Speaker
Petr Vasko
(Charles University)
Description
The S-matrix for a QFT in 4D Minkowski space is an inherently holographic object, i.e. defined at the (conformal) boundary of spacetime. A section of this boundary is the celestial 2-sphere and Lorentz group acts on it by conformal transformations. I will briefly review scattering, when translated from the basis of plane waves (translation eigenstates) to the conformal basis (dilatation eigenstates). The resulting object is called a celestial amplitude and the change of basis is implemented for massless particles by a Mellin transform. I will apply this formalism to amplitudes of Goldstone bosons with an emphasis on their soft theorems. The illustrative example will be the U(1) (non)-linear sigma model.
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Author
Petr Vasko
(Charles University)
