Is the top quark stable in the absence of the Higgs field?

[kodama]

in a universe without the higgs field

fermions would be massless

in absence of the higgs field, would second and third generation fermions such as muon tau top quarks etc be stable?

how to distinguish between a massless electron muon and a tau in a universe without the higgs field, same for neutrinos and quarks of different generation

 

[Orodruin]

You cannot distinguish them - or linear combinations of them - without Yukawa couplings.

 

[kodama]

You cannot distinguish them - or linear combinations of them - without Yukawa couplings.

why does the Yukawa couplings for a tau or muon differ for that of an electron if You cannot distinguish them in a higgless universe?

 

[mfb]

Why do the Yukawa couplings for a tau or muon differ for the electron coupling if there is no Yukawa coupling? Is that your question?

 

[kodama]

Why do the Yukawa couplings for a tau or muon differ for the electron coupling if there is no Yukawa coupling? Is that your question?

no my question is that in a higgless universe, there is no way to distinguish massless electron muon and a tau.

how does the presence of the higgs field distinguish electron muon and a tau?

if the answer is via via Yukawa couplings

then how, in a higgless universe there is no way to distinguish massless electron muon and a tau acquire Yukawa couplings that distinguish them in a higgs universe

 

[mfb]

if the answer is via via Yukawa couplings

It is.

In our universe the particles have different Yukawa couplings, that makes them distinguishable.

In a universe without Higgs (or similar) the particles behave exactly identical, there is nothing that would distinguish them.

 

[kodama]

It is.

In our universe the particles have different Yukawa couplings, that makes them distinguishable.

In a universe without Higgs (or similar) the particles behave exactly identical, there is nothing that would distinguish them.

well ok,

but imagine these 2 scenarios

in one universe, particles have different Yukawa couplings, that makes them distinguishable electrons muons tau

in another universe, only first generation fermions are truly fundamental, such as an electron, but certain quantum processes occur that can change their Yukawa couplings, that makes them distinguishable and the excited first generation fermions are called muons and tau.

 

[Orodruin]

then how, in a higgless universe there is no way to distinguish massless electron muon and a tau acquire Yukawa couplings that distinguish them in a higgs universe

The Yukawa couplings are the couplings of fermions to the Higgs field. In a higgsless universe there are no Yukawa couplings.

 

[mfb]

in another universe, only first generation fermions are truly fundamental, such as an electron, but certain quantum processes occur that can change their Yukawa couplings, that makes them distinguishable and the excited first generation fermions are called muons and tau.

Do you have a reference discussing such a model?
What does "processes that can change a coupling" mean?

 

[kodama]

The Yukawa couplings are the couplings of fermions to the Higgs field. In a higgsless universe there are no Yukawa couplings.

let me put it this way,

in a higgless universe where electrons exist, would muons and tau particles also exist as fundamental particles?

 

[kodama]

Do you have a reference discussing such a model?
What does "processes that can change a coupling" mean?

MSSM and SUSY and GUT models famously predict multiple higgs fields.

if there is more than 1 higgs field, and other higgs fields Yukawa couplings couples to fermions larger than the SM 126 gev higgs, wouldn't those fermions have higher masses?

 

[Orodruin]

let me put it this way,

in a higgless universe where electrons exist, would muons and tau particles also exist as fundamental particles?

This depends on the field content of that universe. If you just removed the Higgs field from the SM, yes - you could tell that there were three generations. You could not tell the generations apart.

MSSM and SUSY and GUT models famously predict multiple higgs fields.

if there is more than 1 higgs field, and other higgs fields Yukawa couplings couples to fermions larger than the SM 126 gev higgs, wouldn't those fermions have higher masses?

The fermion masses depend on the vevs and couplings, not on the Higgs masses.

 

[kodama]

This depends on the field content of that universe. If you just removed the Higgs field from the SM, yes - you could tell that there were three generations. You could not tell the generations apart.

if you remove the Higgs field from the SM how "you could tell that there were three generations. You could not tell the generations apart" at the same time?

 

[kodama]

The fermion masses depend on the vevs and couplings, not on the Higgs masses.

in a universe or theory where there is a second and third higgs field with different vevs and couplings that couple to fermions differently from the first SM higgs field, wouldn't that in effect create a second and third generation?

 

[Orodruin]

if you remove the Higgs field from the SM how "you could tell that there were three generations. You could not tell the generations apart" at the same time?

By looking at the cross sections of different scattering processes.

in a universe or theory where there is a second and third higgs field with different vevs and couplings that couple to fermions differently from the first SM higgs field, wouldn't that in effect create a second and third generation?

No. It is sufficient with one higgs field for that.

 

[kodama]

By looking at the cross sections of different scattering processes.
.

how would the cross sections of different scattering processes of a massless muon differ from a massless tau in absence of the higgs field?

 

[Orodruin]

how would the cross sections of different scattering processes of a massless muon differ from a massless tau in absence of the higgs field?

It wouldn't and I never said it would.

 

[kodama]

It wouldn't and I never said it would.

to clarify i was responding to your earlier claim

This depends on the field content of that universe. If you just removed the Higgs field from the SM, yes - you could tell that there were three generations. You could not tell the generations apart.

.

so i replied to you by saying how "can you tell there were three generations" and "You could not tell the generations apart."

which you replied by cross sections of different scattering processes.

but i had in mind we are still talking about SM in a higgless universe.

 

[Orodruin]

You are misreading my statements. I never said the different generations would have different cross sections. I said cross sections would be different depending on the number of generations.

 

[kodama]

You are misreading my statements. I never said the different generations would have different cross sections. I said cross sections would be different depending on the number of generations.

ok, "cross sections would be different depending on the number of generations" is this true in a higgless universe?

in a higgless universe where electrons muons and tau are all massless, is it still true "cross sections would be different depending on the number of generations"

in a higgless universe what would cross sections would be different depending on the number of generations if the generations is 1, 2, 3 or 4 or higher?

 

[mfb]

Check how LEP measured the number of light neutrinos via Z decays.
The same approach tells us that there are three colors. We cannot distinguish them, but the quark production cross section depends on the number of colors.
The same would work for leptons as well if they wouldn't have different masses.

in a higgless universe where electrons muons and tau are all massless, is it still true "cross sections would be different depending on the number of generations"

Yes, that is what Orodruin told you several posts ago.

 

[kodama]

Ok that answers my original question.

In GUT and SUSY-MSSM theories that posit additional higgs fields over and above the 1 by the SM, do those additional higgs field yukawa interactions also contribute to mass?

 

[Orodruin]

The same would work for leptons as well if they wouldn't have different masses.

If there is no Higgs the Z is massless and does not decay (well, truth with modification). This is why I said cross sections instead of decays. A closer analogue would be the QCD color factors.

Ok that answers my original question.

In GUT and SUSY-MSSM theories that posit additional higgs fields over and above the 1 by the SM, do those additional higgs field yukawa interactions also contribute to mass?

In MSSM there are two higgs fields. They are responsible for the masses of different fermions (up/down type).

 

[kodama]

If there is no Higgs the Z is massless and does not decay (well, truth with modification). This is why I said cross sections instead of decays. A closer analogue would be the QCD color factors.In MSSM there are two higgs fields. They are responsible for the masses of different fermions (up/down type).

i understand that in the MSSM there are two higgs fields. They are responsible for the masses of different fermions (up/down type).

can you have a theory of 2 higgs fields with just the SM, that couple to different fermions?

 

[Orodruin]

i understand that in the MSSM there are two higgs fields. They are responsible for the masses of different fermions (up/down type).

can you have a theory of 2 higgs fields with just the SM, that couple to different fermions?

Yes, but you would likely have to give a very good argument as to why these fields would not couple to all fermions as allowed by the quantum numbers.

 

[nikkkom]

This depends on the field content of that universe. If you just removed the Higgs field from the SM, yes - you could tell that there were three generations.

And it wouldn't be too difficult - you'd notice that atoms can have up to six "electrons" on each orbital, not two - you can put a muon in the same state as the electron. This would have dramatic effects on chemistry, hard to miss.

 

[Orodruin]

And it wouldn't be too difficult - you'd notice that atoms can have up to six "electrons" on each orbital, not two - you can put a muon in the same state as the electron. This would have dramatic effects on chemistry, hard to miss.

There are no bound states. The fermions are massless.

 

[kodama]

And it wouldn't be too difficult - you'd notice that atoms can have up to six "electrons" on each orbital, not two - you can put a muon in the same state as the electron. This would have dramatic effects on chemistry, hard to miss.

what degree of freedom or quantum number does a muon have that differs from an electron?

 

[kodama]

Yes, but you would likely have to give a very good argument as to why these fields would not couple to all fermions as allowed by the quantum numbers.

same argument as the mssm

 

[Orodruin]

same argument as the mssm

Does not work. You need two in MSSM for anomaly cancellation and for giving mass to both up and down type fermions.

 

[kodama]

Yes, but you would likely have to give a very good argument as to why these fields would not couple to all fermions as allowed by the quantum numbers.

are there any proposals to extend the SM with additional degree of freedom and quantum numbers, to allow for a "higgs charge" so that second and third generation fermions have more higgs-charge than first generation via yukawa coupling?

 

[Orodruin]

are there any proposals to extend the SM with additional degree of freedom and quantum numbers, to allow for a "higgs charge" so that second and third generation fermions have more higgs-charge than first generation via yukawa coupling?

What do you think the Yukawa couplings are? They describe how strongly the different fermions couple to the Higgs field.

Edit: Note that they are not a charge in the sense of a charge related to a gauge symmetry.

 

[kodama]

What do you think the Yukawa couplings are? They describe how strongly the different fermions couple to the Higgs field.

Edit: Note that they are not a charge in the sense of a charge related to a gauge symmetry.

that's what i am wondering about

a hypothesis that the reason second and third generation fermions are heavier than first and interact more strongly with the higgs field there is a higgs-charge that is a charge in the sense of a charge related to a gauge symmetry

 

[mfb]

The coupling constants are these charges you are looking for. It doesn't matter if you call them coupling constants or charges. Same thing.

If there is no Higgs the Z is massless and does not decay (well, truth with modification). This is why I said cross sections instead of decays. A closer analogue would be the QCD color factors.

There would also be no physicists to perform experiments ;).

 

[kodama]

The coupling constants are these charges you are looking for. It doesn't matter if you call them coupling constants or charges. Same thing.There would also be no physicists to perform experiments ;).

isn't that another degree of freedom that all fermions and w and z bosons posses? a higgs-charge that determine yukawa interaction.

in a higgless universe, all particles then would be massless and travel at the speed of c is that correct? but they still have their charges so they could form something