Comment on astrophysical consequences of a neutrinophilic 2HDM

TL;DR

This paper constrains the neutrino-scalar coupling in a neutrinophilic two-Higgs-doublet model using supernova and cosmological data, showing it cannot be as strong as electromagnetic interactions, thus challenging the model's original motivation.

Contribution

The study provides new upper bounds on neutrino-scalar couplings in nu2HDM from astrophysical and cosmological observations, limiting the model's ability to explain tiny neutrino masses with large Yukawa couplings.

Findings

Neutrino-scalar couplings are constrained to y_i < 1.5 x 10^{-3} by supernova data.

Cosmological measurements restrict y_i < 2.3 x 10^{-4}.

Energy-loss arguments from supernovae give y_i < 3.5 x 10^{-5}.

Abstract

Several authors have pointed out that the scalar-mediated interaction of neutrinos in a neutriophilic two-Higgs-doublet model (nu2HDM) can be as strong as electromagnetic interaction [1-3]. We show that the coupling constants of neutrino-scalar interaction are actually restricted to be y_i < 1.5 x 10^{-3} by supernova neutrino observation, and further constrained to be y_i < 2.3 x 10^{-4} by precision measurements of acoustic peaks of the cosmic microwave background. Based on the energy-loss argument for supernova cores, we derive a slightly more restrictive bound y_i < 3.5 x 10^{-5}. Therefore, the nu2HDM has lost its spirit of explaining tiny Dirac neutrino masses while keeping neutrino Yukawa couplings of order one.