higgs boson

[Peron]

If the Higgs Boson isn't discovered what does that mean for particle physics?

[ajb]

If the Higgs Boson isn't discovered what does that mean for particle physics?

 

If the Higgs is not discovered at the LHC, then this would be quite exciting. As I see it there are a few possibilities.

 

1. The Higgs is more massive than we believed-- Larger than about 300 GeV/c^{2} would phenomenologically difficult.
   
2. Technicolor will look more attractive.-- so far no tangible evidence of technicolor has been found, but the LHC will be probing the right energies.
   
3. Other Higgless models like extra dimensions, composite W's and Z, top quark condensates, unparticles etc will gain more popularity and people will hunt for phenomenological fits.
   
4. Some other as of yet undiscovered mechanism comes into play.-- the most exciting option.
   

 

This could be a very exciting time for particle physics if the Higgs is not discovered. However we must not allow the "antis" to use this to cut funding by saying "we have sent X-billion Euros and the scientists have no idea what they are doing!". Nature can surprise us and that is the way of fundamental research.

[khaled]

Speculation: Since bosons are vector forces, and Higgs boson is scalar .. then maybe Higgs boson is just a dominant force.

 

Also, I'd imagine that the difference between a boson, and a Higgs boson is like the difference between a fish that swim, and a fish that doesn't ...

 

The relation between boson and fermion is basically energy, a fermion produce a boson when it lose energy\mass,

and it may absorb a boson which gives energy\mass, just like the example of an electron that emits

a photon when it degrade orbitally .. Wrong ?

[ajb]

Also, I'd imagine that the difference between a boson, and a Higgs boson is like the difference between a fish that swim, and a fish that doesn't ...

 

I have no idea what you mean by this.

 

The relation between boson and fermion is basically energy, a fermion produce a boson when it lose energy\mass,

and it may absorb a boson which gives energy\mass, just like the example of an electron that emits

a photon when it degrade orbitally .. Wrong ?

 

It is true that electromagnetically bound electrons change there energy via absorption or emission of photons. It is also true that photons are bosons and electrons fermions.

 

I think it is an oversimplification to state that bosons and fermions are related in the way you state. For example we have to take care of jets which are very complicated in general.

[khaled]

I have no idea what you mean by this.

 

.. Bosons, and Higgs Bosons, Just like the difference between Velocity, and Speed (give that velocity & speed describe the same thing, velocity is a vector)

 

I finds it interesting how that the energy of a fermion is not from its inner quarks, but from the space between them, as theoretical physicists believe ...

Edited September 3, 2011 by khaled

[ajb]

.. Bosons, and Higgs Bosons, Just like the difference between Velocity, and Speed (give that velocity & speed describe the same thing, velocity is a vector)

 

Well, sort of...

 

By a vector boson (not that I really like the nomenclature) is a bosonic field with a space-time index. Lets denote it as [math]A^{\mu}[/math]. Lets not at this stage worry exactly what this is. The key point here is that it transforms as a vector under diffeomorphisms, or lets just restrict to Lorentz transformations. (It also transforms under gauge transformations, but lets not worry about that)

 

A scaler field transforms as a scaler under Lorentz transformations. That is it is invariant.

 

One can then for sure define fields that transform as higher order tensors or tensor-like objects.

 

It is true that speed is a scaler under the Galilean group, as where velocity is a vector. So you do have an analogy, but I am not sure how far you can really take it. I would not say that vector and scaler bosons "contain the same information".

 

I finds it interesting how that the energy of a fermion is not from its inner quarks, but from the space between them, as theoretical physicists believe ...

 

You have to take the binding energy into account when dealing with composites.

[Genius13]

i have a quetion about something i like to call ''the higgs gravity theory''

if the higgs gives all mater mass, and gravity is the force that any body with mass radiates and larger the mass the larger the gravity influence .. so is there any way that the Higgs boson can actualy be the ''graviton'' we r so desperatly looking for?

Pls answer

[ajb]

so is there any way that the Higgs boson can actualy be the ''graviton'' we r so desperatly looking for?

Pls answer

 

Basically the Higgs boson does not have the right degrees of freedom to be the graviton. The graviton will have spin-2, this is related to the gravitational degrees of freedom and required properties of classical gravity. The Higgs is spin-0. The Higgs and the graviton are just different "animals".

[timo]

The interaction with the Higgs field is not what gives all matter mass. It is what gives elementary particles mass. The mass of non-elementary particles like protons and neutrons are primarily (about 95% of it) caused by other mechanisms, but experiences gravity just like the elementary particles (*).

 

More towards you question: The graviton and especially the Higgs boson are mathematical entities. It's not that physicists have spotted some shadowy figures sneaking around the visible horizon and called them "Higgs boson" and "graviton", respectively, and now should ask themselves if this possibly was the same shadowy figure.

It's rather that you want, for whatever reasons, a particle with some particular properties, and therefore postulate it. The properties of the easiest incarnation of the Higgs boson are pretty much written in stone (I think the mass is the only parameter that is not fixed, but even that has to lie within some constraints). Since there is no generally accepted quantum gravity model the possible properties of a prospected graviton are somewhat less fixed. Usually, one expects a massless particle with a spin of two. The Higgs boson has a mass greater than zero and a spin of zero. In other words: the Higgs boson and the graviton are two particles that have been predicted for different reasons and have properties that are mutually exclusive.

 

(*) As a matter of fact I am not even sure that there is an experimental proof that elementary particles do feel gravity at all. So perhaps only bound gluons are subject to gravitational force?

[ajb]

(*) As a matter of fact I am not even sure that there is an experimental proof that elementary particles do feel gravity at all. So perhaps only bound gluons are subject to gravitational force?

 

This is true, but I am not sure how you would understand this in classical or semi-classical gravity. Space-time curvature is going to effect anything travelling on it as compared to the flat space-time. Then elementary particles have energy-momentum and so can act as sources in GR.

 

But then maybe we should not just take this for granted and tests of gravity on the atomic and nuclear scale should be preformed.

[timo]

Space-time curvature is going to effect anything traveling on it as compared to the flat space-time. Then elementary particles have energy-momentum and so can act as sources in GR.

I'm not exactly sure what you meant with that, and there are two ways I could interpret your statement:

 

a) "Elementary particles have energy and so can act as sources in GR": Well, my point was that I am not aware of any experiment that would exclude that only gluons act as a source of gravity.

 

b) "Elementary particles are affected by gravity, therefore they must act as a source of it": That's certainly true for e.g. classical gravity and electromagnetism, where the property causing the field and the property coupling to the field are the same. And in terms of Lagrangians for a QFT I'd indeed find it hard to imagine a mechanism for which that doesn't hold true, since on that level both is (usually or necessarily?) just the same term, there. But on the classical level it is simple to imagine a field that is created by property X and felt by a property Y. Or simply felt equally by all other particles; the classical equation of motion in a gravitational field [math]\ddot x = \Gamma_{ij} \dot x^i \dot x^j[/math] contains neither energy nor momentum, after all (although it admittedly does not contain inertia, either).

[ajb]

a) "Elementary particles have energy and so can act as sources in GR": Well, my point was that I am not aware of any experiment that would exclude that only gluons act as a source of gravity.

 

Sure, no experimental evidence, but I think this would be difficult to reconcile with classical GR.

 

 

b) "Elementary particles are affected by gravity, therefore they must act as a source of it"

 

If they have non-zero energy momentum then they, according to GR act as sources. I was thinking of test particles really, they will be effected by gravity but not act as a source, but this is really a mathematical approximation. I would say that fundamental particles could be considered test particles in most situations. Now if the fundamental particle are truly "test particles" then they would still be effected by the curvature, but not "create any gravity". (Not that I am really sure how formulate this properly in GR, all physical particles will carry energy-momentum)

 

Anyway, I think that any deviation from treating all particles equally would be a violation of the equivalence principle, at least in a classical or semi-classical theory. But then we really have to look at the experimental evidence, rather than just take things for granted.

[IM Egdall]

Assume a single electron (or any particle) passes through a double-slit. Per quantum field theory, the electron's wave function travels through both slits. The results is the electron is detected in one location at the detector screen. But over time with a number of electrons passing through the apparatus one at as time, you get an interference pattern at the detector screen.

 

So here is my question: Per general relativity, the electron (or any other particle) is a source of spacetime curvature (gravity). So could a sensitive-enough gravity detector placed near one slit tell in principle which slit the electron went through?

 

Or maybe a better question is: Is a particle's wave function a source of spacetime curvature?

Edited October 16, 2011 by IM Egdall

[DrRocket]

If the Higgs is not discovered at the LHC, then this would be quite exciting. As I see it there are a few possibilities.

 

1. The Higgs is more massive than we believed-- Larger than about 300 GeV/c^{2} would phenomenologically difficult.

 

The latest estimate seems to be that it is less than 145 Gev.

 

 

http://www.technewsworld.com/story/73450.html

 

 

 

http://www.sciencenews.org/view/feature/id/334164/title/Last_Words

 

 

 

http://news.sciencemag.org/sciencenow/2011/08/hints-of-higgs-boson-appear-weaker.html

[Mystery111]

i have a quetion about something i like to call ''the higgs gravity theory''

if the higgs gives all mater mass, and gravity is the force that any body with mass radiates and larger the mass the larger the gravity influence .. so is there any way that the Higgs boson can actualy be the ''graviton'' we r so desperatly looking for?

Pls answer

 

 

There are many reasons why a Higgs and a graviton are not equivalent.

 

Originally in our search for a gauge invariant theory, we had equations which did not permit symmetries which we sought for:

 

[math]\partial \phi' = [\partial \phi + i \phi \frac{\partial \theta}{\partial x}]e^{i \theta}[/math]

 

[math]\partial \phi' = [\partial \phi + i \phi* \frac{\partial \theta}{\partial x}]e^{i \theta}[/math]

 

multiplying the two we get

 

[math]= \partial \phi \partial \phi* + i (\phi \partial \phi* - \phi* \partial \phi) \frac{\partial \theta}{\partial x}+ \phi* \phi (\frac{\partial \theta}{\partial x})^2[/math]

 

which has no symmetry whatsoever! plus it is horrid to look at.

 

Nevertheless, this was not good, so we had to add an extra four-field to our system, namely the four-vector potential [math]A_{\mu}[/math]. Added with our covariant derivative, which we have seen so far has the form:

 

[math]D_{\mu}\phi = \partial_{\mu}\phi + iA_{\mu}\phi[/math]

 

[math]D_{\mu}\phi* = \partial_{\mu}\phi* - iA_{\mu}\phi*[/math]

 

simply has an addition to our field which has an appearance of [math]\partial \rightarrow \partial - iA[/math].

 

This allowed us to have a nice symmetry in the making - interesting though how we had to mould the equations a few times, a bit of nip and tuck if you will.

 

Now the graviton is much more different than the presence of a spontaneous symmetry breaking. The above calculations simply state that the photon is a massless particle. The graviton equally, does not have a mass, and yet the Higgs particle does because the higgs gobbles up a goldstone boson, which is basically a photon on the minimum energy - which is the minimal energy required to move around the base of a potential well. There is that, if one wants to recite a major difference between the massless particle graviton and the particle higgs which gives mass to all matter and even itself! And it goes to say, that a graviton simply cannot have a mass, if it is supposed to send gravitational signals at vast lengths ..

 

[math]\Box h_{\mu \nu}=0[/math]

 

[math]\Box = \partial_{t}^{2} - c^2 \partial^{2}_{x}[/math]

 

which is the same as saying

 

[math]\partial^{2}_{t} - c^2 \Delta h_{\mu \nu}=0[/math]

 

Which means it moves at the speed of light.

 

Interestingly, I've seen posters ask this question many times...

Edited October 17, 2011 by Mystery111

[Genius13]

i see u know what u talk so can u pls answer ( not in mathmtical but in english ) higgs boson gives matter its mass wright? and gravity is a sideffect of masss wright?

[Mystery111]

i see u know what u talk so can u pls answer ( not in mathmtical but in english ) higgs boson gives matter its mass wright? and gravity is a sideffect of masss wright?

 

Gravity is the presence of matter. Curvature is also related to matter, but in relativity you don't need to have matter to have a non-zero curvature.

 

The Higgs Boson gives about 1% of all matter mass.

[Genius13]

protons and neutrons r not elementary particles but they r made of quarks witch r

abd what gives them mass if its not the Higgs?

 

The mass of non-elementary particles like protons and neutrons are primarily (about 95% of it) caused by other mechanisms, but experiences gravity just like the elementary particles (*).

 

The interaction with the Higgs field is not what gives all matter mass. It is what gives elementary particles mass. The mass of non-elementary particles like protons and neutrons are primarily (about 95% of it) caused by other mechanisms, but experiences gravity just like the elementary particles (*).

 

More towards you question: The graviton and especially the Higgs boson are mathematical entities. It's not that physicists have spotted some shadowy figures sneaking around the visible horizon and called them "Higgs boson" and "graviton", respectively, and now should ask themselves if this possibly was the same shadowy figure.

It's rather that you want, for whatever reasons, a particle with some particular properties, and therefore postulate it. The properties of the easiest incarnation of the Higgs boson are pretty much written in stone (I think the mass is the only parameter that is not fixed, but even that has to lie within some constraints). Since there is no generally accepted quantum gravity model the possible properties of a prospected graviton are somewhat less fixed. Usually, one expects a massless particle with a spin of two. The Higgs boson has a mass greater than zero and a spin of zero. In other words: the Higgs boson and the graviton are two particles that have been predicted for different reasons and have properties that are mutually exclusive.

 

(*) As a matter of fact I am not even sure that there is an experimental proof that elementary particles do feel gravity at all. So perhaps only bound gluons are subject to gravitational force?

Edited October 18, 2011 by Genius13

[Mystery111]

protons and neutrons r not elementary particles but they r made of quarks witch r

abd what gives them mass if its not the Higgs?

 

The mass of non-elementary particles like protons and neutrons are primarily (about 95% of it) caused by other mechanisms, but experiences gravity just like the elementary particles (*).

 

 

 

 

Only very light particles are given mass. Heavier particles like some dark matter proponents do not require the Higgs Mechanism, I forget the reason why off the top of my head, I'd need to check notes. Besides, when we speak about giving ''mass'' to particles, we usually mean we are giving massless particles a mass through the Higgs Mechanism. This means the likes of photons.

[timo]

Heavier particles like some dark matter proponents do not require the Higgs Mechanism, I forget the reason why off the top of my head, I'd need to check notes.

The mainstream candidates for dark matter are supersymmetric partner particles. I actually think one may call the supersymmetry breaking a Higgs-mechanism in the sense that the mathematical idea is the same as the one which breaks electroweak symmetry. I vaguely remember having read the term "super-higgs mechanism" in that context. You are right in the sense that the standard model Higgs field is not what causes this symmetry breaking, though.

 

 

 

Besides, when we speak about giving ''mass'' to particles, we usually mean we are giving massless particles a mass through the Higgs Mechanism. This means the likes of photons.

While it indeed means "the likes of photons" the massless photon is perhaps not the very best example of them. In first consequence it means the W and Z bosons, but I faintly recall there also was a reason why fermion mass is expected to be from interaction with the Higgs field.

[Genius13]

ok im totaly confused can u pls just clearly tell me what does actualy the Higgs boson do cause ive obviusly missunderstud it

Edited October 18, 2011 by Genius13

[Mystery111]

ok im totaly confused can u pls just clearly tell me what does actualy the Higgs boson do cause ive obviusly missunderstud it

 

The Higgs Boson gives particles mass.

 

Simple.

[timo]

The Higgs Boson gives particles mass. Simple.

That's quite a U-turn considering the direction that the discussion in this thread went.

 

ok im totaly confused can u pls just clearly tell me what does actualy the Higgs boson do cause ive obviusly missunderstud it

I can't resist pointing out the interpretation that the Higgs boson does preciously little. That's what makes it so hard to proof experimentally, after all.

A bit more to the point: You have to be a bit careful with terminology: The Higgs field gives mass to unbound elementary particles. The Higgs boson, which is often said to give particles mass, is just a piece of the Higgs field - and ironically the one that is not directly responsible for the mass of unbound elementary particles. That does, however, not exclude that there is other mechanism that may give mass to objects, particularly composite particles. And as I already said a few posts above, most of the mass you encounter on everyday scales is not due to the interaction with the Higgs field, but caused by particles being bound.

[Mystery111]

True.

[twistor59]

I haven't seen this link yet. It's well worth a read.

(Edit : I mean I haven't seen the link in this thread yet, of course I have actually seen the link ! )

Edited October 20, 2011 by twistor59