Stéphane Monteil

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A search has been performed for the Standard Model Higgs boson in the data sample collected with the ALEPH detector at LEP, at centre-of-mass energies up to 209 GeV. An excess of 3 σ beyond the background expectation is found, consistent with the production of the Higgs boson with a mass near 114 GeV/c 2. Much of this excess is seen in the four-jet(More)
The cross sections and forward-backward asymmetries of hadronic and leptonic events produced in e + e − collisions at centre-of-mass energies from 130 to 183 GeV are presented. Results for e + e − , µ + µ − , τ + τ − , q¯ q, b ¯ b and c¯ c production show no significant deviation from the Standard Model predictions. This enables constraints to be set upon(More)
We analyse three different New Physics scenarios for ∆F = 2 flavour-changing neutral currents in the quark sector in the light of recent data on neutral-meson mixing. We parametrise generic New Physics contributions to B q − B q mixing, q = d, s, in terms of one complex quantity ∆ q , while three parameters ∆ tt K , ∆ ct K and ∆ cc K are needed to describe(More)
Measurement of ψ(2S) meson production in pp collisions at √ s = 7 TeV Abstract The differential cross-section for the inclusive production of ψ(2S) mesons in pp collisions at √ s = 7 TeV has been measured with the LHCb detector. The data sample corresponds to an integrated luminosity of 36 pb −1. The ψ(2S) mesons are reconstructed in the decay channels(More)
A measurement of the ratio of the branching fractions of the B(+) → K(+)μ(+)μ(-) and B(+) → K(+)e(+)e(-) decays is presented using proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb(-1), recorded with the LHCb experiment at center-of-mass energies of 7 and 8 TeV. The value of the ratio of branching fractions for the dilepton(More)
Using pp collision data corresponding to an integrated luminosity of 1.0 fb(-1) and collected by LHCb in 2011 at a center-of-mass energy of 7 TeV, we report the measurement of direct CP violation in B(s)(0)→K(-)π(+) decays, A(CP)(B(s)(0)→K(-)π(+)=0.27±0.04 (stat)±0.01 (syst), with significance exceeding 5 standard deviations. This is the first observation(More)
Resonant structures in B^{0}→ψ^{'}π^{-}K^{+} decays are analyzed by performing a four-dimensional fit of the decay amplitude, using pp collision data corresponding to 3  fb^{-1} collected with the LHCb detector. The data cannot be described with K^{+}π^{-} resonances alone, which is confirmed with a model-independent approach. A highly significant(More)
The rate of gluon splitting into c¯ c pairs in hadronic Z decays is measured using the data sample collected by ALEPH from 1991 to 1995. The selection is based on the identification of leptons (electrons and muons) originating from semileptonic charm decays, and on the topological properties of signal events. The result derived from the selected sample is g(More)
An angular analysis of the decay J /ψ → μ + μ − is performed to measure the polarization of prompt J /ψ mesons produced in pp collisions at √ s = 7 TeV. The dataset corresponds to an integrated luminosity of 0.37 fb −1 collected with the LHCb detector. The measurement is presented as a function of transverse momentum, p T , and rapid-ity, y, of the J /ψ(More)
A broad peaking structure is observed in the dimuon spectrum of B+ → K+ μ+ μ- decays in the kinematic region where the kaon has a low recoil against the dimuon system. The structure is consistent with interference between the B+ → K+ μ+ μ- decay and a resonance and has a statistical significance exceeding six standard deviations. The mean and width of the(More)