The supposed Higgs particle

SimonA

If the Higgs field imparts mass, and is composed of Higgs bosons, what gives this supposed "God" particle its mass ?

Of course causation is a deterministic space/time entity. And QM proves that determinism is not the whole story. But I cannot see the logic behind the idea that a particle creates mass, and yet itself has mass as an attribute of itself.

Surely Eintein's view of mass, as condensed energy, is a far better starting point than a particulate based field ?

Civilized

What the Higgs really does is break the symmetry of the electroweak interaction. In this context, breaking the symmetry means that some particles aquire mass, which means the equations change form so that they look like equations for a massive particle. Therefore "creates mass" just means "changes the equations to the version that describes a particle with mass."

The problem is that you are taking the loose idea that "the Higgs creates mass" too far without knowing the details of the physics. At a slightly more detailed level, the Higgs adds an additional term to the equations, and this causes the equations to change form, to become the equations that describe massive particles. I don't mean to give the impression that physics is just equations with no understanding, but it is very hard to explain symmetry breaking to someone who does not know math. Naive pictures of the Higgs "giving mass" are totally mislead e.g. no offense intended, but your question is like imagining the Higgs as a ball and chain which attaches itself to the foot of each particle, slowing it down, and then asking why the ball and chain had mass in the first place. It's nowhere near that simple. The standard model with the Higgs is totally different then a standard model without a Higgs. It's not like you could live in a massless universe and then open a box of Higgs particles that spread out giving things mass. It's more like, the existence of a Higgs particle means that you are living in a particular solution to the equations, a solution in which particles have mass.

I'm sorry if any of that came across as offensive, I blame the journalists and popular book writers who told you the Higgs "creates mass" without explaining that the higgs changes the equations so that new stable, massive, solutions appear.

SimonA

Hi Civilised

I don't find your reply offensive - I prefer these kinds of discussions to be direct and frank, impersonal but directly engaged with each others views. I don't pretend to be great at manipulating the formulas - I often end up with the likes of things dividing by zero when I try and so I know my limitations (given my lack of training). But I do think I have something to offer the discussion as a generalist, actually by being able to step back from the equations.

The breaking of symmetries and the related way the higgs makes the standard model work so well - such that things in nature and the mathematical model fit together (become symmetrical if you like) is amazing. All I'm asking is whether its a true representation of reality.

Your quote here is essentially why I think you missed my point;

"The standard model with the Higgs is totally different then a standard model without a Higgs. It's not like you could live in a massless universe and then open a box of Higgs particles that spread out giving things mass. It's more like, the existence of a Higgs particle means that you are living in a particular solution to the equations, a solution in which particles have mass."

To me that's like when I try to discuss religion with a Muslim. You believe in the standard model, so see no other options. We know the standard model is reliable is predicting the sphere of nature we have access to test empirically. But what is actually true ? We know that Newtons formulas are beautiful. We also know that they don't reflect nature accurately. So why should the standard model be any different ?

jtbell

It's not. No physicist I know thinks that the standard model is the be-all and end-all of particle physics. Ever since I was in grad school thirty years ago, theorists have been suggesting ways that the standard model might break down, and experimentalists have been looking for such breakdowns.

If the LHC finds the Higgs, it will be as significant as the first observations of the W and Z in the 1980s. But it will be a lot more interesting if the LHC doesn't find the Higgs.

SimonA

I agree :)

I suspect that gravity is fundamentally different to the other forces. General relativity proves that in my opinion.

turbo

Will it? In that case, won't the goal-posts be moved yet again to allow the expected energies to be even higher? I don't mean to be cynical about this, but there seems to be a stubborn determination to make a theory work when it is very beautiful, but experimentally unverified. Human nature, I suppose.

As an aside, the universe creates particles with energies that we cannot hope to achieve with our technologies. Should we not already have some tantalizing experimental observations in the data from our detectors that might be collated and characterized as signatures of the Higgs boson? If not, why not? Particle accelerators and experimental detectors have been around for a very long time, now, and even if we can't get concentrated beams of particles to impact targets "just so", at what point does the time-factor (sheer longevity of the technology) make it likely that we would have seen some really high-energy particles go "splat" in just the right way (and enough times) to bolster the case for the Higgs?

ZapperZ

Have you ever SEEN the results of one of these particle collision?

A significant part of the knowledge of analyzing collider data is understanding the "background". Students write their Ph.D theses on things like this. It is THAT significant. The way you wrote above seems to turn this into such a simple "experiment" - let two particles collide and voila, there's a higgs... or not.

The top was discovered out of barely a handful of "events" out of the gazillion collision data at both D0 and CDF. Not only are these events have such low probabilities, but their signature can be mimicked by other types of events. This is on top of the requirement that the true event must have enough of a statistical confidence level.

None of these are ever trivial!

And the goal posts in physics should always move to follow the experimental data. It is why it is NOT a religion! The fact that we continue to reformulate things once we realize that our original understanding either is wrong, or incomplete, is why it is science!

Zz.

ZapperZ

In your semiconductor, if you try to measure the mass of the electron, you'll find a value that is decidedly different than what you would measure for a bare electron. In fact, in some condensed matter systems, the mass of the electron inside such a system can be as high as hundreds of times the bare mass!

In other words, there are already precedent, based on experimental observations alone, for the apparent mass of an object to be a function of the many-body interaction arising out of some quantum field. So it is not a totally outrageous idea for the mass of a particle to due to such a mechanism. In fact, the Higgs mechanism itself came out of an idea from condensed matter dealing with the Nambu's work on spontaneous broken symmetry.

So you need to at least give some credit that these things are not being made up out of thin air. No one woke up one morning and decided to just pursue such line of thinking without any valid impetus.

Zz.

turbo

I was suggesting that (given enough time) we might reasonably expect to extract data from the existing observations to hint at the reality of the Higgs boson. If not, why not? I never simplified things to "let two particles collide" as you said, but at some point, enough on-line detector-time should give us some hints, given the fact that the Earth is bombarded with high-energy particles (beyond out abilities to create) every day. Do you have OOM estimations of why we have not gotten these already from astronomical sources?

jtbell

My understanding is that the mass of the Higgs is now constrained indirectly by other observations in the context of the standard model, so that if there is a Higgs with a significantly larger mass than the LHC range, it would require major changes somewhere in the standard model, not just parameter-tweaking. Someone who knows more about the current state of Higgs theory than I do will have to comment on this.

turbo

Thanks.

ZapperZ

Take a photon with slightly more than 1 MeV of energy. Now, try to get an electron-positron pair out of that. It should be possible, since the energy is just barely equal to the rest mass energy to create such pair.

Yet, we use considerably larger photon energies to make pair production in practice. Why is that, do you think? Because the probability of creating such pair would be significantly higher with higher energies.

Now look at the energy scale for the Higgs, even for the lightest Higgs! At what point, in YOUR calculation, that you think there is a significant statistical chance of not only creating it, but that you can actually have enough sigma confidence that you've detected it out of all the background noise and other decay channels?

Zz.

malawi_glenn

ok here we go;

Particle physics is modelled by the Theory Relativistic Quantum Field Theory, where the particles are quanta of these quantum fields (analogy with light as the quanta of the electric field)

The thing one would like to start off with in his Quantum Field model is the Lagrangian functional which contains the kinetic energy and the potential energy (just as in classical mechanics), the (potential part of) Lagrangian will contain terms which are quadratic in the fields, the coefficient in front of them will then become the Mass of the field quantas (simply due to the equations of motion) and one can also have so called Yukawa terms which also give "mass terms".

So one can have mass in a quantum field theory, no problem at all! And since it is a relativistic quantum field theory, it respects Einstein Special Theory of Relativity 100%, mass-energy-momentum relations and causality etc. So indeed this mass term IS the way Einstein's "mass = energy" would manifest it self.

BUT the particles in the world respects a symmetry which makes it impossible to have this mass term in the Lagrangian (such a term would not be invariant under a transformation under this particular symmetry). So either quantum field theory is not a good theory to describe the elementary particles (despite the HUGE success so far) or is there another mechanism consistent with the rules of Quantum Field Theory?

One suggestion is the Electroweak unification theory with spontaneous symmetry breaking, and one has actually found all the pieces that this model would lead to, except the physics realization of the Higgs boson.

How the mechanism works requires some group theory and some deeper knowledge about Quantum field theory, you can find a quite descent first exposure to it in "Quantum Field Theory Demystified), the main thing is that the higgs field is doublet with respect to the SU(2)_L group, and when/if one component acquire a non zero vacuum expectation value, the other fields in the standard Model Lagrangian will be given mass terms (quadratic and Yukawa ones).

So one has to be careful with that popular science mumbo jumbo description of things, the Higgs mechanism gives MASS TERMS to the W, Z and H bosons. And mass to fermions with yukawa terms, i.e. interactions with the higgs boson field itself. Very simple. The higgs boson gets mass when a higgs doublet component acquire a non zero vacuum expectation value.


So your suggestion "Surely Eintein's view of mass, as condensed energy, is a far better starting point than a particulate based field ?" as already been tried.. do you really think physicists are that stupid and naive?? ...

reading:
http://www.fys.uio.no/forskning/drgr...Eigen/SM-3.pdf



Now I will not comment on your philosophical view "Of course causation is a deterministic space/time entity. And QM proves that determinism is not the whole story. " That is another story...

malawi_glenn

If you haven't been into the equations or done heavy physics, how can you "step back" from it?

A "true" representation of nature (despite the issue that I don't think "true" is a good label, GOOD representation of nature is perhaps better, but never mind) would be something that is consistent with experiment, right? So we can find out if it is by searching for the falsifiable contents of this particular model, namely some mixing angles, corrections to several other things we have already discovered and finally the physical realization of a Higgs boson. The missing piece is the Higgs boson.

There are several other scenarios: http://en.wikipedia.org/wiki/Higgsless_model

And your comparison with religious stances and physics is very rude and wrong, where have Civilized said that he can't see any other options? You are just making things up, I have not met one single particle physicists who thinks/claims that the standard Model is valid for all energies/scales so why are you making these claims? Why don't try to be more of the approach of asking things how they is instead of implying so much? I think you are making a fool out of yourself and it is amusing that you think you have anything to contribute with...

Civilized

I wonder why untrained physics amateurs are often primarily interested in the possibility of our current theories being incomplete. I suppose the reasons that they are attracted to "beyond the standard model" are mostly sociological. The romantic allure of an "einsteinian genius" who "revolutionizes" the "hardest problems"and "deepest questions" that the "greatest minds" are working on, etc. If someone is driven to learn out of a curiosity about the universe, then there are many deep insights in classical mechanics, classical electromagnetism, statistical mechanics, quantum mechanics, and QFT and the standard model.

I disagree with your comparison between muslims and myself. The question "what is actually true?" belongs to the subject of ontology, which religous people are very concerned with, and in my opinion this is much less interesting than the deeper truths found in the interplay of physics and mathematics e.g. the Higgs mechanism.