Browsing by Author "CMS collaboration (2292 authors)"
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- Electroweak production of two jets in association with a Z boson in proton–proton collisions at $\sqrt{s}= $ 13 $\,\text {TeV}$Publication . CMS collaboration (2292 authors); Nayak, Aruna; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Di Francesco, Agostino; Faccioli, Pietro; Galinhas, Bruno; Gallinaro, Michele; Hollar, Jonathan; Leonardo, Nuno; Lloret Iglesias, Lara; Seixas, Joao; Strong, Giles; Toldaiev, Oleksii; Vadruccio, Daniele; Varela, Joao; Vischia, Pietro; David Tinoco Mendes, Andre; Silva, Pedro; Musella, PasqualeA measurement of the electroweak (EW) production of two jets in association with a Z boson in proton-proton collisions at $\sqrt{s} = $ 13 TeV is presented, based on data recorded in 2016 by the CMS experiment at the LHC corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The measurement is performed in the $\ell\ell\mathrm{jj}$ final state with $\ell$ including electrons and muons, and the jets j corresponding to the quarks produced in the hard interaction. The measured cross section in a kinematic region defined by invariant masses $m_{\ell\ell} > $ 50 GeV, $m_{\mathrm{jj}} > $ 120 GeV, and transverse momenta $p_{\mathrm{T j}} > $ 25 GeV is $\sigma_\mathrm{EW}(\ell\ell\mathrm{jj})= $ 552 $\pm$ 19 (stat) $\pm$ 55 (syst) fb, in agreement with leading-order standard model predictions. The final state is also used to perform a search for anomalous trilinear gauge couplings. No evidence is found and limits on anomalous trilinear gauge couplings associated with dimension-six operators are given in the framework of an effective field theory. The corresponding 95% confidence level intervals are $-2.6 < c_{WWW}/\Lambda^2 < 2.6 $ TeV$^{-2}$ and $-8.4 < c_{W}/\Lambda^2 < 10.1 $ TeV$^{-2}$. The additional jet activity of events in a signal-enriched region is also studied, and the measurements are in agreement with predictions.
- Measurements of $t \bar t$ charge asymmetry using dilepton final states in pp collisions at $\sqrt s=8$ TeVPublication . CMS collaboration (2292 authors); Calpas, Betty; Nayak, Aruna; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Di Francesco, Agostino; Faccioli, Pietro; Ferreira Parracho, Pedro Guilherme; Gallinaro, Michele; Hollar, Jonathan; Leonardo, Nuno; Lloret Iglesias, Lara; Nguyen, Federico; Rodrigues Antunes, Joao; Seixas, Joao; Toldaiev, Oleksii; Vadruccio, Daniele; Varela, Joao; Vischia, Pietro; David Tinoco Mendes, Andre; Silva, Pedro; Musella, Pasquale; Pela, JoaoThe charge asymmetry in tt‾ events is measured using dilepton final states produced in pp collisions at the LHC at s=8TeV . The data sample, collected with the CMS detector, corresponds to an integrated luminosity of 19.5fb−1 . The measurements are performed using events with two oppositely charged leptons (electrons or muons) and two or more jets, where at least one of the jets is identified as originating from a bottom quark. The charge asymmetry is measured from differences in kinematic distributions, unfolded to the parton level, of positively and negatively charged top quarks and leptons. The tt‾ and leptonic inclusive charge asymmetries are found to be 0.011±0.011(stat)±0.007(syst) and 0.003±0.006(stat)±0.003(syst) , respectively. These results, as well as charge asymmetry measurements made as a function of the invariant mass, rapidity, and transverse momentum of the tt‾ system, are in agreement with predictions of the standard model.
- Measurements of differential cross sections of top quark pair production as a function of kinematic event variables in proton-proton collisions at $ \sqrt{s}=13 $ TeVPublication . CMS collaboration (2292 authors); Nayak, Aruna; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Di Francesco, Agostino; Faccioli, Pietro; Galinhas, Bruno; Gallinaro, Michele; Hollar, Jonathan; Leonardo, Nuno; Lloret Iglesias, Lara; Seixas, Joao; Strong, Giles; Toldaiev, Oleksii; Vadruccio, Daniele; Varela, Joao; Vischia, Pietro; David Tinoco Mendes, Andre; Silva, Pedro; Musella, PasqualeMeasurements of differential $ \mathrm{t}\overline{\mathrm{t}} $ production cross sections are presented in the single-lepton decay channel, as a function of a number of kinematic event variables. The measurements are performed with proton-proton collision data at $ \sqrt{s}=13 $ TeV, collected by the CMS experiment at the LHC during 2016, with an integrated luminosity of 35.9 fb$^{−1}$. The data are compared to a variety of state-of-the-art leading-order and next-to-leading-order $ \mathrm{t}\overline{\mathrm{t}} $ simulations.
- Search for heavy Majorana neutrinos in e$^{±}$e$^{±}$+ jets and e$^{±}$ $\mu^{±}$+ jets events in proton-proton collisions at $ \sqrt{s}=8 $ TeVPublication . CMS collaboration (2292 authors); Calpas, Betty; Nayak, Aruna; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Di Francesco, Agostino; Faccioli, Pietro; Ferreira Parracho, Pedro Guilherme; Gallinaro, Michele; Hollar, Jonathan; Leonardo, Nuno; Lloret Iglesias, Lara; Nguyen, Federico; Rodrigues Antunes, Joao; Seixas, Joao; Toldaiev, Oleksii; Vadruccio, Daniele; Varela, Joao; Vischia, Pietro; David Tinoco Mendes, Andre; Silva, Pedro; Musella, Pasquale; Pela, JoaoA search is performed for heavy Majorana neutrinos (N) decaying into a W boson and a lepton using the CMS detector at the Large Hadron Collider. A signature of two jets and either two same sign electrons or a same sign electron-muon pair is searched for using 19.7 inverse femtobarns of data collected during 2012 in proton-proton collisions at a centre-of-mass energy of 8 TeV. The data are found to be consistent with the expected standard model (SM) background and, in the context of a Type-1 seesaw mechanism, upper limits are set on the cross section times branching fraction for production of heavy Majorana neutrinos in the mass range between 40 and 500 GeV. The results are additionally interpreted as limits on the mixing between the heavy Majorana neutrinos and the SM neutrinos. In the mass range considered, the upper limits range between 0.00015 - 0.72 for |V[eN]|^2 and 6.6E-5 - 0.47 for |V[eN] V*[muN]|^2 / ( |V[eN]|^2 + |V[muN]|^2 ), where V[lN] is the mixing element describing the mixing of the heavy neutrino with the SM neutrino of flavour l. These limits are the most restrictive direct limits for heavy Majorana neutrino masses above 200 GeV.
- Search for low-mass resonances decaying into bottom quark-antiquark pairs in proton-proton collisions at $\sqrt{s} =$ 13 TeVPublication . CMS collaboration (2292 authors); Nayak, Aruna; Araujo, Mariana; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Di Francesco, Agostino; Faccioli, Pietro; Galinhas, Bruno; Gallinaro, Michele; Hollar, Jonathan; Leonardo, Nuno; Seixas, Joao; Strong, Giles; Toldaiev, Oleksii; Varela, Joao; Vischia, Pietro; David Tinoco Mendes, Andre; Silva, Pedro; Musella, PasqualeA search for narrow, low-mass, scalar, and pseudoscalar resonances decaying to bottom quark-antiquark pairs is presented. The search is based on events recorded in s=13 TeV proton-proton collisions with the CMS detector at the LHC, collected in 2016, and corresponding to an integrated luminosity of 35.9 fb-1. The search selects events in which the resonance would be produced with high transverse momentum because of the presence of initial- or final-state radiation. In such events, the decay products of the resonance would be reconstructed as a single large-radius jet with high mass and two-prong substructure. A potential signal would be identified as a narrow excess in the jet invariant mass spectrum. No evidence for such a resonance is observed within the mass range from 50 to 350 GeV, and upper limits at 95% confidence level are set on the product of the cross section and branching fraction to a bottom quark-antiquark pair. These constitute the first constraints from the LHC on exotic bottom quark-antiquark resonances with masses below 325 GeV.