In addition to charge and baryon number, another conserved quantity in particle interactions is lepton number. The six leptons have lepton number +1, and their antiparticles have lepton number −1. The lepton numbers for each generation (electron, muon, tau) are separately conserved. For example, an electron has electron-lepton number +1, while the electron antineutrino has electron-lepton number −1. What is the missing particle X in the following decay? π⁺ → X + ν_μ A) μ⁻ B) μ⁰ C) π⁻ D) π⁰ E) μ⁺

Question

Quizplus · Accepted Answer

The decay involves a muon neutrino (νμ), indicating the conservation of muon lepton number. Since a neutrino has a lepton number of +1, the missing particle must be a muon (μ) with the same lepton number to conserve the overall muon lepton number. The correct particle is a positively charged muon (μ+), which has a lepton number of +1, matching the conservation requirements.

In Addition to Charge and Baryon Number, Another Conserved Quantity