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.
Highlights
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 133Cs and 127I
The detection of coherent elastic neutrino-nucleus scattering (CEνNS) in 2017 in cesium-iodide (CsI) by the COHERENT experiment [1,2] motivated a burst of studies of diverse physical phenomena, with important implications for high-energy physics, astrophysics, nuclear physics, and beyond [3,4,5,6,7,8,9,10,11,12,13,14,15,16,17]
Form factors represent the Fourier transform of the corresponding nucleon distribution, necessary for obtaining in turn measurements of the neutron rms radius, Rn, which is a crucial ingredient of the nuclear matter equation of state (EOS)
Summary
The detection of coherent elastic neutrino-nucleus scattering (CEνNS) in 2017 in cesium-iodide (CsI) by the COHERENT experiment [1,2] motivated a burst of studies of diverse physical phenomena, with important implications for high-energy physics, astrophysics, nuclear physics, and beyond [3,4,5,6,7,8,9,10,11,12,13,14,15,16,17]. Form factors represent the Fourier transform of the corresponding nucleon distribution, necessary for obtaining in turn measurements of the neutron rms radius, Rn, which is a crucial ingredient of the nuclear matter equation of state (EOS) The latter plays an essential role in understanding nuclei in laboratory experiments and several processes, like heavy-ion collisions, and the structure and evolution of compact astrophysical objects such as neutron stars [23,24,25,26]. For the first time, we obtain a data-driven measurement of the low-energy weak mixing angle with a percent uncertainty, independent of the value of the average neutron rms radius of 133Cs and 127I (that is allowed to vary freely in the analysis), from a simultaneous fit of the COHERENT and APV experimental results.
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