decaywidth

In particle physics, the decay width, often denoted by the Greek letter Gamma (Γ), is a measure of the probability that a particular unstable particle will decay. It is inversely proportional to the average lifetime of the particle. A larger decay width signifies a shorter lifetime and a higher probability of decay, while a smaller decay width indicates a longer lifetime and a lower probability of decay. The decay width has units of energy, typically expressed in units of electronvolts (eV) or mega-electronvolts (MeV), and is related to the mass of the particle through the uncertainty principle.

The concept of decay width is crucial for understanding the properties of unstable particles, such as resonances observed in scattering experiments. When a particle can decay into multiple different final states, its total decay width is the sum of the partial decay widths for each possible decay channel. Each partial decay width quantifies the probability of decay into a specific set of particles. The ratio of a partial decay width to the total decay width gives the branching ratio for that particular decay mode. Therefore, decay widths provide vital information about the fundamental interactions governing particle decay processes.