A search for the production of pairs of heavy Majorana neutrinos (Nℓ) from the decays of Z′ bosons is performed using the CMS detector at the LHC. The data were collected in proton-proton collisions at a center-of-mass energy of s = 13 TeV, with an integrated luminosity of 138 fb−1. The signature for the search is an excess in the invariant mass distribution of the final-state objects, two same-flavor leptons (e or μ) and at least two jets. No significant excess of events beyond the expected background is observed. Upper limits at 95% confidence level are set on the product of the Z′ production cross section and its branching fraction to a pair of Nℓ, as functions of Nℓ and Z′ boson masses (mNℓ and mZ′, respectively) for mZ′ from 0.4 to 4.6 TeV and mNℓ from 0.1 TeV to mZ′/2. In the theoretical framework of a left-right symmetric model, exclusion bounds in the mNℓ-mZ′ plane are presented in both the electron and muon channels. The observed upper limit on mZ′ reaches up to 4.42 TeV. These are the most restrictive limits to date on the mass of Nℓ as a function of the Z′ boson mass.

Search for Z′ bosons decaying to pairs of heavy Majorana neutrinos in proton-proton collisions at √s = 13 TeV

Bruschini, D.;
2023

Abstract

A search for the production of pairs of heavy Majorana neutrinos (Nℓ) from the decays of Z′ bosons is performed using the CMS detector at the LHC. The data were collected in proton-proton collisions at a center-of-mass energy of s = 13 TeV, with an integrated luminosity of 138 fb−1. The signature for the search is an excess in the invariant mass distribution of the final-state objects, two same-flavor leptons (e or μ) and at least two jets. No significant excess of events beyond the expected background is observed. Upper limits at 95% confidence level are set on the product of the Z′ production cross section and its branching fraction to a pair of Nℓ, as functions of Nℓ and Z′ boson masses (mNℓ and mZ′, respectively) for mZ′ from 0.4 to 4.6 TeV and mNℓ from 0.1 TeV to mZ′/2. In the theoretical framework of a left-right symmetric model, exclusion bounds in the mNℓ-mZ′ plane are presented in both the electron and muon channels. The observed upper limit on mZ′ reaches up to 4.42 TeV. These are the most restrictive limits to date on the mass of Nℓ as a function of the Z′ boson mass.
2023
Settore PHYS-01/A - Fisica sperimentale delle interazioni fondamentali e applicazioni
Beyond Standard Model; Hadron-Hadron Scattering
   Advanced Multi-Variate Analysis for New Physics Searches at the LHC
   AMVA4NewPhysics
   European Commission
   Horizon 2020 Framework Programme
   675440

   Search for Higgs bosons decaying to charm quarks
   HIGCC
   European Commission
   Horizon 2020 Framework Programme
   724704

   Direct and indirect searches for new physics in events with top quarks using LHC proton-proton collisions at the CMS detector
   LHCTOPVLQ
   European Commission
   Horizon 2020 Framework Programme
   752730

   Majorana neutrino discovery strategy with CMS
   MajorNet
   European Commission
   Horizon 2020 Framework Programme
   758316

   International Training Network for Statistics in High Energy Physics and Society
   INSIGHTS
   European Commission
   Horizon 2020 Framework Programme
   765710

   The strong interaction at the frontier of knowledge: fundamental research and applications
   STRONG-2020
   European Commission
   Horizon 2020 Framework Programme
   824093

   International, Interdisciplinary & Intersectoral Postdoctoral Fellowships at the Paul Scherrer Institut
   PSI-FELLOW-III-3i
   European Commission
   Horizon 2020 Framework Programme
   884104
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