A novel Hamiltonian formulation of $1+1$ dimensional ${\varphi }^4$ theory in Daubechies wavelet basis: momentum space analysis

Abstract

We employ the wavelet formalism of quantum field theory to study field theories in the nonperturbative Hamiltonian framework. Specifically, we make use of Daubechies wavelets in momentum space. These basis elements are characterised by a resolution and a translation index that provides for a natural nonperturbative infrared and ultraviolet truncation of the quantum field theory. As an application, we consider the ${\varphi }^4$ theory and demonstrate the emergence of the well-known nonperturbative strong-coupling phase transition in the $m^2>0$ sector.

Comments: 13 pages, 4 figures, contribution to the 42nd International Symposium on Lattice Field Theory (LATTICE2025) 2-8 November 2025, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India