Question

Proton or electron charge in the Weinberg-Salam model?

Answer 1

I read Quantum Field Theory, Ryder, second edition. Relation (8.86) brings us the famous result:

e=gsinθWe=gsin⁡θW

Here Ryder says tht ee is the proton charge. However, according to what I understand from the book, that should be the electron charge (which is negative). This is because in relation (8.85) I read that the lagrangian becomes

Li=−gsinθW(e¯γμe)Aμ+....Li=−gsin⁡θW(e¯γμe)Aμ+....

This QED lagrangian can be found on (7.100) as:

Li=−eψ¯γμψAμ+....Li=−eψ¯γμψAμ+....

Just below on the page Ryder states that here e<0 is the electron charge, which would also agree with the QED form of the lagrangian in the (+,-,-,-) convention, as presented in Gauge covariant derivative in different books.

From these I conclude that in the relation e=gsinθWe=gsin⁡θW above ee is the electron charge and not the proton charge as stated by Ryder. Where do I make a mistake

Answer 2

The Standard Model of particle physics is the theory describing three of the four known fundamental forces (the electromagnetic, weak, and strong interactions, and not including the gravitational force) in the universe, as well as classifying all known elementary particles. It was developed in stages throughout the latter half of the 20th century, through the work of many scientists around the world, with the current formulation being finalized in the mid-1970s upon experimental confirmation of the existence of quarks. Since then, confirmation of the top quark (1995), the tau neutrino(2000), and the Higgs boson (2012) have added further credence to the Standard Model. In addition, the Standard Model has predicted various properties of weak neutral currents and the W and Z bosons with great accuracy.