The study of elementary particles and their interactions (Consolidated Grant 2022 - 2025)

This grant is to continue the group's programme of investigation into the properties of elementary particles and the fundamental forces of nature.

One of the main objectives of this grant will be to support the exploitation of the LHC experiments which will be taking data during the period of this grant. The CMS experiment will continue to characterize Higgs boson, which provides a unique window onto new physics, and the use of such measurements to search for this physics. It will also be possible to extend our searches for SUSY, dark matter, long-lived particles and other new phenomena including lepton non-universality. The LHCb experiment will offer complementary tests of the Standard Model (SM) and beyond with the ability to look for extremely rare decays in flavour physics and to measure CP asymmetries in the decays of B mesons, both of which are sensitive to contributions from new physics. Measurements led by the group have revealed deviations from the SM, potentially indicating lepton non-universality and new physics; clarifying the situation is a high priority. The group will also be active in preparing the next generation of CMS and LHCb detectors for the high luminosity upgrade of the LHC.

The T2K long baseline neutrino experiment will allow us to expand our understanding of the masses and mixings in the neutrino sector. We have produced first indications for CP violation in the neutrino sector, and future running will shed further light. To fully characterize this CP violation and its role in the observed matter-antimatter asymmetry will require the next generation detectors, DUNE and Hyper-K, in which we are also involved, with development underway. The SoLid experiment will take continue to take data and should settle the very short baseline neutrino anomaly. One of the other missing pieces of the neutrino puzzle is whether the neutrino is its own antiparticle. We are preparing the SuperNEMO experiment to attempt to determine if the neutrino is a Majorana particle and data-taking will occur during the grant. Heavy neutrino-like particles are predicted in several new physics models and we are continuing R&D towards the SHiP experiment to search for these new particles.

Direct conversion of muons to electrons is heavily suppressed in the Standard Model so any observation of this process would be a major discovery. The COMET experiment is searching for this process and will take data during the grant. Similarly, a measurable electric dipole moment for the electron could only arise through new physics and the eEDM experiment will continue to push down the limits for such an effect.

Around a quarter of the Universe is composed of dark matter and its nature is unknown. This has so far remained undetected in the laboratory and the group will continue its activity in searching for direct evidence of a dark matter candidate through the LUX-ZEPLIN experiment, along with preparations for the next generation detector. An exciting new venture is that of the AION experiment that will use quantum technologies to probe for ultra light dark matter, and, in time, gravitational waves.

Accelerators to produce muon beams will be needed for future neutrino and muon collider experiments. The group is continuing its research in this area through the nuSTORM studies. Proton beams also have potential applications for other scientific fields and for healthcare, and the group is studying how to apply these techniques in those areas.