What about physics before electroweak symmetry breaking?

[naima]

Hi Pf

I would like to know if the standard model without symmetry breaking can describe
the universe after the big bang before the moment when EW symmetry breaking occured.
Had we v = c for all particles?
were electrons electrically charged? were there photons or B ? Z0 were not born?
Could anyone tell me what we know about this period?

 

[ofirg]

If there is no physics beyond the standard model (SM) up to very high energies, then yes the SM with an unbroken gauge symmetry should describe the particles and their interactions at temperatures higher than the phase transition temperature.

All SM particles would be massless except the higgs itself ( protons and neutrons woudn't exist, only massless quarks and gluons). massless of course implies v=c. At least one Additional particle which accounts for the dark matter is thought to exist, which may very well be massive even when the SM symmetry is unbroken.

Electric charge woudn't be a useful quantum number, rather hypercharge and weak isospin would be.

photons and Z bosons woudn't be useful degrees of freedom, rather $B$ and $W^{1,2,3}$ would be.

We know however, that some new physics must be relevant in order to produce the overabundance of matter over antimatter, which can't be explained in the framework of the SM. The asymmetry however might have been produced at temperatures much higher than the EW phase transition.

 

[naima]

thank you
if T3 and Yw are good number why not Q (the sum T3 + Yw/2)?

 

[ofirg]

The electric charge as defined will still be conserved, but its conservation won't give any further information on top of the conservation of $T_{3}$ and $y$ and thus would not be of any particular use.