First Measurement of the Flavor Dependence of Nuclear PDF Modification Using Parity-Violating Deep Inelastic Scattering

We propose a clean and precise measurement of the flavor dependence of the EMC effect using parity-violating deep inelastic scattering on a 48Ca target. While the EMC effect has been known for almost 40 years, there are essentially no reliable experimental constraints on its flavor dependence. The proposed measurement will provide an extremely sensitive test for flavor dependence in the modification of nuclear pdfs for neutron-rich nuclei. A measurement of the flavor dependence will provide new and vital information and help to explain nucleon modification at the quark level. In addition to helping understand the origin of the EMC effect, a flavor-dependent nuclear pdf modification could have a significant impact on a range of processes, including neutrino-nucleus scattering, nuclear Drell-Yan processes, or e-A observables at the Electron-Ion Collider.

The parity-violating asymmetry (A_PV) from ⁴⁸Ca using an 11 GeV beam at 80 μA will be measured using the SoLID detector in its PVDIS configuration. The A_PV provides a particularly sensitive method to obtain flavor-dependent effects in nuclear modification as it is a ratio of the weak-to-electromagnetic interactions, which gives access to ratios of quark distributions. In 68 days of data taking, we will reach 0.7-1.3 % statistical precision for 0.2<x<0.7 with 0.6-0.7 % systematic uncertainties. The proposal has received conditional approval from JLab PAC50 in 2022.