skip to main content


Search for: All records

Creators/Authors contains: "Lontkovskyi, D."

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. A<sc>bstract</sc>

    Results are presented from a search for CP violation in top quark pair production, using proton-proton collisions at a center-of-mass energy of 13 TeV. The data used for this analysis consist of final states with two charged leptons collected by the CMS experiment, and correspond to an integrated luminosity of 35.9 fb1. The search uses two observables,$$ \mathcal{O} $$O1and$$ \mathcal{O} $$O3, which are Lorentz scalars. The observable$$ \mathcal{O} $$O1is constructed from the four-momenta of the charged leptons and the reconstructed top quarks, while$$ \mathcal{O} $$O3consists of the four-momenta of the charged leptons and the b quarks originating from the top quarks. Asymmetries in these observables are sensitive to CP violation, and their measurement is used to determine the chromoelectric dipole moment of the top quark. The results are consistent with the expectation from the standard model.

     
    more » « less
  2. Abstract

    Measurements of the associated production of a W boson and a charm ($${\text {c}}$$c) quark in proton–proton collisions at a centre-of-mass energy of 8$$\,\text {TeV}$$TeVare reported. The analysis uses a data sample corresponding to a total integrated luminosity of 19.7$$\,\text {fb}^{-1}$$fb-1collected by the CMS detector at the LHC. The W bosons are identified through their leptonic decays to an electron or a muon, and a neutrino. Charm quark jets are selected using distinctive signatures of charm hadron decays. The product of the cross section and branching fraction$$\sigma (\text {p}\text {p}\rightarrow \text {W}+ {\text {c}}+ \text {X}) {\mathcal {B}}(\text {W}\rightarrow \ell \upnu )$$σ(ppW+c+X)B(Wν), where$$\ell = \text {e}$$=eor$$\upmu $$μ, and the cross section ratio$$\sigma (\text {p}\text {p}\rightarrow {{\text {W}}^{+} + \bar{{\text {c}}} + \text {X}}) / \sigma (\text {p}\text {p}\rightarrow {{\text {W}}^{-} + {\text {c}}+ \text {X}})$$σ(ppW++c¯+X)/σ(ppW-+c+X)are measured in a fiducial volume and differentially as functions of the pseudorapidity and of the transverse momentum of the lepton from the W boson decay. The results are compared with theoretical predictions. The impact of these measurements on the determination of the strange quark distribution is assessed.

     
    more » « less
  3. Abstract A search for low-mass dilepton resonances in Higgs boson decays is conducted in the four-lepton final state. The decay is assumed to proceed via a pair of beyond the standard model particles, or one such particle and a $${\mathrm{Z}}$$ Z boson. The search uses proton–proton collision data collected with the CMS detector at the CERN LHC, corresponding to an integrated luminosity of 137 $$\,\text {fb}^{-1}$$ fb - 1 , at a center-of-mass energy $$\sqrt{s} = 13\,\text {TeV} $$ s = 13 TeV . No significant deviation from the standard model expectation is observed. Upper limits at 95% confidence level are set on model-independent Higgs boson decay branching fractions. Additionally, limits on dark photon and axion-like particle production, based on two specific models, are reported. 
    more » « less