16 ms·
New exotic matter particle, a tetraquark, discovered at CERN
- akomtu 5y agoThe article (light on details, as usual) mentions that a slightly different configuration of a tetraquark would be very stable (again, not sure if that means nanoseconds or hours). If such stable multiquarks exist, without an electric charge they would be effectively untraceable, right? The only way to see such a particle would be to hit it precisely with an even smaller particle and get it to bounce back.
- sethhovestol 5y agoThe more likely (I'm not a physicist) is to watch the decay of the particle and trace it back from there.
- whatshisface 5y ago>The only way to see such a particle would be to hit it precisely with an even smaller particle and get it to bounce back. Bounce back from what force? Whatever forces would make it interact with a single particle would make it interact with a detector, which is itself made out of particles. They say the extra-stable tetraquark would only be susceptible to decay via the weak force, which means you'd have to wait around until it decayed, and then you'd often be able to see some charged remnants.
- akomtu 5y agoCan such tetraquarks form semi stable macroscopic structures like atoms? For example, if they aren't completely neutral, a group of them would be able to maybe attract an electron and become a quasiatom of some sort.
- whatshisface 5y agoThe stable-to-strong-decay species they're talking about, bb anti-u anti-d, would have a charge of (-1 -1 -2 -1)/3 = -5/3 times the electron charge. I guess its antiparticle would be positive, so maybe an electron could hang around for a while. I don't know how long that tetraquark is expected to live, though.
- FreeFull 5y agoThe charge would actually be (-2 + 1 - 1 - 1)/3 = -1 of a proton's charge. There isn't any physically viable combination of quarks that would produce a non-integer charge. The article mentions the bb tetraquark can only decay through the weak force, but I'm not sure how long it'd live either.
- enkid 5y agoI don't think that's a unique property to tetraquarks. Neutrons or neutrinos also are not electrically charged. I'm not sure what you mean by untraceable, but neutrinos rarely interact with other particles and many, many of them pass through you every second without you even noticing.
- dukwon 5y agoA stable heavy-quark tetraquark shouldn't live longer than, say, the B_c meson, which has a lifetime of about 5×10^-13 s
- danslo 5y ago>Such proximity in mass makes the decay "difficult," resulting in a longer lifetime of the particle, and indeed Tcc+, is the longest-lived exotic hadron found to date. So... how long does it live?
- whatshisface 5y agoThe resonance width is inversely proportional to the lifetime, and if the resonance width is about 400keV, the particle would live for about 10^-21 seconds. For comparison, neutrons decay via the weak force in about 800 seconds, and delta baryons, a randomly chosen strong force decay, live for 10^-24 seconds. That makes this tetraquark long-lived for a strong decay, but that's way, way faster than a weak decay. https://en.wikipedia.org/wiki/Resonance_(particle_physics) https://en.wikipedia.org/wiki/Resonance_(particle_physics)
- Gravityloss 5y agoSo not usable as spaceship fuel
- whatshisface 5y agoIf you're allowed to use something produced in an accelerator as your fuel you can't beat antimatter, which is as stable as normal matter until Kirk orders warp one.
- Gravityloss 5y agoThere's always many considerations. Energy density, stability, what kind of energy can you convert it to, can it be directed easily, how hard is it to store etc...
- whatshisface 5y agoAntimatter's reputation for being incredibly difficult to store comes from the fact that it's produced as individual particles. A superconducting antimatter hockey puck would be much easier to store than a cloud of antiprotons of the same mass. And yeah, you'll need a way to build gamma ray mirrors before antimatter reactions will push you in any direction (the energy comes flying out isotropically and we can't presently do anything to stop or direct it), but we can cross that parsec when we come to it. :-)
- tux3 5y agoThe article points to an ongoing conference as the source, unfortunately (despite having no registration fee) the live-stream is password protected for non-participants :( https://www.eps-hep2021.eu/live_stream/ https://www.eps-hep2021.eu/live_stream/ Edit: It seems the talks may be released, in the end >We would like to record your presentation at the EPS-HEP2021 conference and make it publicly available via the INDICO page and the DESY media streaming server until one week after the end of the conference.
- jandrese 5y agoThey probably don't want internet randos jumping in and flooding the chat with porn.
- tux3 5y agoThat makes sense for the zoom sessions. But, although I've never run a conference, I naively can't see that broadcasting the plenary session's video a little broader (to the three to five latecomers likely to stick around!) would really cause problems. Not to be a stereotypical "Concerned Facebook Taxpayer", but in general I'm really fond of CERN's transparency, and I appreciate all the work they do to keep science open. They're usually way ahead of the field and it's refreshing to see, I love following what comes out of the LHC data. So all that to say, maybe I've set my expectations a little high when it comes to physics and public access =)
- kkylin 5y agoMany online conferences I've attended this past year have both a Zoom meeting for registered participants and a YouTube "simulcast" for people who don't care about asking questions. I haven't run one and don't know if the logistics are complicated; maybe the organizers just didn't think of doing it. Anyway, these days most conferences seem to be pretty quick at putting videos out, though of course our attention will be elsewhere next week...
- whatshisface 5y agoTwo more technical treatments: https://cerncourier.com/a/new-tetraquark-a-whisker-away-from-stability/ https://cerncourier.com/a/new-tetraquark-a-whisker-away-from... https://lhcb-public.web.cern.ch/Welcome.html#Tcc https://lhcb-public.web.cern.ch/Welcome.html#Tcc
- oldspleen 5y agosomeone please ELI5 and how this discovery is important for furthering our understanding of quantum numbers
- whatshisface 5y agoThe laws governing the strong force are somewhat well-known at this point, but calculations involving them are difficult and in many cases beyond our reach. Furthermore the fundamental constants are not known to a very high precision. Both of these problems can be addressed by collecting experimental data about how these particles behave in real life, both to pin down the constants, and to accept or reject calculation techniques.
- lcfcjs 5y agoNo 5 year old could follow that.
- dukwon 5y agoIt won't improve our understanding of quantum numbers in general (a quantum number is just a discrete conserved quantity). The final paragraph mentions measuring the quantum numbers of this particular particle, namely its angular momentum and parity.
- thereddaikon 5y agoIs this the one that makes all the Sci-Fi gadgets do the impossible? I need to know if I should be excited or not. /s
- dmitriid 5y agoYou just need to apply more quantum.
- deleted 5y ago[deleted]
- 4e530344963049 5y agohttps://trimread.org/articles/31 https://trimread.org/articles/31
- amai 5y agoWhat is the charge of a tetraquark? Is it neutral?
- whatshisface 5y agoA tetraquark is four quarks. There exist three -1/3e quarks (dsb), three +2/3e quarks (uct), and then their +1/3e and -2/3e antimatter counterparts. 1e is the charge of one electron. The stability of a tetraquark is mainly a color/strong force thing and the electric charge comes along for the ride. Stable atomic nuclei, which are held together by the strong force, go up to +83e and they still don't fall apart due to electric repulsion. However, there is one constraint that might show up in charge. Tetraquarks always have two antiquarks, which is necessary for the color charge to come out to zero. Working out every possible combination is left as an exercise for the reader. :)
- im3w1l 5y agoThe highest possible charge is 2/3 + 2/3 + 1/3 + 1/3 = 2. Every swap of a quark to a lower charge one reduces the total charge by 1. So the possibilities are 2, 1, 0, -1, -2.
- jjk166 5y agoThis particular one is +1e but there are many other forms a tetraquark may be able to take.
- mirthless 5y agoDoes it fit into the standard model? I thought higgs boson was the last undiscovered particle according to the standard model.
- xhrpost 5y agoYou're referring to elementary particles. This is not elementary as it is composed of Quarks, which are part of the standard model and are elementary.
- x3n0ph3n3 5y agotetra-quark: 4 quarks. It's composed of particles that are already part of the standard model, just an a previously unseen arrangement.
- ur-whale 5y agoParticles are compositional.
- jdeaton 5y agoI wonder if the sophons from Trisolaris would have blocked this discovery.
- xondono 5y agoCongratulations for the discovery of the next epicycle!
- pseudobry 5y agoI recently finished The Three-Body Problem and The Dark Forest, which explore the concept of aliens using their super advanced technology to mess with the results of Earth's particle accelerators, thereby stopping humanity's ability to develop technology based on new physics. Is this discovery exciting? Or are we living in The Three-Body Problem?
- bequanna 5y agoInteresting. For what reason are the aliens trying trying to stop us from discovering new physics? Stop us from blowing ourselves up? Blowing them up?
- sylens 5y agoWithout ruining too much of the books (they are worth a read), there is conflict between us and the aliens and limiting technological progress is an important part of their strategy
- godelski 5y agoThe aliens are coming to Earth to take it over. They aren't much more advanced than us and so don't want us to be more advanced than the fleet that arrives (it takes them a few hundred years to get to Earth).
- FinanceAnon 5y agoIf aliens don't like us, then why wouldn't they just destroy us, rather than troll our physicists and mess with the results? Why would they specifically mess with the particle accelarators at this point? Why not with earlier physics?
- kingkawn 5y agoBecause they're hundreds of years of space travel away so they send sentient protons to sabotage our particle physics so that we can't develop advanced enough technology to stop them by the time they arrive.
- xwdv 5y agoCan someone explain the practical use for this? Better batteries or something?
- piyh 5y agoAnother tick forward in fundamental physics that will pay off as some theoretical framework getting slightly more grounded and paying off in a tangential way 70 years from now.
- spxtr 5y ago> The new particle contains two charm quarks and an up and a down antiquark. Several tetraquarks have been discovered in recent years (including one with two charm quarks and two charm antiquarks), but this is the first one that contains two charm quarks, without charm antiquarks to balance them. This is not the first time a tetraquark has been measured, but instead it's the first time a tetraquark with two charm quarks and no charm antiquarks. That's still nice work, but I was initially confused by the headline ("didn't they discover those already?").
- IAmGraydon 5y agoLike nearly everything from the media, it's a lie designed for clicks.
- elmomle 5y agoLet's not throw baby out with bathwater. This kind of thinking has been so harmful for social cohesion, and we need a cohesive society if we're going to have a prayer of handling the worst problems we've ever faced as a species in a way that future generations will be remotely proud of.
- bawolff 5y agoWe have no hope of facing those problems if our social cohesion is so fragile that it can't even handle calling an article out as clickbait.
- skinwill 5y agoNormal human here, can someone speculate on potential industrial uses?
- Zenst 5y agoToo early for that, though does open up other science that may well. Might finally pave the way for gravity shields, food replictor...or nothing. The aspect that this tetraquark breaks down into something with more mass will certainly be interesting for study.
- nabla9 5y agoNobody expects noting. No reason to expect anything whatsoever. The particle is incredibly short-lived, requires a massive particle accelerator to create, and is hard to detect. This is just another high-energy physics experiment. The hope is that someday something comes out that does not fit into existing models and is a sign of new physics.
- deleted 5y ago[deleted]
- WaitWaitWha 5y agoI am unclear if they produced a tetraquark particle, or they simulated the particle. > ... used Google’s quantum computer to demonstrate a genuine ...
- Algol 5y agoI don't see a mention of quantum computers in the article. I think LHCb detected the particle.
- archsurface 5y agoWhy do these things take so long to find? Do they not show up in all collisions - why not, wrong matter, wrong speed? Do they regularly appear, but the "camera" has limitations? Is the "camera" all-seeing, but measurement interpretation inefficient? All/some of the above?
- ManBlanket 5y agoI think it's a matter of theory supporting observed data. They point the, "camera" at a bunch of experiments, which generates a ton of data, then it's up to theoretical physicists to explain the results. Once the results of a theory have been explained and then reproduced it stands on solid ground. I'm just speculating, of course. But that is sort of how astronomy works, at the polar opposite end of a similar field.
- dukwon 5y agoYour comment kind of implies that theorists analyse the data. (They don't even have access to it.) Analysis is the job of experimental physicists (like me) and can take years. We don't wait until we have theoretical interpretations before publishing the discovery of a new particle. In fact, our results are kept confidential until the end of the collaboration's internal review process. In the absence of leaks, the first any theorist should hear of this new particle would have been the conference talk or press release.
- peter303 5y agoSome physicists will get an idea for a new particle or decay mode. Then they will postulate various decay modes that could be captured by the detectors. The short-lived new particle arent directly detectable, but daughter particles may be. Particles leave characteristic signatures on the two large CERN detectors, each which consists of an onion of thousands of directional and intensity sensors. Then they computer search quadrillions of already recorded events at the detectors for a significant number of candidate events. This may take months for a postdoc or grad student to do. I recall the Higgs had about 80-some possible decay modes. Only a handful of them could be measured above background noise. A couple of teams pursued two classes of them and found results.
- rkagerer 5y agoNeat! What can you imagine might be applications for exotic particles like this? (even if if it's a stretch or fictional)
- svachalek 5y agoGiven the massive energy required to do experiments like these and the microscopic scale in both physical and time dimensions I think we're centuries away from doing something practical with the particle itself. It may be the missing piece of some future technology we can't even imagine yet. I think the more immediate motivation is to help either validate our current understanding of how the universe works, or to break the model in an interesting way.
- dukwon 5y agoIn the world of double-open-heavy-flavour hadrons (to which this particular tetraquark belongs), you get bullshit headlines like this https://www.sciencealert.com/new-quark-fusion-releases-significant-energy-won-t-make-weapons https://www.sciencealert.com/new-quark-fusion-releases-signi...
- ThinkBeat 5y ago"Quarks are the fundamental building blocks from which matter is constructed." I sometimes wish would include "In our current model", "We now think that", or some other qualifier. Such absolute statements have been made frequently prior to our current understanding. I have no special knowledge to lead me to believe that quarks are not the end all of parties. But I was happy with atom being the fundamental thing, and then electrons, neutrons, protons were the thing as well. The other day I read about Fractons "quasiparticles or Partial Particles", so now I have to figure those out as well. I have lost track if the graviton has been found yet. I dont think it has. From a purely layman's sense of esthetics the current model for particle physics is messy and a little spooky. I have an odd hobby. I collect old paper encyclopedias from pre 1970 For every language that I speak. It takes up MASSIVE amounts of space. The oldest I have been able to acquire on a limited budget Is 1880. It is always fun to track concepts over time. They all state what the world is like, and how it works as bombastic facts. Yet over time, most of it gets replaced or at least highly refined and things are removed. Particle physics is an active field with much still to learn or figure out. Let us keep that in mind.
- brianpan 5y ago"We now think that" is the qualifier on the entirety of physics. It's redundant.
- h2odragon 5y agoI'll certainly give the authors of the papers the benefit of a presumption of humility; it's the people "translating into layman's terms" and "passing on knowledge" that introduce Authority, and other errors, as part of the process. "Think for yourself, schmuck" is the only dogma worth petting.
- abainbridge 5y agoHaha. True. Some parts of physics are way shakier than others though. For example, the whole big bang, dark matter, dark energy area needs the qualifier of, "We know we've got something wrong here, but its the best we've got". (eg see https://en.wikipedia.org/wiki/Big_Bang#Problems_and_related_issues_in_physics https://en.wikipedia.org/wiki/Big_Bang#Problems_and_related_...). I'm trying not to be controversial here. I'm just using this as an example of physics with well known problems. Regarding, "Quarks are the fundamental building blocks", do we actually think that? If so, why? I'm genuinely curious. Is it just because we haven't seen anything more fundamental? That would violate your "We now think that" qualifier - ie if that is the reason, the qualifier should be "We have NO reason to think that...".
- atulatul 5y agoI came here to write something else. But after typing I felt it would be sort of bikeshedding. So did not add it. And now I am going to see if any other comments sound like bikeshedding. (including this one probably.) :)