1. Jun 15, 2015

### ScientificMind

So, from what I can tell, anything that is formed from heavier flavors of particles (strange/charm quark, top/bottom quark, muons, taus, etc.) is incredibly unstable, to the point of top quarks only ever being observed indirectly through its decay products. Anyway, I was wondering, is this the same for stuff formed from the antiparticle counterparts of the aforementioned particles? If hadrons, or even atoms were to form from these specific antiparticles, would they last longer, shorter, or about the same miniscule amount of time?

p.s. Sorry if my terminology is incorrect, I had to look several of these terms just to ask this question and I'm still not failiar with them.

2. Jun 15, 2015

### marcus

Last edited: Jun 15, 2015
3. Jun 15, 2015

### rootone

Well the problem of the Universe containing ordinary matter and as far as we know very little if any antimatter does seem to indicate assymmetry.
I don't think anybody cracked that one yet.

4. Jun 15, 2015

### marcus

SciM, your question is really about the conventional established Standard Model of particle physics. You are right that the more massive heavier flavor quarks [and antiquarks] do decay quickly into their lighter u and d brethren.
The Standard Model is covered pretty well in WikiP, which says the antiquark versions have the same masses and lifetimes as the normals.
==wikipedia quark article https://en.wikipedia.org/wiki/Quark#Classification ==
Antiparticles of quarks are called antiquarks, and are denoted by a bar over the symbol for the corresponding quark, such as $\bar{u}$ for an up antiquark. As with antimatter in general, antiquarks have the same mass, mean lifetime, and spin as their respective quarks, but the electric charge and other charges have the opposite sign.[8]
==endquote==

Last edited: Jun 15, 2015
5. Jun 16, 2015

### ohwilleke

"If hadrons, or even atoms were to form from these specific antiparticles, would they last longer, shorter, or about the same miniscule amount of time?"

Basically, they'd behave identically, but CP violating phase of the CKM matrix in the Standard Model slightly tweaks how antiquarks as opposed to quarks decay in a fairly precisely measured way (although the CP violating phase of the CKM matrix is one of its less precisely measured parameters). There is no theoretical difference the decays to charged leptons which are not governed by the CKM matrix in the Standard Model. For any given hadron, it is possible in principle to calculate the probability of every decay possibility from first principles, but one can't really generalize about all hadrons or atoms, one has to evaluate each in turn.

Also, experimentally, CP violation is only present at measurable levels in the case of electrically neutral mesons, even though the CKM matrix applies to all systems involving quarks. CP violation in baryons and electrically charged mesons is theoretically predicted to be, and experimentally found to be, too slight to detect with existing experiments.

A difference in decay rates between matter and antimatter in excess of the Standard Model prediction, of course, would be beyond the Standard Model physics. But, since particle colliders measure lots of both matter and antimatter particles, these violations are largely ruled out and tightly experimentally constrained.

6. Jul 1, 2015

### Staff: Mentor

CP violation with charged mesons has been observed by LHCb, and it is massive in the channel considered. Here are two plots from the LHCb website, CP conservation would mean both peaks have the same height:

7. Jul 6, 2015

### ohwilleke

Thanks for the update. It is a pity that this result wasn't more widely publicized, but I suppose it is hard to make a mass media story after an important empirical confirmation of a key aspect of the SM when the vast majority of people don't know that it hadn't been confirmed in the first place.