Twistor Strings, Scattering Amplitudes and Holography
We've been lucky to be awarded a Marie Curie Career Integration Grant to fund research into applications of twistor theory to scattering amplitudes in quantum field theory.
Details of the team can be found here. A list of publications arising
from the project can be found here. All publications are also available
to free to download from the arXiv and conform to open access requirements. You can also find some slides and videos from talks about our work here.
The project runs from April 2014 to March 2018 and is funded under the European Union's Seventh Framework Programme (FP7/2007-2013), Marie Curie CIG number 631289, "Twistor Strings, Scattering Amplitudes and Holography".
Research Highlights
Here's a (very!) brief introduction to some of the things we've been thinking about. More (many more!) details can be found in the list of publications.
Scattering Amplitudes
From Rutherford's discovery of the atomic nucleus to modern day experiments at the LHC, most of what we know about particle physics has been learned from scattering experiments. Every physics grad student is taught to compute these using Feynman diagrams, but it turns out that these are far from the most efficient way to do things! We've been looking into other ways, based on unitarity, twistors and strings.
Twistor Theory
Penrose's twistor theory treats light rays as more fundamental than events in space-time. Twistor theory has long been a good way to think about self-dual solutions to the Yang-Mills and Einstein equations, in particular being at the heart of the ADHM construction. But in the last few years, it's turned out that twistors are a great way to think about scattering amplitudes in gauge theory and gravity too! The key ideas here are related to string theories that live in twistor space, rather than space-time. The group has been heavily involved in this program.
Flat Holography
The AdS/CFT correspondence is the deepest things we know about quantum gravity with a negative cosmological constant. But no one has a clue how it works in asymptotically flat space-times, where all sorts of weird things happen, like the conformal boundary being disconnected, and the asymptotic symmetry group being infinite dimensional. We're hoping that scattering amplitudes - which live at infinity by definition - can tell us something about their home!
The Team
Tim Adamo
Tim is a Senior Postdoctoral Fellow at Imperial College, London and an affiliate member of the team in DAMTP. He held a Junior Research Fellowship from St. John's College, Cambridge during 2013-2016. He's an expert on many aspects of twistor theory, general relativity, twistor and ambitwistor strings.
Roland Bittleston
Roland is the most recent addition to the team! He began his PhD in the Autumn of 2017, and is mostly working on connections to twistors of the approach to integrability due to Costello, and Costello-Witten-Yamazaki.
Eduardo Casali
Eduardo (2013-2015) completed his PhD on "Worldsheet Methods for Perturbative Quantum Field Theory" in August 2015. He is interested in many aspects of quantum field theory and string theory, and is now a postdoc at the Mathematical Institute in Oxford.
Kai Roehrig
Kai (2014-2018) is a PhD student in the team, funded directly through the Marie Curie Grant. He has worked on various models of ambitwistor strings and is currently investigating a new conjecture for loop amplitudes in maximally supersymmetric gauge theories.
David Skinner
David Skinner (2014-2018) is the principal investigator. David is primarily interested in applications of twistor theory to string theory and quantum field theory. Mostly, this has focussed on on-shell observables such as the S-matrix, though more recently he has become interested in properties of four dimensional CFTs. He arrived in Cambridge in 2013 after postdoc positions in Oxford, Perimeter and IAS Princeton.
Piotr Tourkine
Piotr is now a Postdoctoral Researcher at CERN and a member of the CNRS, France. Prior to this he was a postdoc in DAMTP from 2015-2017. He is interested in various aspects of perturbative string theory and is currently working on obtaining higher loop amplitudes from the ambitwistor string, and on building the connections to the non-conventional quantization of strings investigated by Siegel and Zweibach.
Jack Williams
Jack (2015-2019) began his PhD in October 2015 and is currently working on applications of twistor theory to the AdS/CFT correspondence, both from the point of view of worldsheet models for twistor strings, correlators of self-dual Yang-Mills theory and general twistor space expressions for bulk-to-boundary propagators in AdS in various dimensions.
Publications
- [1] Ambitwistor Strings and the Scattering Equations
Abstract PDF
JHEP 1407 (2014) 048.
Lionel Mason and David Skinner - [2] Ambitwistor Strings and the Scattering Equations at One Loop
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JHEP 1404 (2014) 104.
Tim Adamo, Eduardo Casali and David Skinner - [3] Soft Sub-leading Divergences in Yang-Mills Theory
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JHEP 1408 (2014) 077.
Eduardo Casali - [4] Perturbative Gravity at Null Infinity
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Class. Quant. Grav. 31 (2014) 22 225008.
Tim Adamo, Eduardo Casali and David Skinner - [5] A Worldsheet Theory for Supergravity
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JHEP 1502 (2015) 116.
Tim Adamo, Eduardo Casali and David Skinner - [6] Infrared Behaviour of the One-Loop Scattering Equations and Supergravity Integrands
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JHEP 1504 (2015) 013.
Eduardo Casali and Piotr Tourkine - [7] Scattering Equations, Supergravity Integrands and Pure Spinors
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JHEP 1505 (2015) 120.
Tim Adamo and Eduardo Casali - [8] Perturbative Gauge Theory at Null Infinity
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Phys. Rev. D91 (2015) 12 125022.
Tim Adamo and Eduardo Casali - [9] New Ambitwistor String Theories
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JHEP 1511 (2015) 038.
Eduardo Casali, Yvonne Geyer, Lionel Mason, Ricardo Monteiro and Kai Roehrig - [10] Loop Integrands for Scattering Amplitudes from the Riemann Sphere
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Phys. Rev. Lett. 115 (2015) 12 121603.
Yvonne Geyer, Lionel Mason, Ricardo Monteiro and Piotr Tourkine - [11] On Tree Amplitudes of Supersymmetric Einstein Yang-Mills Theory
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JHEP 1512 (2015) 177.
Tim Adamo, Eduardo Casali, Kai Roehrig and David Skinner - [12] Gravity with a Cosmological Constant from Rational Curves
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JHEP 1511 (2015) 098.
Tim Adamo - [13] One Loop Amplitudes on the Riemann Sphere
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JHEP 1603 (2016) 114.
Yvonne Geyer, Lionel Mason, Ricardo Monteiro and Piotr Tourkine - [14] On the Null Origin of the Ambitwistor String
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JHEP 1611 (2016) 036.
Eduardo Casali and Piotr Tourkine - [15] Twistor Methods for AdS_5
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JHEP 1608 (2016) 167.
Tim Adamo, David Skinner and Jack Williams - [16] Chiral Splitting and N=4 Einstein-Yang-Mills Tree Amplitudes in 4d
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JHEP 1708 (2017) 033.
Kai Roehrig - [17] A Gluing Operator for the Ambitwistor String
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JHEP 1801 (2018) 069.
Kai Roehrig and David Skinner - [18] Minitwistors and 3d Yang-Mills-Higgs Theory
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Submitted to J. Math. Phys.
Tim Adamo, David Skinner and Jack Williams.
Talks and Presentations
Here are the slides and videos from some of the talks I've given.
Technical Presentations
- Twistors, Strings and Twistor Strings
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Audio from the talk can be found here.
- Twistor Strings for N=8 Supergravity
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A video of the talk is available here.
- Ambitwistor Strings and the Scattering Equations
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Talk given at Universite Libre de Bruxelles. - Ambitwistor Strings and the Scattering Equations
A video of the talk is available here. - Ambitwistor Strings and the Scattering Equations
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Talk given at the regional meeting of the London Mathematical Society. - The Secret Life of Scattering Amplitudes
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