Gilles De Lentdecker

Measurement of the tt̄ production cross section in the dilepton channel in pp collisions at √s = 8 TeV

The top-antitop quark (tt) production cross section is measured in proton-proton collisions at √ s = 8 TeV with the CMS experiment at the LHC, using a data sample corresponding to an integrated luminosity of 5.3 fb−1. The measurement is performed by analysing events with a pair of electrons or muons, or one electron and one muon, and at least two jets, one of which is identified as originating from hadronisation of a bottom quark. The measured cross section is 239± 2 (stat.)± 11 (syst.)± 6 (lum.) pb, for an assumed top-quark mass of 172.5 GeV, in agreement with the prediction of the standard model. Published in the Journal of High Energy Physics as doi:10.1007/JHEP02(2014)024. c

Measurement of the tt̄ production cross section in pp̄ collisions at √S = 1-96 TeV using dilepton events

We report a measurement of the ttbar production cross section using dilepton events with jets and missing transverse energy in ppbar collisions at a center-of-mass energy of 1.96 TeV. Using a 197 +/- 12 pb-1 data sample recorded by the upgraded Collider Detector at Fermilab, we use two complementary techniques to select candidate events. We compare the number of observed events and selected kinematical distributions with the predictions of the Standard Model and find good agreement. The combined result of the two techniques yields a ttbar production cross section of 7.0 +2.4/-2.1(stat.) +1.6/-1.1(syst.) +/- 0.4(lum.) pb.

Measurement of the ZZ production cross section and Z → ℓ+ℓ−ℓ′+ℓ′− branching fraction in pp collisions at s=13 TeV

A bstractThis paper describes the search for a high-mass narrow-width scalar particle decaying into a Z boson and a photon. The analysis is performed using proton-proton collision data recorded with the CMS detector at the LHC at center-of-mass energies of 8 and 13 TeV, corresponding to integrated luminosities of 19.7 and 2.7 fb−1, respectively. The Z bosons are reconstructed from opposite-sign electron or muon pairs. No statistically significant deviation from the standard model predictions has been found in the 200-2000 GeV mass range. Upper limits at 95% confidence level have been derived on the product of the scalar particle production cross section and the branching fraction of the Z decaying into electrons or muons, which range from 280 to 20 fb for resonance masses between 200 and 2000 GeV.

Search for massive resonances decaying into pairs of boosted bosons in semi-leptonic final states at (Formula presented.) = 8 TeV

A bstractA search for new resonances decaying to WW, ZZ, or WZ is presented. Final states are considered in which one of the vector bosons decays leptonically and the other hadronically. Results are based on data corresponding to an integrated luminosity of 19.7 fb−1 recorded in proton-proton collisions at s

Search for B 0 s →μ + μ − and B 0 →μ + μ − decays

\sqrt{s}

Measurement of the cross section for prompt diphoton production in pp̄ collisions at TeV

= 8 TeV with the CMS detector at the CERN LHC. Techniques aiming at identifying jet substructures are used to analyze signal events in which the hadronization products from the decay of highly boosted W or Z bosons are contained within a single reconstructed jet. Upper limits on the production of generic WW, ZZ, or WZ resonances are set as a function of the resonance mass and width. We increase the sensitivity of the analysis by statistically combining the results of this search with a complementary study of the all-hadronic final state. Upper limits at 95% confidence level are set on the bulk graviton production cross section in the range from 700 to 10 fb for resonance masses between 600 and 2500 GeV, respectively. These limits on the bulk graviton model are the most stringent to date in the diboson final state.

Search for long-lived doubly charged Higgs bosons in pp̄ collisions at √s = 1.96TeV

A bstractEvent-shape variables, which are sensitive to perturbative and nonperturbative aspects of quantum chromodynamic (QCD) interactions, are studied in multijet events recorded in proton-proton collisions at s=7