Publications by João Miguel Augusto Penedones Fernandes

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

Gravity from quantum mechanics of finite matrices

Xiang Zhao, João Miguel Augusto Penedones Fernandes

We revisit the Berenstein-Maldacena-Nastase (BMN) conjecture relating M-theory on a PP-wave background and Matrix Quantum Mechanics (MQM) of N x N matrices. In particular, we study the BMN MQM at strong coupling and finite N and derive an effective Hamilto ...

SPRINGER2025

Renormalization group flows in AdS and the bootstrap program

João Miguel Augusto Penedones Fernandes

We study correlation functions of the bulk stress tensor and boundary operators in Quantum Field Theories (QFT) in Anti-de Sitter (AdS) space. In particular, we derive new sum rules from the two-point function of the stress tensor and its three-point funct ...

Springer Nature2024

Bounds on photon scattering

Denis Karateev, Kelian Philippe Häring, João Miguel Augusto Penedones Fernandes, Marco Meineri, Aditya Hebbar

We study 2-to-2 scattering amplitudes of massless spin one particles in d = 4 space-time dimensions, like real world photons. We define a set of non-perturbative observables (Wilson coefficients) which describe these amplitudes at low energies. We use full ...

SPRINGER2024

Trace anomalies and the graviton-dilaton amplitude

João Miguel Augusto Penedones Fernandes, Biswajit Sahoo

We consider 3+1 dimensional Quantum Field Theories (QFTs) coupled to the dilaton and the graviton. We show that the graviton-dilaton scattering amplitude receives a universal contribution which is helicity flipping and is proportional to ∆c − ∆a along any ...

Springer Nature2024

Numerical tests of the large charge expansion

João Miguel Augusto Penedones Fernandes

We perform Monte-Carlo measurements of two and three-point functions of charged operators in the critical O(2) model in 3 dimensions. Our results are compatible with the predictions of the large charge superfluid effective field theory. To obtain reliable ...

Springer Nature2024

Where is M-theory in the space of scattering amplitudes?

Andrea Guerrieri, João Miguel Augusto Penedones Fernandes

We use the S-matrix bootstrap to carve out the space of unitary, analytic, crossing symmetric and supersymmetric graviton scattering amplitudes in nine, ten and eleven dimensions. We extend and improve the numerical methods of our previous work in ten dime ...

Springer Nature2023

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

Injecting the UV into the bootstrap: Ising Field Theory

Miguel Alexandre Ribeiro Correia, João Miguel Augusto Penedones Fernandes

We merge together recent developments in the S-matrix bootstrap program to develop a dual setup in 2 space-time dimensions incorporating scattering amplitudes of massive particles and matrix elements of local operators. In particular, the stress energy ten ...

Springer Nature2023