Hunting All the Hidden Photons (1803.05466v3)

Abstract: We explore constraints on gauge bosons of a weakly coupled $U(1){B-L}$, $U(1){L_\mu-L_e}$, $U(1){L_e-L\tau}$ and $U(1){L\mu-L_\tau}$. To do so we apply the full constraining power of experimental bounds derived for a hidden photon of a secluded $U(1)_{X}$ and translate them to the considered gauge groups. In contrast to the secluded hidden photon that acquires universal couplings to charged Standard Model particles through kinetic mixing with the photon, for these gauge groups the couplings to the different Standard Model particles can vary widely. We take finite, computable loop-induced kinetic mixing effects into account, which provide additional sensitivity in a range of experiments. In addition, we collect and extend limits from neutrino experiments as well as astrophysical and cosmological observations and include new constraints from white dwarf cooling. We discuss the reach of future experiments in searching for these gauge bosons.

• The paper presents a comprehensive analysis of hidden photon constraints by recasting diverse experimental data into limits on multiple U(1) gauge symmetries.
• The paper leverages beam-dump, collider, and astrophysical observations, including white dwarf cooling and neutrino interactions, to tighten gauge boson bounds.
• The paper outlines future experimental directions, such as SHiP and Belle II, that promise to probe deeper into unexplored parameter spaces.

Overview of Constraints on Hidden Photons

The paper "Hunting All the Hidden Photons" by Martin Bauer, Patrick Foldenauer, and Joerg Jaeckel presents a comprehensive analysis of constraints on gauge bosons associated with various weakly coupled $U(1)$ gauge symmetries, specifically $U(1)_{B-L}$, $U(1)_{L_\mu-L_e}$, $U(1)_{L_e-L_\tau}$, and $U(1)_{L_\mu-L_\tau}$. By leveraging experimental bounds previously established for a secluded $U(1)_X$ hidden photon model, the authors translate these limits to the additional gauge groups under consideration, taking into account variations in coupling to Standard Model (SM) particles. The paper integrates kinetic mixing effects derived through loop calculations, contributing to sensitivity in experimental setups.

Constraints and Implications

The authors gather and extend experimental and observational constraints from a multitude of sources, including neutrino experiments, astrophysical data like white dwarf cooling, and cosmological observations. They produce new limits derived from such phenomena, significantly broadening the landscape of potential hidden gauge bosons.

1. Experimental Bounds:
   • Various experiments, including beam-dump and fixed-target setups, provide crucial bounds. Electron beam dumps like SLAC E137 and proton beam dumps like CHARM and U70/Nu-Cal contribute significantly to the exclusion limits for these gauge bosons.
   • Collider experiments, such as those conducted at LHCb, BaBar, Belle, and KLOE, also offer critical limits through channels involving vector meson decays as well as rare muon and tau decay processes.
2. Astrophysical and Cosmological Limits:
   • White dwarf cooling constraints offer robust bounds at low masses for some of these gauge bosons.
   • The interaction with cosmic neutrinos can have profound implications for the effective number of neutrino species at Big Bang Nucleosynthesis (BBN).
3. Neutrino Interactions:
   • Neutrino trident production, Borexino, TEXONO, and coherent elastic neutrino-nucleus scattering (CEνNS) experiments provide important constraints, especially on $U(1)_{L_\mu-L_\tau}$ and $U(1)_{L_\mu-L_e}$.

Highlighted Results

The findings include projected constraints from future experiments like SHiP and Belle II, promising to explore new parameter spaces. The paper also discusses how models like $U(1)_{L_\mu-L_\tau}$ remain relevant as potential solutions to address anomalies such as the muon $g-2$.

Future Directions

The paper identifies clear paths for advancing hidden photon searches. Planned improvements in beam dumps, FASER, and muon-specific experiments like NA64μ are anticipated to explore unexplored parameter regions. These initiatives reflect a growing potential for experimental innovation and theoretical advancement in assessing new physics beyond the Standard Model.

In conclusion, this work systematically consolidates and expands the constraints on non-standard gauge bosons, refining the landscape of hidden photon searches. The methodological approach of recasting existing experimental data into stringent bounds for diverse gauge theories illustrates the paper's significant contribution to ongoing investigations in particle physics.