Measurement of Solar $pp$ Neutrino Flux Using Electron Recoil Data from PandaX-4T Commissioning Run

The proton-proton (pp) fusion chain dominates the neutrino production in the Sun. The uncertainty of the predicted pp neutrino flux is at the sub-percent level, whereas that of the best measurement is O(10%). In this study, for the first time, we measure solar pp neutrinos in the electron recoil energy range from 24 to 144 keV using the PandaX-4T commissioning data with 0.63 tonne x year exposure. The pp neutrino flux is determined as, (8.0 +/- 3.9 (stat) +/- 10.0 (syst) x 10(10) s(-1) cm(-2) which is consistent with the Standard Solar Model and existing measurements, corresponding to an upper flux limit of 23.3 x 10(10) at 90% C.L..