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arXiv · 2302.11126

Global QCD Analysis and Dark Photons

N. T. Hunt-Smith·W. Melnitchouk·N. Sato·A. W. Thomas·X. G. Wang·M. J. White
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Abstract

We perform a global QCD analysis of high energy scattering data within the JAM Monte Carlo framework, including a coupling to a dark photon that augments the standard model electroweak coupling via kinetic mixing with the hypercharge $B$ boson. Including the most recent measurement of the anomalous magnetic moment of the muon as a constraint, we find a significant reduction in the combined $\chi^2$, favoring the inclusion of a dark photon, with a statistical significance in excess of 8$\sigma$. With respect to the experimental data, the improvements in the theoretical predictions are spread across a wide range of $x$ and $Q^2$, with the largest improvement corresponding to neutral current data from HERA, while the best fit yields a value of $g-2$ which significantly reduces the disagreement with the latest experimental determination. The best fit yields a dark photon mass in the range 4.2--6.2 GeV and a mixing parameter of order 0.1.

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N. T. Hunt-Smith, W. Melnitchouk, N. Sato, A. W. Thomas, X. G. Wang, M. J. White. 2023-02-22. Global QCD Analysis and Dark Photons. https://arxiv.org/abs/2302.11126

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