Physics

Spacetime

Mathematics

Mathematical physics

Scale invariance

Conformal symmetry

Amplitude

Geometry

Theoretical physics

Quantum mechanics

Conformal map

Scalar (mathematics)

Classical mechanics

Journal of High Energy Physics

Both celestial and momentum space amplitudes in four dimensions are beset by divergences resulting from spacetime translation and sometimes scale invariance. In this paper we consider a (linearized) marginal deformation of the celestial CFT for Yang-Mills theory which preserves 2D conformal invariance but breaks both spacetime translation and scale invariance and involves a chirally coupled massive scalar. The resulting celestial amplitudes are completely finite (apart from the usual soft and collinear divergences) and take the canonical CFT form. Moreover, we show they can be simply rewritten in terms of AdS$_3$-Witten contact diagrams which evaluate to the well-known $D$-functions, thereby forging a direct connection between flat and AdS holography.

Celestial amplitudes as AdS-Witten diagrams