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The goal of the workshop is to foster interaction between researchers working on the S-matrices of conventional strings and on ambitwistor strings. The workshop will exploit synergies between the two frameworks and identify the current key questions in the fields and areas that can benefit from collaboration.
The program of the workshop will be tailored to questions and problems raised by the participants in the run-up to the event. The goal is to spend most of the time on collaborative discussions in order to exchange expertise and to attempt to resolve questions during the workshop. A list of such problems can be found below, and this will be extended by the participants in the run-up to the meeting.
- To obtain ambitwistor integrands & Bern-Carrasco-Johansson (BCJ) numerators for multiloop amplitudes and to connect with superstring worldsheet correlators.
- To develop fully nonlinear approaches by working on curved backgrounds, both for application to AdS/CFT and to problems in perturbative gravity and gauge theory on nontrivial backgrounds.
- To understand the twistor and ambitwistor geometry underpinning both conventional and ambitwistor strings, including the geometry of soft limits, infrared structure and its links with formulations at null infinity.
- To explore mathematical structures behind the integrals of conventional and ambitwistor strings (positive geometries & canonical forms, twisted (co)-cycle, etc.)
- Timothy Adamo, Imperial College London
- Nima Arkani-Hamed, Institute for Advanced Study
- Thales Azevedo, Uppsala University
- Nathan Berkovits, ICTP-SAIFR
- Eduardo Casali, University of Oxford
- Hadleigh Frost, University of Oxford
- Yvonne Geyer, Institute for Advanced Study
- Humberto Gomez, Universidad Santiago de Cali
- Alfredo Guevara, Perimeter Institute
- Song He, ITP-Chinese Academy of Sciences
- Sebastian Mizera, Perimeter Institute
- Ricardo Monteiro, Queen Mary University & CERN
- Ronald Reid-Edwards, University of Cambridge
- Kai Roehrig, University of Cambridge
- Oliver Schlotterer, Perimeter Institute & Max Planck Institute
- David Skinner, University of Cambridge
- Piotr Tourkine, CERN
- Yong Zhang, ITP-Chinese Academy of Sciences
- Timothy Adamo, Imperial College London
- Nima Arkani-Hamed, Institute for Advanced Study
- Thales Azevedo, Uppsala University
- Nathan Berkovits, ICTP-SAIFR
- Freddy Cachazo, Perimeter Institute
- Eduardo Casali, University of Oxford
- Nick Early, University of Minnesota
- Hadleigh Frost, University of Oxford
- Yvonne Geyer, Institute for Advanced Study
- Humberto Gomez, Universidad Santiago de Cali
- Alfredo Guevara, Perimeter Institute
- Song He, ITP-Chinese Academy of Sciences
- Niamh Maher, Perimeter Institute
- Lionel Mason, University of Oxford
- Sebastian Mizera, Perimeter Institute
- Ricardo Monteiro, Queen Mary University & CERN
- Ronald Reid-Edwards, University of Cambridge
- Kai Roehrig, University of Cambridge
- Oliver Schlotterer, Perimeter Institute & Max Planck Institute
- David Skinner, University of Cambridge
- Piotr Tourkine, CERN
- Yong Zhang, ITP-Chinese Academy of Sciences
Monday, April 16, 2018
Time |
Event |
Location |
CURVED SPACETIME |
||
8:30 – 9:00am |
Registration |
Reception |
9:00 – 9:05am |
Freddy Cachazo, Perimeter Institute |
Alice Room |
9:05 – 9:45am |
Eduardo Casali, University of Oxford |
Alice Room |
9:45 – 10:15am |
Coffee Break – Beverages only |
Bistro – 1^{st} Floor |
10:15 – 11:00am |
David Skinner, University of Cambridge |
Alice Room |
11:00 – 11:30am |
Coffee Break |
Bistro – 1^{st} Floor |
11:30 – 12:30pm |
Lecture for PSI Students| |
Time Room |
11:30 – 12:30 pm |
Discussion |
Alice Room |
12:30 – 2:00pm |
Lunch |
Bistro – 2^{nd} Floor |
2:00 – 2:45pm |
Timothy Adamo, Imperial College London |
Alice Room |
2:45 – 3:15pm |
Coffee Break |
Bistro – 1^{st} Floor |
3:15pm Onward |
Discussion |
Alice Room |
Tuesday, April 17, 2018
Time |
Event |
Location |
PURE SPINORS |
||
9:00 – 9:45am |
Nathan Berkovits, ICTP-SAIFR |
Alice Room |
9:45 – 10:15am |
Coffee Break – Beverages only |
Bistro – 1^{st} Floor |
10:15 – 11:00am |
Oliver Schlotterer, Perimeter Institute & Max Planck Institute |
Alice Room |
11:00 – 11:30am |
Coffee Break |
Bistro – 1^{st} Floor |
11:30 – 12:30pm |
Lecture for PSI Students |
Time Room |
11:30 – 12:30pm |
Discussion |
Alice Room |
12:30 – 2:00pm |
Lunch |
Bistro – 2^{nd} Floor |
2:00 – 2:45pm |
Alfredo Guevara, Perimeter Institute |
Alice Room |
2:45 – 3:15pm |
Coffee Break |
Bistro – 1^{st} Floor |
3:15pm Onward |
Discussion |
Alice Room |
Wednesday, April 18, 2018
Time |
Event |
Location |
ALPHA PRIME |
||
9:00 – 9:45am |
Thales Azevedo, Uppsala University |
Alice Room |
9:45 – 10:15am |
Coffee Break – Beverages only |
Bistro – 1^{st} Floor |
10:15 – 11:00am |
Ronald Reid-Edwards, University of Cambridge |
Alice Room |
11:00 – 11:30am |
Coffee Break |
Bistro – 1^{st} Floor |
11:30 – 12:30pm |
Lecture for PSI Students |
Time Room |
11:30 – 12:30pm |
Discussion |
Alice Room |
12:30 – 2:00pm |
Lunch |
Bistro – 2^{nd} Floor |
2:00 – 3:30pm |
Colloquium |
Time Room |
3:30 – 4:00pm |
Coffee Break |
Bistro – 1^{st} Floor |
4:00 – 4:45pm |
Piotr Tourkine, CERN |
Alice Room |
6:00pm Onward |
Banquet |
Bistro – 2^{nd} Floor |
Thursday, April 19, 2018
Time |
Event |
Location |
GEOMETRIC STRUCTURS |
||
9:00 – 9:45am |
Sebastian Mizera, Perimeter Institute |
Alice Room |
9:45 – 10:15am |
Coffee Break – Beverages only |
Bistro – 1^{st} Floor |
10:15 – 11:00am |
Song He, ITP-Chinese Academy of Sciences |
Alice Room |
11:00 – 11:30am |
Coffee Break |
Bistro – 1^{st} Floor |
11:30 – 12:30pm |
Lecture for PSI Students |
Time Room |
11:30 – 12:30pm |
Discussion |
Alice Room |
12:30 – 2:00pm |
Lunch |
Bistro – 2^{nd} Floor |
2:00 – 2:45pm |
Hadleigh Frost, University of Oxford |
Alice Room |
2:45 – 2:55pm |
Photo |
TBA |
2:55 – 3:15pm |
Coffee Break |
Bistro – 1^{st} Floor |
3:15pm Onward |
Discussion |
Alice Room |
Friday, April 20, 2018
Time |
Event |
Location |
BCJ AND LOOPS |
||
9:00 – 9:45am |
Kai Roehrig, University of Cambridge |
Alice Room |
9:45 – 10:15am |
Coffee Break – Beverages only |
Bistro – 1^{st} Floor |
10:15 – 11:00am |
Humberto Gomez, Universidad Santiago de Cali |
Alice Room |
11:00 – 11:30am |
Coffee Break |
Bistro – 1^{st} Floor |
11:30 – 12:30pm |
Lecture for PSI Students |
Time Room |
11:30 – 12:30pm |
Discussion |
Alice Room |
12:30 – 2:00pm |
Lunch |
Bistro – 2^{nd} Floor |
2:00 – 2:45pm |
Yong Zhang, ITP-Chinese Academy of Sciences |
Alice Room |
2:45 – 3:15pm |
Coffee Break |
Bistro – 1^{st} Floor |
3:15pm Onward |
Discussion |
Alice Room |
Timothy Adamo, Imperial College London
Amplitudes on plane waves from the worldsheet
Unlike conventional string theories, ambitwistor strings can be coupled to background fields exactly -- that is, without having to resort to worldsheet perturbation theory. This raises the possibility of using ambitwistor strings to compute scattering amplitudes perturbatively around non-trivial backgrounds. I'll describe how this works for the simplest of amplitudes (3-point, tree-level) on the simplest non-trivial backgrounds (plane waves) in gauge theory and gravity.
Thales Azevedo, Uppsala University
(DF)^2 gauge theories and (ambitwistor) strings
Recently, a gauge theory built out of dimension-six operators such as (DF)^2 appeared in the double-copy construction of conformal supergravity. In this talk, I will show how theories of that kind are related to conventional and ambitwistor string theories.
Nathan Berkovits, ICTP-SAIFR
On pure spinor superfield actions in ten and eleven dimensions
In collaboration with Max Guillen, we show how to derive the interacting equations of motion from Martin Cederwall's pure spinor superfield actions for d=10 super-Born-Infeld and d=11 supergravity.
Eduardo Casali, University of Oxford
Scattering on planes waves and the double-copy
Humberto Gomez, Universidad Santiago de Cali
Double-cover scattering equations and Yang-Mills
In this talk, we describe the double-cover (DC) extension of the scattering equation approach formulated by Cachazo, He and Yuan (CHY). So far, the DC prescription has only been developed for the $\phi^3$ theory. Here, we introduce the DC representation for the Yang-Mills theory and, as a by-product, we obtain a new recurrence relation.
Song He, ITP-Chinese Academy of Sciences
Scattering Forms and the Positive Geometry of Kinematics, Color and the Worldsheet
Hadleigh Frost, University of Oxford
Bi-adjoint phi^3 amplitudes
We discuss new ideas for writing biadjoint scalar amplitudes. We relate the tree amplitudes to a fan of cones in "dual kinematic space"---building on work by Arkani-Hamed, Bai, He and Yan last year. We describe how some of these ideas could be extended to loop integrands.
Sebastian Mizera, Perimter Institute
Scattering Amplitudes as Intersection Pairings of Twisted Cohomology Groups
Ricardo Monteiro, Queen Mary University & CERN
Scattering Amplitudes, String Models and Gravitational Waves
The study of scattering amplitudes in field theory connects a wide range of problems, from the mathematics of string perturbation theory to computations related to gravitational waves. I will discuss a couple of topics that keep scattering amplitudes researchers busy, and that motivate an ongoing workshop at PI. First, I will give an overview of recent progress in describing interactions in particle theories in terms of "ambitwistor strings", a new type of field theory model inspired by string theory. The result is an elegant formalism for scattering amplitudes in certain field theories, based on the "scattering equations". This formalism brings a new light into the "double copy relation", discovered in string theory, that expresses perturbative gravity in terms of perturbative gauge theory. I will review the double copy for scattering amplitudes, and then I will discuss the recent application of this idea to classical solutions. One of the aims is to export to gravitational phenomenology the dramatic simplifications provided by the double copy for scattering amplitudes.
Oliver Schlotterer, Perimeter Institute & Max Planck Institute
The double-copy structure of one-loop open-string amplitudes from pure spinors
Yong Zhang, ITP-Chinese Academy of Sciences
New BCJ representations for one-loop amplitudes in gauge theories and gravity
We explain a procedure to manifest the Bern–Carrasco–Johansson duality between color and kinematics in n-point one-loop amplitudes of a variety of supersymmetric gauge theories. Explicit amplitude representations are constructed through a systematic reorganization of the integrands in the Cachazo–He–Yuan formalism. Our construction holds for any nonzero number of supersymmetries and does not depend on the number of space-time dimensions. The cancellations from supersymmetry multiplets in the loop as well as the resulting power counting of loop momenta are manifested along the lines of the corresponding superstring computations. The setup is used to derive the one-loop version of the Kawai–Lewellen–Tye formula for the loop integrands of gravitational amplitudes. Some discussions about one-loop amplitudes with zero supersymmetry are included.
Scientific Organizers:
- Freddy Cachazo, Perimeter Institute
- Song He, ITP-Chinese Academy of Sciences
- Lionel Mason, University of Oxford
- Oliver Schlotterer, Perimeter Institute & Max Planck Institute
- David Skinner, University of Cambridge