Hogervorst, MatthijsMeineri, MarcoPenedones, JoaoVaziri, Kamran Salehi2021-09-112021-09-112021-09-112021-08-1610.1007/JHEP08(2021)063https://infoscience.epfl.ch/handle/20.500.14299/181267WOS:000686712300003Quantum 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 of QFTs in two-dimensional AdS. The infinite volume of constant timeslices of AdS leads to divergences in the energy levels. We propose a simple prescription to obtain finite physical energies and test it with numerical diagonalization in several models: the free massive scalar field, phi(4) theory, Lee-Yang and Ising field theory. Along the way, we discuss spontaneous symmetry breaking in AdS and derive a compact formula for perturbation theory in quantum mechanics at arbitrary order. Our results suggest that all conformal boundary conditions for a given theory are connected via bulk renormalization group flows in AdS.Physics, Particles & FieldsPhysicsconformal field theoryfield theories in lower dimensionsnonperturbative effectsising field-theoryboundary-conditionsmagnetic-fields-matrixscatteringrenormalizationmodelflowtext::journal::journal article::research article