Essential Asymmetries of Nature

Lead Research Organisation: University of Southampton
Department Name: Sch of Physics and Astronomy

Abstract

ASYMMETRY addresses some of the most fundamental questions about Nature and human identity: what is the Universe made of? What laws do these constituents obey? How did the Universe evolve to be what we observe? These questions underpin science and attract some of the sharpest minds.

The quest for the basic laws of Nature. In spite of all the progress in understanding Nature since
the discovery of electrons, most of the Universe and its working awaits discovery: Neutrinos (Nus) are the most abundant known particle, but the origin of their masses remains unexplained; there is no rationale for the number of fermion generations and its wildly asymmetric spectrum; we have evidence of Dark Matter (DM) but we do not know what particle makes it up; particles and antiparticles behave differently in a subtle way (the so-called CP-violation) resulting in the Universe having only baryons and not antibaryons, but we ignore how this came to be; Dark Energy dominates the energy balance of the Universe but its nature is unknown. These questions cannot find answers in the current picture of particles and interactions --the Standard Model (SM)-- and embody the first (and so far only) observational evidence that the SM needs to be extended to a more fundamental theory with new particles and forces.

The symmetries identified in Nature, explicit or hidden, are at the root of our knowledge in depth of its fundamental laws. Nevertheless, observed asymmetries -departures from that exact pattern-- are at the very heart of its beauty and of the explanation of how the visible Universe came to be, and what we are made of. Well known examples include the matter-antimatter asymmetry of the Universe and the violation of parity and charge conjugation observed in particle physics. ASYMMETRY focuses on the deep understanding of those asymmetries and also on revealing the new fundamental (a)symmetries yet to be discovered to explain major open questions, and the particles on which they act, in particular in the invisible sector, made of neutrinos, dark matter and other elusive particles. The team is strongly focused on this quest within a multidisciplinary approach: mainly phenomenological studies although we bundle in leadership on key experiments such as SuperKamiokande, LEGEND), XENON and key laboratories such as Fermilab, DESY and LBNL.

Symmetries (and their breaking) underlie how the Universe works at the most fundamental level. They dictate what properties the particles can have and how they interact with each other. Local (gauge) symmetries explain the strong, weak, and electromagnetic forces. Thanks to the discovery of the Higgs boson in 2012, we have confirmed that the breaking of a gauge symmetry is responsible for particle masses, and that the Higgs interactions underlie the breaking of family symmetries. It is likely that new hidden (a)symmetries can have the answer to the fundamental questions discussed above. To uncover them is the ultimate goal of ASYMMETRY, targeting the hidden (a)symmetries, and the particles on which they act, in particular in the invisible sector, made of neutrinos, Dark Matter and other elusive particles such as possibly axions and other particles.

Publications

10 25 50