B What does the Higgs particle consist of?

[Serra Nova]

The Higgs particle that were discovered in 2012 - what is it build of?

 

[mfb]

It is an elementary particle. It is not made out of anything else.

 

[Drakkith]

As mfb said, it's a fundamental particle that isn't composed of anything else. This is just just like electrons, quarks, neutrinos, and other fundamental particles. None of them are composed of other things as far as we know.

 

[theoretical_p]

Higgs particle is massless and it gains mass through a process called Higgs process. Professor Peter Higgs got the idea of Higgs process through a very well known fact . That is .. Consider one of your favorite film star happened to pass by a public street . Then people i.e. his fans will gather around him (for autograph or to take a selfie with him). And the number of people will start to increase . From this Peter Higgs got the idea of higgs process and higgs boson. To understand the higgs process you can replace that film star alone by the higgs particle in the initial state. From this state the higgs particle gains mass(like people's gathering around the film star) by the higgs process. A lot of questions are still unanswered about this particle.

 

[mfb]

Higgs particle is massless and it gains mass through a process called Higgs process.

The Higgs has its own mass independent of the Higgs mechanism. This is unique to the Higgs (maybe apart from neutrinos).

Professor Peter Higgs got the idea of Higgs process through a very well known fact . That is .. Consider one of your favorite film star happened to pass by a public street . Then people i.e. his fans will gather around him (for autograph or to take a selfie with him). And the number of people will start to increase . From this Peter Higgs got the idea of higgs process and higgs boson.

No, this poor analogy to describe the mathematics was invented later. It had nothing to do with the original idea of the Higgs mechanism.

 

[ChrisVer]

1. The Higgs particle is not composed of anything at our current understanding. Of course there are theories which still persist in making Higgs a composite particle (such as Technicolor descendants) but they are not verified to any extend.
2. Historically I think, the whole idea of symmetry breaking came from the theory of magnetism/superconductors (the well known thing that the symmetry of random alignment of spins can be broken to a preferred direction if you place them in a magnetic field)... The tool was there and applied to SM as well.. it was some people who proposed that the extra fields you get were physical fields (aka Higgs Boson).

 

[Serra Nova]

As mfb said, it's a fundamental particle that isn't composed of anything else. This is just just like electrons, quarks, neutrinos, and other fundamental particles. None of them are composed of other things as far as we know.

I've read that quarks are composed of up, down and charm quarks. On a very small scale, they might not be elementary..

 

[phinds]

I've read that quarks are composed of up, down and charm quarks. On a very small scale, they might not be elementary..

You misunderstand. Those are not composite elements of quarks, they are TYPES of quarks.

 

[Serra Nova]

You misunderstand. Those are not composite elements of quarks, they are TYPES of quarks.

I see. Thank you for correcting me.

 

[mfb]

Protons and neutrons are composed of up and down quarks, but these quarks are elementary, as phinds said.

There are six types of quarks - up, down, charm, strange, top, bottom. Only the first two play a role in matter around us.

 

[theoretical_p]

@phinds , they are called flavours rather than 'types' of quarks.

 

[mfb]

@phinds , they are called flavours rather than 'types' of quarks.

Types of quarks is perfectly fine, especially if you are not talking to experts.

 

[DanMP]

I read in Wikipedia that:

In the Standard Model, the Higgs particle is a boson with spin zero, no electric charge and no colour charge. It is also very unstable, decaying into other particles almost immediately.

If the Higgs particle decays, it doesn't mean that it is made of something smaller?

 

[Feeble Wonk]

I read in Wikipedia that:

In the Standard Model, the Higgs particle is a boson with spin zero, no electric charge and no colour charge. It is also very unstable, decaying into other particles almost immediately.

If the Higgs particle decays, it doesn't mean that it is made of something smaller?

Good question Dan.
https://home.cern/about/updates/2013/11/atlas-sees-higgs-boson-decay-fermions
This article explains the decay, but I’d appreciate an explanation from one of the physicists as how the Higgs boson can still be categorized as a elemental particle despite this process.

 

[Drakkith]

Well, consider the annihilation of an electron and a positron (anti-electron) to produce two gamma rays. Doesn't this mean that electrons are composed of gamma ray photons? Turns out that no, it doesn't. Particles can decay into other particles without needing to be composed of anything. You can think of it more like a transformation of one particle into something else, or a conversion of that particle's energy into another form.

 

[ChrisVer]

it doesn't mean that it is made of something smaller?

No. Particles are not blocks of "things" that [when decaying] break down to their constituents. Also the idea of smaller doesn't make sense for objects that are considered point-like. What happens resembles more a transition.

 

[Feeble Wonk]

Well, consider the annihilation of an electron and a positron (anti-electron) to produce two gamma rays. Doesn't this mean that electrons are composed of gamma ray photons? Turns out that no, it doesn't. Particles can decay into other particles without needing to be composed of anything. You can think of it more like a transformation of one particle into something else, or a conversion of that particle's energy into another form.

Interesting. But this example considers an annihilation event where in two fermions release energy in the form of bosons. The Higgs decay results in the formation of two fermions. It seems different. I recognize that’s more or less a reversal of the transformation you described, but it does seem different.

 

[Drakkith]

Interesting. But this example considers an annihilation event where in two fermions release energy in the form of bosons. The Higgs decay results in the formation of two fermions. It seems different. I recognize that’s more or less a reversal of the transformation you described, but it does seem different.

Two photons are only one possibility. You can get multiple photons or even neutrinos, though the latter is orders of magnitude less likely since that involves the weak interaction instead of the electromagnetic interaction. Increase the collision energy and you can produce B-mesons (bosons, but composed of quarks, which are fermions).

Smash any two particles together and you can get any particle you like. Bosons, fermions, top quarks, positrons, photons, etc. The idea is that particles can undergo an interaction which changes them into something else. The exact collection particles produced by this interaction depend mostly on the available energy and various conservation laws. Electron-positron annihilation usually produces two photons because their combined energy isn't enough to produce much of anything else unless you use a particle accelerator to increase the collision energy.

 

[mfb]

Interesting. But this example considers an annihilation event where in two fermions release energy in the form of bosons. The Higgs decay results in the formation of two fermions. It seems different. I recognize that’s more or less a reversal of the transformation you described, but it does seem different.

The Higgs can decay to various particles. As an example, it can decay to two photons, or one photon and one Z, both are bosons. In all cases the Higgs stops existing and the decay products start existing.

 

[rootone]

Is it possible that other stuff could be smashed together in the right way and produce a Higgs though?.

 

[phinds]

Is it possible that other stuff could be smashed together in the right way and produce a Higgs though?.

I believe that is in fact exactly how the Higgs was detected at the LHC. They weren't waiting around hoping a Higgs would wander in from space, they were smashing zillions of particles together and hoping a Higgs would pop out and eventually it did. Very rare though, apparently, at the energies currently available.

 

[rootone]

Ah, well we won't be using that technology for the next generation of cars then.

 

[mfb]

Is it possible that other stuff could be smashed together in the right way and produce a Higgs though?.

That's what the LHC is doing.

An electron-positron collider could produce it as well, but it is more difficult to get enough energy there. A hypothetical muon collider could produce it. In principle an electron-proton collider can do so as well, and every other combination can produce a Higgs once in a while, too.

 

[rootone]

Muon collider.
You got my vote.

 

[DanMP]

... this mean that electrons are composed of gamma ray photons?...

No, but it may mean that the photons are made from (part of) "the stuff" present in the electrons ...

It is impossible for particles to be made from some same/similar stuff and, when they decay/collide, that stuff to form other particles?

You wrote that it's like the energy of the particle is converted into another form, but energy and mass are related, so why is impossible to have something material inside the particles, something that can be converted into something else?

 

[Drakkith]

No, but it may mean that the photons are made from (part of) "the stuff" present in the electrons ...

It is impossible for particles to be made from some same/similar stuff and, when they decay/collide, that stuff to form other particles?

You wrote that it's like the energy of the particle is converted into another form, but energy and mass are related, so why is impossible to have something material inside the particles, something that can be converted into something else?

To be made up of something implies some sort of substructure. Composite objects are always formed from smaller particles, which are themselves composed of smaller particles, all the way down to the elementary particles. But for elementary particles like the electron, we can find no substructure. There has been no indication that they are composed of any smaller particle. And if you want to say they might be made up of some sort of non-particle material, you might as well say they are made of energy since energy already fits this description well enough.

Also, given that two particles under enormous collision energies produce all sorts of other particles, it makes more sense to me to say that energy is converted to other forms (other particles) instead of inventing an unobserved substructure and attributing some of this particle production to that substructure being changed. Why do all that when you already have an explanation that fits the observations and calculations perfectly well and have nothing showing it's incorrect?

That doesn't mean that what you suggest is impossible, it just means that it makes things more complicated than necessary and adds nothing of value to our current description.

 

[mfb]

No, but it may mean that the photons are made from (part of) "the stuff" present in the electrons ...

In this case photons would have to have mass. They do not.

There are extremely accurate measurements that all confirm that our elementary particles are indeed elementary. The most prominent example is the electron g-factor. For elementary electrons we can predict it, while for composite particles it can be anything in a range of something like -10 to +10.

The theoretical prediction:
2.002 319 304 362 (where the last digit is uncertain).
The experimental result:
2.002 319 304 361 (where the last digit is certain)

A 1 part in a trillion measurement. It would be extremely odd if this is just a random occurrence.

 

[jtbell]

If the Higgs particle decays, it doesn't mean that it is made of something smaller?

A muon decays into an electron, a muon-neutrino, and an electron-antineutrino. That doesn't mean that a muon is made of those particles, or that they share smaller constituents. In fact, a muon is (as far as we know) just as "elementary" and "pointlike" as an electron, or a neutrino, or an antineutrino.

 

[DanMP]

To be made up of something implies some sort of substructure. Composite objects are always formed from smaller particles, which are themselves composed of smaller particles, all the way down to the elementary particles. But for elementary particles like the electron, we can find no substructure. There has been no indication that they are composed of any smaller particle. And if you want to say they might be made up of some sort of non-particle material, you might as well say they are made of energy since energy already fits this description well enough.

Also, given that two particles under enormous collision energies produce all sorts of other particles, it makes more sense to me to say that energy is converted to other forms (other particles) instead of inventing an unobserved substructure and attributing some of this particle production to that substructure being changed. Why do all that when you already have an explanation that fits the observations and calculations perfectly well and have nothing showing it's incorrect?

That doesn't mean that what you suggest is impossible, it just means that it makes things more complicated than necessary and adds nothing of value to our current description.

Imagine a concrete ball. That ball is not sand, nor gravel, nor water, it is something made from those ingredients (and more), but different ... and also a whole, not a system with moving parts (at least apparently). If you smash it, you obtain different pieces, with different shapes and proprieties (cutting edges, not rolling, etc.). Two or more smashed/crushed balls can be used to form a new concrete thing, maybe a cube. This is an analogy of what I meant with the "same stuff" as common ingredient for all "fundamental" particles.

I'm not very happy with the idea that "they are made of energy". This is too abstract. I remember reading that particles are in fact field excitations, not really particles. This means that the Higgs particle is an excitation in the Higgs field? And this excitation (wave, energy?) decays/splits in 2 or more excitations in other field(s)? How you digest this? I can't.

I have more (and solid) reasons to ask and think about this new, lower level in the structure of matter and about the Higgs boson composition/formation in particular, but I'm not allowed to explain (personal ideas/theories are banned). All I can (and want to) say is that my reasons and my main theory are related with something we (you) don't yet understand, dark matter/energy, so it may add something of value to our current description of the Universe.

I am happy with the last underlined comment in your post :) Thank you for that (and for all the rest).

 

[phinds]

This is an analogy of what I meant with the "same stuff" as common ingredient for all "fundamental" particles.

It's not clear but you seem to have still not gotten it that there IS NO "stuff" in fundamental particles. That's why they are called fundamental (actually elementary)

 

[Drakkith]

I have more (and solid) reasons to ask and think about this new, lower level in the structure of matter and about the Higgs boson composition/formation in particular, but I'm not allowed to explain (personal ideas/theories are banned). All I can (and want to) say is that my reasons and my main theory are related with something we (you) don't yet understand, dark matter/energy, so it may add something of value to our current description of the Universe.

...okay.

 

[ChrisVer]

I'm not very happy with the idea that "they are made of energy". This is too abstract.

Not more abstract than the electron itself, except for if you have ever seen an electron... ["made of" is not a nice expression]
The way we see particles is via their energy depositions in our detectors.
Now are particles mere energy? That's philosophy, but in some sense that's true, as you can produce them by colliding particles at necessary energies.

Imagination is good as long as it goes along with what we observe (look at mfb's post). If it's not, then it's irrelevant. Even if you want to add substructure to elementary particles, via means that they can still agree with the precision measurements, you will still need to introduce these new elementary particles and so on... [as the atom was replaced by protons,neutrons and electrons].

 

[mfb]

Imagine a concrete ball. That ball is not sand, nor gravel, nor water, it is something made from those ingredients (and more), but different ... and also a whole, not a system with moving parts (at least apparently). If you smash it, you obtain different pieces, with different shapes and proprieties (cutting edges, not rolling, etc.). Two or more smashed/crushed balls can be used to form a new concrete thing, maybe a cube. This is an analogy of what I meant with the "same stuff" as common ingredient for all "fundamental" particles.

A concrete ball is made out of atoms. If the elementary particles would be made out of something else in a similar way, all our predictions wouldn't have any reason to fit. But they fit - with excellent precision in cases like the electron g-factor.

This means that the Higgs particle is an excitation in the Higgs field?

Exactly.

How you digest this? I can't.

Whose fault is this? Did you learn QFT?

All I can (and want to) say is that my reasons and my main theory are related with something we (you) don't yet understand, dark matter/energy, so it may add something of value to our current description of the Universe.

Calculate the electron g-factor. If the result agrees, publish it, then we can talk about it.

 

[DanMP]

Not more abstract than the electron itself, ...

Imagination is good as long as it goes along with what we observe (look at mfb's post). If it's not, then it's irrelevant. Even if you want to add substructure to elementary particles, via means that they can still agree with the precision measurements, you will still need to introduce these new elementary particles and so on... [as the atom was replaced by protons,neutrons and electrons].

You are right.

Thank you for pointing out that, for a long period of time, the atom was considered elementary ...

 

[Feeble Wonk]

Now are particles mere energy? That's philosophy, but in some sense that's true, as you can produce them by colliding particles at necessary energies.

I think that this is the crux of the argument, and the core source of the confusion. The definition of being an “elemental particle” appears to become somewhat ambiguous.
As has been pointed out several times, there really is no “stuff” to a particle. It’s a “point” in space/time with zero spatial dimension but definable energetic qualities and quantities. Yet, with sufficient energetic input, the single point can become multiple points, suggesting intuitively that extra points were “hiding inside” the previously single point. Adding to the confusion is that there are various “forms” of energy that contribute to the particle manifestation.
Perhaps it would be helpful (and instructive to us laypeople) if one of you physicists attempted to define the concept of an “elemental” particle in terms of its energetic characteristics.

 

[ChrisVer]

suggesting intuitively that extra points were “hiding inside” the previously single point

That's your flaw. You make a suggestion that is based upon a misconception. You seem like you are trying to conserve something, when there is no such conservation law. The creation of particles/antiparticles is following other conservation laws (charge, energy/momentum, etc).
Again there is no intuition applicable/available if you haven't studied the theory that addresses the problem. Do that without a common ground of understanding the quantum world and you'll be discussing philosophy, as most of the popsci authors/spokespersons are doing.

 

[DanMP]

A concrete ball is made out of atoms. If the elementary particles would be made out of something else in a similar way, all our predictions wouldn't have any reason to fit. But they fit - with excellent precision in cases like the electron g-factor.Exactly.Whose fault is this? Did you learn QFT?Calculate the electron g-factor. If the result agrees, publish it, then we can talk about it.

I probably learned QFT long time ago, but I never used it, so I forgot most of it.

I searched QFT in Wikipedia and found this:

QFT was historically widely believed to be truly fundamental. It is now believed, primarily due to the continued failures of quantization of general relativity, to be only a very good low-energy approximation, i.e. an effective field theory, to some more fundamental theory.

You are right in most of what you wrote (electron g-factor, no mass in the gamma ray photons) and it is very hard to solve all the problems raised by this quest to a lower level, but not impossible. I have promising ideas ... The problem is that this is not my first goal ... Not even the second. Sorry.

Let's return to the Higgs particle, the main topic here. If the Higgs particle is an excitation in the Higgs field, how it decays in two or more excitations in other field(s)?

 

[ChrisVer]

I probably learned QFT long time ago, but I never used it, so I forgot most of it.

Refresh your memory... on the same topic:

If the Higgs particle is an excitation in the Higgs field, how it decays in two or more excitations in other field(s)?

y_{ha} h \bar{\psi}_a \psi_a \in \mathcal{L}

I have promising ideas

we "don't discuss personal ideas" here?

 

[weirdoguy]

How can you have "promising ideas" if you don't even remember the most basic basics of QFT? Seriously? If you want to improve physics you have to know exactly what has been done so far and what is left to improve. And to have that knowledge you have to study textbooks, not wikipedia...

 

[DanMP]

y_{ha} h \bar{\psi}_a \psi_a \in \mathcal{L}

Sorry, but this is a B level topic. Please elaborate.

How can you have "promising ideas"...

We don't discuss personal ideas here, so I can not answer.

Please focus on Higgs particle and, maybe, answer my last question.

 

[ChrisVer]

Sorry, but this is a B level topic. Please elaborate.

Although that was connected to "having studied QFT" (supposingly the standard model as well), the answer is simple:
It can: No violation of any known conservation law. Given that the coupling constants y_{ha} are non-zero. the Higgs field is coupled with the 2 fermion fields (except for on-shell tops because that violates the conservation of energy).

 

[mfb]

Thank you for pointing out that, for a long period of time, the atom was considered elementary ...

Before atoms could be actually studied, and often mainly in a philosophical way.
The situation is not comparable to today.

I have promising ideas

Let me be direct: No you do not, and you are wasting your time following "ideas" if you don't learn QFT first.

If the Higgs particle is an excitation in the Higgs field, how it decays in two or more excitations in other field(s)?

The Higgs field interacts with other fields - via the term ChrisVer posted.

 

[Feeble Wonk]

That's your flaw. You make a suggestion that is based upon a misconception. You seem like you are trying to conserve something, when there is no such conservation law. The creation of particles/antiparticles is following other conservation laws (charge, energy/momentum, etc).

Apologies... I didn’t make my question clear. I was conceding that the “intuitive” concept was flawed. What I was hoping for was a layperson friendly explanation of the limiting energetic factors that define the “elemental” designation of a particle.
I suppose I should add that it would be more helpful if that definition wasn’t limited solely to the aspect of locality... such as, an elemental particle exists when all energetic parameters can be attributed to a specific point in space.
Is it possible to offer a succinct explanation of the limiting energetic factors at a specific point in space that, if exceeded or altered, result in new/different point particle manifestations. I suppose that this would simply be a list of the conserved energetic qualities/quantities at the given point in space, but there must be a reason for the energetic limits that dictate spontaneous decay into other particles.

 

[ChrisVer]

What I was hoping for was a layperson friendly explanation of the limiting energetic factors that define the “elemental” designation of a particle

The particles have a set of quantum numbers that identify and define them. These can be the charge, the mass, the spin, and so on... those numbers originate from symmetries/conservations that manifest themselves in particle physics.

if exceeded or altered, result in new/different point particle manifestations

No. Possible decays (1 particle going to N others) are randomly taking place.
Interactions (2 or more particles going to N others) also have certain probabilities to give certain outcomes... eg colliding an electron with a positron with enough energy (to conserve it for the creation of masses for both outcomes) can give you a 2 photons, 2 muons, but it can also give you quarks.

 

[Feeble Wonk]

No. Possible decays (1 particle going to N others) are randomly taking place.

But, as we’ve seen with the Higgs boson, some particles are very unstable. They require extremely high energy collisions to be produced, and then decay “almost immediately”. That doesn’t seem completely random.

 

[Drakkith]

But, as we’ve seen with the Higgs boson, some particles are very unstable. They require extremely high energy collisions to be produced, and then decay “almost immediately”. That doesn’t seem completely random.

Various particles have a larger or smaller chance of being created at a certain collision energy than others. But at any collision energy, the specific particles created are still determined randomly per their different "weights".

 

[ChrisVer]

First of all, it is random... a tau lepton let's say has a mean lifetime of about 0.3 picosecond... now when a particular tau lepton decays is randomly taken from some distribution (eg poisson)... the mean lifetime only tells you if you had a sample of 100 taus, after that time the taus that decayed were 100/e and so on...

They require extremely high energy collisions

Not very extreme... the protons had like 7-8TeV center-of-mass energy, but that's not the energy that goes into the collision of the proton constituents (that share only a small portion of that energy). The Higgs needs ~125GeV energy to be produced - you only have to make sure you collide things that are coupled to the Higgs more strongly than other particles, otherwise you'll be swelled in background. LHC, colliding protons, does not favor the production of Higgs BUT it bypassed that problem because it achieves a tremendous amount of collisions. The number of data is one important parameter; it made LHCb compete the B-factories that collide electrons-positrons. Oversimplifying, you can deduce a discovery with let's say 10 clean data collected over a year, or with 1,000,000 unclean data collected in 1 month (~12* for the year).

That doesn’t seem completely random.

That's why probabilities are important. Something that is more or less probable is still random.

 

[DanMP]

Although that was connected to "having studied QFT" (supposingly the standard model as well), the answer is simple:
It can: No violation of any known conservation law. Given that the coupling constants y_{ha} are non-zero. the Higgs field is coupled with the 2 fermion fields (except for on-shell tops because that violates the conservation of energy).

Ok, thank you!

 

[Feeble Wonk]

Various particles have a larger or smaller chance of being created at a certain collision energy than others. But at any collision energy, the specific particles created are still determined randomly per their different "weights".

That's why probabilities are important. Something that is more or less probable is still random.

All points conceded. You are both quite correct, of course. It’s all about energy requirements and probabilities, and the “elemental” aspect to particle manifestation really is limited to the locality of defining physical characteristics at an individual “point” in space/time.
As has always been the case, the frustration for curious laypeople like myself is that physical descriptions at the fundamental level always seem to be far more “informational” in nature than ontological. Yet, sadly, I realize that that’s unavoidable. How does one describe “energy” ontologically? It’s a philosophical issue, and not a scientific question. Apologies.

 

[ChrisVer]

. Yet, sadly, I realize that that’s unavoidable.

It's unavoidable because there is no intuition for what happens at the quantum level. Even explaining the true nature of an atom is impossible and most people imagine atoms as the solar system: nucleus in the center and electrons revolving around it. Although that's a good approximation in some cases, it's not true or what quantum-mechanics tells us. How to go even more fundamental?
People who work with those get their intuition out of the formulas or actual observables. Eg the electron mass is clearly seen at the Na22 beta decay spectrum (the large spike at ~500keV),:

of course there are more such examples or different experiments but I remember this particular out of heart because I did the experiment during my undergrad and it was nice to see actual positrons-electrons there. An alternative one was the Thompson experiment to measure q/m of the electron, and it was also nice as you could see the trajectory of the electron beam (of course you saw the result of electrons passing through the gas-ionizing it and after the gas atoms fell at the ground state they'd radiate visible light -like fluoride lights).