New insights into nuclear physics and weak mixing angle using electroweak probes

Using the new results on coherent elastic neutrino-nucleus scattering data in cesium-iodide provided by the COHERENT experiment, we determine a new measurement of the average neutron rms radius of Cs-133 and I-127. In combination with the atomic parity violation (APV) experimental result, we derive the most precise measurement of the neutron rms radii of Cs-133 and I-127, disentangling for the first time the contributions of the two nuclei. By exploiting these measurements we determine the corresponding neutron skin values for Cs-133 and I-127. These results suggest a preference for models which predict large neutron skin values, as corroborated by the only other electroweak measurements of the neutron skin of Pb-208 performed by PREX experiments. Moreover, for the first time, we obtain a data-driven APV+COHERENT measurement of the low-energy weak mixing angle with a percent uncertainty, independent of the value of the average neutron rms radius of Cs-133 and I-127, that is allowed to vary freely in the fit. The value of the low-energy weak mixing angle that we found is slightly larger than the standard model prediction.