**Physics and Mathematics of Scattering Amplitudes**

Organized by Zvi Bern, Lance Dixon, Michael Douglas, Alexander Goncharov, and Lionel Mason

*Fall 2013*

Starting date: August 26, 2013

The study of scattering amplitudes in relativistic quantum field theory has undergone a remarkable renaissance and transformation in recent years, with the advent of new perturbative approaches such as generalized unitarity, recursion relations, twistor variables and topological string theory, color-kinematics duality and double-copy properties. Scattering in N=4 super-Yang-Mills theory, a highly supersymmetric cousin of QCD, can be described, in the planar limit of a large number of colors, in terms of minimal surfaces in anti-de Sitter space. This approach has also led to a remarkable correspondence between scattering amplitudes and polygonal Wilson loops, and to discovery of new symmetries such as dual conformal invariance and Yangian symmetry. The intricate structure of string theory scattering amplitudes is also rapidly being uncovered.

Powerful mathematical notions are rapidly playing important roles, including the (positive) Grassmanian and polytopes, (motivic) multiple zeta values, single-valued multiple (harmonic) polylogarithms, and the symbol of an iterated integral. Other ideas, such as integrability and the OPE expansion, have appeared but are still awaiting full exploitation.

Some of these ideas have had practical payoff within perturbative QCD, for the computation of more accurate cross sections at the LHC. Many of them are the most powerful, or at least best understood, for planar N=4 super-Yang-Mills theory. Due to its large symmetry, this theory can serve as a proving ground for new ideas and approaches. It holds the promise of being exactly solvable, yet it will still require more physical and mathematical insights to fulfill this promise. Other methods can be applied to gravitational theories, in particular the most supersymmetric pointlike theory of gravity, N=8 supergravity, where they have exposed remarkably good ultraviolet behavior at the multi-loop level.

**Speaker and Seminar Schedule:**

The weekly talks take place **Tuesdays and Thursdays** at **11:00am** in** room 313**.

Date and Time | Title | Presenters | |

8/29 at 11:00am – Room 313 | Basics of Scattering Amplitudes | Henriette Elvang | |

8/30 at 3:00pm – Room 313 | From Feynman integrals to polylogarithms | Johannes Henn | |

9/10 at 11:00am – Room 313 | Super-conformal invariance for amplitudes and correlation functions | Emery Sokatchev | |

9/13 at 11:00am – Room 313 | Unexpected relations between Yang-Mills and gravity amplitudes | Donal O’Connell | |

9/17 at 1:00pm – Room 102 | The Amplituhedron | Nima Arkani- Hamed | |

9/18 at 11:00am – Room 313 | Unexpected relations between amplitudes and correlation functions | Paul Heslop | |

9/18 at 2:00pm – Room 313 | Graphical Functions | Oliver Schnetz | |

9/19 at 11:00am – Room 313 | TBA | Alexander Zhiboedov | |

9/24 at 11:00am – Room 313 | Hodge structures and Picard-Fuchs equations in perturbative QFT | Stefan Weinzeriel | |

9/24 at 4:00pm – Harriman 137 | Harmony of Scattering Amplitudes: From Quantum Chromodynamics to Supergravity | Zvi Bern | |

9/26 at 11:00am – Room 313 | Twistors, gravity, and amplitudes | Timothy Adamo | |

10/1 at 11:00am – Room 313 | Space-Time S-matrix and Flux-Tube S-matrix | Pedro Viera | |

10/3 at 11:00am – Room 313 | Polylogarithms and cluster coordinates in N=4 scattering amplitudes | Cristian Vergu | |

10/8 at 11:00am – Room 313 | Amplitudes and the Elliptic dilogarithm: physics and arithmetic of the sunset diagram in two dimensions | Pierre Vanhove | |

10/10 at 11:00am – Room 313 | Generalized Unitarity at One and Two Loops | Jacob Bourjaily | |

10/15 at 11:00am – Room 313 | Radu Roiban | ||

10/17 at 11:00am – Room 313 | Hexagon Functions: Bootstrapping the Three-Loop Remainder Function | Matt von Hippel | |

10/22 at 11:00am – Room 313 | Fundamental representation color-kinematics duality and N<4 supergravity | Henrik Johansson | |

10/23 at 11:00am – Room 313 | Mueller-Navelet Jets, Single-Valued Harmonic Polylogarithms and Multiple Zeta Values | Lance Dixon | |

10/24 at 11:00am – Room 313 | On Yangian Symmetry of Scattering Amplitudes | Niklas Beisert | |

10/28 at 2:00pm – Room 313 | Scattering amplitudes in string theory and Eisenstein series | Michael Green and Stephan Miller | |

10/29 at 11:00am – Room 313 | Introduction to cluster algebras and the positive Grassmannian | Lauren Williams | |

10/30 at 11:30am – Room 313 | Physics and Combinatorics of the Grassmannian | Nima Arkani-Hamed and Alexander Postnikov | |

11/5 at 11:00am – Room 313 | Two topics in infrared behavior | George Sterman | |

11/7 at 11:00am – Room 313 | Scattering of Massless Particles in Arbitrary Dimension | Song He | |

11/12 at 11:00am – Room 313 | BCJ numerators at one–loop from the superstring: Five points and beyond | Oliver Schlotterer | |

11/14 at 11:00am – Room 313 | Motivic Superstring Amplitudes | Stephan Stieberger | |

11/19 at 11:00am – Room 313 | Multiple polylogarithms in weight 4 | Herbert Gangl | |

12/5 at 11:00am – Room 313 | Yangian Symmetry of smooth Wilson Loops in N=4 SYM | Jan Plefka | |

12/6 at 11:00am – Room 313 | Supergravity in a brilliant disguise | Tomasz Taylor |

**ASSOCIATED VIDEOS AND PUBLICATIONS**