Probing Dirac Neutrino Properties with Dilepton Signature

Abstract

The neutrinophilic two Higgs doublet model is one of the simplest models to explain the origin of tiny Dirac neutrino masses. This model introduces a new Higgs doublet with eV scale VEV to naturally generate the tiny neutrino masses. Depending on the same Yukawa coupling, the neutrino oscillation patterns can be probed with the dilepton signature from the decay of charged scalar $H^{\pm }$. For example, the normal hierarchy predicts BR$(H^{+}\to e^{+}\nu )\ll$ BR$(H^{+}\to {\mu }^{+}\nu )\approx$ BR$(H^{+}\to {\tau }^{+}\nu )\simeq 0.5$ when the lightest neutrino mass is below 0.01 eV, while the inverted hierarchy predicts BR$(H^{+}\to e^{+}\nu )/2\simeq$ BR$(H^{+}\to {\mu }^{+}\nu )\simeq$ BR$(H^{+}\to {\tau }^{+}\nu )\simeq 0.25$. By precise measurement of BR$(H^{+}\to {\ell }^{+}\nu )$, we are hopefully to probe the lightest neutrino mass and the atmospheric mixing angle ${\theta }_{23}$. Through the detailed simulation of the dilepton signature and corresponding backgrounds, we find that the 3 TeV CLIC could discover $M_{H^{+}}\lesssim 1220$ GeV for NH and $M_{H^{+}}\lesssim 1280$ GeV for IH. Meanwhile, the future 100 TeV FCC-hh collider could probe $M_{H^{+}}\lesssim 1810$ GeV for NH and $M_{H^{+}}\lesssim 2060$ GeV for IH.

Comments: 18 pages, 9 figures