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arXiv · 2102.06153

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

M. Cadeddu·N. Cargioli·F. Dordei·C. Giunti·Y. F. Li·E. Picciau·C. A. Ternes·Y. Y. Zhang
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Abstract

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 $^{133}\text{Cs}$ and $^{127}\text{I}$. In combination with the atomic parity violation (APV) experimental result, we derive the most precise measurement of the neutron rms radii of $^{133}\text{Cs}$ and $^{127}\text{I}$, disentangling for the first time the contributions of the two nuclei. By exploiting these measurements we determine the corresponding neutron skin values for $^{133}\text{Cs}$ and $^{127}\text{I}$. 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 $^{208}\text{Pb}$ 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 $^{133}\text{Cs}$ and $^{127}\text{I}$, 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.

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M. Cadeddu, N. Cargioli, F. Dordei, C. Giunti, Y. F. Li, E. Picciau, C. A. Ternes, Y. Y. Zhang. 2021-09-11. New insights into nuclear physics and weak mixing angle using electroweak probes. https://doi.org/10.1103/physrevc.104.065502

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