Angular analysis of the decay B+ → K∗(892)+ μ + μ − in proton-proton collisions at √s = 8 TeV

Angular distributions of the decay B+→ K∗(892)+μ+μ− are studied using events collected with the CMS detector in s = 8 TeV proton-proton collisions at the LHC, corresponding to an integrated luminosity of 20.0 fb−1. The forward-backward asymmetry of the muons and the longitudinal polarization of the K∗(892)+ meson are determined as a function of the square of the dimuon invariant mass. These are the first results from this exclusive decay mode and are in agreement with a standard model prediction.CMS Collaboration (ukupan broj autora: 2333

Search for new physics in top quark production with additional leptons in proton-proton collisions at √s = 13 TeV using effective field theory

Events containing one or more top quarks produced with additional prompt leptons are used to search for new physics within the framework of an effective field theory (EFT). The data correspond to an integrated luminosity of 41.5 fb −1 of proton-proton collisions at a center-of-mass energy of 13 TeV at the LHC, collected by the CMS experiment in 2017. The selected events are required to have either two leptons with the same charge or more than two leptons; jets, including identified bottom quark jets, are also required, and the selected events are divided into categories based on the multiplicities of these objects. Sixteen dimension-six operators that can affect processes involving top quarks produced with additional charged leptons are considered in this analysis. Constructed to target EFT effects directly, the analysis applies a novel approach in which the observed yields are parameterized in terms of the Wilson coefficients (WCs) of the EFT operators. A simultaneous fit of the 16 WCs to the data is performed and two standard deviation confidence intervals for the WCs are extracted; the standard model expectations for the WC values are within these intervals for all of the WCs probed.CMS Collaboration (ukupan broj autora: 2333

Search for a heavy vector resonance decaying to a Z boson and a Higgs boson in proton-proton collisions at √s=13Te

A search is presented for a heavy vector reso- nance decaying into a Z boson and the standard model Higgs boson, where the Z boson is identified through its leptonic decays to electrons, muons, or neutrinos, and the Higgs boson is identified through its hadronic decays. The search is per- formed in a Lorentz-boosted regime and is based on data col- lected from 2016 to 2018 at the CERN LHC, corresponding to an integrated luminosity of 137 fb−1. Upper limits are derived on the production of a narrow heavy resonance Z′, and a mass below 3.5 and 3.7 TeV is excluded at 95% confidence level in models where the heavy vector boson couples predomi- nantly to fermions and to bosons, respectively. These are the most stringent limits placed on the Heavy Vector Triplet Z′ model to date. If the heavy vector boson couples exclusively to standard model bosons, upper limits on the product of the cross section and branching fraction are set between 23 and 0.3 fb for a Z′ mass between 0.8 and 4.6 TeV, respectively. This is the first limit set on a heavy vector boson coupling exclusively to standard model bosons in its production and decay.CMS Collaboration (ukupan broj autora: 2355

Erratum to: Search for dark matter produced in association with a leptonically decaying Z boson in proton–proton collisions at s = 13 Te (The European Physical Journal C, (2021), 81, 1, (13), 10.1140/epjc/s10052-020-08739-5)

A Correction to this paper has been published: https://doi.org/10.1140/epjc/s10052-020-08739-5CMS Collaboration (ukupan broj autora: 2349)Link to the corrected article: [https://vinar.vin.bg.ac.rs/handle/123456789/9513

Search for dark matter produced in association with a leptonically decaying Z boson in proton–proton collisions at √s=13Te

A search for dark matter particles is performed using events with a Z boson candidate and large missing transverse momentum. The analysis is based on proton–proton collision data at a center-of-mass energy of 13Te, collected by the CMS experiment at the LHC in 2016–2018, corresponding to an integrated luminosity of 137fb-1. The search uses the decay channels Z → e e and Z → μ μ. No significant excess of events is observed over the background expected from the standard model. Limits are set on dark matter particle production in the context of simplified models with vector, axial-vector, scalar, and pseudoscalar mediators, as well as on a two-Higgs-doublet model with an additional pseudoscalar mediator. In addition, limits are provided for spin-dependent and spin-independent scattering cross sections and are compared to those from direct-detection experiments. The results are also interpreted in the context of models of invisible Higgs boson decays, unparticles, and large extra dimensions.CMS Collaboration (ukupan broj autora: 2349)Link to erratum: [https://vinar.vin.bg.ac.rs/handle/123456789/9653

Search for dark photons in Higgs boson production via vector boson fusion in proton-proton collisions at √s = 13 TeV

A search is presented for a Higgs boson that is produced via vector boson fusion and that decays to an undetected particle and an isolated photon. The search is performed by the CMS collaboration at the LHC, using a data set corresponding to an integrated luminosity of 130 fb −1, recorded at a center-of-mass energy of 13 TeV in 2016–2018. No significant excess of events above the expectation from the standard model background is found. The results are interpreted in the context of a theoretical model in which the undetected particle is a massless dark photon. An upper limit is set on the product of the cross section for production via vector boson fusion and the branching fraction for such a Higgs boson decay, as a function of the Higgs boson mass. For a Higgs boson mass of 125 GeV, assuming the standard model production rates, the observed (expected) 95% confidence level upper limit on the branching fraction is 3.5 (2.8)%. This is the first search for such decays in the vector boson fusion channel. Combination with a previous search for Higgs bosons produced in association with a Z boson results in an observed (expected) upper limit on the branching fraction of 2.9 (2.1)% at 95% confidence level.CMS Collaboration (ukupan broj autora: 2353