Gauge Boson: Higgs vs Graviton

[Deamito]

Forgive my lack of particle physics undestanding, I'm still trying to teach myself!

I've been looking into gauge bosons and I'm trying to distinguish between the Higgs and the graviton.

From what I know, the Higgs is the particle postulated by the standard model to give all others mass, while the graviton is postulated by some theories of quantum gravity to be the "force carrier" for gravity. Does this make them both the same thing?

 

[humanino]

No they are quite different beasts. The Higgs particle is the quantum of an hypothetical scalar field (spin 0). The graviton particle is the quantum of a known symmetric tensor field (spin 2).

 

[JustinLevy]

They are different things. For example the Higgs boson is spin 0, while the graviton would be spin 2.

Also, using the electron as an example: the Higgs couples to the electron to make a term that looks like an electron mass. This way the electron can be masseless in the theory to maintain the gauge symmetry, but obtain an "effective mass" term once the vacuum gets a non-zero expectation value for the higgs. This is the sense in which the higgs "gives mass" to the electron. [Note that the majority of mass in a hydrogen atom doesn't come from these Higgs terms at all. All interactions can change the energy of a system, and hence effect the mass of a system.]

Also, note that the graviton couples to the stress energy tensor. Not just "mass". And coupling to something is not the same as "creating" it. For example I wouldn't claim the photon, which couples to electric charge, gives particles electric charge.

EDIT: Oops. I apparently type too slow.

 

[bcrowell]

Hi, Deamito,

Welcome to PF!

No, they are not the same thing. There are two different kinds of mass, inertial and gravitational. When you lift a book, you're sensing its gravitational mass compared to other objects in the Earth's field. When you shake a book back and forth, you're getting a feel for its inertial mass.

The Higgs is hypothesized to be responsible for inertial mass. A swarm of Higgses would surround an electron, giving it its mass.

The gravitation would hypothetically cause gravitational interactions. If you have *two* electrons, the reason they attracted each other gravitationally would be that they're tossing gravitons back and forth.

In practical terms, the Higgs is expected to be found in a matter of years, maybe months. The existence of gravitons cannot be tested empirically with any present or foreseeable technology. When our great grandchildren are dead in their graves, gravitons will probably not have been detected directly.

-Ben

 

[Kevin_Axion]

Essentially as JustinLevy stated the graviton is what says how space-time should curve through the stress-energy tensor, this is the T_{\mu\nu} term in the Einstein Field Equations:http://en.wikipedia.org/wiki/Einstein_field_equations#Mathematical_form.
"The Higgs boson particle is one quantum component of the theoretical Higgs field. In empty space, the Higgs field has an amplitude different from zero; i.e., a non-zero vacuum expectation value. The existence of this non-zero vacuum expectation plays a fundamental role: it gives mass to every elementary particle that couples to the Higgs field, including the Higgs boson itself. In particular, the acquisition of a non-zero vacuum expectation value spontaneously breaks electroweak gauge symmetry, which scientists often refer to as the Higgs mechanism. This is the simplest mechanism capable of giving mass to the gauge bosons while remaining compatible with gauge theories. In essence, this field is analogous to a pool of molasses that "sticks" to the otherwise massless fundamental particles that travel through the field, converting them into particles with mass that form, for example, the components of atoms." - Higgs Boson, Wikipedia

 

[Deamito]

Thanks Ben, Kevin, Justin and humanino. I can see I won't be going to bed any time soon, I'll have to go and get more of a grasp on tensors and look up Einstein field equations. Maybe those guys at CERN will find the Higgs before I understand it fully!

 

[Kevin_Axion]

I wish it was that easy, maybe a class in partial differential equations would suffice before learning tensor algebra/calculus, Riemann geometry and Gravitational Physics. Although I'd recommemend The Road to Reality by Roger Penrose, it's a pretty remarkable book.

 

[Deamito]

Yeah, I tried reading a Very Short Introduction to Particle Physics by Frank Close, thinking it might explain some of my uncertainties and clarify the "particle zoo" for me. It just opened more doors!

Thanks for the reference, I'll have to see if my student card's still valid for that one, although at 1100 pages I'm sure they'll find the Higgs first!

Out of interest, I was going to buy a DVD lecture series by Steven Pollock called "Particle Physics for Non-Physicists: A Tour of the Microcosmos," would anyone recommend it?

 

[Deamito]

Seems this is the fifth time someone has asked this question on PF. At least I'm not the only one then.

 

[Kevin_Axion]

Yea, these questions are usually posted approximately three times a week.

 

[Deamito]

Really? Then you guys must be the patient users that didn't slam their cups of tea down and shout "Again?!" I think between what you guys have said here and on other similair posts I almost understand each. Thanks! Now back to the particle zoo - after I write a bit on the Higgs I'll move onto conjugate bosons. Expect more confusion!

Dean

 

[Kevin_Axion]

It's fine, sometimes people should use the search function though.

 

[bcrowell]

It's not necessary to learn a huge amount of math or technical stuff to learn something about this kind of thing. For relativity, Gardner's Relativity Simply Explained is good. For quantum gravity, try Smolin, Three Roads to Quantum Gravity and Susskind, The Black Hole War. For field theory, Feynman, QED: The Strange Theory of Light and Matter.

 

[turbo]

Let's engage in some practicality. It has been a fad for some time to postulate the existence of particles to mediate the forces of fundamental fields. So we have the proposed Higgs particle to mediate the mass-conferring force of the Higgs field, and we have the proposed graviton to mediate the attractive force of the gravitational field.

Trouble is, fields are not static. They can be densified and attenuated, and they can evolve with time. If the Higgs boson and the graviton are real, their respective fields must have been amazingly congruent over the course of all the existence of our visible universe, because the objects that we observe 13G years ago are not demonstrably different from stuff in our own cosmological back-yard. There have been quite a number of cosmological coincidences cited in the literature in the past 30-40 years, but the amazing evident congruence of the evolution of the Higgs field and the gravitational field for 13 billion years doesn't get a mention. Why?

 

[bcrowell]

Let's engage in some practicality. It has been a fad for some time to postulate the existence of particles to mediate the forces of fundamental fields. So we have the proposed Higgs particle to mediate the mass-conferring force of the Higgs field, and we have the proposed graviton to mediate the attractive force of the gravitational field.

The Higgs field is not something that has already been observed and that we would now like to observe quantization of. "Fad" is also the wrong word here; it's been a highly successful strategy for doing physics.

Trouble is, fields are not static. They can be densified and attenuated, and they can evolve with time. If the Higgs boson and the graviton are real, their respective fields must have been amazingly congruent over the course of all the existence of our visible universe, because the objects that we observe 13G years ago are not demonstrably different from stuff in our own cosmological back-yard. There have been quite a number of cosmological coincidences cited in the literature in the past 30-40 years, but the amazing evident congruence of the evolution of the Higgs field and the gravitational field for 13 billion years doesn't get a mention. Why?

Here you seem confused about what these fields are or are hypothesized to be and how they behave or are hypothesized to behave.