2012/05/01 by Yuxiang Gu, Gu, Yuxiang
Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #High Energy Physics - Theory (hep-th) #Particle physics theoretical and experimental studies #hep-ph #hep-th
paper · pdf · doi:10.48550/arxiv.1205.0226
12 pages
arxiv created 2012/05/01 · openalex publication_date 2012/05/01 · arxiv updated 2012/05/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Motivated by the success of Hodges' momentum twistor variables in planar Yang-Mills, in this note we introduce a set of new variables, the S variables, which are tailored for gravity (or more generally for theories without color ordering). The S variables trivialize all on-shell constraints on kinematic data and momentum conservation while keeping permutation invariance. We explicitly show the relation between the S variables and the spinor-helicity variables as well as the connection to momentum twistors. The S variables can be nicely understood using the geometry of Grassmannians and are determined by a 2-plane and a 4-plane in Cn, with n the number of the particles. As an illustration of their utility, we use the S variables to present a reference-free form of soft factors and tree level MHV amplitudes of gravity which is obtained by using the recent formula given by Hodges.