About this Research Topic
The discovery of the Higgs at the Large Hadron Collider (LHC) in 2012 is a crowning confirmation of the Standard Model (SM) of particle physics, and the mass generation mechanism incorporated through the Brout–Englert–Higgs mechanism. Nevertheless, the origin of the neutrino masses remains a mystery as we do not understand why neutrinos are so much lighter than the quarks and the charged leptons. The quest, first to experimentally determine the absolute scale and nature of neutrino masses and second to theoretically understand the mechanism of neutrino mass generation, is thus at the forefront of particle physics research. It is a crucial aspect required to pinpoint Beyond-the-Standard Model (BSM) physics and which very likely will shed light on other particle physics puzzles such as the origin of the baryon asymmetry of the universe and Dark Matter (DM).
The aim of this Research Topic is to provide a forum to discuss phenomenological and theoretical aspects of neutrino masses and their implications. A special focus is set on the potential impact of models and the associated mechanisms for neutrino mass generation on the wider efforts to search for BSM physics. This will for example include DM searches, physics at the LHC and searches for rare flavor processes.
The Research Topic will provide a firm basis by reviewing the current status of, and future prospects for, neutrinos and their properties coming from oscillation experiments, direct mass probes, neutrinoless double beta decay and cosmological observations. It will also include a general discussion of how masses and thus scales are incorporated in particle physics, an issue which has been playing a crucial role in the development of the SM and its BSM extensions. The Research Topic will thus review the properties of the Higgs particle and the mechanism of charged fermion mass generation.
The Research Topic will incorporate a comprehensive overview of neutrino mass models. A major focus will be put on scenarios that have distinctive signatures in wider particle and astroparticle searches. The smallness of neutrino masses and the corresponding challenges in model building to connect neutrinos with other physics will naturally play an important role in this context. This part will start with the well-known seesaw mechanism and associated high scale models where light neutrino Majorana masses are generated through their coupling with very heavy states. It will then move on to radiative models where neutrino masses are generated at the quantum loop level through the exchange of new states that are for example accessible at the LHC. Other classes of models will include slightly broken lepton number scenarios as well as neutrino mass generation from higher-dimensional operators. Despite the apparent preference for Majorana neutrino scenarios, reflecting the contemporary model landscape, the Research Topic is fully model-agnostic and will also discuss Dirac neutrino models and their phenomenology as well as more exotic suggestions such as fermion condensates and gravitational torsion.
The Research Topic further aims to provide recommendations and pathways for future research efforts guided by forthcoming neutrino experiments.
Keywords: Neutrinos, Flavor, Colliders, Beyond the Standard Model, Dark Matter
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.