Sorry
What I meant to ask is which W particle is considered matter and which antimatter? Or is that question meaningless.
The W+ weak boson is the antiparticle of the W- boson, though I don’t think one is specifically designated “matter” and the other “antimatter”. Even though these particular bosons have mass, bosons in general are particles of force; fermions are the particles usually thought of as matter and antimatter.
A W- boson decays into an electron and and electron antineutrino, and a W+ boson decays into an positron and and electron neutrino. Since a W+ could only be annihilated by a W- and the W bosons have a decay half-life of about 3×10−25 seconds anyway, which one you designate as the ‘nominal’ antiparticle is kind of semantics, although there are obviously more W- bosons occurring in nature (at least in the visible universe) than W+ bosons.
Stranger
Ah then it makes sense that the W- is the regular particle as, like the mu- and tau- regular particles, it decays into an electron.
If you like. Textbooks just note that W- and W+ are each others antiparticle and Z0 bosons are their own antiparticle. People often have the notion that any two antiparticles with opposite charges will annihilate each other but in fact they have to have the same mass (presumably) and opposite chirality, so it isn’t as if a W- boson can annihilate a proton.
Stranger
You get the same issue with the mesons. A meson is composed of one quark and one antiquark. If the quark and antiquark are of the same kind, then the meson is neutral, and is obviously its own antiparticle. If they’re different kinds, though, you can get an antiparticle to it by swapping which one is which. For instance, an up quark and a down antiquark will make a pi+, and a down quark and an up antiquark will make a pi-. And up quarks and down quarks are both commonly found in ordinary matter (protons and neutrons both contain both kinds), so there’s no grounds for calling one more “normal” than the other.
Oh, and while we’re at it, matter-antimatter annihilation, even between matched particles, isn’t usually a neat, tidy process. An electron and a positron (AKA antielectron) will annihilate directly to two high-energy photons and that’s the end of it, but not so, say, a proton and an antiproton. A proton and an antiproton (or a neutron and an antineutron) will usually first become three pions, either all three neutral, or one each positive, neutral, and negative. The neutral pions will in turn decay into two photons each, but the charged ones will decay into a muon and an anti-mu-neutrino (for a pi-; reverse that for a pi+), and the muons will then each decay to an electron, a mu neutrino, and an electron antineutrino (reverse that for the antimuons).
And if you have matter composed of both protons and neutrons, and the matching antimatter, there’s no guarantee that the protons will match up with the antiprotons and the neutrons with the antineutrons.
Yes and no… You could, for instance, have a reaction between an e+ and a mu-, that resulted only in neutrinos and antineutrinos (which would presumably count as an “annihilation”).
Does “obvious” really apply to the W boson charge ratio of the universe? In any case, the answer has to be the other way around. The only W bosons in the universe today are those made from very high energy collisions, and the most prolific natural producer will be high energy protons colliding with other matter. And given that protons are positive, there will be a predominance of W+ over W-.
I wouldn’t call that annihilation. An e+ and mu- can never directly merge into a single virtual intermediary that carries all of the four-momentum of the system and that also possibly erases some of the initial quantum numbers. Without that, it’s just… an interaction. Indeed, in this case the two initial leptons haven’t even gone away, although they have exchanged a unit of charge to become neutral leptons.
(In contrast, calling the (up quark)-(down antiquark) interaction an annihilation is okay in the right context, as these can become a W boson and thus can lose their initial identity completely.)
Most standard charts are kind of silly in this regard. If both W bosons are shown, why not both charges of electrons, muons, up quarks, etc.? And if we’re showing different electrical charges as distinct particles, why not also different strong-force charges, which would require showing three (well, six) types of each quark and showing eight gluons instead of one?
Anytime I show a simple table of the Standard Model’s fundamental particles, I opt not to include multiple copies of things that differ only in charge (so, just one W boson for me).
I assume OldGuy deleted this line at some point, but it made me curious.
I did an image search for “table of particles”. There were no examples of charts with two W particles, except for charts expansive enough to include antiparticles as well.
Somewhat surprisingly, the W and Z bosons don’t even merit separate Wikipedia pages. Their interactions require three degrees of freedom, with charges of -1, 0, 1, and so you get three particles out of it, but in some sense they’re just three aspects of the same thing.
Indeed. The calculation of the mass ratio between them was one of the triumphs of Electroweak Theory.
Though one can go even further and say that those three and the photon are all four of them aspects of the same thing.
I was quoting the thread title there.
For the image search: The doubling is usually indicated by a “+/-” symbol, not necessarily as a separate entry (although sometimes that). Most of the image results do this.
How did you do that? The pointer goes to post #2.
Some do, but I took another look at that page and I’d say that most don’t. As I said, just curious.
Ah, I should have edited that out. I originally quoted his post 2 but then decided that the title was actually what I was replying to, and I edited the content but not the metadata.
Weird. Can’t imagine we’re getting such different results. I went through the first ten unique examples and eight of them indicated both charges on just the W, matching my sense from the wild.
The big book I have from the Particle Data Group just has it under W boson.
Eg check out the summary table: