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Result from LHCb experiment challenges the Standard Model
- reedf1 6y agoThis really grinds my gears, we purposefully moved away from "beauty quark" as it was a bit too whimsical (at the expense of descriptiveness), now science communicators keep using it as it seems to capture the imagination of non-sci readers. So please, as an informed individual, replace "beauty quark" with "bottom quark" every time you see it in this piece.
- lovemenot 6y agoI'd heard of bottom quark before. Never beauty. Does top quark have its antecedent too?
- reedf1 6y agoYes, "Truth quark". Because they don't exist naturally it lead my physics prof to say "There is no truth in the universe". Also, Some physicists call the fourth, fifth, and sixth derivative of position, "snap, crackle, and pop" respectively. Physicists are a fun lot aren't they?
- lovemenot 6y agoT and B retained. They clearly like symmetry, even through terminological adjustments. Not defending BBC's using non-prescribed terms, but quarks were always named whimsically. The word quark itself having been taken from Ulysses. It's hard to argue with snap following jerk, then acceleration then velocity. The next two follow snap, if not physically then at least historically.
- jcims 6y agoAlso jounce, flounce and pounce lol https://en.wikipedia.org/wiki/Fourth,_fifth,_and_sixth_derivatives_of_position https://en.wikipedia.org/wiki/Fourth,_fifth,_and_sixth_deriv... I thought were all useless terms but apparently snap is quite commonly used in quadrotor motion control.
- rocqua 6y agoSnap is that feeling you get when a train is braking and comes to a halt. The breaking force suddenly falls of, which is noticeable. In general, snap shows how smoothly the acceleration occurs. This allows anything that flexes (like flesh) to slowly take-up the slack. I've also heard this is important for self-driving convoys. You want the cars in the convoy to all accelerate and brake smoothly rather than jostle all the things inside them.
- b3orn 6y ago> In general, snap shows how smoothly the acceleration occurs. That's third derivative of position and called jerk.
- ragebol 6y agoNot just quadrotor motion control, it applies to precision machinery as well. Eg. it's used in those big ASML wafer stepper machines that help power Moores Law for example, but also 3D printers etc. Low values for these derivatives help reduce vibrations in the machines IIRC.
- DrBazza 6y ago> Physicists are a fun lot aren't they? Atomic cross section is measured in barns. As in "you couldn't hit a barn door".
- quchen 6y agoIn particle physics a barn is a huge area though, so the joke kind of makes sense there.
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- isaacg 6y agoThe official name of the LHCb experiment is the "Large Hadron Collider beauty" experiment, as named by the scientists themselves. So "beauty quark" is more correct in this context. https://home.cern/science/experiments/lhcb https://home.cern/science/experiments/lhcb Moreover, the paper that describes the result that this article is discussing has "beauty quark" in the name: https://arxiv.org/abs/2103.11769 https://arxiv.org/abs/2103.11769
- pmontra 6y agoAnd "b is for beauty" https://lhcb-public.web.cern.ch/en/Physics/Beauty-en.html https://lhcb-public.web.cern.ch/en/Physics/Beauty-en.html
- reedf1 6y agoAnd I wish they wouldn't have, for the sake of scientific clarity.
- irjustin 6y agoYea scientists are up there in terms of the people with the worst ability to name things. Right there with developers but our terrible naming conventions don't really make it to publications.
- andrewinardeer 6y agoSpaghettification
- twic 6y agoDrosophila geneticists have entered the chat
- aYsY4dDQ2NrcNzA 6y agoExplain?
- d_theorist 6y agoWhy though? What's wrong with being whimsical and capturing people's imagination?
- reedf1 6y agoWell because you can encode intuition in names. e.g. Quarks come in pairs, and each pair has one quark with +2/3e charge and one with -1/3e. The names can give you intuition for their charge, i.e. Up quark is +2/3e Down quark is -1/3e. And if you give names that give you intuition for the charge it is considerably easier to remember (as a former undergrad physicist trust me you need assistance here). The name name "top" allows you to immediately think "up" and +2/3e and "bottom" allows you to immediately think "down" and -1/3e.
- stan_rogers 6y agoAnd the pair, in this case, is truth and beauty. Are you saying that strange and charm give you an intuitive feel for the charge number?
- deleted 6y ago[deleted]
- goldenkey 6y agoWhat you are describing is association, not intuition. It is not the responsibility of scientific laborers to name and structure things in order to create convenient associations for cramming physics undergrads. Intuition involves a deep understanding of the objects and processes, a lot more harrowing than memorizing charges..
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- shawnz 6y agoWhat is intuitive about the up quark and down quark charges? The fact that "up" is associated with positivity is totally arbitrary, and even the fact that positive charges are called positive is totally arbitrary.
- Kaibeezy 6y agoHow do you/scientists feel about strange and charm? I’ve seen “sideways” sub for strange, which actually seems to fit the mnemonic better anyway. Why not “curly” or something instead of charm?
- chriswarbo 6y ago'Strange' predates the quark/parton model, and was a placeholder name for a particular unexplained phenomenon; similar to how the prefix 'dark' gets used. In particular, collider experiments were giving rise to a 'particle zoo' of pions, kaons, lambdas, etc. all of which were assumed to be fundamental. Some of these lasted much longer than expected, and were called "strange". It turned out that these could be modelled by giving fundamental particles a new property, which got the name "strangeness". Similar to how particles can have "charge", which is zero for neutral particles; non-strange particles have zero strangeness. Their long lifetime was explained due to the strong force conserving strangeness: collisions between non-strange particles can make pairs of particles with positive/negative strangeness (as long as it sums to zero); but once those individual particles have separated they can no longer decay via the strong force; they have to wait for the weak force, which gives them a longer half-life. It was only later, once the quark model became more accepted, that these particles were no longer considered fundamental, and "strangeness" could be explained as "containing strange quarks". On the other hand charm, beauty/bottom and truth/top seem to all be built on the quark model from the start; which makes the whimsy in their names more deliberate. --- FYI the BBC's Horizon did an episode in the 60s called "Strangeness Minus Three" ( https://www.bbc.co.uk/programmes/p01z4p1j https://www.bbc.co.uk/programmes/p01z4p1j ) which is interesting to watch in hindsight, now that we have quarks and the standard model; and makes a nice comparison to the more recent search for the Higgs boson. --- Tangentially this idea, of a new property whose conservation prevents massive particles from decaying, also arises in supersymmetric models of dark matter. There, supersymmetric particles have a different "R parity" to normal particles, which prevents them decaying even if they're very massive; such particles are a candidate for dark matter.
- ars 6y agoIsospin is another property that has been explained better in a new way. They still teach it for some reason though.
- deleted 6y ago[deleted]
- amadsen 6y agoI'm a physicist who spent seven years working at the LHC and I've never heard of a "purposeful" move away from the term beauty quark. It just fell out of favor but some, including myself, still like to use that name on occasion, personally I like it much better. The particle does not have a name in the official (PDG) listing, only a symbol "b". The "bottom" quantum number is universally called as such so one talks of "bottom hadrons" and so on. On the other hand the general area of research is called "b-physics" or "beauty physics", LHCb is the LHC-beauty experiment and so on. It makes perfect sense that this article uses "beauty" throughout for consistency. At the end of the day its just a name and this particle happens to have more than one (as does the J/psi and others) and neither is more whimsical than the other. Physicists tend to be quite whimsical anyway, particle physicists perhaps especially so.
- goldenkey 6y agoIn any case, which authority told /u/reedf1 that studying the universe should be barred from being whimsical? Alan Watts would be laughing. So would the Joker. The universe is not meant to be taken so seriously. It is whimsical. And that is part of its beauty ;-)
- reedf1 6y agoI have absolutely no problem with it being whimsical. Actually I would like it to be as whimsical as possible, while still being easy and consistent to learn that is.
- reedf1 6y agoI was given the impression by my professors that it was a purposeful move, maybe it was just in teaching and not research. I'll defer to you, the actual particle physicist.
- goldenkey 6y agoHow can something you wear so light on your sleeve cause you such angst that it "grinds your gears." Though you may have resigned in this tumult, I believe you still need to resolve something far deeper in your perspective on knowledge with regard to yourself and others.
- deleted 6y ago[deleted]
- burundi_coffee 6y agoAre there any primary sources for this?
- mhh__ 6y agoI had a look and I couldn't immediately see any papers, seems fresh out of the university press departments https://www.ukri.org/news/result-from-lhcb-experiment-challenges-leading-theory-in-physics/ https://www.ukri.org/news/result-from-lhcb-experiment-challe... Where the universities involved are Bristol University of Cambridge Imperial College London.
- dukwon 6y agoAlso the University of Zürich. The Cambridge involvement is just because someone from Imperial moved there.
- isaacg 6y agoI believe this is the relevant arxiv preprint: https://arxiv.org/abs/2103.11769 https://arxiv.org/abs/2103.11769 And here is a post by some of the main authors describing their findings: https://theconversation.com/evidence-of-brand-new-physics-at-cern-why-were-cautiously-optimistic-about-our-new-findings-157464 https://theconversation.com/evidence-of-brand-new-physics-at...
- nabla9 6y agoCERN: https://home.cern/news/news/physics/intriguing-new-result-lhcb-experiment-cern https://home.cern/news/news/physics/intriguing-new-result-lh... LHCb article : https://lhcb-public.web.cern.ch/Welcome.html#RK2021 https://lhcb-public.web.cern.ch/Welcome.html#RK2021 VNR : https://videos.cern.ch/record/2758757 https://videos.cern.ch/record/2758757 LHCb paper : https://arxiv.org/abs/2103.11769 https://arxiv.org/abs/2103.11769
- DavidSJ 6y agoThe measurement from LHCb is three-sigma - meaning there is roughly a one in 1,000 chance that the measurement is a statistical coincidence. No, that’s not what this means. But this is about one in 1,000 BBC Science articles that have repeated this confusion. Edited to add: What this actually means is that, conditional on the null hypothesis (that there is nothing there to find), there is a one out of 1,000 chance of seeing an observation such as this by chance. But the BBC article has inverted this. Rather than giving you the probability of the data given the hypothesis, they're purporting to give you the probability of the hypothesis given the data (which in general cannot be objectively stated; this is a standard difficulty in the philosophy of science and statistics): "there is roughly a one in 1,000 chance that the measurement is a statistical coincidence [i.e. the null hypothesis is true and there's nothing to see here]". They make it sound like the scientists are virtually certain that they've found something here, when in reality this is probably nothing (although that's a matter of opinion).
- skissane 6y agoI believe you that isn't what it means, but for those (like myself) who have limited familiarity with this topic, could you please explain what it actually means.
- mhh__ 6y agoThe p-value of a physics experiment isn't the probability of the result coming from thin air but rather than the probability of a result as or more extreme under the assumption of the null hypothesis (i.e. the effect we are looking for doesn't exist). The rub is that the design of the experiment and thus the hypothesis test is all dependent on various subjective factors, especially the people designing the experiment themselves. I'm not statistician however so presumably I'm just as wrong
- Kaibeezy 6y agoGood explanation of sigmas here: https://news.mit.edu/2012/explained-sigma-0209 https://news.mit.edu/2012/explained-sigma-0209 I’m thinking it would be more accurate (by being less precise) for BBC to describe the 1:1000 possibility as just coincidence rather than “statistical” coincidence.
- albertTJames 6y agoIts surprising that a 3sigma results is promoted in such a way. It is not psychology.. in Physics we usually expect a 5sigma.
- morbia 6y agoIndeed, there have been 3sigma deviations before (e.g. the diphoton resonance) which attracted a lot of attention and turned out to be nothing. I'd encourage people to read up on the Look-elsewhere Effect when you see something like this: https://en.wikipedia.org/wiki/Look-elsewhere_effect https://en.wikipedia.org/wiki/Look-elsewhere_effect I'm not saying this isn't potentially an interesting result, but 3sigma deviations when your parameter space is so large is actually not a big deal.
- rocqua 6y ago3 Sigma seems like it is very much worthy of more research, though not necessarily cause to say this is the new truth.
- dukwon 6y agoUnlike that 750 GeV lump, there are other observables in this case which build a consistent picture. Some fits to Wilson coefficients in b->sll were at almost 7σ even before this new result.
- amadsen 6y ago3 sigma is termed "evidence" in particle physcis (while "discovery" is reserved for 5 sigma) and is often enough to get people interested. Keep in mind that these are just numbers and must be interpreted in context. There have been tensions in various heavy flavour measurements for a looong time and across multiple experiments. It is very plausible that this is where we'll finally see new physics at the LHC. So it is worth serious consideration. The super-luminous neutrinos had 6 sigma significance and still no one took it seriously because it was simply such a ridiculous claim. Obviously the number of zeros in your p-value don't mean a damn if you haven't plugged in your equipment correctly!
- nabla9 6y agoCERN: https://home.cern/news/news/physics/intriguing-new-result-lhcb-experiment-cern https://home.cern/news/news/physics/intriguing-new-result-lh... Video News release : : https://videos.cern.ch/record/2758757 https://videos.cern.ch/record/2758757 LHCb article : https://lhcb-public.web.cern.ch/Welcome.html#RK2021 https://lhcb-public.web.cern.ch/Welcome.html#RK2021 LHCb paper : https://arxiv.org/abs/2103.11769 https://arxiv.org/abs/2103.11769
- JosephRedfern 6y agoThe title of the submission no longer seems to refer directly to the content of the article. If the feeling is that the article is dumbed down too much (as some of the comments suggest), could the URL also be changed? Maybe the UKRI press release, or CERN update? https://www.ukri.org/news/result-from-lhcb-experiment-challenges-leading-theory-in-physics/ https://www.ukri.org/news/result-from-lhcb-experiment-challe... https://lhcb-public.web.cern.ch/Welcome.html#RK2021 https://lhcb-public.web.cern.ch/Welcome.html#RK2021
- DJBunnies 6y agoBiggest pet peeve of this place, editorializing.
- jackweirdy 6y agoIt’s very common for BBC headlines to change 3-5 times after being posted. I don’t know whether they are A-B testing or just twitchy, but it’s annoying for sharing new articles
- mamon 6y agoI think it is a clickbait - you see new title on their main page and click only to realize that you've read that before.
- BelenusMordred 6y ago> I don’t know whether they are A-B testing or just twitchy Have worked in the dark basements for a news company, it's A-Z testing for some online pieces to see what gets more fish on the hook. They'll use wildly different headlines without changing a single word in the article.
- Kaibeezy 6y agoFTR, OP here. I didn’t change the title. Perhaps HN will comment. In my experience their reasoning is typically solid. When I posted, I believe it was “LHC machine finds tantalising hints of new physics”. I remember that seemed oddly redundant, like an “ATM machine”. Current title for the article is showing as “Machine finds tantalising hints of new physics”, but a search is also coming up “LHC machine challenges leading theory of physics”.
- mellosouls 6y agoMore in depth, but plain English summary from the researchers here: https://theconversation.com/amp/evidence-of-brand-new-physics-at-cern-why-were-cautiously-optimistic-about-our-new-findings-157464 https://theconversation.com/amp/evidence-of-brand-new-physic...
- xenophonf 6y agoNon-AMP link: https://theconversation.com/evidence-of-brand-new-physics-at-cern-why-were-cautiously-optimistic-about-our-new-findings-157464 https://theconversation.com/evidence-of-brand-new-physics-at...
- mellosouls 6y agoYeah I normally take it out, just forgot this time. I don't mind it myself, but try and default to neutral.
- random5634 6y agoThis is interesting - normally AMP is great and I'm (generally) a fan of it. But somehow they messed up AMP here - I've not seen that before. The AMP page is really poor (third party blocking, time to paint, even JANK is here - shift after load). The non AMP page is 1.4MB and 45 requests, the AMP page is 400KB and 16 requests - normally this means AMP just blows everything out of the water (despite HN hate). Something is messed up here that AMP is so poor, initial server response is terrible.
- asplake 6y agoAny clues as to what new physics might be out there if this gets confirmed?
- dalewe 6y agoThe paper mentions leptoquarks (particles that interact with leptons and quarks with potentially different coupling strengths for different leptons therefore breaking lepton universality) or some unknown heavy (didn't look into it any further but I guess the heavy requirement is there because otherwise we would already have observed its effects, I don't think it's necessary for this particular observation) neutral boson that would for example allow flavor changing of leptons ("flavor" means whether it is an electron, muon our tau lepton). Edit: https://arxiv.org/pdf/2103.11769.pdf https://arxiv.org/pdf/2103.11769.pdf - references 54 to 90 are about potential new physics models.
- deleted 6y ago[deleted]
- debacle 6y agoThe current standard model is slowly getting messier and messier. At some point we will make a discovery that adds some degree of elegance into our understanding of these interactions.
- jokoon 6y agoNice to see the LHC can still be useful to make discoveries.
- Cthulhu_ 6y agoIt'll be in operations for years if not decades to come still. They're working on an upgrade to increase the 'luminosity' (dunno what that means yet) by a factor 10 as we speak, slated to be finished in 2027 (see https://en.wikipedia.org/wiki/High_Luminosity_Large_Hadron_Collider https://en.wikipedia.org/wiki/High_Luminosity_Large_Hadron_C...)
- ShinyRice 6y agoLuminosity is the number of particles (in the LHC's case, protons) flowing per unit area and unit time. Additionally, integrated luminosity is luminosity integrated over time, and is just the number of events produced per unit area. It is the main metric used when CERN releases data and shares just how many events are in a given data set; this is done such that you can take the cross section of a given event (like Higgs production), multiply it by this value, and get how many events of that type happen (how many Higgs were produced).
- FinanceAnon 6y agoI don't know much about physics (I am trying to learn more), but does anyone else find the idea that the universe is made of "little balls" fundamentally wrong? It just feels like it will never end. First, we thought that atom is fundamental. Then electrons, protons and neutrons were discovered. Then, we discovered that there are smaller particles. Are we ever going to discover a fundamental particle that cannot be broken up? What would it be made of? How much space would it take up? Just some armchair philosophy.
- shadowofneptune 6y agoIt gets worse when you consider that they are also equally valid as waves.
- kosh2 6y agoI would say it is filled with not made out of. The emptiness of space is not made out of particles.
- vesinisa 6y agoDo not think about "little balls". It's a fundamentally broken mental image that everyone was taught in high school chemistry. Already at atomic level things are adequedly expressed only as wave functions. Matter is not little balls made up of even tinier balls, but something altogether stranger - recall that matter and energy are interchangeable. I like to imagine the subatomic particles (like neutrons and protons) as beautiful rays of energy only temporarily trapped in particle form as ugly matter.
- rrmm 6y agoThe result is three-sigma, so not yet there (5 sigma). As usual, interesting if true.
- whatshisface 6y agoI will give you $999 if it's just noise in exchange for $1 if it's not.
- lainga 6y agoLooks like some people didn't like you putting the concept in more accessible terms. "Three sigma" has a real interpretation, it's not just a little score where you pull out LaTeX when it reaches 6.
- rrmm 6y agoBut LaTeX seems to take a whole lot longer to run when it's 6 sigma than when it's 3.
- mlyle 6y agoOf course, to perform any valid statistical reasoning, you need to consider the prior. The standard model has held up very well, and we do a lot of experiments-- any of which has a small chance of popping out a result that looks highly significant by chance. There's a reason why 6 sigma is the line to take things super seriously (in fundamental physics).
- rrrrrrrrrrrryan 6y agoBreak-even for three sigma would be 997:1, so the parent should actually take this bet.
- whatshisface 6y agoThe result was past three sigma, not exactly at three sigma. But good point, because if it was exactly at three sigma I would have snookered myself. :)
- geuis 6y agoJeebus, another frustrating air-filled article to up the word count. Meat: > The LHCb produces sub-atomic particles called "beauty quarks", which are not usually found in nature but are produced at the LHC. Sub-atomic particles undergo a process known as decay, where one particle transforms into several, less massive ones. According to the Standard Model, beauty quarks should decay into equal numbers of electron and muon particles. Instead, the process yields more electrons than muons. One possible explanation is that an as-yet undiscovered particle known as a leptoquark was involved in the decay process and made it easier to produce electrons.
- shmageggy 6y ago> which ultimately could allow us to unravel any number of established mysteries. These include the nature of the invisible dark matter that fills the universe, or the nature of the Higgs boson. It could even help theorists unify the fundamental particles and forces... To this non-physicist, it's not clear at all how this potential discovery might do any of that. From here, it looks like a mininally consequential addendum to the standard model, almost like a single epicycle to a geocentric cosmology. The effect only shifts by a few percent the chance of some obscure and rare interaction. Is it really plausible that it could have such grand implications?
- ISL 6y agoTo continue the epicycle analogy: The problem in modern physics is that the epicycles work too well. There are some big obvious mysteries and an incredibly-successful epicycle-based theory. Essentially everyone expects that the epicycles are not the truly fundamental theory of things. So, physicists keep comparing the predictions of the "epicycle-theory" with reality in new ways, ways where a deviation from the prediction would be an unambiguous signpost pointing a direction toward which one might be able to address a big mystery. As those tests become established, they are then performed with higher and higher precision. The signal potentially seen with LHCb is, if it persists, important. In a nutshell, electrons are, in this particular way, predicted to act exactly like muons. No ifs, ands, or buts. What they see is that electrons and muons might be acting slightly differently. If so, some new physics (or a major error in our understanding of the epicycles -- I'm looking at you, loops) must be at work. If this result persists, it is guaranteed that we will learn something. Too convoluted? Here is a different analogy: You're pretty sure someone is embezzling from your company. You look at your bank account, and you have ~95% less money than you thought you should. Really. Oh, no. You check the summary budgets, they're balanced. So you do this for all the company's divisions. Yep. Still balanced. You get paranoid. You do this for decades -- the books balance, but at the end of the day? 5%. Then an employee runs up to you and says, "Shmageggy! We're not sure yet, but it looks like one of our most-trusted partners, whom the firm has worked with since 1936, transferred thirty-seven cents to an account in the Cayman Islands!" Until we find the embezzler, that's what every one of these precision physics tests that makes the news is all about.
- omgwtfbbq 6y agoAs someone with a background in Physics I get a very strong Gell-Man Amnesia vibe any time Physics is discussed on HN. The takes are nearly always bad and generally not even wrong, it makes me seriously question all discussion on HN.