Theoretical Particle Physics at City, University of London

Particle physics is at a critical juncture. The LHC experiments have found the last missing element of the Standard Model: the Higgs boson, and placed stringent restrictions on new physics beyond. At the same time, in the theoretical physics community there are outstanding problems in our understanding of quantum gauge and gravity theories, which undoubtedly would benefit from new observations at the LHC and other experiments. This project will investigate two key problems in modern theoretical physics.

Firstly, we will examine strongly coupled gauge theories using the so-called gauge/string correspondence. Much remains to be learnt about strongly coupled gauge theories. In recent years, there have been significant breakthroughs in understanding certain gauge theories using the gauge/string correspondence. In particular, our group has been at the forefront of developing mathematical tools known as integrability which provide us with a powerful tool with which to investigate strongly-interacting gauge theories with little supersymmetry as well as precision test holography. Our group has also been pioneering Lattice Field Theory methods for strings in holographic backgrounds. LFT is particularly effective, because the low-dimensionality of the string worldsheet (1+1d) and the anti-commuting scalar nature of Green-Schwarz fermions significantly reduce the processor power needed, while being applicable in a many physically-important holographic backgrounds. Low-supersymmetry gauge theories have also been shown, through the so-called dimer models to have intimate links to the mathematics of algebraic geometry and algebraic number theory. In this project we will significantly build on these results to exploit these new mathematical tools and methods to understand the strong-coupling dynamics of less supersymmetric gauge theories and their gauge/string dualities.

Secondly, we will explore beyond-the-Standard-Model physics that can be obtained as a consistent low-energy theory from string theory. String theory has provided a framework for unifying gauge and gravity interactions into a single consistent quantum theory. One of the key challenges has been to identify particular examples of string theory compactifications which will lead to realistic low-energy physics. This has remained a major challenge since conventional algorithms have very long run-times. Our group has pioneered the use of novel Machine Learning methods to obtain high-precision, detailed information about stringy phenomenology models. In this project we will exploit these developments to systematically chart the String Theory Landscape. The remarkable speed of the new methods means that we can explore physical properties of string models that were completely out of reach with conventional algorithms. Additionally, because of our strong links with Data and Computer Science experts, we are in a unique position to exploit the synergies that will arise in this multi-disciplinary Theoretical Physics-focused collaboration and their potential impact on a much wider set of applications.

The combined expertise of our group, our track-record and our international and UK collaborators, places us in an ideal position to achieve the goals set-out above.

This project will support Theoretical Particle research at City, University of London. Its two key aims are (i) the study of gauge theories, which describe interactions between elementary particles, using analytical and numerical tools; and (ii) finding a theory of particle physics consistent with real-world observations from string theory using Machine Learning. The principal beneficiaries of this research will be academics across a broad range of fields from particle physics theory, phenomenology and lattice field theory, through mathematical disciplines such as algebraic geometry or integrability, to computer and data scientists.

Our research will increase scientific knowledge, which over the long-run has had a significant impact on UK society and will likely have in the future. Over shorter time scales, there are four areas where more immediate societal impact may occur: (a) He's recent links with SIAM (Society for Industrial and Applied Mathematics), (b) through our training programs, (c) by public outreach, and (d) by developing and promoting mechanisms for increasing women's participation and retention in Theoretical Physics.

(a) He's work on Machine Learning and the String Landscape uses sophisticated numerical and computational algorithms that are of interest to SIAM, an organisation with tens of thousands of members meeting at large international conferences. This is the first time SIAM has engaged with Theoretical Physics. He will organize a symposium session at SIAM 2019 entitled "Fundamental physics, geometry and data science". Given the strong relation between SIAM and industry, these links may have a medium term impact on the UK economy. The interdisciplinary nature of He's work, is rather unique in bringing together experts who have never spoken to each other before, offering ample scope for interdisciplinary impact

(b) We will provide training and career development of early career researchers. A well-educated work-force is an essential ingredient of a modern economy and plays a strong role in UK's success in the post-industrial world. This project offers an opportunity to significantly enhance our role in contributing to UK's knowledge based economy. We will train the RA and our doctoral students in sophisticated analytic and computer methods, which have wide applications outside of Theoretical Physics, as well as in knowledge acquisition and communication skills, significantly increasing their future employability. Further, we will continue to organize advanced schools and training activities including through Forini's ITN network. Our group has a strong track record of nurturing early career researchers, to significant academic success or high-level jobs in industry, allowing us to have an immediate positive impact on the UK work-force pool

(c) we will continue outreach activities like Science Festivals, school visits and Popular Science Magazines. We request support from STFC to host a biannual Theoretical Physics Public Lecture series which will inspire a young generation of East Londoners to the world of fundamental research. We will involve women and minority speakers and develop ties with the City School of Journalism to increase the reach of these Lectures

(d) Forini is part of GenHET: Gender in High Energy Theory, lead by Prof. M. Taylor (Southampton) and sponsored by the CERN Theory Group. GenHET will raise awareness of gender issues in our field, which has one of the lowest levels of representation by female scientists, to develop actions that address gender inequality with input of academics actively working in the area and developing a series of workshops and website resources. Forini is also involved in "CityUniWomen Focus Group Sessions", which provide guidance and support for women at City with progression pathways, mentoring networks and support groups across the University. Ensuring women are retained throughout their academic career represents an important societal goal.