The Edge of Entanglement: Getting the Boundary Right for Non-Minimally Coupled Scalar Fields

Abstract

In entanglement computations for a free scalar field with coupling to background curvature, there is a boundary term in the modular Hamiltonian which must be correctly specified in order to get sensible results. We focus here on the entanglement in flat space across a planar interface and (in the case of conformal coupling) other geometries related to this one by Weyl rescaling of the metric. For these "half-space entanglement" computations, we give a new derivation of the boundary term and revisit how it clears up a number of puzzles in the literature, including mass corrections and twist operator dimensions. We also discuss how related boundary terms may show up in other field theories.

34 + 7 pages, 8 figures, v2: references added, typos corrected, v3: minor changes

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Cited by in corpus (4)

• Monodromy Defects in Free Field Theories
• On the continuum limit of the entanglement Hamiltonian of a sphere for the free massless scalar field
• Hyperbolic cylinders and entanglement entropy: gravitons, higher spins, $p$-forms
• Partition functions of higher derivative conformal fields on conformally related spaces