Factorization and polarization in linearized gravity

Abstract

We investigate all the four-body graviton interaction processes: gX → γX, gX → gX, and gg → gg with X as an elementary particle of spin less than two in the context of linearized gravity except the spin-3/2 case. We show explicitly that gravitational gauge invariance and Lorentz invariance cause every four-body graviton scattering amplitude to be factorized. We explore the implications of this factorization property by investigating polarization effects through the covariant density matrix formalism in each four-body graviton scattering process. PACS number(s) : 04.60.+n, 12.25.+e, 13.88.+e

On-shell techniques and universal results in quantum gravity

“…1 The representation of the massive gravitational Compton scattering of a massive matter field of spin s = 0, 1/2, 1 in terms of (Abelian) Compton amplitude was already noticed in [16,16,24] and [40]. It would be interesting to understand if this factorization using purely Abelian interactions can be achieved with other types of gravitational amplitudes.…”

“…We have also checked that our amplitude correctly satisfies the relation to the QED amplitude [24] which we discuss below in the context of the helicity formalism.…”

Pair production of small black holes in heterotic string theories

“…This entails various sign changes with respect to Field Theory formulae in e.g. [39]. Moreover κ ref [39] = 2κ standard .…”

“…Either by brute force computation of the relevant Feynmann diagrams or by exploiting KLT-like relations with gauge theory amplitudes, the resulting transition amplitude reads [39] …”

“…BPS BH's are very special in that their temperature vanishes and they behave pretty much like very massive particles, with a large number of degenerate microstates, accounting for their entropy. To set the stage for a full-fledged heterotic string computation at tree level, we first describe a field theory toy model for pair production of charged massive scalars [39]. Since the pair-produced small BH's are BPS and stable they do not emit Hawking radiation.…”