Hyperladung

Hyperladung, also known as hypercharge in English, is a quantum number in particle physics associated with the U(1)_Y gauge symmetry of the electroweak sector of the Standard Model. It is a organizing principle that, together with weak isospin, helps classify particles and determine their electric charges before electroweak symmetry breaking.

In the Standard Model, each fundamental field carries a hypercharge Y determined by its representation under SU(2)_L × U(1)_Y. Typical assignments are: left-handed leptons form SU(2)_L doublets with Y = -1; right-handed charged leptons are singlets with Y = -2; left-handed quarks are doublets with Y = 1/3; right-handed up quarks have Y = 4/3; right-handed down quarks have Y = -2/3. The Higgs field has Y = 1. These assignments are chosen to ensure gauge anomaly cancellation and to reproduce observed electric charges.

The electric charge Q of a particle is related to its hypercharge and weak isospin I3 by the relation Q = I3 + Y/2. This formula, together with the mechanism of electroweak symmetry breaking, explains how the photon and Z boson emerge from the original gauge fields and how observed charges such as −1 for the electron or +2/3 for the up quark arise.

Hyperladung is a fundamental gauge quantity in the electroweak theory and remains a core part of the Standard Model’s gauge structure. Its history is tied to the development of electroweak unification in the 1960s and 1970s by Glashow, Weinberg, and Salam. In German-language physics literature, Hyperladung is the standard term for hypercharge.