U(1)_B-L: Neutrino Physics and Inflation

TL;DR

This paper explores a supersymmetric U(1)_B-L model linking neutrino mass generation, inflation, and leptogenesis, predicting specific neutrino masses, inflationary parameters, and addressing MSSM issues.

Contribution

It introduces a unified framework connecting U(1)_B-L symmetry breaking with inflation and neutrino physics, including novel predictions for neutrino masses and inflationary observables.

Findings

Neutrino masses are constrained to be below 10^14 GeV.

Scalar spectral index n_s approximately 0.99 with negligible tensor-to-scalar ratio.

M_B-L scale estimated around 10^16 GeV.

Abstract

A gauged U(1)_B-L symmetry predicts three right handed handed neutrinos and its spontaneous breaking automatically yields the seesaw mechanism. In a supersymmetric setting this breaking can be nicely linked with inflation to yield deltaT/ T proportional to (M_B-L / M_P)^2, where M_B-L (M_P) denote the B-L breaking (Planck) scale. Thus M_B-L is estimated to be of order 10^16 GeV, and the heaviest right handed neutrino mass is less than or of order 10^14 GeV. A second right handed neutrino turns out to have a mass of order 10-10^2 T_r, where T_r (<~10^9 GeV) denotes the reheat temperature. A U(1) R symmetry plays an essential role in implementing inflation and leptogenesis, resolving the MSSM mu problem and eliminating dimension five nucleon decay. An unbroken Z_2 subgroup plays the role of matter parity. The scalar spectral index n_s=0.99+-0.01 for the simplest models, while in smooth hybrid inflation n_s>=0.97. The tensor to scalar ratio r is negligible, and dn_s/dlnk<~10^-3.