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Maximal sets with no solution to x + y = 3z
No full textInternational audienceIn this paper, we are interested in a generalization of the notion of sum-free sets. We address a conjecture first made in the 90s by Chung and Goldwasser. Recently, after some computer checks, this conjecture was formulated again by Matolcsi and Ruzsa, who made a first significant step towards it. Here, we prove the full conjecture by giving an optimal upper bound for the Lebesgue measure of a 3-sum-free subset A of [0, 1], that is, a set containing no solution to the equation x + y = 3z where x, y and z are restricted to belong to A. We then address the inverse problem and characterize precisely, among all sets with that property, those attaining the maximal possible measure
The Q-curve construction for endomorphism-accelerated elliptic curves
No full textInternational audienceWe give a detailed account of the use of -curve reductions to construct elliptic curves over with efficiently computable endomorphisms, which can be used to accelerate elliptic curve-based cryptosystems in the same way as Gallant--Lambert--Vanstone (GLV) and Galbraith--Lin--Scott (GLS) endomorphisms. Like GLS (which is a degenerate case of our construction), we offer the advantage over GLV of selecting from a much wider range of curves, and thus finding secure group orders when is fixed for efficient implementation. Unlike GLS, we also offer the possibility of constructing twist-secure curves. We construct several one-parameter families of elliptic curves over equipped with efficient endomorphisms for every , and exhibit examples of twist-secure curves over for the efficient Mersenne prime
Long time asymptotics for fully nonlinear Bellman equations: a Backward SDE approach
No full textWe study the large time behavior of solutions to fully nonlinear parabolic equations of Hamilton-Jacobi-Bellman type arising typically in stochastic control theory with control both on drift and diffusion coefficients. We prove that, as time horizon goes to infinity, the long run average solution is characterized by a nonlinear ergodic equation. Our results hold under dissipativity conditions, and without any nondegeneracy assumption on the diffusion term. Our approach uses mainly probabilistic arguments relying on new backward SDE representation for nonlinear parabolic, elliptic and ergodic equations
Multiphysics and multiscale modelling, data-model fusion and integration of organ physiology in the clinic: ventricular cardiac mechanics
No full textInternational audienceWith heart and cardiovascular diseases continually challenging healthcare systems worldwide, translating basic research on cardiac (patho)physiology into clinical care is essential. Exacerbating this already extensive challenge is the complexity of the heart, relying on its hierarchical structure and function to maintain cardiovascular flow. Computational modelling has been proposed and actively pursued as a tool for accelerating research and translation. Allowing exploration of the relationships between physics, multiscale mechanisms and function, computational modelling provides a platform for improving our understanding of the heart. Further integration of experimental and clinical data through data assimilation and parameter estimation techniques is bringing computational models closer to use in routine clinical practice. This article reviews developments in computational cardiac modelling and how their integration with medical imaging data is providing new pathways for translational cardiac modelling
Measurement of double-differential muon neutrino charged-current interactions on CH without pions in the final state using the T2K off-axis beam
No full text44 pages, 17 figures, see paper for full list of authorsInternational audienceWe report the measurement of muon neutrino charged-current interactions on carbon without pions in the final state at the T2K beam energy using 5.734 protons on target. For the first time the measurement is reported as a flux-integrated, double-differential cross-section in muon kinematic variables (, ), without correcting for events where a pion is produced and then absorbed by final state interactions. Two analyses are performed with different selections, background evaluations and cross-section extraction methods to demonstrate the robustness of the results against biases due to model-dependent assumptions. The measurements compare favorably with recent models which include nucleon-nucleon correlations but, given the present precision, the measurement does not solve the degeneracy between different models. The data also agree with Monte Carlo simulations which use effective parameters that are tuned to external data to describe the nuclear effects. The total cross-section in the full phase space is and the cross-section integrated in the region of phase space with largest efficiency and best signal-over-background ratio ( and MeV) is
Search for direct pair production of scalar top quarks in the single- and dilepton channels in proton-proton collisions at sqrt(s) = 8 TeV
No full textSubmitted to JHEP ; see paper for full list of authorsInternational audienceResults are reported from a search for the top squark, the lighter of the two supersymmetric partners of the top quark. The data sample corresponds to 19.7 inverse femtobarns of proton-proton collisions at sqrt(s) = 8 TeV collected with the CMS detector at the LHC. The search targets top squark to b chi+/- and top squark to t(*) chi0 decay modes, where chi+/- and chi0 are the lightest chargino and neutralino, respectively. The reconstructed final state consists of jets, b jets, missing transverse energy, and either one or two leptons. Leading backgrounds are determined from data. No significant excess in data is observed above the expectation from standard model processes. The results exclude a region of the two-dimensional plane of possible top squark and chi0 masses. The highest excluded top squark and chi0 masses are about 700 GeV and 250 GeV, respectively
A numerical approach for the Poisson equation in a planar domain with a small inclusion
No full textInternational audienceWe consider the Poisson equation in a domain with a small hole of size δ. We present a simple numerical method, based on an asymptotic analysis, which allows to approximate robustly the far field of the solution as δ goes to zero without meshing the small hole. We prove the stability of the scheme and provide error estimates. We end the paper with numerical experiments illustrating the efficiency of the technique
Study of Z boson production in pPb collisions at sqrt(s[NN]) = 5.02 TeV
No full textSubmitted to Phys. Lett. B ; see paper for full list of authorsInternational audienceThe production of Z bosons in pPb collisions at sqrt(s[NN])=5.02 TeV is studied by the CMS experiment via the electron and muon decay channels. The inclusive cross section is compared to pp collision predictions, and found to scale with the number of elementary nucleon-nucleon collisions. The differential cross sections as a function of the Z boson rapidity and transverse momentum are measured. Though they are found to be consistent within uncertainty with theoretical predictions both with and without nuclear effects, the forward-backward asymmetry suggests the presence of nuclear effects at large rapidities. These results provide new data for constraining nuclear parton distribution functions
Measurement of spin correlations in t-tbar production using the matrix element method in the muon+jets final state in pp collisions at sqrt(s) = 8 TeV
No full textSubmitted to Phys. Lett. B ; see paper for full list of authorsInternational audienceThe consistency of the spin correlation strength in top quark pair production with the standard model (SM) prediction is tested in the muon+jets final state. The events are selected from pp collisions, collected by the CMS detector, at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 inverse-femtobarns. The data are compared with the expectation for the spin correlation predicted by the SM and with the expectation of no correlation. Using a template fit method, the fraction of events that show SM spin correlations is measured to be 0.72 +/- 0.08 (stat) +0.15 -0.13 (syst), representing the most precise measurement of this quantity in the lepton+jets final state to date
Transverse momentum spectra of b jets in pPb collisions at sqrt(s[NN]) = 5.02 TeV
No full textSubmitted to Phys. Lett. B, see paper for full list of authorsInternational audienceWe present a measurement of b jet transverse momentum (pt) spectra in proton-lead (pPb) collisions using a dataset corresponding to about 35 inverse nanobarns collected with the CMS detector at the LHC. Jets from b quark fragmentation are found by exploiting the long lifetime of hadrons containing a b quark through tagging methods using distributions of the secondary vertex mass and displacement. Extracted cross sections for b jets are scaled by the effective number of nucleon-nucleon collisions and are compared to a reference obtained from PYTHIA simulations of pp collisions. The PYTHIA-based estimate of the nuclear modification factor is found to be 1.22 +/- 0.15 (stat+syst pPb) +/- 0.27 (syst PYTHIA) averaged over all jets with pt between 55 and 400 GeV/c and with abs(eta[lab])<2. We also compare this result to predictions from models using perturbative calculations in quantum chromodynamics