New Constraints on Tau-Coupled Heavy Neutral Leptons with Masses mN=280–970 MeV

Research output: Contribution to journalArticlepeer-review

  • Authors:
  • R. Acciarri
  • C. Adams
  • J. Asaadi
  • B. Baller
  • V. Basque
  • And 16 others
  • External authors:
  • F. Cavanna
  • A. de Gouvêa
  • R. S. Fitzpatrick
  • B. Fleming
  • P. Green
  • C. James
  • K. J. Kelly
  • I. Lepetic
  • X. Luo
  • O. Palamara
  • G. Scanavini
  • M. Soderberg
  • J. Spitz
  • A. M. Szelc
  • W. Wu
  • T. Yang


A search for heavy neutral leptons has been performed with the ArgoNeuT detector exposed to the NuMI neutrino beam at Fermilab. We search for the decay signature N→νμ+μ-, considering decays occurring both inside ArgoNeuT and in the upstream cavern. In the data, corresponding to an exposure to 1.25×1020 POT, zero passing events are observed consistent with the expected background. This measurement leads to a new constraint at 90% confidence level on the mixing angle |UτN|2 of tau-coupled Dirac heavy neutral leptons with masses mN=280-970 MeV, assuming |UeN|2=|UμN|2=0.

Bibliographical metadata

Original languageEnglish
Article number121801
JournalPhysical Review Letters
Issue number12
Publication statusPublished - 15 Sep 2021