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CERN experiment discovers five new particles
- teddythetwig 10y agoI assume these particles were already predicted as part of the Standard Model?
- gpderetta 10y agoyes, and note that these are not fundamental particles (like the Higgs was for example), but composite particles of yet another combination of the fundamental quarks. The SM predicts the existence of hundreds (thousands?) of these.
- inlineint 10y agoActually it is even a one new particle (Omega_c baryon), but they observed five different excited energy states of it (like observing different excited states of a Hydrogen atom), so called resonances [1]. But the discovery is still exciting because it should have been really hard to find something that we don't really know how looks like in such large amount of noise. The problem is that it is hard for us to predict masses/energies of new composite particles because although Standard Model provides hypothetical way to do it, it is infeasible computationally. [1] http://physics.stackexchange.com/questions/64862/resonances-in-high-energy-physics http://physics.stackexchange.com/questions/64862/resonances-...
- nonbel 10y ago>"it should have been really hard to find something that we don't really know how looks like in such large amount of noise." But if there are thousands of different such "surprising-to find-particles" to possibly detect, is it actually surprising to observe one of them? Edit: Also, from the top answer at your link: "The first generation of elementary particles are by observation not composite and therefore not seen to decay...The Standard Model of elementary particles, with the three generations of matter, gauge bosons in the fourth column and the Higgs boson in the fifth." From wikipedia: "In the Standard Model, the Higgs particle is a boson with no spin, electric charge, or colour charge. It is also very unstable, decaying into other particles almost immediately." https://en.wikipedia.org/wiki/Higgs_boson https://en.wikipedia.org/wiki/Higgs_boson So do elementary particles decay or not?
- inlineint 10y ago> But if there are thousands of different such "surprising-to find-particles" to possibly detect, is it actually surprising to observe one of them? It is hard to correctly identify what exactly particles from those possible thousands are observed in given data. The are two main problems: the properties of those not yet observed particles are not well known (because it is computationally hard to predict them from the standard model) and because the number of useful events is much much smaller than the number of events that correspond to already known events. > So do elementary particles decay or not? I don't see a contradiction here: the first generation of elementary particles does not decay (or has not been observed to decay yet), Higgs boson is not from then because the author of the answer are talking about the first generation of fermions and Higgs boson is not one of them.
- nonbel 10y agoThanks, I missed that "first generation" detail.
- brutuscat 10y agoProfessor Tim Gershon, Professor of Physics at University of Warwick and UK spokesperson for the LHCb experiment: “After the LHCb experiment is upgraded in the next long shutdown of the LHC (during 2019-20), it will be able to move to the next stage in the search for new particles: namely, doubly heavy baryons. These states – which contain two charm quarks or two beauty quarks or one of each – have long been predicted, but never yet observed. Their discovery will help to address important unsolved questions about how hadrons are bound together by the strong interaction.” So I would assume that yes they have been predicted and is opening the doors for further confirmations?
- wolfgke 10y ago> Their discovery will help to address important unsolved questions about how hadrons are bound together by the strong interaction. If the particles were already predicted by the standard model, what kind of unsolved questions are to address here, besides validating the predictions of the standard model even further? (serious question)
- binarymax 10y agoBecause a prediction is just an assumption (theory), and it can become a house of cards when basing future science on that assumption. Observation is proof, so future science can use that proof without worry.
- nonbel 10y agoCan you clarify? In my mind "prediction" != "assumption" != "theory" and "observation" != "proof" Basically I seem to disagree with everything you wrote.
- herpdorplarp 10y agoBy assuming validity of a theory you can make predictions. Observations provide evidence in support of this.
- guitarbill 10y agoAFAIK, the experimentally determined rest masses of these excited states/particles (same thing, different was of looking at it) agree with the calculated ones well. So yes, they were predicted. No surprises sadly; of course it's still a huge achievement!
- dukwon 10y agoThe theory uncertainties are large. Any measurements within a broad range would also agree with some calculated masses. That doesn't tell you much. See e.g. https://arxiv.org/abs/1311.4806 https://arxiv.org/abs/1311.4806
- sidlls 10y agoYes, but these experiments serve at least three purposes. One, to verify the Model (after all, if its predictions fail in some part it will have to be revised). Another, to verify the characteristics of the predicted particles (there might be some differences from the prediction that are important, but not hypothesis-breaking). Finally, however unlikely and yet most excitingly (to me at least), to open new avenues of questioning and hypothesis up by really throwing into question some things.
- M_Grey 10y agoIt's worth remembering that the Higgs particle was also predicted by the standard model, and no one underestimates the importance of that confirmation.
- cynicalkane 10y agoNot in the same way. There was no experimental evidence for the Higgs field before the Higgs was observed. These new particles arise naturally out of parts of the Standard Model that are already experimentally tested.
- M_Grey 10y agoYou're not wrong, but you'd have been really hard-pressed to find someone of significance who didn't already believe the Higgs mechanism was there. In the sense that mass exists, there was a high degree of expectation there too. It's actually quite amazing to have so many of these recent discoveries, also be confirmations. It's been over a century of this, starting with Relativity.
- whyever 10y agoThe Higgs is an elementary particle, so its discovery was much more exciting. There are a lot of particles made up of quarks, like the five mentioned in the article: http://pdg.lbl.gov/2016/tables/rpp2016-qtab-mesons.pdf http://pdg.lbl.gov/2016/tables/rpp2016-qtab-mesons.pdf http://pdg.lbl.gov/2016/tables/rpp2016-qtab-baryons.pdf http://pdg.lbl.gov/2016/tables/rpp2016-qtab-baryons.pdf
- ajross 10y agoYes. They're baryons (three-quark states). This is analogous to the discovery/synthesis of new isotopes in the middle of the last century. Technically they were "predicted", but it's still important to take the measurements. Occasionally there are surprises.
- deleted 10y ago[deleted]
- grabcocque 10y agoI have to admit, I rather admire their putting a brave face on things, with their mildly-too-insistent claim that the LHC is vital for finding new physics despite the increasing likelihood it's not going to find any. In that sense the LHC is a political failure, because it has failed at its primary political job, which is to make the argument for an even bigger collider.
- Pharylon 10y agoNone of that makes any sense.
- bpicolo 10y agoHow'd it fail at it's primary task? Wasn't the Higgs a big part of that? Or is the argument that is hasn't found anything outside of the standard model?
- shepardrtc 10y agoIt succeeded at its primary task, and the Higgs was a big part of it. Its still doing its job, so give it time. Finding nothing can often be just as important as finding something unexpected.
- wolfgke 10y ago> Finding nothing can often be just as important as finding something unexpected. From a scientific point you are right. From a political point or the point of securing further funding this statement is (unluckily) wrong.
- kuschku 10y agoNot really, the European funding isn’t that relying on new findings.
- TheGRS 10y agoI think its a fundamental problem with teaching science history. We tend to look at achievements in history as being inevitable, like of course we discovered flight after the locomotive was invented, that's just how it happened! But those discoveries were all a circumstances of chance. If we're going to continue to make progress in science we need to accept that new, groundbreaking discoveries don't happen inevitably, they happen from people doing a lot of the dirty work and from imaginative people putting the puzzle pieces together in new ways. There's no inevitability to discovery.
- jamesdwilson 10y agoyou forgot to beg for more funding
- M_Grey 10y agoPeople who just want funding don't work on things like the LHC. If you want to solve a problem while someone is throwing money at you, then you work in defense. You shouldn't be so quick to harshly judge people who are making the choice to explore the edges of what we can achieve rather than make a quick buck developing the best new way to kill someone.
- jamesdwilson 10y agoright right. i am just totally making up this thing where research and results are forged, driven by state grants.
- TheOtherHobbes 10y agoYes you are. Do you really think no one would have noticed if the Standard Model was - as you call it - a forgery?
- jamesdwilson 10y agohttp://www.smithsonianmag.com/science-nature/scientists-replicated-100-psychology-studies-and-fewer-half-got-same-results-180956426/ http://www.smithsonianmag.com/science-nature/scientists-repl... http://www.nature.com/news/over-half-of-psychology-studies-fail-reproducibility-test-1.18248 http://www.nature.com/news/over-half-of-psychology-studies-f... http://www.nature.com/news/science-journalism-can-be-evidence-based-compelling-and-wrong-1.21591 http://www.nature.com/news/science-journalism-can-be-evidenc... 40,000 scientific papers invalidated. - https://jonrappoport.wordpress.com/2017/03/14/scandal-mri-brain-imaging-completely-unreliable/ https://jonrappoport.wordpress.com/2017/03/14/scandal-mri-br... http://nautil.us/blog/we-should-not-accept-scientific-results-that-have-not-been-repeated http://nautil.us/blog/we-should-not-accept-scientific-result... http://www.economist.com/news/leaders/21588069-scientific-research-has-changed-world-now-it-needs-change-itself-how-science-goes-wrong http://www.economist.com/news/leaders/21588069-scientific-re... https://explorable.com/research-grant-funding https://explorable.com/research-grant-funding - "Let's start by saying money does matter. It matters in every sector including science. Even if the researcher has a pure love of the scientific method, given the right circumstances, such as pride or the right amount of money, there may be some consideration given to skewing the data or holding back on publishing results for a little longer than they should." http://www.economist.com/news/briefing/21588057-scientists-think-science-self-correcting-alarming-degree-it-not-trouble http://www.economist.com/news/briefing/21588057-scientists-t... https://www.theguardian.com/science/2012/sep/13/scientific-research-fraud-bad-practice https://www.theguardian.com/science/2012/sep/13/scientific-r...
- dkural 10y agoJust to give a bit more context: * These are not elementary particles. * It was predicted for a long time that these composite particles should exist. So it is not "new" in the sense that it was unexpected, but we finally have the resolution (energy, luminosity etc.) to detect these with statistical significance. * These belong to the same class as protons and neutrons - these are hadrons made with multiple quarks. Here's a super simple overview of Quantum Field Theory & Particle Physics: Everything is made of force fields and matter fields. * We discovered that force fields (i.e. electromagnetism) is quantized, giving rise to quantum mechanics etc. * Matter fields are also quantized, hence their excitations behave like discrete particles - the ones we observe at the atomic scale, for instance. * In hindsight, we should've been able to predict this after E = mc^2 telling us energy <> matter, thus if energy is quantized so should matter.
- wfunction 10y agoI've never heard the term "matter field"... Is that a thing?
- danbruc 10y agoThey are properly called fermionic fields [1] as opposed to bosonic fields. I also want to note that the »super simple overview of Quantum Field Theory & Particle Physics« really is super simple. As far as I can tell - I am not a physicist - none of the statements is actually correct. [1] https://en.wikipedia.org/wiki/Fermionic_field https://en.wikipedia.org/wiki/Fermionic_field
- dkural 10y agoMatter fields are indeed a real thing. a Google Books search will reveal hundreds of books etc. They're also called fermionic field. Here's the full range of elementary particles, all 19 of them, in the Standard Model: Fermions: - Leptons (6) (electrons, neutrinos etc.) - Quarks (6) (protons and neutrons are made of this) Bosons: - Gauge Bosons (aka Force Carriers) (4) - Higgs Boson (gives mass to stuff) (1) What classical physics called force fields (i.e. Maxwell's equations), now we call them gauge bosons. Electromagnetism : Photon Strong Force: Gluon Weak Force: W&Z boson Gravity: No one knows! One extra boson that gives everything mass - the higgs. Force fields are quantized (see re: Photoelectric effect & Einstein's paper in 1905, winning a nobel). Matter fields aka fermionic fields are also quantized, which makes these fields behave as if they are composed of discrete states -- giving raise to the particles & discrete states. Indeed, in the Wikipedia article you link to, the first sentence reads: "fermionic field is a quantum field whose quanta are fermions". ie: matter/fermionic fields are quantum fields, whose quanta are fermions, i.e. electrons, protons. So, actually, all my statements are correct. Do you care to give a concrete example as to which one is not correct?
- grkvlt 10y agoFor more in-depth information see the CERN press release "LHCb observes an exceptionally large group of particles" at https://home.cern/about/updates/2017/03/lhcb-observes-exceptionally-large-group-particles https://home.cern/about/updates/2017/03/lhcb-observes-except... Or, the paper "Observation of five new narrow Ω0c states decaying to Ξ+cK−" is available at https://arxiv.org/abs/1703.04639 https://arxiv.org/abs/1703.04639 And finally, the LHCb web site section on "Observation of five new narrow Ωc0 excited states" at http://lhcb-public.web.cern.ch/lhcb-public/Welcome.html#Omega_c http://lhcb-public.web.cern.ch/lhcb-public/Welcome.html#Omeg...