Soft gravity by squaring soft QED on the celestial sphere

Infrared divergences in perturbative gravitational scattering amplitudes have been recently argued to be governed by the two-point function of the supertranslation Goldstone mode on the celestial sphere. We show that the form of this celestial two-point function simply derives from an effective action that also controls infrared divergences in the symplectic structure of General Relativity with asymptotically flat boundary conditions. This effective action finds its natural place in a path integral formulation of a celestial conformal field theory, as we illustrate by re-deriving the infrared soft factors in terms of celestial correlators. Our analysis relies on a well-posed action principle close to spatial infinity introduced by Compère and Dehouck.

Section: Jhep09(2021)144mentioning

confidence: 69%

Celestial IR divergences and the effective action of supertranslation modes

Nguyen

Salzer²

2021

“…There the IR divergences are captured by correlators of vertex operators built from the supertranslation Goldstone mode. A higher derivative 2D effective action is given in [59,60].…”

Section: Jhep11(2021)143mentioning

confidence: 99%

Revisiting the conformally soft sector with celestial diamonds

Pasterski¹,

Puhm

Trevisani

2021

Celestial diamonds encode the structure of global conformal multiplets in 2D celestial CFT and offer a natural language for describing the conformally soft sector. The operators appearing at their left and right corners give rise to conformally soft factorization theorems, the bottom corners correspond to conserved charges, and the top corners to conformal dressings. We show that conformally soft charges can be expressed in terms of light ray integrals that select modes of the appropriate conformal weights. They reside at the bottom corners of memory diamonds, and ascend to generalized currents. We then identify the top corners of the associated Goldstone diamonds with conformal Faddeev-Kulish dressings and compute the sub-leading conformally soft dressings in gauge theory and gravity which are important for finding nontrivial central extensions. Finally, we combine these ingredients to speculate on 2D effective descriptions for the conformally soft sector of celestial CFT.

“…Up until now, many steps have been taken in this direction. In [7] a theory of free scalars was put forward in order to describe the infrared sector of abelian gauge theory and graviton amplitudes. In [6,8] an analogous theory of free colored scalars was proposed in order to reproduce the celestial correlation function given by the celestial soft factor Z in nonabelian gauge theory.…”

Section: Jhep01(2022)136mentioning

confidence: 99%

“…In [6], all (known) contributions to the soft anomalous dimension beyond the dipole approximation were considered, but only in the large N limit. In both these cases, and in the abelian construction in [7], one may suspect that the absence of the effects from collinear divergences may be responsible for the apparent simplicity of the holographic description obtained [9]. Therefore, we believe that a richer 2-dimensional theory, beyond free colored-scalars, must be at play governing the dynamics of the infrared sector of nonabelian gauge theory.…”

Section: Jhep01(2022)136mentioning

confidence: 99%

See 1 more Smart Citation

Celestial IR divergences in general most-subleading-color gluon and gravity amplitudes

Năstase

Rojas

Rubio

2022

Gluon amplitudes at most-subleading order in the 1/N expansion share a remarkable simplicity with graviton amplitudes: collinear divergences are completely absent in both and, as a consequence, their full IR behavior arises from soft gluon/graviton exchange among the external states. In this paper we study the effect of all-loop IR divergences of celestial most-subleading color gluon amplitudes and their similarities with the celestial gravity case. In particular, a simple celestial exponentiation formula for the dipole part can be written. We also analize how this exponentiation is modified by non-dipole contributions. Finally we also show that, in the Regge limit, the soft factor satisfies the Knizhnik-Zamolodchikov equation hinting at the possibility that, in this limit, an effective Wess-Zumino-Witten model would describe the dynamics of the infrared sector.