Publications by Kamran Salehi Vaziri

Hilbert space of quantum field theory in de Sitter spacetime

Kamran Salehi Vaziri, João Miguel Augusto Penedones Fernandes

We study the decomposition of the Hilbert space of quantum field theory in (d+1)-dimensional de Sitter spacetime into unitary irreducible representations (UIRs) of its isometry group SO(1,d+1). First, we consider multiparticle states in free theories start ...

2025

The Källén-Lehmann representation in de Sitter spacetime

Kamran Salehi Vaziri, Manuel Loparco, João Miguel Augusto Penedones Fernandes

We study two-point functions of symmetric traceless local operators in the bulk of de Sitter spacetime. We derive the Kallen-Lehmann spectral decomposition for any spin and show that unitarity implies its spectral densities are nonnegative. In addition, we ...

Springer Nature2023

Towards the non-perturbative cosmological bootstrap

Kamran Salehi Vaziri, João Miguel Augusto Penedones Fernandes, Matthijs Jan Hogervorst

We study quantum field theory on a de Sitter spacetime dS(d+1) background. Our main tool is the Hilbert space decomposition in irreducible unitary representations of its isometry group SO(d + 1, 1). As the first application of the Hilbert space formalism, ...

Springer Nature2023

Nonperturbative Quantum Field Theory in Curved Spacetime

Kamran Salehi Vaziri

Quantum Field Theory(QFT) as one of the most promising frameworks to study high energy and condensed matter physics, has been mostly developed by perturbative methods. However, perturbative methods can only capture a small island of the space of QFTs. QFT ...

EPFL2022

Hamiltonian truncation in Anti-de Sitter spacetime

Kamran Salehi Vaziri, João Miguel Augusto Penedones Fernandes, Marco Meineri, Matthijs Jan Hogervorst

Quantum Field Theories (QFTs) in Anti-de Sitter (AdS) spacetime are often strongly coupled when the radius of AdS is large, and few methods are available to study them. In this work, we develop a Hamiltonian truncation method to compute the energy spectrum ...

Springer Nature2021