João Miguel Augusto Penedones Fernandes

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We bootstrap the S matrix of massless particles in unitary, relativistic two dimensional quantum field theories. We find that the low energy expansion of such S matrices is strongly constrained by the existence of a UV completion. In the context of flux tu ...

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, ...

How can a renormalization group fixed point be scale invariant without being conformal? Polchinski (1988) showed that this may happen if the theory contains a virial current a non-conserved vector operator of dimension exactly (d - 1), whose divergence exp ...

We consider constraints on the S-matrix of any gapped, Lorentz invariant quantum field theory in 3+1 dimensions due to crossing symmetry, analyticity and unitarity. We extremize cubic couplings, quartic couplings and scattering lengths relevant for the ela ...

We set up a scattering experiment of matter against an impurity which separates two generic one-dimensional critical quantum systems. We compute the flux of reflected and transmitted energy, thus defining a precise measure of the transparency of the interf ...

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 ...

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 ...

We propose a new non-perturbative method for studying UV complete unitary quantum field theories (QFTs) with a mass gap in general number of spacetime dimensions. The method relies on unitarity formulated as positive semi-definiteness of the matrix of inne ...

We consider the S-matrix bootstrap of four-dimensional scattering amplitudes with O(3) symmetry and no bound states. We explore the allowed space of scattering lengths which parametrize the interaction strength at threshold of the various scattering channe ...

We study gapped 4d quantum field theories (QFTs) obtained from a relevant deformation of a UV conformal field theory (CFT). For simplicity, we assume the existence of a Z(2) symmetry and a single Z2-odd stable particle and no Z(2)-even particles at low ene ...

We review unitarity and crossing constraints on scattering amplitudes for particles with spin in four dimensional quantum field theories. As an application we study two to two scattering of neutral spin 1/2 fermions in detail. Assuming Mandelstam analytici ...

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 ...

We numerically construct asymptotically AdS(4) solutions to Einstein-Maxwell-dilaton theory. These have a dipolar electrostatic potential turned on at the conformal boundary S-2 x R-t. We find two classes of geometries: AdS soliton solutions that encode th ...

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 ...

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 ...

We explore the space of consistent three-particle couplings in Z(2)-symmetric two-dimensional QFTs using two first-principles approaches. Our first approach relies solely on unitarity, analyticity and crossing symmetry of the two-to-two scattering amplitud ...

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 ...

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 ...

We study correlation functions of a conserved spin-1 current J in three dimensional Conformal Field Theories (CFTs). We investigate the constraints imposed by permutation symmetry and current conservation on the form of three point functions and the four p ...

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 ...

João Miguel Augusto Penedones Fernandes

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Flux Tube S-Matrix Bootstrap

Towards the non-perturbative cosmological bootstrap

A structural test for the conformal invariance of the critical 3d Ising model

The S-matrix bootstrap. Part III: higher dimensional amplitudes

Colliders and conformal interfaces

Hamiltonian truncation in Anti-de Sitter spacetime

The Källén-Lehmann representation in de Sitter spacetime

Bootstrapping massive quantum field theories

Bootstrapping QCD Using Pion Scattering Amplitudes

Bootstrapping the a-anomaly in 4d QFTs

Spinning S-matrix bootstrap in 4d

Bounds on photon scattering

Polarised black holes in ABJM

Injecting the UV into the bootstrap: Ising Field Theory

Numerical tests of the large charge expansion

The S-matrix bootstrap IV: multiple amplitudes

Gravity from quantum mechanics of finite matrices

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

Charting the space of 3D CFTs with a continuous global symmetry

Hilbert space of quantum field theory in de Sitter spacetime