Speaker
Description
In this talk, we report two advances that extend the symbol bootstrap programme from planar N=4 super Yang–Mills to QCD. In the first part, we bootstrap the four-point NMHV stress-tensor form factor in N=4 sYM, where symmetry conditions together with multi-collinear consistency conditions uniquely fix the symbol through three loops. We find that the known 88 letter alphabet for MHV form factors captures the alphabet for the NMHV sector as well. This provides the first multi loop non MHV form factor data and confirms the alphabet’s universality beyond the MHV sector. In the second part, we perform the first bootstrap computation of two loop six gluon MHV amplitudes in massless planar QCD at the symbol level, by concentrating on its maximal transcendentality part. We compute the prefactors using on shell diagrams, and establish the connection between the transcendental functions and prescriptive unitarity integrals, both imported from N=4 sYM. Finally, we discuss a generalized version of the maximal transcendentality principle, which provides a systematic bridge for amplitudes between supersymmetric theories and practical QCD.