Cosmological constraint on vector mediator of neutrino-electron interaction in light of XENON1T excess

Recently, the XENON1T collaboration reported an excess in the electron recoil energy spectrum. One of the simplest new physics interpretation is a new neutrino-electron interaction mediated by a light vector particle. However, for the parameter region favored by this excess, the constraints from the stellar cooling are severe. Still, there are astrophysical uncertainties on those constraints. In this paper, we discuss the constraint on the light mediator from the effective number of neutrino Neff in the CMB era, which provides an independent constraint. We show that Neff is significantly enhanced and exceeds the current constraint in the parameter region favored for the XENON1T excess. As a result, the interpretation by a light mediator heavier than about 1 eV is excluded by the Neff constraint.

MODEL INDEPENDENT CONSTRAINTS OF THE AVERAGED NEUTRINO MASSES REVISITED

Averaged neutrino masses defined by [Formula: see text] are reanalyzed using up-to-date observed MNS parameters and neutrino masses by the neutrino oscillation experiments together with the cosmological constraint on neutrino masses. The values of 〈mν〉ab are model-independently evaluated in terms of effective neutrino mass defined by [Formula: see text] which is observable in the single beta decay. We obtain lower bound for 〈mν〉ee in the inverted hierarchy (IH) case, 17 meV ≤〈mν〉ee and one for 〈mν〉τμ in the normal hierarchy (NH) case, 5 meV ≤〈mν〉τμ. We also obtain that all the averaged masses 〈mν〉ab have upper bounds which are at most 80 meV.

Leptogenesis in Supersymmetric Economical 3-3-1 Model

We study a leptogenesis scenario in which the heavy Majorana neutrinos are produced non-thermally in inflaton decays in the supersymmetric economical \(\mathrm{SU}(3)_C\otimes \mathrm{SU}(3)_L \otimes \mathrm{U}(1)_X\) model with inflationary scenario. The lepton-number violating interactions among the inflaton and right-handed neutrinos appear at the one-loop level, and this is a reason for non-thermal leptogenesis scenario. The bound followed from the gravitino abundance and the cosmological constraint on neutrino mass/the neutrino oscillation data is: \(m_{\nu 3} \simeq \frac{0.05}{\delta_{eff}}\) eV. By taking the reheating temperature as low as \(T_R= 10^6\) GeV, we get a limit on the ratio of masses of the light heavies neutrino to those of the inflaton to be: \(\frac{M_{R1}}{M_{\phi}} = 0.87\).