Large Hadron Collider Discovers Three New Exotic Particles (home.cern) 91
The international LHCb collaboration at the Large Hadron Collider (LHC) has observed three never-before-seen particles: a new kind of "pentaquark" and the first-ever pair of "tetraquarks," which includes a new type of tetraquark. The findings, presented today at a CERN seminar, add three new exotic members to the growing list of new hadrons found at the LHC. They will help physicists better understand how quarks bind together into these composite particles. From a report: Quarks are elementary particles and come in six flavours: up, down, charm, strange, top and bottom. They usually combine together in groups of twos and threes to form hadrons such as the protons and neutrons that make up atomic nuclei. More rarely, however, they can also combine into four-quark and five-quark particles, or "tetraquarks" and "pentaquarks." These exotic hadrons were predicted by theorists at the same time as conventional hadrons, about six decades ago, but only relatively recently, in the past 20 years, have they been observed by LHCb and other experiments.
Most of the exotic hadrons discovered in the past two decades are tetraquarks or pentaquarks containing a charm quark and a charm antiquark, with the remaining two or three quarks being an up, down or strange quark or their antiquarks. But in the past two years, LHCb has discovered different kinds of exotic hadrons. Two years ago, the collaboration discovered a tetraquark made up of two charm quarks and two charm antiquarks, and two "open-charm" tetraquarks consisting of a charm antiquark, an up quark, a down quark and a strange antiquark. And last year it found the first-ever instance of a "double open-charm" tetraquark with two charm quarks and an up and a down antiquark. Open charm means that the particle contains a charm quark without an equivalent antiquark.
Most of the exotic hadrons discovered in the past two decades are tetraquarks or pentaquarks containing a charm quark and a charm antiquark, with the remaining two or three quarks being an up, down or strange quark or their antiquarks. But in the past two years, LHCb has discovered different kinds of exotic hadrons. Two years ago, the collaboration discovered a tetraquark made up of two charm quarks and two charm antiquarks, and two "open-charm" tetraquarks consisting of a charm antiquark, an up quark, a down quark and a strange antiquark. And last year it found the first-ever instance of a "double open-charm" tetraquark with two charm quarks and an up and a down antiquark. Open charm means that the particle contains a charm quark without an equivalent antiquark.
Three more? (Score:2)
Re: (Score:2)
There used to be 108 of them, but demand was so high that they had to invent more in order to cash in on that large-particle-collider profit machine. Depending on who you ask, there may be anywhere between 418 and 913 so far.
Gotta catch 'em all!
Re:Three more? (Score:5, Informative)
You put the cart before the horse. In particle physics, the theory is posited first and then experiments are done to look for what the theory predicts. And the theory doesn't exist in isolation, it must be consistent with other confirmed theories. Even then the theories are only confirmed up to some epsilon. So what they see could have another explanation. However, when you choose some alternate explanation, you are choosing an alternate theory. That alternate must now be consistent in the same way the first theory was. Now you have two competing theories.
One doesn't just wind up the LHC's rubber band and look for shit.
Re: (Score:1)
One doesn't just wind up the LHC's rubber band and look for shit.
However, that's in essence what they are proposing for LHC's successor given that, the Higgs aside, they have found nothing of the stuff predicted decades ago.
Re: Three more? (Score:1)
Re: (Score:2)
photons.
is there a model that describes a photon.
using the same particles that describe a proton
Re: (Score:3)
It wasn't that many generations of collider ago that they did just throw shit at other shit and observe the trainwreck. The LHC does it in a much more controlled manner, but also automatically dumps null results rather than attempt to process them -- because it has 100 billion other collisions to worry about this second. Before the hardware got smart enough to do that, experiments had to worry about staying out of their own way, and each others'. With the LHC, the beam is there, and the experiments do what
Re: (Score:2)
That's only part of what's going on. Or at least it should be. (I don't really know if they do things this way, but they ought to.)
Yes, when they do a run they're looking for something in particular, but each run collects a huge amount of data that "isn't the kind of thing we're looking for". This means that you can troll through that data for "interesting shit", and then see is it is matched elsewhere. Now you've got a bunch of observations to hang a theory off of. Then you predict where else you'll f
The Particle Zoo (Score:3)
You put the cart before the horse. In particle physics, the theory is posited first and then experiments are done to look for what the theory predicts.
This is not a rule and in the past it was not the case. In the 1950s and 60s there was what was known as the "particle zoo" where lots of new particles were appearing every time a new accelerator turned on. As we now know these were all new hadronic states but there was no theory to explain them. Indeed, in 1955 Willis Lamb suggested in his Nobel Prize speech that physicists should get fined $10k for finding new particles instead of awarded with prizes!
Today it is a lot rarer but only because of the stu
Re: (Score:3)
That's because we've theorized the existence of the "graviton" but have never found one, yet. The 'thing' is, time causes gravity and we have only a very rudimentary understanding of how time works.
https://www.quora.com/Does-tim... [quora.com]
So once we figure out time, we'll figure out gravity. Or vice versa.
Re: (Score:2)
Gravity. It's going to be gravity that makes or breaks the SM!
I'd love to know how gravity will "make" the Standard Model given that the SM says absolutely nothing about it, gravitons are not SM particles and indeed gravity is one of the reasons why we already know the SM is broken! Absent of some new, experimentally-testable idea for quantum gravity though my money would be on either Dark Matter or the hierarchy(or fine-tuning) problem as the most likely way we go beyond the SM...although something else entirely unexpected can never be ruled out. There are good reas
Re: (Score:1)
Re: (Score:2)
Re: Three more? (Score:2)
My periodic table has 118 elements on it.
Re: Three more? (Score:4, Funny)
Well that ought to be enough for anybody...!
Re: (Score:2)
Re: Three more? (Score:1)
Re: (Score:2)
And phlogiston.
Luminiferous aether, and dark matter. Now we have a set.
Re: Three more? (Score:4, Insightful)
Well that ought to be enough for anybody...!
Over 40 years old and this joke is still giving :)
Re: (Score:1)
Over 40 years old and this joke is still giving :)
It was said over 40 years ago, it has only been a joke for about 38 years...
Re: (Score:2)
It was said over 40 years ago, it has only been a joke for about 38 years...
For what it's worth, Gates denies having ever said it at all, but your point is well taken regardless :)
Re: (Score:1)
A charm quark can be used to repel Dementors, so we need more of them.
Combi Hint (Score:2)
Rather than "types" of things, it sounds more like combinations of something still not understood. It's kind of like "elements" before the atomic model was devised: they all seemed like multitudes of "dedicated" substances, when in fact they were merely combinations of electrons, protons, neutrons, and croutons. (Okay, I added the last because I'm hungry.)
I'll propose these quark-ish things are all made of 3 types of undiscovered Dark Specks.
Re: (Score:2)
Re: (Score:2)
It's not even that. These are things with really short half-lives. It's sort of like the unstable transition stages in a chemical reaction, only much faster, and on a much smaller scale.
And again, just like chemistry, it might be really useful to be able to predict how those transition stages worked. But it also might not And you can't tell ahead of time.
Re: Three more? (Score:1)
Re: (Score:2)
e=mc2 tells us that energy and mass are the same things. Particles are waves and we know that there can be an infinite variation of waves (think music), a few of which can be the stable quantum standing waves we call particles.
Their existence provides empirical evidence to verify the mathematical models we use to describe reality which is the core purpose of physics.
Are these _new_ or just never observed before? (Score:2)
TFS suggest they were predicted by theory but never observed before. So the title is misleading?
It would be interesting if these were truly new - not predicted by the theories.
Re: (Score:2)
They are new observations of something that was only theorized before.
They are not new particles... (Score:4, Insightful)
Re: (Score:2)
Yes, it's true they're not fundamental particles, but they're still considered particles. What matters is that their energies and lifespans place additional constraints on the strength and behaviour of the strong nuclear force (the only nuclear force not adequately combined with the others, the model for the electro-weak force being now on pretty solid ground). If they can pin the strong nuclear force down sufficiently to merge with electro-weak, they'll have the Unified Theory they've been after for a whil
Re: (Score:1)
Ya, it was really hard to see if quantum theory was going to amount to any practical applications. What were those scientists thinking? And the germ theory? What a crock! And Einstein, where did he get off coming up with all that nonsense instead of positing GPS satellites first? What a dolt. The double helix for DNA was such a crap shoot, they couldn't even point to a single application and patented nothing.
Re:I used to get excited by this type of thing. (Score:4, Funny)
Nobody needs your school. They just need to open their enteric consciousness to the universe and latch onto the first thing that springs to mind.
Oh, and crystals can help.
Re: (Score:2)
The largest of the 4 above us would be the 11th largest US state in terms of population.
Several of the US states larger than that country (UAE) have median incomes well above it.
I get that you are personally depressed. You're not feeling good about shit. But you need to ground your opinions in reality, or you just look like a dumbfuck.
Re: (Score:2)
To be completely fair, our costs of living are astronomical compared to most countries. And, since you don't know my personal circumstances, and there's zero incentive for you to have even the slightest compassion, since this is the Internet, I'll just leave it at that.
Re: (Score:2)
But it's silly to call the country a backwater, is all.
In international income metrics, we use PPP dollars, which are adjusted for cost-of-living.
Just like real dollars, which are adjusted for inflation, the US is still the 5th richest in the world.
The country isn't a backwater, we're rich as fuck. The median American is doing better, even factoring in cost of living, than all of
Re: (Score:2)
Thing is, the US used to be unquestionably first, due to a big boost from WWII, but hasn't been growing as fast as everyone else. Since we're dumb and measure our wealth relative to our neighbours, watching everyone else catch up must hit a lot of people in the ego.
The US also hasn't kept up so well with social development, and seems to be intent on rolling back some big steps. For a big hunk of people who are below that median income, and a lot above it too, that's going to be much more relevant.
Re: (Score:2)
Another way to look at it is, "the economies of our competitors were utterly destroyed by WWII, due to them fighting a full scale war in their actual home territory for years before we were materially involved"
But either way, yes, there's no doubt that the decline of the middle class in America is real.
And also no argument that our social development problems are pretty unique to us in the developed western world.
But still, even with all that- if
Re: (Score:2)
The economies of most countries that aren't the US did experience a bit of a setback during WWII, which definitely provided a big head start. There was *also* a big boost during the first part of the war where the US was selling stuff to everyone but not fighting. It's pretty notable on a graph [ourworldindata.org].
I completely agree, the OP is clearly someone who makes broad generalizations based on their own short term experience. Although, I suppose if you want to be pedantic, a backwater is an area where a river stops flowi
Re: (Score:2)
Although, I suppose if you want to be pedantic, a backwater is an area where a river stops flowing forwards.
Can't argue with that
Re: I used to get excited by this type of thing. (Score:1)
Oh look ! The shitful moron is back.
We were worried something had happened to you Comrade !
Re: (Score:2)
Here I am talking up the stats for the shining light of Capitalism, and you're still calling me Comrade?
Hey, let's go ahead and add some of those racist slurs you're so famous for.
Seriously, Gimpy. Get back in the fucking basement.
And what person with a high school educate puts a space between the end of the sentence and the exclamation point? So fucking bizarre.
quarks and antiquarks in same particle? (Score:1)
Re: (Score:1)
> change its terminology because anti particles are not exactly antimatter.
"Misunderstood matter"?
> Anti particles do not have negative gravity.
Nothing may have negative gravity, as it may not be a "force" like the other 3. Nobody really knows, gravity is still a great mystery. It would be nice if there were such a thing because then we could have flying cars that don't wake up the entire town.
Re: quarks and antiquarks in same particle? (Score:1)
Re: (Score:2)
From a purely theoretical perspective, however, something with negative energy would have negative "gravity" (ignoring all of the massive fucking problems that exist if that is really possible)
Re: (Score:2)
If gravity is just "bent space/time" how could something ever "fall up" using gravity alone? Other than maybe it can "fiddle with" time?
Re: (Score:2)
Other than maybe it can "fiddle with" time?
That's GR in a nutshell.
Diverging four-vectors through spacetime (which have longer proper distances than are visible in 3d space) are responsible for what we see as attraction (or repulsion in the case of a negative stress-energy tensor). This is why time dilates in a gravity well. "Space" is smaller and "Time" is longer (those 2 being intimately linked).
I.e., gravity is the distortion of (space)time.
In the case of a positive stress-energy tensor, the curvature of space (as projected in 3d space- but
Re: (Score:2)
" it is just a unique kind of matter particle that happens to annihilate a specific kind of similar particle and has an opposite charge"
Hence the term "antimatter". What the hell difference would it make if they called it them, say, Oppositely Concerned Paired Molides.
Re: (Score:2)
Quarks and anti-quarks can form as virtual particle pairs and can mutually annihilate in some configurations.
Re: (Score:2)
Yep, those quantum particles will never amount to much. Maybe you could tell them to give the money back that they pissed off on them.
split a quark (Score:2)
Re: (Score:2)
It's fractal recursive turtles all the way down to the fractal recursive turtles.
Re: (Score:2)
Quite possibly not, or possibly not in a way we will be able to observe.
Re: (Score:2)
If quarks are made of anything, it's likely to be either superstrings or pure mathematics. We can't build an accelerator to split something into strings, although it's just possible that the energies in space are sufficiently high that we can see strings if we built a detector there. However, we can potentially detect supersymmetry particles and these necessitate superstrings, although we really want the long-promised 100 mile accelerator to be sure of finding those.
Again, building a detector in space stand
Re: (Score:2)
Fun Fact: Did you know that the force carrier for some of these subatomic particles is the photon? That means that you're being held together by light!
Re: (Score:2)
Not saying it's impossible, but I'm not going to bet on it happening.
Composite leptons pose all kinds of problems that we should have encountered by now. Pair production statistics and muon/electron annihilation would be all wrong.
So no, quarks likely aren't made of stuff too.
Re: (Score:2)
Re: (Score:2)
I'm just saying that, as far as we can measure the observable Universe, it's highly unlikely we'll ever find muons to be composite particles within that limited framework.
That's string theory stuff- which hell, could ultimately end up being right. But the standard model is what it is, because it works as the universe is observed. Any speculation that directly breaks it is unlikely to be true in any way we can ever measure.
LOL! (Score:2)
Unless you are in the field, how can you read the following and not feel absolutely worthless?
Two years ago, the collaboration discovered a tetraquark made up of two charm quarks and two charm antiquarks, and two "open-charm" tetraquarks consisting of a charm antiquark, an up quark, a down quark and a strange antiquark. And last year it found the first-ever instance of a "double open-charm" tetraquark wit
Re: (Score:2)
Re: LOL! (Score:1)
Re: (Score:2)
Been a while, but I basically remember quarks being the basic building blocks of protons and neutrons. 6 types of quarks:
top, bottom, strange, charm, up, down. (Not sure why up and down AND top and bottom). But the above just describes some new particles made up of these things. I guess there are antiquarks too. If I recall correctly, protons and neutrons contain 3 quarks generally.
This is just saying there are some particles that contain 4 or 5 quarks. I don't think it's too hard to parse the sentenc
What's so special about charm? (Score:2)
What's so special about charm, and why is an open-charm tetraquark more significant than an open-bottom tetraquark for instance?
On another note, I just learned charm and bottom are the heaviest types of quark. Other quarks decay to lighter quarks, eventually into charm and bottom. I made up a mnemonic device about "bottom" and "charm" but I'm not going to share it.
Re: (Score:2)
I hope your mnemonic doesn't break too hilariously when you substitute "truth" for "top" and "beauty" for "bottom", as some sources do. They're the same quarks, but only the initial is actually a standard. The rest of the name is convention, and there happen to be two conventions.
Re: (Score:2)
You might want to reconsider your mnemonic. The top and bottom quarks are the heaviest. Quarks can decay in various ways, but often end up as the lightest ones: the up and down.
Re: (Score:2)
Ugh, thank you for the correction, and I'm not sure how I got that so completely wrong. Obviously conservation of energy says a particle can't decay to a heavier particle. I must have been too mentally occupied trying to imagine what it really meant for particles to be so perfectly opposite that they become pure energy upon contact (intentionally not thinking of them as waves).
Re: (Score:2)
Well, if it makes you feel better, they're just creating a system with zero net conserved quantities (charge being the main one) so they can decay into photons.
If it makes you feel even better, all the particles concerned are just energy to start with.
Scraping the bottom of the barrel (Score:1)
Re: Scraping the bottom of the barrel (Score:1)
Re: (Score:3)
Well, the biggest thing they found (the Higgs) is incredibly fucking small.
And here I thought they made a massive discovery...