Possible Beyond the Standard Model Physics Motivated by Muonic Puzzles

TL;DR

This paper investigates potential new physics beyond the Standard Model motivated by discrepancies in muonic measurements, exploring scalar bosons, form factors, and model-independent constraints to explain the proton radius and muon magnetic moment puzzles.

Contribution

It introduces novel methods to analyze experimental data and constrains possible new particles that could resolve muonic puzzles, advancing beyond previous theoretical approaches.

Findings

Constraints on new spin-0 and spin-1 particles from beam dump experiments.

Proposed measurements to test nucleon form factors.

Model-independent bounds on new physics explanations.

Abstract

Recent measurements of the proton radius using the Lamb shift in muonic hydrogen are troublingly discrepant with values extracted from hydrogen spectroscopy and electron-proton scattering experiments. This discrepancy, which differs by more than five standard deviations, may be a signal of new physics caused by a violation of lepton universality. Another candidate for a new physics signal is the muon anomalous magnetic moment. The measurement at BNL differs from the standard model prediction by at least three standard deviations. Motivated by these two puzzles, first we use polarized lepton-nucleon elastic scattering to search for a new scalar boson, and furthermore we suggest new measurements of the nucleon form factors. Next, we display a method to analyze the beam dump experiments without using approximation on phase space, and we use it to constrain all possible new spin-0 and spin-1 particles, and a variety of other measurements to study the possibility of the new physics. Finally, assuming a new scalar boson can solve the two puzzles simultaneously, we present a general model-independent analysis and constrain the existence of the new physics.