Subleading Soft Theorem for arbitrary number of external soft photons and gravitons

We obtain the subleading soft theorem for a generic theory of quantum gravity, for arbitrary number of soft photons and gravitons and for arbitrary number of finite energy particles with arbitrary mass and spin when all the soft particles are soft in the same rate. This result is valid at tree level for spacetime dimensions equal to four and five and to all loops in spacetime dimensions greater than five. We verify that in classical limit low energy photon and graviton radiation decouple from each other.Comment: 55 pages, 14 figures, covariantization in photon background improved, appendix-B adde

Conformal Structure of Massless Scalar Amplitudes Beyond Tree level

We show that the one-loop on-shell four-point scattering amplitude of massless $\phi^4$ scalar field theory in 4D Minkowski space time, when Mellin transformed to the Celestial sphere at infinity, transforms covariantly under the global conformal group ($SL(2,C)$) on the sphere. The unitarity of the four-point scalar amplitudes is recast into this Mellin basis. We show that the same conformal structure also appears for the two-loop Mellin amplitude. Finally we comment on some universal structure for all loop four-point Mellin amplitudes specific to this theory.Comment: 15 pages, 4 figures, V2: Reference Adde

Light transformed gluon correlators in CCFT

In the present work, we study celestial correlators of light transformed gluon operators at tree level. We also discuss the transformation of light transformed operators under the action of 4D translations. The two, three and four-point functions arising from MHV amplitudes in terms of light transformed operators satisfy translation invariance constraints, are non-distributional and contain ordinary CFT power law terms. There is a new channel dependent term in the three point function. We show that the three-point light transformed correlation function is conformally covariant after contributions from all the three channels are added. We also study the OPE limit of the different channels of the three-point function in an attempt to construct a map between the OPE in the Mellin basis and that in the light transformed one

Light transformed gluon correlators in CCFT

Abstract In the present work, we study celestial correlators of light transformed gluon operators at tree level. We also discuss the transformation of light transformed operators under the action of 4D translations. The two, three and four-point functions arising from MHV amplitudes in terms of light transformed operators satisfy translation invariance constraints, are non-distributional and contain ordinary CFT power law terms. There is a new channel dependent term in the three point function. We show that the three-point light transformed correlation function is conformally covariant after contributions from all the three channels are added. We also study the OPE limit of the different channels of the three-point function in an attempt to construct a map between the OPE in the Mellin basis and that in the light transformed one

Second order Galilean fluids and Stokes’ law

We study the second derivative effects on the constitutive relations of an uncharged parity-even Galilean fluid using the null fluid framework. Null fluids are an equivalent representation of Galilean fluids in terms of a higher dimensional relativistic fluid, which makes the Galilean symmetries manifest and tractable. The analysis is based on the off-shell formalism of hydrodynamics. We use this formalism to work out a generic algorithm to obtain the constitutive relations of a Galilean fluid up to arbitrarily high derivative orders, and later specialize to second order. Finally, we study the Stokes’ law which determines the drag force on an object moving through a fluid, in presence of certain second order terms. We identify the second order transport coefficients which leave the drag force invariant