New Directions in Conventional and Ambitwistor String Theories

Conference Date: 
Monday, April 16, 2018 (All day) to Friday, April 20, 2018 (All day)
Scientific Areas: 
String Theory

 

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.)

Funding for this workshop has been provided by:

  • 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
Welcome and Opening  Remarks

Alice Room

9:05 – 9:45am

Eduardo Casali, University of Oxford
Scattering on planes waves and the double-copy

Alice Room

9:45 – 10:15am

Coffee Break – Beverages only

Bistro – 1st Floor

10:15 – 11:00am

David Skinner, University of Cambridge
TBA

Alice Room

11:00 – 11:30am

Coffee Break

Bistro – 1st Floor

11:30 – 12:30pm

Lecture for PSI Students|
Eduardo Casali, University of Oxford
Introduction to Ambitwistors I (Genus 0)

Time Room

11:30 – 12:30 pm

Discussion

Alice Room

12:30 – 2:00pm

Lunch

Bistro – 2nd Floor

2:00 – 2:45pm

Timothy Adamo, Imperial College London
Amplitudes on plane waves from the worldsheet 

Alice Room

2:45 – 3:15pm

Coffee Break

Bistro – 1st Floor

3:15pm Onward

Discussion
Timothy Adamo, Imperial College London
Lionel Mason, University of Oxford
David Skinner, University of Cambridge

Alice Room

 

Tuesday, April 17, 2018

Time

Event

Location

PURE SPINORS

9:00 – 9:45am

Nathan Berkovits, ICTP-SAIFR
On pure spinor superfield actions in ten and eleven dimensions

Alice Room

9:45 – 10:15am

Coffee Break – Beverages only

Bistro – 1st Floor

10:15 – 11:00am

Oliver Schlotterer, Perimeter Institute & Max Planck Institute
The double-copy structure of one-loop open-string amplitudes from pure spinors

Alice Room

11:00 – 11:30am

Coffee Break

Bistro – 1st Floor

11:30 – 12:30pm

Lecture for PSI Students
Yvonne Geyer, Institute for Advanced Study
Introduction to Ambitwistors II (Genus>0)

Time Room

11:30 – 12:30pm

Discussion

Alice Room

12:30 – 2:00pm

Lunch

Bistro – 2nd Floor

2:00 – 2:45pm

Alfredo Guevara, Perimeter Institute
TBA

Alice Room

2:45 – 3:15pm

Coffee Break

Bistro – 1st Floor

3:15pm Onward

Discussion
Nathan Berkovits, ICTP-SAIFR

Alice Room

 

Wednesday, April 18, 2018

Time

Event

Location

ALPHA PRIME

9:00 – 9:45am

Thales Azevedo, Uppsala University
(DF)^2 gauge theories and (ambitwistor) strings

Alice Room

9:45 – 10:15am

Coffee Break – Beverages only

Bistro – 1st Floor

10:15 – 11:00am

Ronald Reid-Edwards, University of Cambridge
TBA

Alice Room

11:00 – 11:30am

Coffee Break

Bistro – 1st Floor

11:30 – 12:30pm

Lecture for PSI Students
Piotr Tourkine, CERN
Ambitwistors vs. Conventional Strings

Time Room

11:30 – 12:30pm

Discussion

Alice Room

12:30 – 2:00pm

Lunch

Bistro – 2nd Floor

2:00 – 3:30pm

Colloquium
Ricardo Monteiro, Queen Mary University of London & CERN
Scattering Amplitudes, String Models and Gravitational Waves

Time Room

3:30 – 4:00pm

Coffee Break

Bistro – 1st Floor

4:00 – 4:45pm

Piotr Tourkine, CERN
TBA

Alice Room

6:00pm Onward

Banquet

Bistro – 2nd Floor

 

Thursday, April 19, 2018

Time

Event

Location

GEOMETRIC STRUCTURS

9:00 – 9:45am

Sebastian Mizera, Perimeter Institute
Scattering Amplitudes as Intersection Pairings of Twisted Cohomology Groups

Alice Room

9:45 – 10:15am

Coffee Break – Beverages only

Bistro – 1st Floor

10:15 – 11:00am

Song He, ITP-Chinese Academy of Sciences
Scattering Forms and the Positive Geometry of Kinematics, Color and the Worldsheet

Alice Room

11:00 – 11:30am

Coffee Break

Bistro – 1st Floor

11:30 – 12:30pm

Lecture for PSI Students
Nima Arkani-Hamed, Institute for Advanced Study
TBA

Time Room

11:30 – 12:30pm

Discussion

Alice Room

12:30 – 2:00pm

Lunch

Bistro – 2nd Floor

2:00 – 2:45pm

Hadleigh Frost, University of Oxford
Bi-adjoint phi^3 amplitudes

Alice Room

2:45 – 2:55pm

Photo

TBA

2:55 – 3:15pm

Coffee Break

Bistro – 1st Floor

3:15pm Onward

Discussion
Nima Arkani-Hamed, Institute for Advanced Study
Song He, ITP-Chinese Academy of Sciences

Alice Room

Friday, April 20, 2018

Time

Event

Location

BCJ AND LOOPS

9:00 – 9:45am

Kai Roehrig, University of Cambridge
TBA

Alice Room

9:45 – 10:15am

Coffee Break – Beverages only

Bistro – 1st Floor

10:15 – 11:00am

Humberto Gomez, Universidad Santiago de Cali
Double-cover scattering equations and Yang-Mills

Alice Room

11:00 – 11:30am

Coffee Break

Bistro – 1st Floor

11:30 – 12:30pm

Lecture for PSI Students
Thales Azevedo, Uppsala University
Introduction to Pure Spinors

Time Room

11:30 – 12:30pm

Discussion

Alice Room

12:30 – 2:00pm

Lunch

Bistro – 2nd Floor

2:00 – 2:45pm

Yong Zhang, ITP-Chinese Academy of Sciences
New BCJ representations for one-loop amplitudes in gauge theories and gravity

Alice Room

2:45 – 3:15pm

Coffee Break

Bistro – 1st Floor

3:15pm Onward

Discussion
Yvonne Geyer, Institute for Advanced Study
Ricardo Monteiro, Queen Mary University & CERN

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