Browsing by Author "CMS collaboration (2223 authors)"
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- Measurement of normalized differential $ \mathrm{t}\overline{\mathrm{t}} $ cross sections in the dilepton channel from pp collisions at $ \sqrt{s}=13 $ TeVPublication . CMS collaboration (2223 authors); Nayak, Aruna; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Calpas, Betty; Di Francesco, Agostino; Faccioli, Pietro; Gallinaro, Michele; Hollar, Jonathan; Leonardo, Nuno; Lloret Iglesias, Lara; Seixas, Joao; Toldaiev, Oleksii; Vadruccio, Daniele; Varela, Joao; Vischia, Pietro; David Tinoco Mendes, Andre; Silva, Pedro; Musella, Pasquale; Pela, JoaoNormalized differential cross sections for top quark pair production are measured in the dilepton (e$^+$e$^-$, $\mu^+\mu^-$, and $\mu^\mp$e$^\pm$) decay channels in proton-proton collisions at a center-of-mass energy of 13 TeV. The measurements are performed with data corresponding to an integrated luminosity of 2.1 fb$^{-1}$ using the CMS detector at the LHC. The cross sections are measured differentially as a function of the kinematic properties of the leptons, jets from bottom quark hadronization, top quarks, and top quark pairs at the particle and parton levels. The results are compared to several Monte Carlo generators that implement calculations up to next-to-leading order in perturbative quantum chromodynamics interfaced with parton showering, and also to fixed-order theoretical calculations of top quark pair production up to next-to-next-to-leading order.
- Measurement of the triple-differential cross section for photon+jets production in proton-proton collisions at $\sqrt{s}$=7 TeVPublication . CMS collaboration (2223 authors); Hollar, Jonathan; Nayak, Aruna; Calpas, Betty; Almeida, Nuno; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Faccioli, Pietro; Ferreira Parracho, Pedro Guilherme; Gallinaro, Michele; Nguyen, Federico; Rodrigues Antunes, Joao; Seixas, Joao; Varela, Joao; Vischia, Pietro; Lloret Iglesias, Lara; David Tinoco Mendes, Andre; Musella, Pasquale; Silva, Pedro; Pela, Joao; Leonardo, NunoA measurement of the triple-differential cross section, $ {{{{{\mathrm{d}}^3}\sigma }} \left/ {{\left( {\mathrm{d}\mathrm{p}_T^{\gamma}\mathrm{d}{\eta^{\gamma }}\mathrm{d}{\eta^{\mathrm{jet}}}} \right)}} \right.} $ , in photon + jets final states using a data sample from proton-proton collisions at $ \sqrt{s} $ = 7 TeV is presented. This sample corresponds to an integrated luminosity of 2.14 fb$^{−1}$ collected by the CMS detector at the LHC. Photons and jets are reconstructed within a pseudorapidity range of |η| < 2.5, and are required to have transverse momenta in the range 40 < $ p_{\mathrm{T}}^{\mathrm{jet}} $ < 300 GeV and $ p_{\mathrm{T}}^{\mathrm{jet}} $ > 30 GeV, respectively. The measurements are compared to theoretical predictions from the sherpa leading-order QCD Monte Carlo event generator and the next-to-leading-order perturbative QCD calculation from jetphox. The predictions are found to be consistent with the data over most of the examined kinematic region.
- Search for vectorlike light-flavor quark partners in proton-proton collisions at $\sqrt s$ =8 TeVPublication . CMS collaboration (2223 authors); Nayak, A.; Bargassa, P.; Beirão Da Cruz E Silva, C.; Calpas, B.; Di Francesco, A.; Faccioli, P.; Gallinaro, M.; Hollar, J.; Leonardo, N.; Lloret Iglesias, L.; Seixas, J.; Toldaiev, O.; Vadruccio, D.; Varela, J.; Vischia, P.; David, A.; Veckalns, V.; Musella, P.; Pela, J.; Delgado, A.A search is presented for heavy vectorlike quarks (VLQs) that couple only to light quarks in proton-proton collisions at s=8 TeV at the LHC. The data were collected by the CMS experiment during 2012 and correspond to an integrated luminosity of 19.7 fb−1. Both single and pair production of VLQs are considered. The single-production search is performed for down-type VLQs (electric charge of magnitude 1/3), while the pair-production search is sensitive to up-type (charge of magnitude 2/3) and down-type VLQs. Final states with at least one muon or one electron are considered. No significant excess over standard model expectations is observed, and lower limits on the mass of VLQs are derived. The lower limits range from 400 to 1800 GeV, depending on the single-production cross section and the VLQ branching fractions B to W, Z, and Higgs bosons. When considering pair production alone, VLQs with masses below 845 GeV are excluded for B(W)=1.0, and below 685 GeV for B(W)=0.5, B(Z)=B(H)=0.25. The results are more stringent than those previously obtained for single and pair production of VLQs coupled to light quarks.