**Part 2: Timothy J Hollowood, J Luis Miramontes and David M Schmidtt ‘An integrable deformation of the AdS5 × S5 superstring’**

Since 2009, the *Journal of Physics A* has awarded a Best Paper Prize, which serves to celebrate and applaud well written papers that make a significant contribution to their field. In 2016, the Editorial Board awarded 3 prizes using the criteria of novelty, achievement, potential impact and presentation.

In the second of a series of three interviews, meet Timothy J Hollowood, J Luis Miramontes and David M Schmidtt, the authors of ‘An integrable deformation of the AdS5 × S5 superstring’ Timothy J Hollowood *et al* 2014 *J. Phys. A: Math. Theor.* 47 495402.

### Meet the authors

Tim Hollowood is a Professor in the Physics Department, Swansea University who works on fundamental problems in high energy physics and theoretical physics. This includes string theory, supersymmetric gauge theories and semi-classical methods.

For many years he, along with co-author Professor Luis Miramontes from the University of Santiago de Compostela, have been using the property of integrability that some theories have, and in particular some string theories, to investigate these theories and as a tool to uncover their properties.

They joined up with Doctor David Schmidtt who has a research fellowship at the Instituto de Fisica Teorica, Sao Paulo, to pursue this investigation of integrability of string theory and the gauge-gravity correspondence. The work was started when David Schmidtt visited the Physics Department in Swansea in 2014-2015.

### What prompted you to pursue this field of research?

One cannot understate the importance of the gauge-gravity correspondence discovered by Maldacena in 1997. It implies that a ten dimensional quantum theory of gravity defined by a theory of strings moving in a particular background geometry is precisely equivalent to an ordinary quantum field theory of the kind that describes the standard model of particle physics, *i.e*. a gauge theory. On the one hand this means that for the first time we have a consistent definition of a quantum theory of gravity provided by the gauge theory and on the other hand it gives us new tools to investigate the gauge theory.

One important insight in this area, is that the theory that describes the motion of the string in the geometry is a very special quantum field theory in its own right with the remarkable property of integrability. Loosely speaking integrable theories have so many conserved quantities, over and above the energy and momentum that all theories have, that many things can be calculated exactly. An underlying integrable structure also appears in the gauge theory and relating the two integrable structures provides a very powerful way to relate the two sides of the gauge– gravity correspondence. The authors of the present work have worked on many aspects of integrable quantum field theories and using integrability as a tool to gain a deeper understanding of the gauge-gravity correspondence is a key problem.

### What is the winning paper all about?

The present work is concerned with the problem of how the conventional gauge-gravity correspondence could be generalized. The idea is to take the integrable theory that describes the dynamics of strings in the conventional set up and ask whether the background that the string moves in can be deformed whilst preserving integrability. Building on earlier work, we find that it is indeed possible to write down such a deformed theory for the string whilst preserving integrability and other desirable features of the string theory. The new consistent space time for the string is now known as the lambda background and our paper defines the theory of the string in this geometry.

### What do you plan to do next?

One of the key problems that remains is to understand the meaning of the deformed string theory from both from a spacetime perspective and also from the view of the gauge theory. The key problem is to use the symmetries of the theory in order to understand its classical structure and then ultimately to tackle the issue of how to quantize it. The hope is that these deformed theories will have some interesting and useful properties. Knowing that the gauge–gravity correspondence is part of a much larger class of theories is likely to have lots of applications and will give us a greater insight into this fascinating duality.

To see the rest of the winners and the nomination process for the *Journal of Physics A* Best Paper Prize 2017, visit this page.

This work is licensed under a Creative Commons Attribution 3.0 Unported License. Images used with permission from the authors.

Categories: Journal of Physics A: Mathematical and Theoretical