| DATE: |
2006-11-17 14:00 - 15:00 |
| PLACE: |
Kenkyu Honkan 2F RM 220 |
| TITLE: |
Twistor strings and supergravity |
| CONTACT: |
tsuda |
| SPEAKER: |
Mohab Abou Zeid (Vrije Universiteit Brussel/ The International Solvay Institutes) |
| LANGUAGE: |
English |
| ABSTRACT: |
I will present a modification of the Berkovits twistor string model which gives Einstein supergravity coupled to Yang-Mills, and has a limit in which the gravity modes can be decoupled to give pure gauge theory amplitudes. I will start by reviewing a number of relevant aspects of twistor theory, including: special features associated with different space-time signatures; supertwistor space; the Penrose transform; the infinity twistor; and Penrose's non-linear graviton construction. I will then review the Witten and Berkovits twistor strings, with emphasis on the latter. The world-sheet formulation of the Berkovits model involves so-called beta-gamma systems; I will describe the symmetries of such systems and their gauging, and explain how the analysis can be applied to the construction of a family of new gauged Berkovits twistor strings which are free from world-sheet anomalies. I will also describe the corresponding spectra in space-time, and show that they give Einstein supergravities instead of the higher derivative conformal supergravities arising in the original twistor string models. The new theories include one with the spectrum of N=8 supergravity, two theories with the spectrum of N=4 supergravity coupled to N=4 Yang-Mills, a family of N>0 models with the spectra of self-dual supergravity coupled to self-dual super-Yang-Mills, and a non-supersymmetric string with the spectrum of self-dual gravity coupled to self-dual Yang-Mills and a scalar. Time permitting, I will discuss what is known about the interactions. |
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