4 Search Results

We study the impact of nuclear structure uncertainties on a measurement of the weak charge of ¹²C at the future Mainz Energy Recovering Superconducting Accelerator (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 . Furthermore, we show that a combination of measurements of the parity-violating asymmetry at forward and backward angles for the same electron-beammore » 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.« less

The recent experimental determination of the parity violating asymmetry A_PV in ⁴⁸Ca and ²⁰⁸Pb at Jefferson Lab is important for our understanding on how neutrons and protons arrange themselves inside the atomic nucleus. To better understand the impact of these measurements, we present a rigorous theoretical investigation of A_PV in ⁴⁸Ca and ²⁰⁸Pb and assess the associated uncertainties. Here, we complement our study by inspecting the static electric dipole polarizability in these nuclei. The analysis is carried out within nuclear energy density functional theory with quantified input. We conclude that the simultaneous accurate description of A_PV in ⁴⁸Ca and ²⁰⁸Pbmore » cannot be achieved by our models that accommodate a pool of global nuclear properties, such as masses and charge radii, throughout the nuclear chart, and describe—within one standard deviation—the experimental dipole polarizabilities in these nuclei.« less

The parity-violating asymmetry A_PV in ²⁰⁸Pb, recently measured by the PREX-2 Collaboration, is studied using modern relativistic (covariant) and nonrelativistic energy density functionals. We first assess the theoretical uncertainty on A_PV which is intrinsic to the adopted approach. To this end, we use quantified functionals that are able to accommodate our previous knowledge on nuclear observables such as binding energies, charge radii, and the dipole polarizability α_D of ²⁰⁸Pb. We then add the quantified value of A_PV together with α_D to our calibration dataset to optimize new functionals. Based on these results, we predict a neutron skin thickness in ²⁰⁸Pbmore » r_skin = 0.19 ± 0.02 fm and the symmetry-energy slope L = 54 ± 8 MeV. These values are consistent with other estimates based on astrophysical data and are significantly lower than those recently reported using a particular set of relativistic energy density functionals. Here, we also make a prediction for the A_PV value in ⁴⁸Ca that will be soon available from the CREX measurement.« less

Here, we present a feasibility study of a simultaneous sub-percent extraction of the weak charge and the weak radius of the ¹²C nucleus using parity-violating electron scattering, based on a largely model-independent assessment of the uncertainties. The corresponding measurement is considered to be carried out at the future MESA facility in Mainz with E_beam = 155 MeV. We find that a combination of a 0.3% precise measurement of the parity-violating asymmetry at forward angles with a 10% measurement at backward angles will allow to determine the weak charge and the weak radius of ¹²C with 0.4% and 0.5% precision, respectively.more » These values could be improved to 0.3% and 0.2% for a 3% backward measurement. This experimental program will have impact on precision low-energy tests in the electroweak sector and nuclear structure.« less