1,866 research outputs found
Right-handed lepton mixings at the LHC
We study how the elements of the leptonic right-handed mixing matrix can be
determined at the LHC in the minimal Left-Right symmetric extension of the
standard model. We do it by explicitly relating them with physical quantities
of the Keung-Senjanovi\'c process and the lepton number violating decays of the
right doubly charged scalar. We also point out that the left and right doubly
charged scalars can be distinguished at the LHC, without measuring the
polarization of the final state leptons coming from their decays.Comment: 12 pages, 6 figures, discussion in section III expanded and
sharpened, one appendix added, updated reference
Spike trains statistics in Integrate and Fire Models: exact results
We briefly review and highlight the consequences of rigorous and exact
results obtained in \cite{cessac:10}, characterizing the statistics of spike
trains in a network of leaky Integrate-and-Fire neurons, where time is discrete
and where neurons are subject to noise, without restriction on the synaptic
weights connectivity. The main result is that spike trains statistics are
characterized by a Gibbs distribution, whose potential is explicitly
computable. This establishes, on one hand, a rigorous ground for the current
investigations attempting to characterize real spike trains data with Gibbs
distributions, such as the Ising-like distribution, using the maximal entropy
principle. However, it transpires from the present analysis that the Ising
model might be a rather weak approximation. Indeed, the Gibbs potential (the
formal "Hamiltonian") is the log of the so-called "conditional intensity" (the
probability that a neuron fires given the past of the whole network). But, in
the present example, this probability has an infinite memory, and the
corresponding process is non-Markovian (resp. the Gibbs potential has infinite
range). Moreover, causality implies that the conditional intensity does not
depend on the state of the neurons at the \textit{same time}, ruling out the
Ising model as a candidate for an exact characterization of spike trains
statistics. However, Markovian approximations can be proposed whose degree of
approximation can be rigorously controlled. In this setting, Ising model
appears as the "next step" after the Bernoulli model (independent neurons)
since it introduces spatial pairwise correlations, but not time correlations.
The range of validity of this approximation is discussed together with possible
approaches allowing to introduce time correlations, with algorithmic
extensions.Comment: 6 pages, submitted to conference NeuroComp2010
http://2010.neurocomp.fr/; Bruno Cessac
http://www-sop.inria.fr/neuromathcomp
Resummation in QFT with Meijer G-functions
We employ a recent resummation method to deal with divergent series, based on
the Meijer G-function, which gives access to the non-perturbative regime of any
QFT from the first few known coefficients in the perturbative expansion. Using
this technique, we consider in detail the model where we estimate the
non-perturbative function and prove that its asymptotic behavior
correctly reproduces instantonic effects calculated using semiclassical
methods. After reviewing the emergence of the renormalons in this theory, we
also speculate on how one can resum them. Finally, we resum the
non-perturbative function of abelian and non-abelian gauge-fermion
theories and analyze the behavior of these theories as a function of the number
of fermion flavors. While in the former no fixed points are found, in the
latter, a richer phase diagram is uncovered and illustrated by the regions of
confinement, large-distance conformality, and asymptotic safety.Comment: 22 pages, 10 figures, final version with minor changes, as accepted
in NP
Defragmenting Beethoven: Sound appropriation as bridge between classical tradition and electroacoustic music
This thesis serves as a written companion for two artistic-based research products built upon the concept of appropriation as connecting bridge between music technology and the classical tradition of music composition. The first artistic work is a set of 9 pieces called "Collages Vol 2", a continuation of a first release meant to be an exploratory work for the present research. The second work is the sound interaction design, and the creation of two compositions for the Network of Intelligent Sound Agents, or "NOISA", built at the Sound and Physical Interaction Research Group from the Department of Media, Aalto University. After providing context and a short survey of influences on music appropriation, I made a comprehensive documentation of each of the pieces created for this thesis, describing form, content, compositional approach and sound processing in a systematic way.
I investigated on the diverse forms of appropriation as a technique for electroacoustic music composition. The most influential references for my work are documented in this written work: From the historical approach of appropriation to borrowing in music of the XX century and recent times; including a description of the first volume of my original Collages. Later on, I described my second collection of Collages and the utilisation of appropriation theories in the context of NOISA, a music interface for live performance. Finally, there is a section dedicated to a discussion featuring a commentary of a number of reviews of "Collages” preceding a closing segment with conclusions and further plans to expand this research in the future
Time-reversal symmetry violation in several Lepton-Flavor-Violating processes
We compute a T-odd triple vector correlation for the decay and the conversion process. We find simple results
in terms of the CP violating phases of the effective Hamiltonians. Then we
focus on the minimal Left-Right symmetric extension of the Standard Model,
which can lead to an appreciable correlation. We show that under rather general
assumptions, this correlation can be used to discriminate between Parity or
Charge-conjugation as the discrete Left-Right symmetry.Comment: 22 pages, 5 figures. Comments added. Sections 5 and 6 expanded.
Appendices A and B expanded, accepted for publication in JHE
La réforme des forces de police au Canada : les tensions entre la sécurité des citoyens, les libertés fondamentales et le fédéralisme
Cet article envisage les politiques en matière de sécurité citoyenne et la réforme des forces de police au Canada pendant les 25 dernières années. La Charte canadienne des droits et libertés a établi dans l’article 7 la garantie à la « sécurité de la personne ». La poursuite de cette garantie a supposé, d’une part, une tension entre la décentralisation, le désengagement de l’État et le rôle de la police et, d’autre part, une tension entre son mandat de préserver l’ordre public, entendu comme la sauvegarde de l’État, et la protection des citoyens. Même si ces tensions se révèlent problématiques, elles n’ont pas empêché que le Canada soit un pays sûr dont le taux de criminalité est bas et où règne un important sentiment de sécurité parmi les citoyens.This article looks at policies concerning citizen security and reform among Canada's police forces during the last twenty-five years. Article 7 of the Canadian Charter of Rights and Freedoms established a guarantee of "security of the person". Pursuit of this guarantee has supposed, on one hand, a tension between decentralization, withdrawal of the State, and the role of police, and on the other hand, a tension between the Charter's mandate to preserve public order, understood as the safeguard of the State, and the protection of citizens. Even if revealed as problematic, these tensions did not prevent Canada from being a confident country with low crime rates and a heightened sense of security among its citizens
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