5–9 Jul 2026
University of Canterbury
Pacific/Auckland timezone

Perturbative unitarity bounds on field-space curvature in de Sitter spacetime: purity vs scattering amplitude

6 Jul 2026, 12:05
2m
Room E8 (Rātā / Engineering Core Building, University of Canterbury)

Room E8

Rātā / Engineering Core Building, University of Canterbury

63 Creyke Road, Ilam, Christchurch 8041, New Zealand

Speaker

Masataka Ishikawa (the University of Tokyo)

Description

We study perturbative unitarity bounds on the field-space curvature in de Sitter spacetime, using the momentum-space entanglement approach recently proposed by Duaso Pueyo, Goodhew, McCulloch, and Pajer. As an illustration, we perform a perturbative computation of the purity in two-scalar models and compare the resulting unitarity bounds with those obtained via a flat space approximation. In particular, we find that perturbative unitarity imposes an upper bound on the field-space curvature of the Hubble scale order, in addition to a bound analogous to the flat space result. This reflects the thermal nature of de Sitter spacetime. We also discuss generalizations to higher-dimensional field spaces. This poster presentation is based on arXiv: 2507.00850.

Research Area High-Energy Particle Physics

Author

Masataka Ishikawa (the University of Tokyo)

Co-authors

Dr Kanji Nishii Mr Qianhang Cai (The University of Tokyo) Tomoya Inada (The University of Tokyo, Komaba) Prof. Toshifumi Noumi (The University of Tokyo)

Presentation materials