Search for long-lived heavy neutrinos in the decays of B mesons produced in proton-proton collisions at √(s) = 13 TeV
arxiv(2024)
摘要
A search for long-lived heavy neutrinos (N) in the decays of mesons
produced in proton-proton collisions at √(s) = 13 TeV is presented. The
data sample corresponds to an integrated luminosity of 41.6 fb^-1 collected
in 2018 by the CMS experiment at the CERN LHC, using a dedicated data stream
that enhances the number of recorded events containing B mesons. The search
probes heavy neutrinos with masses in the range 1 m_N 3
GeV and decay lengths in the range 10^-2 cτ 10^4 mm,
where τ_N is the N proper mean lifetime. Signal events are
defined by the signature B → ℓ_BNX; N → ℓ^±π^∓, where the leptons ℓ_B and ℓ can be either a muon
or an electron, provided that at least one of them is a muon. The hadronic
recoil system, X, is treated inclusively and is not reconstructed. No
significant excess of events over the standard model background is observed in
any of the ℓ^±π^∓ invariant mass distributions. Limits at 95
confidence level on the sum of the squares of the mixing amplitudes between
heavy and light neutrinos, | V_N|^2, and on cτ are
obtained in different mixing scenarios for both Majorana and Dirac-like N
particles. The most stringent upper limit | V_N|^2
2.0×10^-5 is obtained at m_N = 1.95 GeV for the Majorana
case where N mixes exclusively with muon neutrinos. The limits on |
V_N|^2 for masses 1 m_N 1.7 GeV are the
most stringent from a collider experiment to date.
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