Phases of Surface Defects in Scalar Field Theories

We study mass-type surface defects in a free scalar and Wilson-Fisher (WF) $O(N)$ theories. We obtain exact results for the free scalar defect, including its RG flow and defect Weyl anomaly. We classify phases of such defects at the WF fixed point near four dimensions, whose perturbative RG flow is investigated. We propose an IR effective action for the non-perturbative regime and check its self-consistency.