723 research outputs found

    The theory of heterogeneous dielectric nanostructures with non-typical low-threshold nonlinearity

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    AbstractThe recently discovered, ultralow-threshold, nonlinear refraction of low-intensity laser radiation in dielectric nanostructures has an atypical dependence on radiation intensity in the pulsed and continuous modes. In this study, we present a theoretical explanation. The theory suggests that the nonlinearity is photoinduced in nature, rather than thermal, and depends directly on the nanoparticle electronic structure and the relationship between permittivities of the dielectric matrix and the nanoparticles

    Green’s Function Method for Electromagnetic and Acoustic Fields in Arbitrarily Inhomogeneous Media

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    An analytical method based on the Green’s function for describing the electromagnetic field, scalar-vector and phase characteristics of the acoustic field in a stationary isotropic and arbitrarily inhomogeneous medium is proposed. The method uses, in the case of an electromagnetic field, the wave equation proposed by the author for the electric vector of the electromagnetic field, which is valid for dielectric and magnetic inhomogeneous media with conductivity. In the case of an acoustic field, the author uses the wave equation proposed by the author for the particle velocity vector and the well-known equation for acoustic pressure in an inhomogeneous stationary medium. The approach used allows one to reduce the problem of solving differential wave equations in an arbitrarily inhomogeneous medium to the problem of taking an integral

    Flexible constrained sampling with guarantees for pattern mining

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    Pattern sampling has been proposed as a potential solution to the infamous pattern explosion. Instead of enumerating all patterns that satisfy the constraints, individual patterns are sampled proportional to a given quality measure. Several sampling algorithms have been proposed, but each of them has its limitations when it comes to 1) flexibility in terms of quality measures and constraints that can be used, and/or 2) guarantees with respect to sampling accuracy. We therefore present Flexics, the first flexible pattern sampler that supports a broad class of quality measures and constraints, while providing strong guarantees regarding sampling accuracy. To achieve this, we leverage the perspective on pattern mining as a constraint satisfaction problem and build upon the latest advances in sampling solutions in SAT as well as existing pattern mining algorithms. Furthermore, the proposed algorithm is applicable to a variety of pattern languages, which allows us to introduce and tackle the novel task of sampling sets of patterns. We introduce and empirically evaluate two variants of Flexics: 1) a generic variant that addresses the well-known itemset sampling task and the novel pattern set sampling task as well as a wide range of expressive constraints within these tasks, and 2) a specialized variant that exploits existing frequent itemset techniques to achieve substantial speed-ups. Experiments show that Flexics is both accurate and efficient, making it a useful tool for pattern-based data exploration.Comment: Accepted for publication in Data Mining & Knowledge Discovery journal (ECML/PKDD 2017 journal track

    Les droits disciplinaires des fonctions publiques : « unification », « harmonisation » ou « distanciation ». A propos de la loi du 26 avril 2016 relative à la déontologie et aux droits et obligations des fonctionnaires

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    The production of tt‾ , W+bb‾ and W+cc‾ is studied in the forward region of proton–proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98±0.02 fb−1 . The W bosons are reconstructed in the decays W→ℓν , where ℓ denotes muon or electron, while the b and c quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions.The production of tt‾t\overline{t}, W+bb‾W+b\overline{b} and W+cc‾W+c\overline{c} is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98 ±\pm 0.02 \mbox{fb}^{-1}. The WW bosons are reconstructed in the decays W→ℓνW\rightarrow\ell\nu, where ℓ\ell denotes muon or electron, while the bb and cc quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions

    Measurement of the J/ψ pair production cross-section in pp collisions at s=13 \sqrt{s}=13 TeV

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    The production cross-section of J/ψ pairs is measured using a data sample of pp collisions collected by the LHCb experiment at a centre-of-mass energy of s=13 \sqrt{s}=13 TeV, corresponding to an integrated luminosity of 279 ±11 pb−1^{−1}. The measurement is performed for J/ψ mesons with a transverse momentum of less than 10 GeV/c in the rapidity range 2.0 < y < 4.5. The production cross-section is measured to be 15.2 ± 1.0 ± 0.9 nb. The first uncertainty is statistical, and the second is systematic. The differential cross-sections as functions of several kinematic variables of the J/ψ pair are measured and compared to theoretical predictions.The production cross-section of J/ψJ/\psi pairs is measured using a data sample of pppp collisions collected by the LHCb experiment at a centre-of-mass energy of s=13 TeV\sqrt{s} = 13 \,{\mathrm{TeV}}, corresponding to an integrated luminosity of 279±11 pb−1279 \pm 11 \,{\mathrm{pb^{-1}}}. The measurement is performed for J/ψJ/\psi mesons with a transverse momentum of less than 10 GeV/c10 \,{\mathrm{GeV}}/c in the rapidity range 2.0<y<4.52.0<y<4.5. The production cross-section is measured to be 15.2±1.0±0.9 nb15.2 \pm 1.0 \pm 0.9 \,{\mathrm{nb}}. The first uncertainty is statistical, and the second is systematic. The differential cross-sections as functions of several kinematic variables of the J/ψJ/\psi pair are measured and compared to theoretical predictions

    A study of CP violation in B-+/- -&gt; DK +/- and B-+/- -&gt; D pi(+/-) decays with D -&gt; (KSK +/-)-K-0 pi(-/+) final states

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    A first study of CP violation in the decay modes B±→[KS0K±π∓]Dh±B^\pm\to [K^0_{\rm S} K^\pm \pi^\mp]_D h^\pm and B±→[KS0K∓π±]Dh±B^\pm\to [K^0_{\rm S} K^\mp \pi^\pm]_D h^\pm, where hh labels a KK or π\pi meson and DD labels a D0D^0 or D‾0\overline{D}^0 meson, is performed. The analysis uses the LHCb data set collected in pppp collisions, corresponding to an integrated luminosity of 3 fb−1^{-1}. The analysis is sensitive to the CP-violating CKM phase γ\gamma through seven observables: one charge asymmetry in each of the four modes and three ratios of the charge-integrated yields. The results are consistent with measurements of γ\gamma using other decay modes

    Measurement of the B0s→μ+μ− Branching Fraction and Effective Lifetime and Search for B0→μ+μ− Decays

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    A search for the rare decays Bs0→μ+μ- and B0→μ+μ- is performed at the LHCb experiment using data collected in pp collisions corresponding to a total integrated luminosity of 4.4  fb-1. An excess of Bs0→μ+μ- decays is observed with a significance of 7.8 standard deviations, representing the first observation of this decay in a single experiment. The branching fraction is measured to be B(Bs0→μ+μ-)=(3.0±0.6-0.2+0.3)×10-9, where the first uncertainty is statistical and the second systematic. The first measurement of the Bs0→μ+μ- effective lifetime, τ(Bs0→μ+μ-)=2.04±0.44±0.05  ps, is reported. No significant excess of B0→μ+μ- decays is found, and a 95% confidence level upper limit, B(B0→μ+μ-)<3.4×10-10, is determined. All results are in agreement with the standard model expectations.A search for the rare decays Bs0→μ+μ−B^0_s\to\mu^+\mu^- and B0→μ+μ−B^0\to\mu^+\mu^- is performed at the LHCb experiment using data collected in pppp collisions corresponding to a total integrated luminosity of 4.4 fb−1^{-1}. An excess of Bs0→μ+μ−B^0_s\to\mu^+\mu^- decays is observed with a significance of 7.8 standard deviations, representing the first observation of this decay in a single experiment. The branching fraction is measured to be B(Bs0→μ+μ−)=(3.0±0.6−0.2+0.3)×10−9{\cal B}(B^0_s\to\mu^+\mu^-)=\left(3.0\pm 0.6^{+0.3}_{-0.2}\right)\times 10^{-9}, where the first uncertainty is statistical and the second systematic. The first measurement of the Bs0→μ+μ−B^0_s\to\mu^+\mu^- effective lifetime, τ(Bs0→μ+μ−)=2.04±0.44±0.05\tau(B^0_s\to\mu^+\mu^-)=2.04\pm 0.44\pm 0.05 ps, is reported. No significant excess of B0→μ+μ−B^0\to\mu^+\mu^- decays is found and a 95 % confidence level upper limit, B(B0→μ+μ−)<3.4×10−10{\cal B}(B^0\to\mu^+\mu^-)<3.4\times 10^{-10}, is determined. All results are in agreement with the Standard Model expectations

    Measurement of the Z plus b-jet cross-section in pp collisions at root s=7 TeV in the forward region

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    The associated production of a Z boson or an off-shell photon γ∗\gamma^* with a bottom quark in the forward region is studied using proton-proton collisions at a centre-of-mass energy of 7 TeV7{\mathrm{\,Te\kern -0.1em V}}. The Z bosons are reconstructed in the Z/γ∗→μ+μ−{\text{Z}/\gamma^*}\rightarrow{\mu^{+}\mu^{-}} final state from muons with a transverse momentum larger than 20 GeV20{\mathrm{\,Ge\kern -0.1em V}}, while two transverse momentum thresholds are considered for jets (10 GeV10{\mathrm{\,Ge\kern -0.1em V}} and 20 GeV20{\mathrm{\,Ge\kern -0.1em V}}). Both muons and jets are reconstructed in the pseudorapidity range 2.010 GeV2.0 10{\mathrm{\,Ge\kern -0.1em V}}, and \sigma(\text{\text{Z}/\gamma^*(\mu^{+}\mu^{-})+b-jet}) = 167 \pm 47 (\text{stat}) \pm 29 (\text{syst}) \pm 6 (\text{lumi}) {\,{fb}} for {p_{\rm T}}(jet)>20 GeV>20{\mathrm{\,Ge\kern -0.1em V}}
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