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arXiv · 2609.04016

Quasi-local form for $\alpha$--$z$ R\'enyi QNEC from fixed-ray escorts

Tanay Kibe·Pratik Roy
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Abstract

The fixed-ray escort integral representation expresses $\alpha$--$z$ R\'enyi divergence as an average over ordinary relative entropy of a family of escort states. Working in the standard UV-regulated density-matrix description of QFT subregions, we use this representation to derive an escort-averaged entanglement first law, an escort-averaged representation of the $\alpha$--$z$ information kernel, and an escort-averaged Bekenstein-type bound for ball-shaped regions in conformal field theories. For the conjectural $\alpha$--$z$ quantum null energy condition (QNEC), we obtain a quasi-local form in which the null energy is evaluated in an escort-averaged state and is corrected by an escort-transport term encoding the failure of escort formation to commute with restriction to a null-deformed region. The $z=\alpha$ specialization gives a similar quasi-local form of the R\'enyi QNEC for sandwiched R\'enyi divergence. We explicitly compute the R\'enyi QNEC, including the explicit escort transport term, for coherent-state excitations in a free scalar field theory. For the same coherent family, we obtain a positive $\alpha$--$z$ null Hessian, verifying the conjectured diagonal $\alpha$--$z$ QNEC for this family.

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Tanay Kibe, Pratik Roy. 2026-09-03. Quasi-local form for $\alpha$--$z$ R\'enyi QNEC from fixed-ray escorts. https://arxiv.org/abs/2609.04016

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