Speaker
Description
We present a first-principle lattice QCD calculation of the axial γZ box correction, which is necessary to be taken into account to determine the weak charge in low energy parity violating ep scattering. We calculate the electron energy dependence of axial γZ box up to 155MeV, which perfectly matches the beam energy range of the upcoming PVES experiment at Mainz E < 155MeV . Combining the axial γZ correction given by this work and latest vector γZ contribution calculated by phenomenological method, we update the value of full γZ box correction at E = 155MeV , illustrating that the vector contribution now dominates the uncertainty of total γZ box correction. We also update SM prediction of weak charge using our result at E = 0MeV , and our preliminary result shows that it probably shows a small deviation from the original value in 2022 PDG.
