CP violation in rare lepton-number-violating W decays at the LHC

A bstract Some models of leptogenesis involve a quasi-degenerate pair of heavy neutrinos N 1 , 2 whose masses can be small, O (GeV). Such neutrinos can contribute to the rare lepton-number-violating (LNV) decay W ± → ℓ 1 ± ℓ 2 ± q ′ q ¯ ∓ . If both N 1 and N 2 contribute, there can be a CP-violating...

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Published in:The journal of high energy physics 2021-04, Vol.2021 (4), p.1-17, Article 21
Main Authors: Najafi, Fatemeh, Kumar, Jacky, London, David
Format: Article
Language:English
Subjects:
Asymmetry
Beyond Standard Model
Classical and Quantum Gravitation
CP violation
Elementary Particles
High energy physics
Leptons
Matter & antimatter
Neutrino Physics
Neutrinos
Physics
Physics and Astronomy
Quantum Field Theories
Quantum Field Theory
Quantum Physics
Regular Article - Theoretical Physics
Relativity Theory
String Theory
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Summary:A bstract Some models of leptogenesis involve a quasi-degenerate pair of heavy neutrinos N 1 , 2 whose masses can be small, O (GeV). Such neutrinos can contribute to the rare lepton-number-violating (LNV) decay W ± → ℓ 1 ± ℓ 2 ± q ′ q ¯ ∓ . If both N 1 and N 2 contribute, there can be a CP-violating rate difference between the LNV decay of a W − and its CP-conjugate decay. In this paper, we examine the prospects for measuring such a CP asymmetry A CP at the LHC. We assume a value for the heavy-light neutrino mixing parameter | B ℓN | 2 = 10 − 5 , which is allowed by the present experimental constraints, and consider 5 GeV ≤ M N ≤ 80 GeV. We consider three versions of the LHC — HL-LHC, HE-LHC, FCC-hh — and show that small values of the CP asymmetry can be measured at 3 σ , in the range 1% ≲ A CP ≲ 15%.
ISSN:1029-8479
1029-8479
DOI:10.1007/JHEP04(2021)021