Constraints on Hidden Photon Models from Electron g-2 and Hydrogen Spectroscopy

TL;DR

The paper evaluates constraints on hidden photon models using electron g-2 and hydrogen spectroscopy within a self-consistent framework that accounts for how hidden photons affect the determination of the fine-structure constant and R∞. It derives the leading electron g-2 contributions from hidden-photon loops and alpha-shift, showing the electron bound is stronger than previous work and largely excludes much of the muon g-2–favored parameter space. Hydrogen transition frequencies are exploited via R∞-independent frequency ratios to obtain a independent bound, which is weaker but complementary and potentially improvable. Overall, the study tightens the viable hidden-photon parameter space and emphasizes the importance of consistent input parameter treatment for low-energy precision tests of new physics, with future experiments anticipated to probe remaining regions.

Abstract

The hidden photon model is one of the simplest models which can explain the anomaly of the muon anomalous magnetic moment (g-2). The experimental constraints are studied in detail, which come from the electron g-2 and the hydrogen transition frequencies. The input parameters are set carefully in order to take dark photon contributions into account and to prevent the analysis from being self-inconsistent. It is shown that the new analysis provides a constraint severer by more than one order of magnitude than the previous result.

Figures (2)

• Figure 1: The constraints on the hidden photon model are shown. The red--solid line is updated by the analysis in this paper, which is compared to the previous one Pospelov:2008zw, drawn by the red--dashed line. The constraint from the transition frequencies is also displayed by the blue solid line, where the $1S_{1/2}-2S_{1/2}$ and $2S_{1/2}-8D_{5/2}$ transitions are analyzed with the proton radius input by the electron--proton experiment Mohr:2012ttBernauer:2010wm. The regions favored by the muon $g-2$ at the 1 and 2$\sigma$ levels are shown by the dark and light green bands, respectively.
• Figure 2: The updated constraint from the electron $g-2$ is compared to the other experimental bounds Hewett:2012nsBabusci:2012cr. The gray regions have been already excluded by them. The green bands are favored by the muon $g-2$ (see Fig. \ref{['fig:darkphoton']}). The regions enclosed by the colored--dashed lines are suggested to be covered in future. See Ref. Hewett:2012ns for details of the experiments, where the excluded regions and future sensitivities are found. The recent update of the KLOE bound Babusci:2012cr is included (see Note Added).