Detecting a heavy neutrino electric dipole moment at the LHC

TL;DR

This paper explores the potential of the milliQan detector at the LHC to detect heavy neutrinos with an electric dipole moment, providing sensitivity estimates and exclusion limits for various neutrino masses.

Contribution

It introduces a novel method to detect heavy neutrino EDMs using the milliQan experiment, extending its application beyond millicharged particles.

Findings

Sensitivity to EDMs as small as 10^{-17} e-cm

Expected exclusion and sensitivity ranges for neutrino masses 5-1000 GeV

Potential detection over different luminosities at the LHC

Abstract

The milliQan Collaboration has proposed to search for millicharged particles by looking for very weakly ionizing tracks in a detector installed in a cavern near the CMS experiment at the LHC. We note that another form of exotica can also yield weakly ionizing tracks. If a heavy neutrino has an electric dipole moment (EDM), then the milliQan experiment may be sensitive to it as well. In particular, writing the general dimension-5 operator for an EDM with a scale of a TeV and a one-loop factor, one finds a potential EDM as high as a few times $10^{-17}$ e-cm, and models exist where it is an order of magnitude higher. Redoing the Bethe calculation of ionization energy loss for an EDM, it is found that the milliQan detector is sensitive to EDMs as small as $10^{-17}$ e-cm. Using the production cross-section and analyzing the acceptance of the milliQan detector, we find the expected $95\%$ exclusion and $3\sigma$ sensitivity over the range of neutrino masses from $5-1000$ GeV for integrated luminosities of $300$ and $3000\ {\rm fb}^{-1}$ at the LHC.