Production Shape Effects Beyond Rate Rescaling in Dark Photon Searches
Abstract
Production model uncertainties in long-lived particle searches can affect both the inclusive yield and the kinematic distributions sampled by the experimental acceptance. We isolate the latter effect by comparing the modified Weizsäcker--Williams description with the effective quasireal approximation for dark photon production via proton bremsstrahlung after normalizing both spectra on a common physical domain. At fixed production yield within this domain, the resulting acceptance difference directly measures the departure from rate factorization. In the NA62 beam dump geometry, the central calculation gives a fractional acceptance shift δNF>0.3 at every numerically converged grid point within the displayed NA62 sensitivity overlap. This conclusion persists for effective QRA off-shell scales of 1.0, 1.5, and 2.0~GeV and under the aperture variations considered. Separately, the public NA62 full selection acceptances give a nonconstant dimuon acceptance ratio between the Mixing and Bremsstrahlung production categories, ranging from approximately 0.58 to 4.23, with a median absolute departure from unity of approximately 0.79 over the analyzed HEPData grid. This provides complementary evidence that the published full selection acceptance depends on the production category. More generally, the projection criterion provides a quantitative test of rate factorization. The normalized production shape variation must have negligible projection onto the acceptance response at the required accuracy. When this condition is not satisfied, production model dependence must be propagated through the acceptance calculation or treated as an acceptance uncertainty.
Related
- Indirect searches for dark photon-photon tridents in celestial objects
- Invisible dark-sector radiation: analytic resummation for dark photon searches
- Axion-Like Particle Searches at Muon Colliders: Photon-Neutrino Signatures and Heavy-Neutral-Lepton Feasibility
- Sensitivity targets for dark photon searches in charged kaon decays
- An optimal strategy for experimental searches in high-mass dilepton production at the LHC
BibTeX
@misc{zhong2026production,
title = {{Production Shape Effects Beyond Rate Rescaling in Dark Photon Searches}},
author = {X. Zhong and H. Y. Qiu and X. Q. Shen},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.40052},
eprint = {2609.40052},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.40052},
}
RIS
TY - UNPB
TI - Production Shape Effects Beyond Rate Rescaling in Dark Photon Searches
AU - X. Zhong
AU - H. Y. Qiu
AU - X. Q. Shen
PY - 2026
DA - 2026/09/30
PB - arXiv
DO - 10.48550/arxiv.2609.40052
UR - https://arxiv.org/abs/2609.40052
AB - Production model uncertainties in long-lived particle searches can affect both the inclusive yield and the kinematic distributions sampled by the experimental acceptance. We isolate the latter effect by comparing the modified Weizsäcker--Williams description with the effective quasireal approximation for dark photon production via proton bremsstrahlung after normalizing both spectra on a common physical domain. At fixed production yield within this domain, the resulting acceptance difference directly measures the departure from rate factorization. In the NA62 beam dump geometry, the central calculation gives a fractional acceptance shift δ_NF>0.3 at every numerically converged grid point within the displayed NA62 sensitivity overlap. This conclusion persists for effective QRA off-shell scales of 1.0, 1.5, and 2.0~GeV and under the aperture variations considered. Separately, the public NA62 full selection acceptances give a nonconstant dimuon acceptance ratio between the Mixing and Bremsstrahlung production categories, ranging from approximately 0.58 to 4.23, with a median absolute departure from unity of approximately 0.79 over the analyzed HEPData grid. This provides complementary evidence that the published full selection acceptance depends on the production category. More generally, the projection criterion provides a quantitative test of rate factorization. The normalized production shape variation must have negligible projection onto the acceptance response at the required accuracy. When this condition is not satisfied, production model dependence must be propagated through the acceptance calculation or treated as an acceptance uncertainty.
ER -