Tag Archives: particles

Why The Electron Can’t Have a Mass Without the Higgs Field

After a hiatus for a hurricane and a trip to a conference in Asia, I am adding one more article to my series on How the Higgs Field Works, following my series of articles on Fields and Particles. (These sets of articles require a little math and physics background, the sort you’d get in your first few months of a beginning university or pre-university physics class.  I’m still thinking about how to structure a similar set of articles that require no math or physics; that’s much harder, of course!)

The first article in the series explained the basic Idea behind how the Higgs field works. Then came an article about why and how the Higgs field becomes non-zero, and a third concerning how the Higgs particle arises as the quantum of waves that oscillate around the non-zero value of the Higgs field.  The new article tries to clarify why there’s no alternative to introducing a Higgs field, explaining that it’s otherwise impossible to reconcile two apparently contradictory features of our world: a mass for the electron (and many other types of known particles) and the properties of the weak nuclear force.

This article contains the most elaborate equations and concepts that I’ve had to introduce to my readers, so it won’t be suitable for everyone (though it still only requires some first-year physics/math.)  But on the other hand, it seems necessary for me to write it, since it’s the only place that I’ve explained not only why the Higgs field can give mass to the known particles, but why it (or something very much like it) must do so.

(Note that in these articles I’m mainly concentrating on the simplest type of Higgs, the Standard Model Higgs field and particle.  However, most of the basic concepts in these articles apply even for more complicated cases.)

Theory Killers at the HCP conference

There were many interesting results presented yesterday at the HCP conference in Kyoto, and they were both too numerous and too detailed for me to completely absorb as yet — a follow-up will clearly be needed.  But a few are obviously so important that I want to point them out now.

First, both ATLAS and CMS, the two general purpose experiments at the Large Hadron Collider [LHC], produced important new results on “multileptons”.  Based on a significant fraction of their 2012 data, they looked for signs of new phenomena that would appear as proton-proton collisions that produce at least three leptons or anti-leptons, or even (in unusual combinations and/or along with other unusual things) two leptons or anti-leptons.  (I’ll just summarize this class of studies as “multileptons” for the purpose of this brief post and be more specific at a later date.) ATLAS used about 50% more data than CMS, but CMS had a more intricate analysis of their data, so I believe the results were similar where they can be compared.  [By the way, the CMS result was approved to be shown at this conference under extreme conditions; at least two of the major players in the analysis had no power or internet for over a week following Hurricane Sandy!]

The bottom line is simple: neither CMS nor ATLAS sees any significant deviation from what is predicted by the Standard Model.  And this now kills off another bunch of variants of many different speculative ideas.  The details are extremely complicated to describe, but essentially, what’s dead is any theory variant that leads to many proton-proton collisions containing

  • two or more top quark/anti-quark pairs
  • multiple W and Z particles
  • two or more as-yet unknown moderately heavy particles that often decay to muons, electrons and/or their anti-particles
  • new moderately heavy particles that decay to many tau leptons

and probably a few others I’m forgetting. While multilepton searches (especially those for 3 or more leptons) are often touted as a great way to look for supersymmetry in particular, that description vastly understates their power — they are a great way to look for many different types of phenomena not predicted in the Standard Model.  (This is something that a number of scientists at Rutgers University have been emphasizing in talks and papers.)  And both experiments have demonstrated this with various interpretations of their results; CMS has over a dozen of them! Continue reading

Does the Higgs Field Give the Higgs Particle Its Mass, or Not?

When I wrote my article last week about the relation between the Higgs and gravity, emphasizing that there really was no relation at all, I said that the Higgs field is not the universal giver of mass. I cited four reasons:

  1. The Higgs field does not give an atomic nucleus all of its mass, and since the nucleus is the vast majority of the mass of an atom, that means it does not provide all of the mass of ordinary matter.
  2. Black holes appear at the centers of galaxies, and they appear to be crucial to galaxy formation; but the Higgs field does not provide all of a black hole’s mass. In fact the Higgs field’s contribution to a black hole’s mass can even be zero, because black holes can in principle be formed from massless objects, such as photons.
  3. There is no reason to think that dark matter, which appears to make up the majority of the masses of galaxies and indeed of all matter in the universe, is made from particles that get all of their mass from the Higgs field.
  4. The Higgs field, though it provides the mass for all other known particles with masses, does not provide the Higgs particle with its mass.

Although it doesn’t matter too much to the main point of the Higgs-and-gravity article (since the first three points are not in question), the editor of a leading physics journal, Robert Garisto, took issue with the fourth point, arguing that I was making a statement that really wasn’t right, or at least is too strong. His argument has some merit, though in the end, I stick with my statement. I think it’s worth describing what he had in mind (as best I understand it) and why I feel strongly that one should think about it differently. There are some semantic aspects to the disagreement, but there are also some interesting and important subtle scientific points.  I don’t want to suggest that this discussion is really that big a deal — the very fact that we can argue about whether the Higgs field does or doesn’t provide the Higgs particle with its mass distinguishes the Higgs particle from, say, the W particle, whose mass indisputably arises from the Higgs field. But there’s something to learn here about quantum field theory and how the Higgs mechanism works. Continue reading

How the Higgs Field Does Its Thing

Last week I finished up a set of articles explaining what Fields and “Particles” are.  These articles require a small amount of math and physics, the sort you’d get in an advanced pre-university or a beginning university course.

[Articles with no technical requirements will come soon; in the meantime, try my widely read article on Why the Higgs Particle Matters.]

The Particles and Fields articles are a prerequisite to the next set of articles, which will explain what the (simplest type of) Higgs field is and how it does what it does. The first article, just completed, outlines the basic idea. Future articles to appear over coming days and weeks will fill in many details.

Two Major Steps Forward

Apologies to those who’ve been asking questions: I’ve been away from the website for a few days (family matters) and have not been able to keep up with comments.  I will try to catch up over the coming day or two.

But I do have two pieces of good news.

First, I gave a public lecture over the weekend, on-line, called “The Quest for the Higgs”, which I believe many of my readers will find at the right level.  Because of some technical difficulties with the sound recording, I didn’t immediately recommend that you listen; but those problems are now fixed and the sound is pretty good.  The audio is to be found here at BlogTalkRadio, through the Virtually Speaking Science series; on that website, there’s a link to the slides accompanying the talk, or you can just click here to get them.  [Note the slides are under copyright; please ask permission before reproducing or using ideas you find therein.] 

Second, the long-awaited final article in the series on Particles and Fields (with a little math) has arrived.

  1. Ball on a Spring (Classical)
  2. Ball on a Spring (Quantum)
  3. Waves (Classical Form)
  4. Waves (Classical Equation of Motion)
  5. Waves (Quantum)
  6. Fields
  7. Particles are Quanta (new!)

As a bonus, you can then find out what the key technical difference is between bosons and fermions (the consequences of this difference are described, without technicalities, here.)

Next month: a series of articles on How the Higgs Field Works.

After Springs, Waves

On Monday I started a series of articles to explain particles and fields, aimed at those who’ve had a little bit of physics in their past (perhaps a semester or two just before or just at the beginning level at a university), and containing a very little amount of math.

I first brought you the story of the ball on a spring, both the classical [i.e. pre-quantum] version from the 1700s and the quantum version from the early 1900s.

Now it’s time to turn to waves. This is the longest subject I’ll have to cover, I think, so I split even the pre-quantum story of waves up into two parts, one aimed at getting the right formula for describing a wave, and the other at getting the right equation of motion for which that formula is a solution. If you’ve had first-year physics you’ve seen most of this, but there’s a twist toward the very end that is probably novel — you’ll see a wave equation you’ll probably recognize, but also one that, quite possibly, you haven’t seen before.

A Little Math; A Lot of Physics

One of my current goals is to explain how the Higgs field works to anyone who’s learned a bit of physics at the beginning-university or advanced pre-university level. As a step toward the goal, I am creating a set of pages that explain how fields work, why quantum mechanics implies that sufficiently simple fields have particles, and which aspect of a field’s behavior determines the masses of its particles.  You will find that knowing a little physics and a little math is helpful.

[I’m afraid that most of you who never had a beginning physics class at all will have to be patient. It’s an even greater challenge for me to explain the Higgs field to someone who’s allergic to math, or hasn’t had much math yet; I’m hoping my current efforts will help me see how surmount that challenge.  But meanwhile you might like to read my Higgs FAQ and my popular article on Why the Higgs Particle Matters.]

The first step is to remember how a ball on a spring works — one of the first things one learns in any physics class — and then learn a little bit about how quantum mechanics changes the answer — one of the first things one learns in a quantum mechanics class.  This is where the concept of a “quantum” first makes its appearance in physics.  Those articles are now ready for you to look at.  The next step [waves, both without and with quantum mechanics] will follow over the coming week.

Note: I’ve included, for the first time on this website, some animated gifs among the figures.  These should animate when you click on them.  I know they need improvement; over the next day I’ll be trying to make them faster to load and run.  Please be patient and let them load; but do let me know if you can’t make them work at all, and if so, what browser and hardware you’re using.  Update: they should be much faster now.

CMS Finds a New (Expected, Composite) Particle

Yes, it’s true what you’ve read; the CMS experiment at the Large Hadron Collider has found a new particle.  However, this isn’t one to get excited about.  Or rather, it’s the particle that’s excited, not the rest of us.  It’s a nice result; a neat result; but this particle is a slightly more massive version of a hadron that we already knew about, a composite object similar to a proton, built out of more fundamental particles we discovered over 30 years ago.  So in the grand scheme of things, this is minor news; no big mysteries to resolve here.  Nevertheless, congratulations to CMS! Finding such particles always involves reconstructing them from their decay products, and since this one decays in a very complicated way, the result represents a technical tour-de-force!

This is a similar story to one from last December, when ATLAS announced that it had found, with confidence, a new particle.  I explained to you then that there are particles and there are particles; Continue reading