beecee Posted March 21, 2019 Posted March 21, 2019 (edited) https://phys.org/news/2019-03-physicists-reveal-dominates-universe.html Physicists reveal why matter dominates universe March 21, 2019, Syracuse University: Physicists in the College of Arts and Sciences at Syracuse University have confirmed that matter and antimatter decay differently for elementary particles containing charmed quarks. Distinguished Professor Sheldon Stone says the findings are a first, although matter-antimatter asymmetry has been observed before in particles with strange quarks or beauty quarks. He and members of the College's High-Energy Physics (HEP) research group have measured, for the first time and with 99.999-percent certainty, a difference in the way D0 mesons and anti-D0 mesons transform into more stable byproducts. Mesons are subatomic particles composed of one quark and one antiquark, bound together by strong interactions. "There have been many attempts to measure matter-antimatter asymmetry, but, until now, no one has succeeded," says Stone, who collaborates on the Large Hadron Collider beauty (LHCb) experiment at the CERN laboratory in Geneva, Switzerland. "It's a milestone in antimatter research." The findings may also indicate new physics beyond the Standard Model, which describes how fundamental particles interact with one another. "Till then, we need to await theoretical attempts to explain the observation in less esoteric means," he adds. Read more at: https://phys.org/news/2019-03-physicists-reveal-dominates-universe.html#jCp https://phys.org/news/2019-03-cern-physics-biggest-mysteries-antimatter.html https://cds.cern.ch/record/2668357/ http://lhcb-public.web.cern.ch/lhcb-public/Welcome.html#CPVcharm Edited March 21, 2019 by beecee
QuantumT Posted March 21, 2019 Posted March 21, 2019 1 hour ago, beecee said: Mesons are subatomic particles composed of one quark and one antiquark, bound together by strong interactions. I thought that matter and antimatter annihilated each other on contact. So are the rules different with sub-particle quarks? Like tiny singularities?
swansont Posted March 21, 2019 Posted March 21, 2019 21 minutes ago, QuantumT said: I thought that matter and antimatter annihilated each other on contact. So are the rules different with sub-particle quarks? Like tiny singularities? Two things: 1. They have to be antiparticles of each other to annihilate. An electron will annihilate a positron, but it takes time, since it forms a bound state first. Same with quarks. 2. Unmatched pairs form mesons that decay into other particles 1
beecee Posted March 21, 2019 Author Posted March 21, 2019 (edited) 35 minutes ago, QuantumT said: I thought that matter and antimatter annihilated each other on contact. So are the rules different with sub-particle quarks? Like tiny singularities? Yes, and the reason that we obviously had an excess of matter was the quandary that worried physicists and cosmologists. The article confirms that the most fundamental parts of matter [quarks] decay at different rates in matter and anti matter and thus illustrates some differences in matter, anti matter particles, other then simply charge as was once thought. This may give clues with future LHC experiments as to why the obvious excess of matter. And of course what he said, just up there. Edited March 21, 2019 by beecee 1
Eise Posted March 22, 2019 Posted March 22, 2019 8 hours ago, swansont said: They have to be antiparticles of each other to annihilate. An electron will annihilate a positron, but it takes time, since it forms a bound state first. Same with quarks. That touches a point I was wondering about again when I read this yesterday. There are several mesons that are a combination of a quark and its anti-quark. And as another example, there seems to be a (short-lived of course) system like 'positronium'. How must I imagine this? Are most of these states excited states? And when in the ground state, the particles have the biggest chance to annihilate? But especially those mesons astonish me. They interact via colour force, the strongest force. Shouldn't these quarks annihilate immediately? 8 hours ago, beecee said: 9 hours ago, QuantumT said: I thought that matter and antimatter annihilated each other on contact. So are the rules different with sub-particle quarks? Like tiny singularities? Yes, and the reason that we obviously had an excess of matter was the quandary that worried physicists and cosmologists. Hmmm. I wouldn't say 'yes' on QuantumT's questions. See my positronium example, it is not made up of quarks. The most important is that there is a small asymmetry between matter and anti-matter. But if that explains the domination of matter over anti-matters is still not sure. Until now it is the only possible explanation, but if these slight asymmetries are enough to explain this, is AFAIK still an open question.
swansont Posted March 22, 2019 Posted March 22, 2019 2 hours ago, Eise said: That touches a point I was wondering about again when I read this yesterday. There are several mesons that are a combination of a quark and its anti-quark. And as another example, there seems to be a (short-lived of course) system like 'positronium'. How must I imagine this? Are most of these states excited states? And when in the ground state, the particles have the biggest chance to annihilate? They de-excite and then are in the ground state for a short time. The lifetime of positronium is about a tenth of a nanosecond (for antiparallel spins) Quote But especially those mesons astonish me. They interact via colour force, the strongest force. Shouldn't these quarks annihilate immediately? ~10^-16 seconds (π0) or less seems pretty short to me. The eta mesons are orders of magnitude shorter. https://en.wikipedia.org/wiki/List_of_mesons Quote The most important is that there is a small asymmetry between matter and anti-matter. But if that explains the domination of matter over anti-matters is still not sure. Until now it is the only possible explanation, but if these slight asymmetries are enough to explain this, is AFAIK still an open question. This experiment may not be directly related. "not everything about CP violation is necessarily related to baryogenesis. We don’t know how baryogenesis actually happened — there are many theories on the market, and any of them or none of them may be right. Therefore, there’s no way of knowing whether any particular manifestation of CP violation is in any way related to baryogenesis." http://www.preposterousuniverse.com/blog/2010/06/04/marketing-cp-violation/ 1
Eise Posted March 22, 2019 Posted March 22, 2019 2 hours ago, swansont said: This experiment may not be directly related. "not everything about CP violation is necessarily related to baryogenesis. We don’t know how baryogenesis actually happened — there are many theories on the market, and any of them or none of them may be right. Therefore, there’s no way of knowing whether any particular manifestation of CP violation is in any way related to baryogenesis." http://www.preposterousuniverse.com/blog/2010/06/04/marketing-cp-violation/ Right, that confirms my intuition. It is time to publish 'important' results, otherwise we have built the LHC only for the Higgs. Thanks for your explanations.
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