Electron capture and positron emission are competing modes of decay that lead to what?

Electron capture and positron emission are both types of beta decay that involve a proton in the nucleus transforming into a neutron. Despite differing in their mechanisms—electron capture involves an inner orbital electron being captured by the nucleus, while positron emission involves the ejection of a positron—both processes ultimately result in the same transformation of the element.

In both decay processes, a proton is converted to a neutron, resulting in a decrease in the atomic number by one while the mass number remains unchanged. This leads to the formation of the same daughter nuclide. For example, when a proton in a carbon-11 nucleus undergoes positron emission, it transforms into boron-11, while electron capture from carbon-11 also produces boron-11. Thus, both decay modes yield the same daughter nuclide, emphasizing the nature of these specific decay processes being competing channels leading to an identical outcome.