Talks

Unimodular Henneaux-Teitelboim (HT) Gravity provides a fully diffeomorphism-invariant route to unimodular gravity by promoting the cosmological constant to a conjugate variable with an associated “unimodular time”. I will present two complementary applications. In 4D minisuperspace, starting from the connection representation, unimodular Hartle–Hawking wave packets yield a unitary inner product and normalizable states whose peaks track classical FRW dynamics. This work reframes “creation from nothing” as the emergence of a semiclassical Universe from interference of incident/reflected packets near the bounce, without invoking Vilenkin’s contour. In parallel, I will introduce a 2D cousin obtained via a centrally extended JT/KSY construction. In de Sitter quantum cosmology, superposing Lambda-eigenstates produces unitary evolution in unimodular time, controlled interference near T=0, and sharply separated WKB branches at late times. The same mechanism naturally accommodates transient quantum deformations of global dS and suggests a topology change interpretation in which contracting/expanding branches play the role of Universe/anti-Universe pairs.

In QFT, there exists a well-known set of relations between the scattering amplitudes of gluons in gauge theory and those of gravitons in gravity, known collectively as the double copy. There are many beautiful ways in which this is manifested, famous examples being the KLT double copy, the double copy in the CHY formalism, and the BCJ double copy. In this talk I will show how the double copy relation can be seen arising from amplitude expressions derived using twistor sigma models and the RSVW and Cachazo-Skinner formulae. This talk is based on 2406.04539, with Tim Adamo.