# Is the mass of the Z due to mixing with the photon “precursor” B or to interaction with the Higgs?

I want to get something clear that I do not seem to understand. I used to read that the photon A and the Z boson are (different) linear combinations between the W^0 (neutral weak boson before SU(2) breaking) and the B ("photon precursor" before SU(2) symmetry breaking).

Nowadays it is more common to say that the Z gets its mass from the Higgs through Yukawa coupling.

Which is the right way to look at things? What is wrong or incomplete in the previous description? Where exactly does the Z mass come from - and is it due to the Higgs mass or not?

• no, the Z mass is not coming from Yukawa coupling (Yukawa coupling means a coupling between a scalar and 2 fermions, while the Z boson is a spin 1 boson). It comes from the gauge interaction, Higgs boson carrying both weak hypercharge and weak isospin quantum numbers. – Paganini Jul 28 '15 at 19:39
• Paganini, thank you. So what is the exact origin of the Z mass? And does the Higgs play a role in the mass of the Z or not? – Hans973 Jul 29 '15 at 4:06

It seems to me that there is nothing fundamentally wrong about your statements, thus I also don't see any contradictions. The electroweak unification states that, as you said, the $Z$ and the $\gamma$ are different linear combinations of $B^0$ and $W^0$. This all works very nicely, there is just the problem of the masses which is then fixed my the Higgs mechanism.