Neutrino mass origin: from colliders to gravitational waves

The NuPhaseGW proposal addresses two major challenges in fundamental science of basic interactions: searches for new physics at colliders, precise characterization of first order phase transitions and the resulting gravitational waves (GW). These topics are very much in the forefront of current interest and will be addressed in unison by establishing and highlighting the inter-connections within theoretical frameworks, motivated by the existence of neutrino masses. Such interdisciplinary studies between high energy colliders and cosmology are quite remarkable and we will raise the level of research on both frontiers by proposing and completing new and original ideas. Each topic has a dedicated work package: WP1 for colliders and WP2 for cosmology. The topics in WP1 are further separated into studies regarding the current searches and efforts at the LHC and another one for future colliders (one task for leptonic and another one for hadronic machines). The project will leverage the existing expertise and provide novel insights into the physics of neutrino mass at the LHC and give a detailed study of opportunities for future colliders. Some of the proposed signatures are unique to either the enhanced luminosity, clean environments at leptonic colliders, or increase of energy and enhanced reach of 100 TeV machines. Within the project, the interplay between collider searches and phase transitions/GW production will be established in the context of neutrino mass theories. The team of Nemevšek et al. has created an original, robust and universally applicable tool FindBounce, which is being used by the community in calculations of phase transitions. This approach will be further applied to one loop corrections. Building on the expertise of Nemevšek et al., the project will thereby strengthen the theoretical underpinnings of neutrino mass motivated phase transitions and usher a new era of precision and reliability for the false vacuum decay rates and subsequent GW spectra predictions. Another fascinating phenomenon that will be investigated is symmetry non-restoration at high temperatures. This is a somewhat unconventional and counterintuitive behaviour of certain systems. The project aims are characterized by five disctintinct objectives. Each objective is described in detail and the intermediate steps are broken down for easier and clearer planning. These objectives are demanding and ambitious, our aim is to deliver a set of outstanding results. The goals are realistic and will be addressed in a collaboration by leveraging an existing extensive network of international collaborators that will join the work envisaged here by carrying out specific tasks. The project is expected to deliver exceptional outcomes to be published in highly visible journals and presented at international events. The NuPhaseGW team consists of the PI Assist. Prof. Miha Nemevšek and the young researcher Marco Matteini, accompanied by Prof. Borut Bajc, Prof. Jernej Fesel Kamenik, Nejc Košnik and Saša Prelovšek. The members of the team have significant expertise in BSM physics, ranging from grand unification, neutrino physics, colliders, flavor physics, dark matter and conformal theories. They have an oustanding record of establishing groundbreaking results that significantly contributed to the field, created new pathways, strengthed theoretical understanding, motivated and helped carry out experimental searches. They also have a strong record in mentoring and guiding younger researchers into the frontiers of our field, giving them opportunities to excel and jump-start their careers. The project will be carried out at the Jožef Stefan Institute's department for theoretical physics. Team members will have full administrative support and access to necessary computational and communicational facilities. They have extensive experience in managing and conducting research and ameliorating potential risks, which are well specified and addressed in the proposal.