  Among the unitarity cuts of 4-loop massless propagators two kinds are
currently fully known: the 2-particle cuts with 3 loops corresponding to
form-factors, and the 5-particle phase-space integrals. In this paper we
calculate master integrals for the remaining ones: 3-particle cuts with 2
loops, and 4-particle cuts with 1 loop. The 4-particle cuts are calculated by
solving dimensional recurrence relations. The 3-particle cuts are integrated
directly using 1->3 amplitudes with 2 loops, which we also re-derive here up to
transcendentality weight 7. The results are verified both numerically, and by
showing consistency with previously known integrals using Cutkosky rules. We
provide the analytic results in the space-time dimension 4-2{\epsilon} as
series in {\epsilon} with coefficients being multiple zeta values up to weight
12. In the ancillary files we also provide dimensional recurrence matrices and
SummerTime files suitable for numerical evaluation of the series in arbitrary
dimensions with any precision.
