Gravitational Wave Production and Baryogenesis in a Simple Left-Right model

Abstract

The left-right model with the simplest Higgs structure has a $SU(2{)}_L$ doublet $H_L$, a $SU(2{)}_R$ doublet $H_R$, and a singlet $\ddot{I}ƒ$ that couples to the doublets as $\ddot{I}ƒ(|H_L{|}^2-|H_R{|}^2)$. The left-right symmetry has $H_L\leftrightarrow H_R$ and $\ddot{I}ƒ\leftrightarrow -\ddot{I}ƒ$. We study gravitational wave production and baryogenesis in the electroweak phase transitions in the model. For two benchmark points, $\ddot{I}ƒ$ first gets a vev, followed by $H_R$ and then $H_L$. An interesting feature is that the vev of $H_L$ is initially much higher than its zero temperature value, leading to a more strongly first-order transition and higher frequency gravitational waves. An unusual benchmark point has the $\ddot{I}ƒ$ vev at zero when the electroweak symmetry breaks. This results in both $H_L$ and $H_R$ vevs being equal and in the multi-TeV range. At a lower temperature, the $\ddot{I}ƒ$ vev turns on, breaking the left-right symmetry and $H_L$ drops to its standard model value. Since the electroweak symmetry is broken at the multi-TeV scale, the frequency of gravitational waves will be much higher than usual. Baryogenesis is also discussed.

28 pages, 3 tables, 3 figures. Version published in Phys.Rev. D