Beyond the Standard Model with leptogenesis and neutrino data

In this short review I discuss how high energy (type I) seesaw models can be nicely embedded within grand-unified models and reproduce the observed matter-antimatter asymmetry with leptogenesis. In particular, after discussing general features and results in leptogenesis, I focus on $SO(10)$-inspired leptogenesis and on a particular solution, the strong thermal $SO(10)$-inspired solution, that provides an interesting way to understand neutrino mixing parameters: the non-vanishing reactor mixing angle, the emerging negative sign of $\sin\delta$ and the slight hints favouring normally ordered neutrino masses and an atmospheric mixing angle in the first octant. I also briefly discuss leptogenesis within two right-handed seesaw neutrino models. In this case a a third decoupled right-handed neutrino can provide a candidate for very heavy cold decaying dark matter produced from right-handed neutrino mixing with a mass in the TeV-EeV range and its decays would give a contribution to the IceCube high energy neutrino events in addition to an astrophysical component.Comment: 12 pages, 2 Figures; compendium of plenary talks given at Neutrino 2016, NuFact 2016 and IPA 2016; v2: Ref.'s adde

Flavor effects in thermal leptogenesis

We review recent developments in leptogenesis on flavor effects. Their account discloses an important connection between the matter-antimatter asymmetry of the Universe and CP violation at low energies. Besides, they modify the upper bound on the neutrino masses holding in the unflavored case. In this respect, it is important to identify the exact condition for flavor effects to be relevant and for the `fully flavored' Boltzmann equations to be valid.Comment: 3 pages, no figure ; contribution to the proceedings of NOW 2006, Conca Specchiulla, Sep. 9-16, 200

SO(10)-inspired solution to the problem of the initial conditions in leptogenesis

We show that, within SO(10)-inspired leptogenesis, there exists a solution, with definite constraints on low energy neutrino parameters, able simultaneously to reproduce the observed baryon asymmetry and to satisfy the conditions for the independence of the final asymmetry of the initial conditions (strong thermal leptogenesis). We find that the wash-out of a pre-existing asymmetry as large as O(0.1) requires: i) reactor mixing angle in the range \theta_13 = (2 - 20) degrees, in agreement with the experimental result \theta_13 = (8 - 10) degrees; ii) atmospheric mixing angle in the range \theta_23 = (16 - 41) degrees, compatible only with current lowest experimentally allowed values; iii) Dirac phase in the range \delta \simeq -\pi/2 - \pi/5, with the bulk of the solutions around \delta \simeq -\pi/5 and such that sign(J_CP)= - sign(\eta_B); iv) neutrino masses m_i normally ordered; v) lightest neutrino mass in the range m_1 \simeq (15 - 25) meV, corresponding to \sum_i m_i \simeq (85 - 105) meV; vi) neutrinoless double beta decay (0\nu\beta\beta) effective neutrino mass m_ee \simeq 0.8 m_1. All together this set of predictive constraints characterises the solution quite distinctively, representing a difficultly forgeable, fully testable, signature. In particular, the condition m_ee \simeq 0.8 m_1 \simeq 15 meV can be tested by cosmological observations and (ultimately) by 0\nu\beta\beta experiments. We also discuss different aspects such as theoretical uncertainties, stability under variation of the involved parameters, form of the orthogonal and RH neutrino mixing matrices.Comment: 44 pages, 8 figures; v3: typos corrected, matches NPB versio

The minimal scenario of leptogenesis

We review the main features and results of thermal leptogenesis within the type I seesaw mechanism, the minimal extension of the Standard Model explaining neutrino masses and mixing. After presenting the simplest approach, the vanilla scenario, we discuss various important developments in recent years, such as the inclusion of lepton and heavy neutrino flavour effects, a description beyond a hierarchical heavy neutrino mass spectrum and an improved kinetic description within the density matrix and the closed-time-path formalisms. We also discuss how leptogenesis can ultimately represent an important phenomenological tool to test the seesaw mechanism and the underlying model of new physics.Comment: 37 pages, 4 figures; invited review chapter for the "Focus on the Origin of Matter" issue published in the New Journal of Physic

Supersymmetric SO(10)SO(10)-inspired leptogenesis and a new N2N_2-dominated scenario

We study the supersymmetric extension of $SO(10)$-inspired thermal leptogenesis showing the constraints on neutrino parameters and on the reheat temperature $T_{\rm RH}$ that derive from the condition of successful leptogenesis from next-to-lightest right handed (RH) neutrinos ($N_2$) decays and the more stringent ones when independence of the initial conditions (strong thermal leptogenesis) is superimposed. In the latter case, the increase of the lightest right-handed neutrino ($N_1$) decay parameters helps the wash-out of a pre-existing asymmetry and constraints relax compared to the non-supersymmetric case. We find significant changes especially in the case of large $\tan\beta$ values $(\gtrsim 15)$. In particular, for normal ordering, the atmospheric mixing angle can now be also maximal. The lightest (ordinary) neutrino mass is still constrained within the range $10 \lesssim m_1/{\rm meV} \lesssim 30$ (corresponding to $75\lesssim \sum_i m_i/{\rm meV} \lesssim 120$). Inverted ordering is still disfavoured, but an allowed region satisfying strong thermal leptogenesis opens up at large $\tan\beta$ values. We also study in detail the lower bound on $T_{\rm RH}$ finding $T_{\rm RH}\gtrsim 1 \times 10^{10}\,{\rm GeV}$ independently of the initial $N_2$ abundance. Finally, we propose a new $N_2$-dominated scenario where the $N_1$ mass is lower than the sphaleron freeze-out temperature. In this case there is no $N_1$ wash-out and we find $T_{\rm RH} \gtrsim 1\times 10^{9}\,{\rm GeV}$. These results indicate that $SO(10)$-inspired thermal leptogenesis can be made compatible with the upper bound from the gravitino problem, an important result in light of the role often played by supersymmetry in the quest of a realistic model of fermion masses.Comment: 35 pages, 10 figures; v3: matches JCAP versio