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 × year exposure. The pp neutrino flux is determined as (8.0±3.9(stat)±10.0(syst))×10¹⁰ s⁻¹cm⁻², which is consistent with the Standard Solar Model and existing measurements, corresponding to an upper flux limit of 23.3×10¹⁰ s⁻¹cm⁻² at 90% C.L..