Remote HET seminar: Chi Zhang

Speaker: Chi Zhang

Title: Algebraic letters and NMHV last entry conditions from Qbar equations

Abstract: Qbar equations are a set of first-order differential equations obeyed by the S-matrix of planar N=4 SYM theory, which arise from the dual superconformal anomaly of this theory. Perturbatively, these equations express the derivatives of amplitudes at a given loop order as integrals of lower-loop amplitudes with more legs. I will show how to use Qbar equations to calculate the differential of two-loop n-point NMHV amplitudes and give the explicit expression of algebraic letters that may appear in the 2-loop NMHV amplitudes. Besides, I will comment on the last entry conditions to which all NMHV loop amplitudes should subject.

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