On-Shell Methods

On-shell methods are techniques in quantum physics used to calculate particle interactions by focusing solely on observable, real particles—those that can be directly detected. Instead of dealing with complex intermediate steps involving hypothetical or "virtual" particles, these methods analyze scattering processes using only the measurable properties of particles, like their energy and momentum. This approach simplifies calculations, improves efficiency, and provides deeper insight into particle behavior, making it a powerful tool for understanding fundamental forces without relying on complicated, abstract mathematical constructs beyond what can be physically observed.