Polarized Lepton-Nucleon Elastic Scattering and a Search for a Light Scalar Boson

TL;DR

This paper investigates how polarized lepton-nucleon elastic scattering can be used to search for a light scalar boson, which might explain anomalies like the proton radius and muon g-2 puzzles, and proposes new measurement techniques.

Contribution

It introduces a novel approach to detect a light scalar boson via polarized scattering and generalizes methods to measure nucleon form factors more precisely.

Findings

Scalar boson effects are significant in specific kinematic regions.

New techniques for measuring nucleon form factors with polarized muons.

Potential to resolve proton radius and muon g-2 anomalies.

Abstract

Lepton-nucleon elastic scattering, using the one-photon and one-scalar-boson exchange mechanisms considering all possible polarizations, is used to study searches for a new scalar boson and suggest new measurements of the nucleon form factors. A new light scalar boson, which feebly couples to leptons and nucleons, may account for the proton radius and muon $g-2$ puzzles. We show that the scalar boson produces relatively large effects in certain kinematic region when using sufficient control of lepton and nucleon spin polarization. We generalize current techniques to measure the ratio $G_E/G_M$ and present a new method to separately measure $G_M^2$ and $G_E^2$ using polarized incoming and outgoing muons.