On relating the genesis of cosmic baryons and dark matter View the table of contents for this issue, or go to the journal homepage for more 2012 New J. Phys. 14 095011

If neutrino masses arise from a TeV-scale minimal Left-Right seesaw model, the ensuing extended Higgs sector with neutral, singly and doubly-charged scalars has a plethora of implications for new Higgs boson searches beyond the Standard Model at future hadron colliders, such as the \( \sqrt{s} \) = 14 TeV High-Luminosity Large Hadron Collider (HL-LHC) and the proposed \( \sqrt{s} \) = 100 TeV collider (FCC-hh or SPPC). In this article, we provide a glimpse of this new physics in the Higgs sector. Our discussion focuses on the minimal non-supersymmetric version of the Left-Right model with high-scale parity breaking but TeV-scale SU(2) _R -breaking, a property desirable to suppress the type-II seesaw contribution to neutrino masses. We analyze the masses and couplings of the physical Higgs bosons in this model, and discuss their dominant production and decay modes at hadron colliders. We identify the best discovery channels for each of the non-SM Higgs bosons and estimate the expected SM backgrounds in these channels to derive the sensitivity reaches for the new Higgs sector at future hadron colliders under discussion. Following a rather conservative approach, we estimate that the heavy Higgs sector can be effectively probed up to 15 TeV at the \( \sqrt{s} \) = 100 TeV machine. We also discuss how the LR Higgs sector can be distinguished from other extended Higgs sectors.

We derive bounds on the Dirac Yukawa couplings of the neutrinos in seesaw models using the recent Large Hadron Collider (LHC) data on Higgs decays for the case where the Standard Model singlet heavy leptons needed for the seesaw mechanism have masses in the 100 GeV range. Such scenarios with large Yukawa couplings are natural in inverse seesaw models since the small neutrino mass owes its origin to a small Majorana mass of a new set of singlet fermions. Large Yukawas with sub-TeV mass right-handed neutrinos are also possible for certain textures in Type-I seesaw models, so that the above bounds also apply to them. We find that the current Higgs data from the LHC can put bounds on both electron- and muon-type Yukawa couplings of order ${10}^{-2}$.

We discuss a simple non-supersymmetric model based on the electroweak gauge group SU(2) L × SU(2) × U(1) B-L where the lightest of the right-handed neutrinos, which are part of the leptonic doublet of SU(2) , play the role of a long-lived unstable dark matter with mass in the multi-PeV range. We use a resonant s-channel annihilation to obtain the correct thermal relic density and relax the unitarity bound on dark matter mass. In this model, there exists a 3-body dark matter decay mode producing tau leptons and neutrinos, which could be the source for the PeV cascade events observed in the IceCube experiment. The model can be tested with more precise flavor information of the highest-energy neutrino events in future data.

A generalized $CP$ symmetry for leptons is presented where $CP$ transformations are part of an $S_4$ symmetry that connects different families. We study its implications for lepton mixings in a gauge model realization of the idea using a type II seesaw for neutrino masses. The model predicts maximal atmospheric mixing, nonzero ${\theta }_{13}$ and maximal Dirac phase ${\delta }_D=\pm \frac{\pi }{2}$.