Low scale leptogenesis with an SU(2)_L singlet scalar

Abstract

We consider thermal leptogenesis as the origin of the matter-antimatter asymmetry of the Universe. Some phenomenologically unpleasant features of the usual leptogenesis scenario are reviewed. We propose a minimal alternative, which makes use of a charged scalar $\hat{I}{´}^{+}$, singlet under $SU(2{)}_L$. Such particle is contained in natural extensions of the Standard Model. The lepton asymmetry is generated by the decays of a right-handed neutrino into $\hat{I}{´}^{+}$ and a right-handed charged lepton and it turns out to be sufficiently large for scales as low as $\sim$ TeV. The phenomenological signatures at colliders are discussed.

4 pages, 2 epsi figures, revtex4.cls, slac_two.rtx; talk presented at the IPM Conference on Lepton and Hadron Physics, Tehran, Iran, May 15-20, 2006; PSN: IPM-LHP06-19May