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in the epochs of the very early universe, the different forces separated from each other in succession. if this is true then at one point there was an electroweak force. and before that, there was the electronuclear force, and before that all four were unified.

my question is about what order the different particles of the standard model came into existence. but the question is in light of the unified nature of the forces.

how did the electroweak force behave before it split? where were w-bosons and photons at this time? where were the leptons? if the forces were "unified," were the particles unified as well? was there a boson that mediated the electroweak interaction? a boson that no longer exists?

and likewise, was there another boson that mediated the electronuclear force when the strong force was still unified with the electroweak?

i have a very rudimentary understanding, but my current framework has me thinking along these lines.

the higgs boson would had to have come first, in order for anything else to even occupy spacetime. then some sort of 4-force boson and 4-way unified fermions? then gravitons split off, leaving a 3-force boson. then the gluons split,leaving a two-force boson and quarks and leptons. and finally the w-bosons and photons separated, allowing for all the elementary and composite particles we have now.

how far off am i?

do we know what particles came in what order and during which epochs?

blacktopshaman
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  • Why the other particles can't occupy space without the Higgs? Only after the Higgs potential broke, particles acquired mass. Like the W- and Z- particles, while gluons and photons and gravitons remained massless. I think all particles existed in a massless state, interacting by the unbroken force field. One by one they split off giving the massless graviton and massless stringweakelectrofirce particles, from which the massless gluons and massless electroweak force emerged, and at last the massive weak and massless photon. Im not sure when the matter particles got their mass. – Gerald Aug 18 '22 at 18:54

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The current mainstream cosmological model is the Big Bang. The model uses our particle physics standard model in order to project back in time, and see if the predictions fit the astrophysical observations. Here the symmetry breaking order in the BB model is summarized:

big bang timeline

It presupposes that a unified quantum field theory exists including gravity, which is not true because gravity is not definitively quantized, only effective models exist.It gives the order of the symmetry breaking according to the existing BB model.

All the elementary particles in the standard model of particle physics are hypothesized to exist , as the SU(3)xSU2xU(1) symmetry has the location of the particles whether symmetry is broken or not.

So the particles in the present theory are always there, whether mass less before symmetry breaking, or massive after.

anna v
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  • When did the matter particles acquire mass? For example, did the electrons acquire mass at the breaking of SU(2)×U(1)? Or only the W and Z? – Gerald Aug 18 '22 at 18:56
  • Mass comes with the higgs mechanism https://en.wikipedia.org/wiki/Higgs_mechanism. see also https://physics.stackexchange.com/questions/253762/why-do-people-say-that-the-higgs-mechanism-gives-mass-to-the-gauge-bosons-withou – anna v Aug 18 '22 at 19:16
  • But aren't it only W- and Z- acquiring mass in the electroweak symmetry break? – Gerald Aug 18 '22 at 19:24
  • If you read the question and answer you will see that it is easy for the spin 1/2 to acquire mass at the same time with the symmetry breaking for the bosons, it is the bosons that require special mathematics. – anna v Aug 18 '22 at 19:27
  • So quarks get their mass before the quarks? Is the same Higgs field involved in SU(3)×SU(2)×U(1) symmetry break as in the SU(2)×U(1) symmetry break? – Gerald Aug 18 '22 at 19:33
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    AFAIK in the mainstream physics model the Higgs mechanism is unique for the breaking of the weak interactions – anna v Aug 19 '22 at 03:13
  • @annav I'm confused by particles existing in a massless state. Isn't a particle's mass an intrinsic, defining property? An up quark has a mass of 2.4 MeV. So if a particle has a spin of 1/2, a charge of +2/3, but its mass equals 0, not 2.4, then is it really an up quark? Isn't it some unnamed primordial particle? Before a particle gains a defining property, like spin, mass, or charge, is it not a different species of particle? Is a .51 MeV lepton an electron or positron if it was not yet interacting with the EM field? If a definitely massive species has no mass, is it even that species? – blacktopshaman Nov 14 '23 at 18:08
  • @blacktopshaman The standard model is a mathematical model, i.e. with the extra laws postulates and principles , the solutions of the model's theoretical equations fit the data and ,important, predict new experimental results that are validated withing the experimental errors. This model has the higgs mechanism to give a mass to the particles in the model. Without it the elementary particles have zero mass, but the symmetries of the system remain, all the other quantum numbers are there. see https://en.wikipedia.org/wiki/Elementary_particle – anna v Nov 14 '23 at 21:04
  • the electron has a quantum number called electron, up quark is identified as an upquark quantum number etc. they do not overlap even if the mass is zero before symmetry breaking . – anna v Nov 14 '23 at 21:11
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    @blacktopshaman Isn't a particle's mass an intrinsic, defining property? No, it is an emergent property. – Ghoster Nov 15 '23 at 06:03
  • @Ghoster What event gives the particle its specific emergent property of mass? – blacktopshaman Nov 17 '23 at 15:02
  • @blacktopshaman in mainstream theory mass is acquired by the particles at symmetry breaking time in cosmology http://hyperphysics.phy-astr.gsu.edu/hbase/Forces/unify.html – anna v Nov 17 '23 at 16:14
  • @blacktopshaman As the universe cools, the Higgs field takes on a nonzero vacuum expectation value because the “Mexican hat” potential for the Higgs field’s self-interaction — which is the logo of this site, by the way. — favors it. This is the symmetry breaking Anna just mentioned. – Ghoster Nov 17 '23 at 18:02
  • @ghoster What is meant by "non-zero?" Just... anything not equal to zero? Like, as the symmetry is broken, it just takes on a value that is equal to anything that is not zero? If so, why the specific amounts for each particle? Why those specific values? – blacktopshaman Nov 18 '23 at 16:25
  • At low temperatures, the Higgs field takes on the particular expectation value of 246 GeV that minimizes the Mexican hat potential. (The field expectation value is the radial coordinate; the vertical coordinate is the energy density.) Different fermions get different masses because they have different Yukawa couplings to the Higgs field. The Standard Model does not explain the values of these coupling constants, just like it does not explain the value of the fine structure constant. In string theory I believe they would be related to the geometry of the compactified dimensions. – Ghoster Nov 18 '23 at 17:46