Trace and Weyl anomaly for λφ4 theory in curved spacetimes

We define the notion of Weyl anomalies, measuring the violation of local scale invariance, for a general interacting quantum field theory on a curved background spacetime. We discuss some general properties of Weyl anomalies, in particular their relation to the trace anomaly for the interacting stress tensor. We study the trace anomaly in detail for λφ⁴ theory, determining it up to second order in λ and third order in \hbar. We show that to this order in can be brought into a form that fulfills the Wess-Zumino consistency conditions, by exploiting the renormalization freedom in curved spacetime. Our approach is based on the framework of locally covariant QFT. Based on arXiv:2504.17854, joint work with J. Zahn.