3D mouse
The development of new interaction paradigms requires a natural interaction. This means that people should be able to interact with technology with the same models used to interact with everyday real life, that is through gestures, expressions, voice. Following this idea, in this paper we propose a non intrusive vision based tracking system able to capture hand motion and simple hand gestures. The proposed device allows to use the hand as a "natural" 3D mouse, where the forefinger tip or the palm centre are used to identify a 3D marker and the hand gesture can be used to simulate the mouse buttons. The approach is based on a monoscopic tracking algorithm which is computationally fast and robust against noise and cluttered backgrounds. Two image streams are processed in parallel exploiting multi-core architectures, and their results are combined to obtain a constrained stereoscopic problem. The system has been implemented and thoroughly tested in an experimental environment where the 3D hand mouse has been used to interact with objects in a virtual reality application. We also provide results about the performances of the tracker, which demonstrate precision and robustness of the proposed syste
Spatial Complex Network Analysis and Accessibility Indicators: the Case of Municipal Commuting in Sardinia, Italy
In this paper a contribution is presented with respect to accessibility indicators modelling for commuters moving through the municipalities of Sardinia, in Italy. In this case, spatial complex network analysis is integrated into the construction of accessibility measures: one of the most relevant outcomes of the first tool âthe detection of shortest road paths and distances- is adopted as an input for the second in modelling accessibility indicators. Instead of Euclidean distances often adopted in the literature, shortest road distances are chosen, as commuting implies movements that are usually repeated daily and very likely subjected, even unconsciously, to space and time minimization strategies.
In particular, two commuter accessibility indicators are constructed according to approaches based on a travel cost and a spatial interaction model with impedance function calibrated in exponential and in power form. The accessibility indicators are confronted each other and with relevant socio-economic and infrastructure characteristics of Sardinia.
In addition, they are described, with respect to their spatial distribution and their different implications, when adopted in decision-making and planning. The travel cost based accessibility indicator has a municipal spatial distribution strongly influenced by the main road infrastructure of the Island. By contrast, spatial interaction model based accessibility indicators are more reliable, with respect to their capacity to confirm a leading socio-economic role of the municipalities comprehended in the metropolitan area of the capital town Cagliari
Pseudo-Dirac Dark Matter Leaves a Trace
Pseudo-Dirac Dark Matter is a viable type of dark matter which originates
from a new Dirac fermion whose two Weyl states get slightly split in mass by a
small Majorana term. The decay of the heavier to the lighter state naturally
occurs over a detectable length scale. Thus, whenever pseudo-Dirac Dark Matter
is produced in a collider, it leaves a clear trace: a visible displaced vertex
in association with missing energy. Moreover, pseudo-Dirac Dark Matter behaves
Dirac-like for relic abundance and Majorana-like in direct detection
experiments: it has efficient s-wave annihilations but it lacks of dangerous
vector interactions with the quarks in the nuclei. We provide a general
treatment using an effective field theory approach, then specializing to the
supersymmetric situation of a pseudo-Dirac Bino. The dark matter mass and the
mass splitting can be extracted from measurements of the decay length and the
invariant mass of the products, even in presence of missing energy.Comment: 16 pages, 5 figures. Extended version of the letter published in PR
Introduction to cosmology and dark matter
These are the lectures notes for the course on Introduction to Cosmology and Dark Matter given at the CERN European School for High Energy Physics (ESHEP) 2018. The audience consists of graduate students with particle physics background
Quantum Boltzmann equations in resonant leptogenesis
The quantum Boltzmann equations relevant for leptogenesis, obtained using
non-equilibrium quantum field theory, are described. They manifest memory
effects leading to a time-dependent CP asymmetry which depends upon the
previous history of the system. This result is particularly relevant in
resonant leptogenesis where the asymmetry is generated by the decays of nearly
mass-degenerate right-handed neutrinos. The impact of the non-trivial time
evolution of the CP asymmetry is discussed either in the generic resonant
leptogenesis scenario or in the more specific Minimal Lepton Flavour Violation
framework. Significant quantitative differences arise with respect to the usual
approach in which the time dependence of the CP asymmetry is neglected.Comment: 6 pages, 1 figure. Talk given at the 43rd Rencontres de Moriond - EW
session, La Thuile (Italy), 1-8 March 200
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