NonthermalCPviolation in soft leptogenesis

Abstract

Soft leptogenesis is a mechanism which generates the matter-antimatter asymmetry of the Universe via the out-of-equilibrium decays of heavy sneutrinos in which soft supersymmetry breaking terms play two important roles: they provide the required CP violation and give rise to the mass splitting between otherwise degenerate sneutrino mass eigenstates within a single generation. This mechanism is interesting because it can be successful at the lower temperature regime T 10 9 GeV in which the conflict with the overproduction of gravitinos can possibly be avoided. In earlier works the leading CP violation is found to be nonzero only if finite temperature effects are included. By considering generic soft trilinear couplings, we find two interesting consequences: (1) the leading CP violation can be nonzero even at zero temperature realizing nonthermal CP violation, and (2) the CP violation is sufficient even far away from the resonant regime allowing soft supersymmetry breaking parameters to assume natural values at around the TeV scale. We discuss phenomenological constraints on such scenarios and conclude that the contributions to charged lepton flavor violating processes are close to the sensitivities of present and future experiments.

Probing leptogenesis

“…In the following, however, we will focus on a generic trilinear soft A α term [343] in soft leptogenesis [344], which results in interesting consequences: In order to discuss the aforementioned consequences, we assume the temperature range T 10 8 GeV for m soft ∼ 1 TeV, where the effective global symmetries discussed in Ref. [333] are absent.…”

“…[339,340], thermal effects are crucial to prevent the cancellation of leading CP asymmetries from the decays of N ± to leptons and sleptons. However, terms higher order in m soft /M N can dominate when considering generic A α [343].…”

“…The explicit expressions of r B (T ) and c B,F (T ) are given in the Appendix A of Ref. [343]. (ii) In the limit λ α A α /M N , we have…”

Leptogenesis in supersymmetry with one L violating coupling

“…One may get non-zero asymmetry from the interference of tree and higher order diagram without right of the 'cut' condition, but it would vanish if other diagrams with all possible intermediate and final states are considered. The cases where some authors have found vanishing of total asymmetry [9][10][11] are examples of this feature. In our case in leptogenesis, above-mentioned condition is satisfied in the higher order Feynman diagram for neutralino decay as shown in Fig.…”

Soft leptogenesis in the NMSSM with a singlet right-handed neutrino superfield

“…In Ref. [28], it is shown that considering most generic soft trilinear couplings and one loop self energy contributions for sneutrino decay it is possible to generate CP violation even without finite temperature effects within the same setup.…”