Constraints on SUSY seesaw parameters from leptogenesis and lepton flavor violation

We study the constraints on a minimal supersymmetric seesaw model imposed by neutrino data, charged lepton flavor violation, thermal leptogenesis, and perturbativity. We show that it is possible to constrain the three heavy Majorana neutrino masses as well as the complex Yukawa coupling matrix. Our results provide a first step towards a seesaw benchmark model for further phenomenological studies and model building.

Figure 1

Regions in the plane ($x_2$, $x_3$) consistent with the generation of the baryon asymmetry via leptogenesis and the gravitino bound $M_1={10}^{10,11,12}\mathrm{GeV}$, from left to right, respectively. The procedure yielding the scatter plots is described in the text. Also shown are the contours of constant $M_1(x_2,x_3)={10}^{10,11,12}\mathrm{GeV}$ with all other parameters fixed (best-fit values of oscillation parameters, $m_1=0$, vanishing $CP$ phases, $x_1=0$ and $y_i=0.2$, $i=1,2,3$).

Figure 2

Region in the plane $(x_2,M_1)$ consistent with the generation of the baryon asymmetry via leptogenesis. The procedure yielding the scatter plot is described in the text.

Figure 3

Branching ratio of $\mu \to e\gamma$ as a function of the heaviest Majorana mass $M_3$ in SUSY scenario SPS1a, for $M_1={10}^{10,11,12}\mathrm{GeV}$, respectively. The solid (dashed) line indicates the present (expected future) experimental sensitivity. For a description of the scatter procedure see text.

Figure 4

Ratio $\mathrm{Br}(\mu \to e\gamma )/\mathrm{Br}(\tau \to \mu \gamma )$ as a function of $x_1$ in SUSY scenario SPS1a and for $M_1={10}^{11}\mathrm{GeV}$. For a description of the scatter procedure see text. Superimposed are two curves for which all parameters other than $x_1$ are fixed (best-fit oscillation parameters, $m_1=0\mathrm{eV}$, no $CP$ phases, and $y_{2,3}=0$). The solid (dashed) curve corresponds to $y_1=0.01$ ($y_1=0.1$).