Eoulsan : analyse du séquençage à haut débit dans le cloud et sur la grille

Eoulsan : analyse du séquençage à haut débit dans le cloud et sur la grill

Study of J /ψ production in Jets

The production of J/ψ mesons in jets is studied in the forward region of proton-proton collisions using data collected with the LHCb detector at a center-of-mass energy of 13 TeV. The fraction of the jet transverse momentum carried by the J/ψ meson, z(J/ψ)≡pT(J/ψ)/pT(jet), is measured using jets with pT(jet)>20 GeV in the pseudorapidity range 2.5<η(jet)<4.0. The observed z(J/ψ)distribution for J/ψ mesons produced in b-hadron decays is consistent with expectations. However, the results for prompt J/ψ production do not agree with predictions based on fixed-order nonrelativistic QCD. This is the first measurement of the pT fraction carried by prompt J/ψ mesons in jets at any experiment

Energy Resolution Performance of the CMS Electromagnetic Calorimeter

The energy resolution performance of the CMS lead tungstate crystal electromagnetic calorimeter is presented. Measurements were made with an electron beam using a fully equipped supermodule of the calorimeter barrel. Results are given both for electrons incident on the centre of crystals and for electrons distributed uniformly over the calorimeter surface. The electron energy is reconstructed in matrices of 3 times 3 or 5 times 5 crystals centred on the crystal containing the maximum energy. Corrections for variations in the shower containment are applied in the case of uniform incidence. The resolution measured is consistent with the design goals

Study of J=ψ Production in Jets

The production of J/ψ mesons in jets is studied in the forward region of proton-proton collisions using data collected with the LHCb detector at a center-of-mass energy of 13 TeV. The fraction of the jet transverse momentum carried by the J/ψ meson, z(J/ψ)≡p[subscript T](J/ψ)/p[subscript T](jet), is measured using jets with p[subscript T](jet) > 20  GeV in the pseudorapidity range 2.5<η(jet)<4.0. The observed z(J/ψ) distribution for J/ψ mesons produced in b-hadron decays is consistent with expectations. However, the results for prompt J/ψ production do not agree with predictions based on fixed-order nonrelativistic QCD. This is the first measurement of the p[subscript T] fraction carried by prompt J/ψ mesons in jets at any experiment.National Science Foundation (U.S.

Search for long-lived scalar particles in B + → K + χ ( μ + μ − ) decays

A search for a long-lived scalar particle χ is performed, looking for the decay B[superscript +]→K[superscript +]χ with χ→μ[superscript +]μ[superscript -] in pp collision data corresponding to an integrated luminosity of 3  fb[superscript -1], collected by the LHCb experiment at center-of-mass energies of √s =7 and 8 TeV. This new scalar particle, predicted by hidden sector models, is assumed to have a narrow width. The signal would manifest itself as an excess in the dimuon invariant mass distribution over the Standard Model background. No significant excess is observed in the accessible ranges of mass 250<m(χ)<4700  MeV/c[superscript 2] and lifetime 0.1<τ(χ)<1000  ps. Upper limits on the branching fraction B(B[superscript +]→K[superscript +]χ(μ[superscript +]μ[superscript -])) at 95% confidence level are set as a function of m(χ) and τ(χ), varying between 2×10[superscript -10] and 10[superscript -7]. These are the most stringent limits to date. The limits are interpreted in the context of a model with a light inflaton particle.National Science Foundation (U.S.

CMS physics technical design report : Addendum on high density QCD with heavy ions

Peer reviewe

Observation of B+c → D0K+ decays

Using proton-proton collision data corresponding to an integrated luminosity of 3.0 fb−1, recorded by the LHCb detector at center-of-mass energies of 7 and 8 TeV, the B+ c → D0K+ decay is observed with a statistical significance of 5.1 standard deviations. By normalizing to B+ → D¯ 0π+ decays, a measurement of the branching fraction multiplied by the production rates for B+ c relative to B+ mesons in the LHCb acceptance is obtained, R D 0 K = ( f c / f u ) × B ( B + c → D 0 K + ) = ( 9. 3 + 2.8 − 2.5 ± 0.6 ) × 10 − 7, where the first uncertainty is statistical and the second is systematic. This decay is expected to proceed predominantly through weak annihilation and penguin amplitudes, and is the first B+ c decay of this nature to be observed

Search for the decays Bs0→τ+τ− and B0→τ+τ−

A search for the rare decays B0 s → τþτ− and B0 → τþτ− is performed using proton–proton collision data collected with the LHCb detector. The data sample corresponds to an integrated luminosity of 3 fb−1 collected in 2011 and 2012. The τ leptons are reconstructed through the decay τ− → π−πþπ−ντ. Assuming no contribution from B0 → τþτ− decays, an upper limit is set on the branching fraction BðB0 s → τþτ−Þ &lt; 6.8 × 10−3 at the 95% confidence level. If instead no contribution from B0 s → τþτ− decays is assumed, the limit is BðB0 → τþτ−Þ &lt; 2.1 × 10−3 at the 95% confidence level. These results correspond to the first direct limit on BðB0 s → τþτ−Þ and the world’s best limit on BðB0 → τþτ−Þ

Measurements of prompt charm production cross-sections in pp collisions at root s=13 TeV

Production cross-sections of prompt charm mesons are measured with the first data from pp collisions at the LHC at a centre-of-mass energy of 13 TeV. The data sample corresponds to an integrated luminosity of 4.98 +/- 0.19 pb(-1) collected by the LHCb experiment. The production cross-sections of D-0, D+, D (s) (+) , and D*+ mesons are measured in bins of charm meson transverse momentum, p(T), and rapidity, y, and cover the range 0 &lt;p(T) &lt;15GeV/c and 2.0 &lt;y &lt;4.5. The inclusive cross-sections for the four mesons, including charge conjugation, within the range of 1 &lt;p(T) &lt;8 GeV/c are found to besigma(pp -&gt; D-0 X) = 2460 +/- 3 +/- 130 mu bsigma(pp -&gt; D+ X) = 1000 +/- 3 +/- 110 mu bsigma(pp -&gt; Ds+X) = 460 +/- 13 +/- 100 mu bsigma(pp -&gt; D*+ X) = 880 +/- 5 +/- 140 mu bwhere the uncertainties are due to statistical and systematic uncertainties, respectively.</p

Measurement of the B_{s}^{0}→μ^{+}μ^{-} Branching Fraction and Effective Lifetime and Search for B^{0}→μ^{+}μ^{-} Decays.

A search for the rare decays B_{s}^{0}→μ^{+}μ^{-} and B^{0}→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 B_{s}^{0}→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(B_{s}^{0}→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 B_{s}^{0}→μ^{+}μ^{-} effective lifetime, τ(B_{s}^{0}→μ^{+}μ^{-})=2.04±0.44±0.05  ps, is reported. No significant excess of B^{0}→μ^{+}μ^{-} decays is found, and a 95% confidence level upper limit, B(B^{0}→μ^{+}μ^{-})<3.4×10^{-10}, is determined. All results are in agreement with the standard model expectations