Introducing tools to test Higgs boson interactions via WW scattering: One-loop calculations and renormalization in the Higgs effective field theory

Effective field theories are useful tools to search for physics beyond the Standard Model (SM). However, effective theories can lead to nonunitary behavior with fast growing amplitudes. This unphysical behavior may induce a too large sensitivity to SM deviations, making necessary a unitarization of the amplitudes prior to a comparison with experiment. In the present work, we focus on all the processes entering twoHiggs production via longitudinal WW scattering. We perform a one-loop calculation in the Higgs effective field theory framework of all relevant processes, determining the necessary counterterms in the on-shell scheme, and we study how the full inclusion of the gauge degrees of freedom modifies the previously computed masses and widths of the dynamical resonances arising from the unitarization process in the vector-isovector channel. Altogether, we are able to provide the technical tools that are needed to study the low-energy couplings in the Higgs effective theory under the requirements of unitarity and causality.