The lepton number is generalized to the lepton charge.

我们把轻子数推广为轻子荷。

When a neutrino transforms a quark, a lepton is emitted.

当中微子使一种夸克转化为另一种夸克时,会发射出一个轻子.

After the lepton era, its number density would be higher than that of baryon by a factor of about 109.

中微子是唯一的始终可与光子数密度相比拟的粒子。