225 citations · 1.8k across the 70 of their papers we have counts for
71 papers
Nonsingular solutions to the Einstein equations on piecewise-Lorentzian manifolds
Bob Holdom
We consider 4-dimensional spacetime manifolds that are piecewise Lorentzian, where the Lorentzian components of the manifold are separated by codimension-one planes (spacelike or t…
Running couplings and unitarity in a 4-derivative scalar field theory
Bob Holdom
We obtain the -functions for the two dimensionless couplings of a 4d renormalizable scalar field theory with cubic and quartic 4-derivative interactions. Both couplings can be a…
Cosmologies with turning points
Bob Holdom
We explore singularity-free and geodesically-complete cosmologies based on manifolds that are not quite Lorentzian. The metric can be either smooth everywhere or non-degenerate eve…
Towards rotating 2-2-holes
Bob Holdom
Static 2-2-hole solutions of quadratic gravity have been investigated to be a possible horizonless replacement for black holes as the endpoint of gravitational collapse. Realistica…
2-2-holes simplified
Bob Holdom
Quadratic gravity illustrates how a replacement for black holes can emerge from a UV completion of gravity. 2-2-holes are extremely compact horizonless objects with an entropy $S_{…
Photon-photon scattering from a UV-complete gravity QFT
Bob Holdom
Quantum quadratic gravity (QQG) produces a tree-level differential cross section for that is well-behaved at all energies. From this we can study how the corrections to l…