Revisiting the shadow stress tensor in celestial CFT
Shamik Banerjee, Sabrina Pasterski
Abstract
A bstract We revisit the standard construction of the celestial stress tensor as a shadow of the subleading conformally soft graviton. In its original formulation there is an obstruction to reproducing the expected $$ \overline{TT} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mover> <mml:mi>TT</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> OPE in the double soft limit. We propose a modification to the definition which circumvents this obstruction and then extend this change of basis beyond the conformally soft and single helicity sectors. In the process we investigate how (non)-commutativity of double soft limits is tied to the decoupling of primary descendants, and how our choice of celestial basis determines which symmetries are manifest at the level of the OPE beyond the MHV sector.