Abstract
We study the possibility of realising cosmic inflation, dark matter (DM), baryon asymmetry of the universe (BAU) and light neutrino masses in non-supersymmetric minimal gauged B-L extension of the standard model with three right handed neutrinos. The singlet scalar field responsible for spontaneous breaking of B-L gauge symmetry also plays the role of inflaton by virtue of its non-minimal coupling to gravity. While the lightest right handed neutrino is the DM candidate, being stabilised by an additional Z_2 symmetry, we show by performing a detailed renormalisation group evolution (RGE) improved study of inflationary dynamics that thermal DM is generally overproduced due to insufficient annihilations through gauge and scalar portals. This happens due to strict upper limits obtained on gauge and other dimensionless couplings responsible for DM annihilation while assuming the non-minimal coupling to gravity to be at most of order unity. The non-thermal DM scenario is viable, with or without Z_2 symmetry, although in such a case the B-L gauge sector remains decoupled from the inflationary dynamics due to tiny couplings. We also show that the reheat temperature predicted by the model prefers non-thermal leptogenesis with hierarchical right handed neutrinos while being consistent with other requirements.
Highlights
Precision measurements of the cosmic microwave background (CMB) anisotropies by experiments like Planck [1,2,3] reveal that our universe is homogeneous and isotropic on large scales upto a remarkable accuracy
We have considered two possibilities based on inflation mass being smaller or larger compared to reheat temperature and showed that required FIMP dark matter (DM) abundance can be successfully produced in both the scenarios
In the case where inflation mass is larger compared to reheat temperature so that it is not present in the thermal bath afterwards, we find that the correct FIMP abundance can be produced only when we discard the Z2 stabilising symmetry of DM and allow for more possibilities of its production from standard model (SM) bath to open up
Summary
Precision measurements of the cosmic microwave background (CMB) anisotropies by experiments like Planck [1,2,3] reveal that our universe is homogeneous and isotropic on large scales upto a remarkable accuracy. Proposed to solve the horizon, flatness and unwanted relic problems in standard cosmology, the inflationary paradigm was subsequently supported by the adiabatic and scale invariant perturbations observed in the CMB [1,2] Such an early accelerated phase of expansion can be generated by the presence of one or more scalar fields whose dynamics crucially decides the period of inflation. Generation of baryon asymmetry of the universe (BAU) from out-of-equilibrium decays of heavy particles has been a wellknown mechanism for baryogenesis [34,35] Another interesting way, which connects the lepton sector physics, is known as leptogenesis, proposed a few decades back [36].
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