Measuring the Electric and Magnetic Form Factors of Protons and Antiprotons at small $Q^2$ and the charge radii of hadrons

Stephan Paul

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arXiv · 2311.00498

Measuring the Electric and Magnetic Form Factors of Protons and Antiprotons at small $Q^2$ and the charge radii of hadrons

Stephan Paul

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Abstract

Charge radii of hadrons are back in the focus since precision spectroscopic measurements in muonic hydrogen revealed a proton charge radius considerably smaller than generally accepted ever since R.~Hofstaedter's pioneering experiments. Recent experimental results also point to an underestimation of systematic uncertainties in most previous measurements. A new method was thus proposed by AMBER at CERN using elastic scattering by very high energy muons using an active hydrogen target. With a simplified setup we may resume elastic scattering of $\pi$ and K mesons on electrons in inverse kinematics, and, for the first time, probe antiprotons with few percent precision for their charge radius. Applying this method also for protons allows a separation of $G_E^p(Q^2)$ and $G_M^p(Q^2)$ down to $Q^2=10^{-3}(GeV/c)^2$.

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Stephan Paul. 2023-11-01. Measuring the Electric and Magnetic Form Factors of Protons and Antiprotons at small $Q^2$ and the charge radii of hadrons. https://arxiv.org/abs/2311.00498

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