Subatomic Particles

[blike]

Very nice chart here.

[fafalone]

Very cool. They forgot alot tho :/

[aman]

Thanks, I'll stick it in my reference folder. Thanks for any additions.

Just aman

[Tom Mattson]

Originally posted by fafalone

Very cool. They forgot alot tho :/

 

Such as...?

[fafalone]

The antineutron, Xi₀, sigma₀, M⁺, all of the antineutrinos, all of the antiquarks (though these are mentioned, as they, with a quark, compose mesons), delta (baryon), the lamba baryon (incidently, the simple where it says lambda is actually the symbol for a hyperon, so this is an omission as well), the phi meson, the delta meson.. i think thats it. some of these omissions are generally not talked about; but since once again you had to challenge me, I've included as many as I could find

 

[Tom Mattson]

Nah, I'm not challenging you. It's just that all the threads here seem to go something like this:

 

Person 1: Here's an interesting fact....

Person 2: Thanks, I didn't know that.

Person 3: That's cool!

Person 4: I think so too.

Person 5: I'm confused.

 

Talk about :zzz:

 

I was just trying to squeeze something more out of this one.

 

The antineutron, Xi0, sigma0, M+, all of the antineutrinos, all of the antiquarks (though these are mentioned, as they, with a quark, compose mesons),

 

Yeah, the antiparticles are conspicuously absent from the chart. As for the other particles, I would not have included them anyway. I would have dispensed with all the hadrons altogether, cuz the title of the chart refers to 'fundamental particles'.

 

delta (baryon),

 

This one I think we can let slide. The delta is just an excited state of the nucleons, which are included. It really isn't a seperate particle, any more than a hydrogen atom in, say, an n=2 state is a different atom from the ground state.

 

Tom

[fafalone]

They do mention the antiproton though, that's why I considered all the other antiparticles as admissions. And it says there are 120 types of baryons... I sure don't know them all :/

[aman]

I was just pondering about the properties of antimatter when science can build heavier elements with it. If we make anti-matter neon and run an electrical charge through it, will the atoms become excited and emit anti-photons that travel at the speed of dark, oops, I mean light? Just curious if there are such things as anti-photons.

Just aman

[fafalone]

That's the question. Right now it's exceedingly diffult to even make anti-hydrogen, much less anti-neon. I suspect it might be a few decades before we can make higher atomic number elements.

[Tom Mattson]

The photon is its own antiparticle.

 

Let |e,i> represent the state vector of some particle with 'e' standing for a collective index of the external quantum numbers (parity, energy, momentum, polarization, etc.), and 'i' standing for a collective index of the internal quantum numbers (charge, flavor, color, etc).

 

Let C represent the charge conjugation operator that transforms particle states into antiparticle states and vice versa. An empirical fact is that particles differ from their antiparticles only by a difference in sign in the internal quantum numbers, so the operation:

 

C|e,i>=|e,-i>

 

transforms any particle into its antiparticle.

 

However, for the photon, all quantum numbers represented by the collective index 'i' are zero.

 

Tom

[fafalone]

But isn't the spin quantum number of a photon 1?

[Tom Mattson]

It is, but that's an external quantum number. The internal numbers are the ones that have to do with gauge symmetries, and thus interactions.

 

Now that I think more about it, another problem pops up: Why isn't mass included in that list? That is, after all, the "gravitational charge".

 

Perhaps it has to do with the fact that the gravitational field is not a rank-1 tensor, but rank-2...

[fafalone]

Does that suggest that photons may have mass, or that the influence of gravity affects the trajectory of objects indirectly, through warping spacetime?

[Tom Mattson]

No, it doesn't suggest a photon mass, it suggests that there is something about gravity which would cause no sign change in that particular internal quantum number. For instance, the mass of the anti-u quark is not the negative of the mass of the u-quark, even though all the other "charges" (electric, flavor, color") are conjugated under the action of 'C' operator.

 

Of course, we know that there is something special about gravity, namely that it is a spin-2 field, as opposed to the other 3 forces, which are all spin-1.

 

I'm just wondering if that is the cause of the difference. Unfortunately, it is not that I forgot the answer, it is that I never knew it. I never did learn anything about quantum gravity, although hopefully I will be able to fix that in the future.

 

Tom

[aman]

I tried researching more on the Higgs Boson which is supposed to be the answer to why things have mass but I don't know if it has actually be discovered yet. If it is an attachment to sub-atomic particles that adds the mass, would there be an anti-Higgs Boson for anti-protons or are there some quantum "particles" like possibly photons and Higgs Bosons that may be neutral in either enviroment?

Just aman

[fafalone]

I think something worth mentioning in this thread is an experiment done a couple years ago using :beta: mesons... it was found that anti-:beta: mesons had a decay rate that was very slightly different than :beta: mesons. This could partially explain how the dominance of matter came about during the first milliseconds of the universe.