# Dual conformal invariance for form factors

## TL;DR

This paper demonstrates that form factors in N=4 supersymmetric Yang-Mills theory exhibit dual conformal symmetry, similar to scattering amplitudes, and computes their one-loop anomalies with explicit checks for specific cases.

## Contribution

It establishes dual conformal invariance for form factors and calculates their one-loop anomalies, extending symmetry understanding from amplitudes to form factors.

## Key findings

- Dual conformal symmetry holds for form factors in N=4 SYM.
- One-loop dual conformal anomaly matches that of amplitudes.
- Explicit checks confirm symmetry in MHV and NMHV cases.

## Abstract

Form factors of the stress-tensor multiplet operator in $\mathcal{N}=4$ supersymmetric Yang-Mills reveal surprisingly simple structures similar to those appearing in scattering amplitudes. In this paper we show that, as for the case of amplitudes, they also enjoy dual conformal symmetry. We compute the dual conformal anomaly at one loop for an arbitrary number of particles and generic helicities, which matches the expression of the dual conformal anomaly of amplitudes, and perform explicit checks for MHV and NMHV one-loop form factors. In the NMHV case the realisation of dual conformal symmetry requires a delicate cancellation of offending terms arising from three-mass triangles, which we explicitly check in the case of the four-point NMHV form factor.