## Abstract

We use the embedding of Einstein gravity with cosmological constant into

conformal gravity as a basis for using the twistor action for conformal gravity

to obtain maximal-helicity-violating (MHV) scattering amplitudes not just for

conformal gravity, but also for Einstein gravity on backgrounds with nonzero

cosmological constant. The new formulae for the gravitational MHV amplitude with cosmological constant arise by summing Feynman diagrams using the matrix-tree theorem. We show that this formula is well-defined (i.e.,

is independent of certain gauge choices) and that it non-trivially reproduces

Hodges’ formula for the MHV amplitude in the flat-space limit. We give a

preliminary discussion of an MHV formalism for more general amplitudes

obtained from the conformal gravity twistor action in an axial gauge. We also

see that the embedding of Einstein data into the conformal gravity action can

be performed off-shell in twistor space to give a proposal for an Einsten twistor

action that automatically gives the same MHV amplitude. These ideas extend

naturally to N = 4 supersymmetry.

conformal gravity as a basis for using the twistor action for conformal gravity

to obtain maximal-helicity-violating (MHV) scattering amplitudes not just for

conformal gravity, but also for Einstein gravity on backgrounds with nonzero

cosmological constant. The new formulae for the gravitational MHV amplitude with cosmological constant arise by summing Feynman diagrams using the matrix-tree theorem. We show that this formula is well-defined (i.e.,

is independent of certain gauge choices) and that it non-trivially reproduces

Hodges’ formula for the MHV amplitude in the flat-space limit. We give a

preliminary discussion of an MHV formalism for more general amplitudes

obtained from the conformal gravity twistor action in an axial gauge. We also

see that the embedding of Einstein data into the conformal gravity action can

be performed off-shell in twistor space to give a proposal for an Einsten twistor

action that automatically gives the same MHV amplitude. These ideas extend

naturally to N = 4 supersymmetry.

Original language | English |
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Article number | 4 |

Pages (from-to) | 2-46 |

Number of pages | 45 |

Journal | Classical and quantum gravity |

DOIs | |

Publication status | Published - 28 Jan 2014 |