Resource
2015 EN
Michele Lucente
We explore the hypothesis of having an approximate lepton number conservationas a way to achieve a successful leptogenesis in low-scale seesaw mechanisms.The smallness of the active neutrino masses, as well as a strong degeneracy inthe mass spectrum of the heavy sterile states, are both consequence of theassumed approximate symmetry. We propose a minimal extension of the StandardModel in order to implement the idea, and perform an analytical and numericalstudy to determine the viable solutions in the model and the testability ofthis leptogenesis scenario in future experiments.
Resource
2015 EN
Thomas Müller · Paolo Arosio · Luke Rajah
+5 more
Conventional approaches for simulating steady-state distributions ofparticles under diffusive and advective transport at high P\'eclet numbersinvolve solving the diffusion and advection equations in at least twodimensions. Here, we present an alternative computational strategy by combininga particle-based rather than a field-based approach with the initialisation ofparticles in proportion to their flux. This method allows accurate predictionof the steady state and is applicable even at high P\'eclet numbers wheretraditional particle-based Monte-Carlo methods starting from randomlyinitialised particle distributions fail. We demonstrate that generating a fluxof particles according to a predetermined density and velocity distribution ata single fixed time and initial location allows for accurate simulation of masstransport under flow. Specifically, upon initialisation in proportion to theirflux, these particles are propagated individually and detected by summing uptheir Monte-Carlo trajectories in predefined detection regions. We demonstratequantitative agreement of the predicted concentration profiles with the resultsof experiments performed with fluorescent particles in microfluidic channelsunder continuous flow. This approach is computationally advantageous andreadily allows non-trivial initial distributions to be considered. Inparticular, this method is highly suitable for simulating advective anddiffusive transport in microfluidic devices.
Resource
2015 EN
Ernesto Estrada · Michele Benzi
Core-satellite graphs (sometimes referred to as generalized friendshipgraphs) are an interesting class of graphs that generalize many well knowntypes of graphs. In this paper we show that two popular clustering measures,the average Watts-Strogatz clustering coefficient and the transitivity index,diverge when the graph size increases. We also show that these graphs aredisassortative. In addition, we completely describe the spectrum of theadjacency and Laplacian matrices associated with core-satellite graphs.Finally, we introduce the class of generalized core-satellite graphs, and weanalyze the spectral properties of such graphs.
Resource
2015 EN
Alex Parker · Noemi Pinilla-Alonso · Pablo Santos-Sanz
+14 more
Studies of the physical properties of Trans-Neptunian Objects (TNOs) are apowerful probe into the processes of planetesimal formation and solar systemevolution. JWST will provide unique new capabilities for such studies. Here weoutline where the capabilities of JWST open new avenues of investigation,potential valuable observations and surveys, and conclude with a discussion ofcommunity actions that may serve to enhance the eventual science return ofJWSTs TNO observations.
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2015 EN
PPS Thomas Ehrhard · PPS Michele Pagani · PPS Christine Tasson
We present a probabilistic version of PCF, a well-known simply typeduniversal functional language. The type hierarchy is based on a single groundtype of natural numbers. Even if the language is globally call-by-name, weallow a call-by-value evaluation for ground type arguments in order to providethe language with a suitable algorithmic expressiveness. We describe adenotational semantics based on probabilistic coherence spaces, a model ofclassical Linear Logic developed in previous works. We prove an adequacy and anequational full abstraction theorem showing that equality in the modelcoincides with a natural notion of observational equivalence.
Resource
2015 EN
Leonardo Giusti · Michele Pepe
We present an accurate computation of the Equation of State of the SU(3)Yang-Mills theory using shifted boundary conditions in the temporal direction.In this framework, the entropy density s can be obtained in a simple way fromthe expectation value of the space-time components T0k of the energy-momentumtensor. At each given value of the temperature, s is measured in an independentway at several values of the lattice spacing. The extrapolation to thecontinuum limit shows small discretization effects with respect to thestatistical errors of approximatively 0.5%.
Resource
2015 EN
Elena Pastorelli · Pier Stanislao Paolucci · Roberto Ammendola
+7 more
This short report describes the scaling, up to 1024 software processes andhardware cores, of a distributed simulator of plastic spiking neural networks.A previous report demonstrated good scalability of the simulator up to 128processes. Herein we extend the speed-up measurements and strong and weakscaling analysis of the simulator to the range between 1 and 1024 softwareprocesses and hardware cores. We simulated two-dimensional grids of corticalcolumns including up to ~20G synapses connecting ~11M neurons. The neuralnetwork was distributed over a set of MPI processes and the simulations wererun on a server platform composed of up to 64 dual-socket nodes, each socketequipped with Intel Haswell E5-2630 v3 processors (8 cores @ 2.4 GHz clock).All nodes are interconned through an InfiniBand network. The DPSNN simulatorhas been developed by INFN in the framework of EURETILE and CORTICONIC EuropeanFET Project and will be used by the WaveScalEW tem in the framework of theHuman Brain Project (HBP), SubProject 2 - Cognitive and Systems Neuroscience.This report lays the groundwork for a more thorough comparison with the neuralsimulation tool NEST.
Resource
2015 EN
Francesca Arrigo · Michele Benzi · Caterina Fenu
We develop numerical algorithms for the efficient evaluation of quantitiesassociated with generalized matrix functions [J. B. Hawkins and A. Ben-Israel,Linear and Multilinear Algebra 1(2), 1973, pp. 163-171]. Our algorithms arebased on Gaussian quadrature and Golub--Kahan bidiagonalization. Block variantsare also investigated. Numerical experiments are performed to illustrate theeffectiveness and efficiency of our techniques in computing generalized matrixfunctions arising in the analysis of networks.
Resource
2015 UN
IMAG Paul-Emile Paradan · IMJ Michele Vergne
We describe the admissible coadjoint orbits of a compact connected Lie groupand their spin-c quantization.
Resource
2015 EN
Michele Selvaggi
The High-Luminosity LHC is expected to provide $3 ab^{-1}$ of integratedluminosity. As a result billions of events containing top quarks will bedetected at the CMS and ATLAS experiments, allowing for precise measurements ofthe top quark properties. The experimental challenges that will be faced in ahigh luminosity environment, with a special focus on top quark relatedobservables are examined. We discuss prospects for measuring top quarkanomalous couplings at the HL-LHC. Projections for detecting flavor changingneutral currents involving top quarks are also reviewed.