New Frontiers in Particle Physics, Cosmology and Gravity

Particle physics is the study of the fundamental building blocks of nature, how they interact and how they lead to what we observe from the smallest scales to the largest. The Standard Model, which is built on quantum field theory, is an impressively accurate description of all data to date, from colliders to astronomical observations. Nevertheless, there are many aspects we do not understand from the pattern of particle masses to our lack of a quantum theory of gravity.

The Large Hadron Collider (LHC) continues to accumulate data; it famously discovered the Higgs particle in 2012 and could yet discover new physics beyond the SM. Currently there are possible hints of new physics in the muon g-2 experiment and in b-quark physics at LHC. We are actively engaged, through the NExT institute, in understanding these and other possible signatures, for example, through our easy-to-use interface to supercomputers (HEPMDB) and the definition of new experimental triggers. We are also developing models of what new physics could be and how they impact cosmology (early-universe physics). We try to explain the sizes of the different particle masses and why the Universe is dominated by matter rather than anti-matter.

Many signatures involve hadrons, such as protons, made of quarks bound by the strong nuclear force. The strong force is poorly understood but we have expertise in using supercomputer simulations to study these particles. These simulations are vital to understand the LHC b-quark anomalies.

It is important to continue to develop Quantum Field Theories, the structure that underpins all particle physics work. We study how to make very precise calculations of how particles scatter, trying to reduce the complexity of these computations. Understanding how the strong nuclear force generates hadron masses and how the Higgs field contributes other masses to particles such as the electron remain open questions we work on. There is also as yet no complete quantum theory of gravity and we work towards developing new ideas for gravity. String theory is a leading candidate for this theory and we study many aspects of this theory including scattering signatures.

The notion of "holography", that emerged from string theory, has linked apparently very different systems such as QCD and Black Holes. We are developing it to learn more about a quantum gravity, and use gravity to study QCD including in extreme environments such as the cores of neutron stars. How black holes encode information is also a very deep question which shows we do not yet understand what happens at a black hole event horizon (the edge of a black hole from which even light can't escape). We are developing models of black holes and their microstates and we test their consistency. Quantum gravity should underpin the physics of the very early universe and we develop holographic models to model the physics of the Big Bang. We are extending lattice field theory simulations to study gravity and cosmology, including testing holographic models.