We analyze the chart containing both spontaneous and β-delayed proton emission processes in terms of the Coulomb parameter, reduced radius, and angular momentum ($\chi , \rho , l$). We then compare the methods to estimate the decay width $\mathrm{\Gamma }$ of a resonant state in a proton mean field, namely, the continuity equation for outgoing Gamow states, phase shift analysis of real scattering states, and numerical integration of the Schrödinger equation in the complex plane. We show that they provide similar results in the region where it is possible to evaluate the imaginary part of the energy for a resonant (Gamow) state. We then investigate the role of the centrifugal barrier induced by Coulomb interaction and also by proton single-particle orbitals. We show that the so-called universal decay law, connecting the logarithm of the monopole reduced width to the fragmentation potential, remains also valid for β-delayed proton emission processes. This fact allows us to describe experimental data for all proton emission processes in terms of a linear dependence connecting the logarithm of the monopole Coulomb-reduced decay width to the logarithm of the monopole Coulomb penetrability and fragmentation potential within a factor of 3 for absolute values.

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• Beta decay
• Nuclear structure & decays
• Proton emission