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arXiv · 2607.09660

Nonlinear particle detectors across the Rindler firewall

Matheus H. Zambianco·Eduardo Martín-Martínez
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Abstract

We investigate Unruh-DeWitt detectors coupled to composite observables of a quantum scalar field, including quadratic coupling to the field momentum and coupling to the local energy density. We develop a distributional framework for evaluating the corresponding detector response functions and apply it to detectors crossing the Rindler firewall. While we recover the finite response of the derivative-coupling model, we show that quadratic momentum coupling leads to products of distributions that do not admit a canonical, regulator-independent definition in the sharp-firewall idealization. The vacuum correspondence between the local energy-density and quadratic momentum responses motivates the conjecture that analogous difficulties may arise for energy-density coupling in the sharp firewall model. Within the sharp, pointlike composite-coupling model considered here, our analysis further suggests that these pathologies originate from the discontinuous severing of correlations across the Rindler horizon.

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Matheus H. Zambianco, Eduardo Martín-Martínez. 2026-07-10. Nonlinear particle detectors across the Rindler firewall. https://arxiv.org/abs/2607.09660

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