Search for Light Gauge Bosons of the Dark Sector at the Mainz Microtron

TL;DR

This paper reports a new experimental limit on light gauge bosons that could mediate interactions between dark matter and standard model particles, using electron scattering at the Mainz Microtron.

Contribution

The study provides the first significant constraints on light gauge bosons in a specific mass range, improving previous limits by nearly an order of magnitude.

Findings

Reduced the limit for a narrow gauge boson coupling to e^+e^- by nearly tenfold.

Demonstrated the effectiveness of high current, high resolution fixed target experiments in beyond-standard-model searches.

Extended exclusion limits for dark sector gauge bosons in the 210-300 MeV/c^2 mass range.

Abstract

A new exclusion limit for the electromagnetic production of a light U(1) gauge boson {\gamma}' decaying to e^+e^- was determined by the A1 Collaboration at the Mainz Microtron. Such light gauge bosons appear in several extensions of the standard model and are also discussed as candidates for the interaction of dark matter with standard model matter. In electron scattering from a heavy nucleus, the existing limits for a narrow state coupling to e^+e^- were reduced by nearly an order of magnitude in the range of the lepton pair mass of 210 MeV/c^2 < m_e^+e^- < 300 MeV/c^2. This experiment demonstrates the potential of high current and high resolution fixed target experiments for the search for physics beyond the standard model.