Simultaneous Extraction of the Weak Radius and the Weak Mixing Angle from Parity-Violating Electron Scattering on ¹²C

We study the impact of nuclear structure uncertainties on a measurement of the weak charge of ¹²C at the future MESA facility in Mainz. Information from a large variety of nuclear models, accurately calibrated to the ground-state properties of selected nuclei, suggest that a $0.3$% precision measurement of the parity-violating asymmetry at forward angles will not be compromised by nuclear structure effects, thereby allowing a world-leading determination of the weak charge of ¹²C. Further, we show that a combination of measurements of the parity-violating asymmetry at forward and backward angles for the same electron beam energy can be used to extract information on the nuclear weak charge distribution. We conclude that a $0.34$% precision on the weak radius of ¹²C may be achieved by performing a $3$% precision measurement of the parity-violating asymmetry at backward angles.