Heavy neutral leptons from kaons in effective field theory

Author:

Rebeca Beltrán, Julian Günther, Martin Hirsch, Arsenii Titov, Zeren Simon Wang

Keyword:

High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph)

journal:

date:

2023-09-19 16:00:00

Abstract

In the framework of the low-energy effective theory containing in addition to the Standard Model fields heavy neutral leptons (HNLs), we compute the decay rates of neutral and charged kaons into HNLs. We consider both lepton-number-conserving and lepton-number-violating four-fermion operators, taking into account also the contribution of active-heavy neutrino mixing. Assuming that the produced HNLs are long-lived, we perform simulations and calculate the sensitivities of future long-lived-particle (LLP) detectors at the high-luminosity LHC to the considered scenario. When applicable, we also recast the existing bounds on the minimal mixing case obtained by NA62, T2K, and PS191. Our findings show that for some of the effective operators considered the future LLP detectors, in particular, MATHUSLA and ANUBIS, will probe (i) new parts of the parameter space spanned by HNL mass and active-heavy neutrino mixing, and (ii) new-physics scales in excess of $2000$ TeV.

PDF: Heavy neutral leptons from kaons in effective field theory.pdf