  We present the MSHT20qed set of parton distribution functions (PDFs). These
are obtained from the MSHT20 global analysis via a refit including QED
corrections to the DGLAP evolution at ${\cal O}(\alpha),{\cal
O}(\alpha\alpha_S)$ and ${\cal O}(\alpha^2)$, and containing the photon PDF of
the proton. As in the previous MMHT15qed study we use an input distribution for
the photon that is derived from the LUXqed formulation, and find good
consistency for the photon PDF with that of MMHT15qed, as well as with other
recent sets. We also present a set of QED corrected neutron PDFs and
accompanying photon distribution, and provide the photon PDF of the nucleons
separated into elastic and inelastic contributions. We assess the general
expectations for the impact of photon-initiated (PI) corrections to processes
entering PDF fits, and review the effect of QED corrections on the other
partons and on the fit quality, where electroweak corrections (including PI
production) are appropriately added to the cross sections wherever possible. We
explore the phenomenological implications of this set by comparing to a variety
of benchmark cross sections, finding small but significant corrections due to
the inclusion of QED effects in the PDFs.

High Energy Physics - Phenomenology;High Energy Physics - Experiment