How many pairs of leptons exist, according to standard particle physics?

In standard particle physics, leptons are categorized into three generations, with each generation containing a pair of leptons: a charged lepton and its corresponding neutrino. The charged leptons are the electron, muon, and tau, while their corresponding neutrinos are the electron neutrino, muon neutrino, and tau neutrino.

Thus, there are three generations of leptons, leading to three distinct pairs:

1. The electron and electron neutrino.

2. The muon and muon neutrino.

3. The tau and tau neutrino.

This structure of leptons is fundamental to the Standard Model of particle physics, which organizes all known elementary particles into these families. Each of these pairs contributes to the understanding of weak interactions in particle physics. Therefore, the correct answer reflects the three pairs of leptons that exist in this framework.