Higgs boson

sazzles

Hi, I don't really know much about string theory, but I was wondering whether the discovery of the Higgs boson would back up string theory, or contradict it?
Thanks.

Chen

Isn't it the Standard Model that requires the existence of the Higgs boson? String theory has enough room in it for as many particles as you want.

sazzles

I'm not sure, I was under the impression that the mode of vibration of a string gave rise to its mass, so a particle like a Higgs Boson would not be necessary. But, like I said, I don't really know much about string theory.

Chen

Well, me neither. [6)] You should probably wait from an answer from someone who knows about this... [:)]

Antonio Lao

The string theory is made to describe the four fundamental forces:

1. Gravity
2. EM
3. Strong
$. Weak

These are all vector (force) fields with their respective quanta: the graviton, the photon, the gluons, the W's and Z.

Although the graviton is still not found, its existence can be describe by string theory. These are all vector bosons, i.e., force particles.

The Higgs field is a scalar field. This means that a force is not defined in this kind of field although the mass is a consequence of the gravitational field which causes the force of gravity.

The Higgs field causes mass and mass causes the force of gravity.

The Higgs mechanism theorizes the existence of Higgs bosons. So that if we say that all the particles are massless to begin with, they subsequently acquire mass by swallowing the Higgs bosons.

Can we relate the Higgs field to the gravitational field? This is a reasonable question since Higgs field creates mass and in turn mass creates the force of gravity.

Mike2

So is the Higgs mechanism responsible for super symmetry, where each boson captures a Higgs boson to become a fermion?

sazzles

I'm still confused, is Antonio Lau saying the Higgs boson is part of string theory or not?

Antonio Lao

Mike2,

Supersymmetry is the pairing of all fermions (1/2 spin) with a partner of boson (integral spin). This symmetry is broken at this stage of the universe since the superpartners cannot be found by the available energy scale.

Some of these particles (fermions or bosons) get their mass by the Higgs mechanicism. There are fermions like the neutrinos, that have practically no mass, means Higgs mechanism does work very weakly on them. The photon, the gluons, all vector boson with no mass, means the Higgs mechanicism does not work on them. These particle refuse to eat the Higgs bosons in order to get full in the belly of mass.

______________________________

Sazzles,

String deals with vector bosons (force fields).

Higgs theory deals with scalar bosons (scalar fields without a defining force).

Mike2

Correct me if I'm wrong, I'm not an expert. But a photon of sufficinet energy when it swings by an object of sufficient mass can be converted into electron-positron pair that has mass. Isn't the eletcton the fermion associated with the photon as the bosson. The photon is the force carrier for the massiive electron? If so, then we see the photon seeming to acquire mass to create electrons, etc. Do the Higgs particles reside more densely around massive objects?

selfAdjoint

Your questions go into the details of the standard model, rather than the high level description. Notice that in the electroweak theory the photon has three "co-bosons", the positive B particle, the negative B-particle, and the Z-particle. These other bosons are massive, but the photon isn't. All that is explained in the math of the electroweak model, but I don't think there is any popular book that goes into such matters. At the very least it would have to explain the Langrangean and how that relates to gauge symmetry.

Of course physicists have shorthand ways of thinking about these things, and perhaps lethe or somebody can give us an intro to those.

sazzles

I thought string theory was champoined as a TOE by some people, but how can it be if it doesn't resolve the problen of mass.

Antonio Lao

Sazzles,

At the moment, there is still no theory that resolve the problem of mass. Not string, not supersymmetry, not supergravity, not even Higgs theory. The TOE (the final theory or the primary theory) is supposed to also resolve the mass problem among others (unifying forces, the field and quantum, wave-particle duality, the meaning of life?).

rick1138

Observed interactions of W+ and W- particles are stong indirect evidence for the existence of the Higgs boson, as the interactions would have a probability > 1 without the Higgs mechanism.

Antonio Lao

Still Higgs boson needs to be found to validate the theory once and for all.

rick1138

Of course it does, emphasis was on indirect.

Antonio Lao

What is mass? Why W's have mass and photon have no mass? Yet both are the quanta of the electroweak theory. These questions need a direct answer.

clothoid

Some kind of a Higgs mechanism probably has to exists in string theory if it turns out to be the right theory. I think I've read from Green-Schwartz-Witten's book that if the masses were due to higher vibration modes of the string, then the observed particles would be too heavy. So in string theory particles (or strings) still get their masses by coupling to stringy Higgs bosons, if I've understood right. Except I am not sure where the Higgs boson gets its mass in string theory. Maybe it works differently for scalar particles, too bad I don't have the book here right now.

That calculation of the masses of fundamental particles if the masses were from string vibrations is one of those calculations that I've been too lazy to do myself, and I'm not even sure if I could do it correctly, but Green-Schwartz-Witten is probably a source you can trust..