Stability of Heavier Flavor Hadrons vs Anti-hadrons

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Discussion Overview

The discussion centers on the stability of hadrons formed from heavier flavor particles and their antiparticles, exploring whether these hadrons and atoms would have different lifetimes based on their composition. The scope includes theoretical considerations within the Standard Model of particle physics, as well as experimental observations related to particle decay.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants note that heavier flavor particles, such as strange, charm, top, and bottom quarks, are generally unstable, with top quarks being observed only indirectly through decay products.
  • One participant suggests that the question pertains to the Standard Model, indicating that heavier flavor quarks and their antiquarks decay quickly into lighter quarks.
  • Another participant states that the masses and lifetimes of antiquarks are the same as their corresponding quarks, but the decay behavior may differ slightly due to the CP violating phase of the CKM matrix.
  • It is mentioned that while theoretically, decay probabilities can be calculated for hadrons, generalizations across all hadrons or atoms are not feasible, and each must be evaluated individually.
  • Some participants discuss the presence of CP violation in electrically neutral mesons and its implications for decay rates, noting that it is not significantly observed in baryons and charged mesons.
  • One participant references recent experimental observations of CP violation with charged mesons, suggesting that these findings may not have received adequate media attention.

Areas of Agreement / Disagreement

Participants express varying views on the implications of CP violation and its effects on decay rates, indicating that there is no consensus on whether hadrons formed from antiparticles would behave identically to those formed from particles. The discussion remains unresolved regarding the broader implications of these findings.

Contextual Notes

Participants highlight that the decay behavior of hadrons is influenced by complex factors such as the CKM matrix and CP violation, which may not be fully understood or universally applicable across all particle types.

ScientificMind
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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.
 
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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.
 
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.
ScientificMind said:
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?
...
==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==
 
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"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.
 
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:

Bm_pikk_kk_lower_1_5.png
Bp_pikk_kk_lower_1_5.png
 
mfb said:
CP violation with charged mesons has been observed by LHCb, and it is massive in the channel considered.

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.
 

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