Inflation and majoron dark matter in the neutrino seesaw mechanism

We propose that inflation and dark matter have a common origin, connected to the neutrino mass generation scheme. As a model we consider spontaneous breaking of global lepton number within the seesaw mechanism. We show that it provides an acceptable inflationary scenario consistent with the recent cosmic microwave background B-mode observation by the BICEP2 experiment. The scheme may also account for the baryon asymmetry of the Universe through leptogenesis for reasonable parameter choices.

Figure 1

Majoron inflation: The tensor-to-scalar ratio $r$ is shown vs the spectral index $n_s$. Black line is the Majoron inflation scenario with $v_{\mathrm{L}}>M_P$. The small black points on each branch, from left to right, indicate the values $v_{\mathrm{L}}/M_P=12,14,20$ and 100. The dashed branch corresponds to $\sigma <v_{\mathrm{L}}$ and the solid one to $\sigma >v_{\mathrm{L}}$. The point and the triangle are the quartic and quadratic inflation predictions, respectively. The blue (gray) line is for $v_{\mathrm{L}}\ll M_P$. The contours are the 68% and 95% CL allowed region, combining PLANCK, WP, highL and BICEP2, given in [8] and $N$ is taken to be 60.

Figure 2

Majoron inflation: $\alpha$ vs $n_s$ for various $v_{\mathrm{BL}}$ values. See caption of Fig. 1 for more details.

Figure 3

Majoron inflation: $Y_N$ vs $v_{\mathrm{L}}$ for various $Y_D$. Dashed lines show some values of the coefficient $a$ of the Coleman-Weinberg term in the potential. Solid black lines are upper bounds on $Y_N$ for the corresponding Dirac neutrino Yukawa coupling $Y_D$.