back to article LHC finds a new and very charming particle: the Xicc++ baryon

What happens if you get two charm quarks together in one baryon? Something four times as heavy as a proton that can help the world understand the strong nuclear force, according to boffins at the Large Hadron Collider. Last week, CERN announced the first “unambiguous” observation of a particle comprising the two charm quarks …

1.7 femtobarns?

That's a pretty small barn.

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Anonymous Coward

Re: 1.7 femtobarns?

Yup but with the exploding costs of real estate around Geneva that's about all a nuclear scientist can afford these days.

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Re: 1.7 femtobarns?

I think they have it wrong; the luminosity should be 1.7 inverse femtobarns, which is a pretty big number. A barn is a measure of particle cross-section for a collision; a femtobarn is 10-15 barns; 1.7 inverse femtobarns is therefore 1.7 * 1015 collisions per particle cross section, which is an awful lot.

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Re: 1.7 femtobarns?

No, it's almost two pretty small barns.

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Anonymous Coward

Re: 1.7 femtobarns?

Only imperial stormtroopers can be so precise as to hit that.

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Anonymous Coward

Re: 1.7 femtobarns?

You wouldn't say that after you saw how they fire every time the heroes try to escape... they can't hit a slow moving robot... but, oh well, hitting a Java vehicle should be easier, it's quite larger than a barn... probably Obi Wan meant "they just hit the vehicle, not everything in a ten miles radius..."

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Re: 1.7 femtobarns?

hitting a Java vehicle should be easier, it's quite larger than a barn

It's probably a Java Enterprise Edition vehicle then.

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Awe

I "read" this article and frankly, haven"t a clue what it in on about. I am honestly in awe of these people that understand this stuff.

I would offer them a beer but I suppose they would be too busy looking for the next quantamy quarky higgs thingy to come along.

The thing is, how do they know to look for these things if they don't know they exist?

Gentlemen, seriously, I take my hat off to you. Even if you do make my brain hurt!

Cheers… Ishy

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Re: Awe

Go ahead and offer them a beer. Eventually one will spill it on the control panel, and we'll end up with a varient of D.A's Limited Improbability Engine, which some will then connect to a cup of tea to make an Unlimited Improbability Engine.

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LDS
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"how do they know to look for these things if they don't know they exist?"

Sometimes they know they probably exist, and how they should look: "something the researchers say is predicted by the Standard Model and has been sought for many years" (caps mine, as it should be).

Sometimes your data show something unexpected - and you get busy understanding why.

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Re: Awe

Most good scientists appreciate the value of a beer or several it can ,stimulate different thought processes and discussio. Humans and elephants are evolved to cope with alcohol, drunken elephants like to pull down trees and socialise, drunken scientists like to pull down trees (or blow things up) socialise and experiment.

I'll there are a few discoveries that would never have happened if beer had ever been invented.

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Re: Awe

Top physicists and scientists > Rock Stars > footballers.

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Re: Awe

"I would offer them a beer but I suppose they would be too busy looking for the next quantamy quarky higgs thingy to come along."

Its very important to remember the brain is a complicated system and like all complicated systems it can get locked in unideal states. This is cured by annealing and the brain is best annealed with beer and similarly annealing company.

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Boffin

Re: Awe

- I "read" this article and frankly, haven"t a clue what it's on about.

- I am honestly in awe of these people that understand this stuff.

I'm definitely putting Quantum Dynamics as my religion / "belief system" on the next census.

At least scientists can prove what they believe even if the rest of us can't understand it.

btw - They got me confused with scientologist last time ;-)

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LDS
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Re: Awe

Actually, some appreciate the virtue of old Cognac...

https://www.quantamagazine.org/supersymmetry-bet-settled-with-cognac-20160822/

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Re: Awe

Top physicists and scientists > Rock Stars > footballers

Top physicists and scientists > Lots and lots of other people > Rock Stars > footballers

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Headmaster

Re: Awe

"Finite" and "Infinite" improbability engines, actually.

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Re: Awe

"I'm definitely putting Quantum Dynamics as my religion / "belief system" on the next census."

Can something be a religion if there is evidence to support it's claims?

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Re: Awe

"Can something be a religion if there is evidence to support it's claims?"

Of course. It just can't be a supernatural religion.

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Coat

Re: Awe

I'm definitely putting Quantum Dynamics as my religion / "belief system" on the next census

If you definitely believe in quantum dynamics, you probably don't!

Mine's the one with "Favourite Quantum Dynamic Quotes and Other Animals" in the pocket.

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Re: "a few discoveries that would never have happened if beer hadn't been invented"

... giving rise to the phrase "Hold my Nobel Prize and watch this!"

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Re: Awe

Top physicists and scientists > Lots and lots of other people > Rock Stars > footballers

Top physicists and scientists > Lots and lots of other people > Rock Stars > lice > footballers

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Re: Awe

I would offer them a beer but I suppose they would be too busy looking for the next quantamy quarky higgs thingy to come along.

Nope, beer works well no matter what, offer away!

In fact beer was the inspiration for the bubble chamber, a now sadly obsolete detector type that used vast quantities of superheated liquid hydrogen to form bubbles around the tracks of particles which were then photographed.

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Re: Awe

@ Ishtiaq

Actually it is not that complicated, it is more that the terminology is somewhat daunting, if you are unfamiliar with the whole "particle zoo".

* Quarks and anti-quarks are the fundamental particles which carry the strong nuclear force. There are many types of quarks (and each has its corresponding anti-quark) but they are usually categorized in generations. Quarks from the first generation are the lightest, and each generation gets progressively heavier (just like Americans). Unlike Americans, the heavier generations tend to decay very fast into the lighter ones.

* A hadron is a compound particle made of multiple quarks or anti-quarks.

* A baryon is a hadron made of three quarks. The most familiar baryons are protons and neutrons, which make up most of the mass of your beer. Protons and neutrons are made of the lightest (first) generation quarks, which is fortunate otherwise you would have to finish your beer within a few femto-seconds before its constituent quarks would decay.

* A meson is a hadron made of exactly one quark and one anti-quark. They tend to have short and eventful lives, since the quark and anti-quark want to annihilate each other. (However, the quark and anti-quark are not necessarily, ahum, "compatible").

* Pions and kaons are particular types of mesons. I'll spare you the details.

* A Lambda baryon is a baryon which has one quark from the heavier generations, and two first-generation quarks.

* A Xi baryon is a baryon which has two quarks from the heavier generations, and one first-generation quark.

So the Xi cc++ baryon consists, being a baryon, of three quarks. One up-quark, which is a bog-standard first-generation quark very common in your beer, and *two* charm quarks, which are heavy second-generation quarks. (The cc means "two charms".) It then decays into a Lambda baryon with only one charm quark, and some mesons to make up for the various conversation law.

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Re: Awe

Thanks StephanH, that was very informative.

What do the ++ in Xi cc++ denote? Is that the up-quark or the spin of the charm quarks or something?

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Re: Awe

The ++ refers to its electric charge, which is twice the elementary charge. ( i.e. charge of a proton)

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Anonymous Coward

I would offer them a beer but I suppose they would be too busy looking for the next quantamy quarky higgs thingy to come along.

Nonsense - give them that beer. I find having a beer with colleagues is a quicker route to solving problems than trying to hammer it out in a too brightly lit office with not enough oxygen and too many suits and other distractions around. The only thing missing is a white board.

At least, that's how I am going to try expensing pub visits :).

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A pub with a whiteboard - OMG!!! What a fantastic idea :D

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Hmmm...except that....

the time for said whiteboard to be covered in CDC graffiti would be measured in microseconds........

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Careful, Sir Runcible

If they know you can count they'll have you chalking up all night.

Not that being a physicist means you can count, of course. Too human.

At least physics is capable of being explained to the layman such that the gist of something can be grasped. J. G. made a certain cat the most famous thing in quantum physics, as far as the layman is concerned. And a good job he did too.

But explaining, for example, how the solution to FLT was finally arrived at, well I read the book, and it's still a fog to me. I had a close relative who was a mathematician. He was always trying to explain things. You see, I am genuinely interested, but I just can't get my head around it.

Is there out there such a thing as a very abstract 'overview' of what all these different things are 'for' in their own right?

I'm starting to think that they walk among us, they look like us, but they are not us! Or am I just thick?!

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Re: Careful, Sir Runcible

"Not that being a physicist means you can count, of course. Too human."

Actually counting is not inherent in people beyond about 3 - numbers require teaching just as does integral calculus, we just tend to be younger when it happens. Jackdaws seem to be innately better at counting than people.

Being a physicist means you lose count because you've just thought of an interesting idea about dart trajectory and are too busy thinking about it, just as my grandfather put a lot of effort into making absolutely perfectly balanced darts, including home designed flights - but didn't have the motor skills to be really good at it.

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Re: Careful, Sir Runcible

"If they know you can count they'll have you chalking up all night."

That was how I got away with being in the pub on my own from about 14 :)

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". . . observation of a particle comprising the two charm quarks and one up quark – something the researchers say is predicted by the standard model . . ."

Provided the constituents add to a whole charge, are there any 2 or 3 quark particles that are not predicted?

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From what I understand, it's just a case of arranging the basic building components into non-repeating, i.e. elementary groups. Given this there's a nice grid of particles that could/should exist as there's quite a finite set of possibilities.

Until of course some bugger finds a way of breaking the lower level components into parts to see how they're made up and then predicts some new basic building blocks to play with.

(I'm not a particle physicist by a long way, but know enough to appreciate some of the issues without my mind imploding)

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LDS
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"are there any 2 or 3 quark particles that are not predicted?"

If so, the Standard Model would suffer a blow - and new models would be needed to explain those particles.

Anyway, the electromagnetic charge is not the only limit, there are other "exclusion" requirement regarding the quantum states (see Pauli exclusion principle).

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Re: "are there any 2 or 3 quark particles that are not predicted?"

Since all quarks have a charge that is a multiple of 1/3, any three-quark particle has a whole number charge. For the "familiar" quarks, all the combinations have been seen and catalogued. We've found triple-up, triple-down, and triple-strange, for instance. The only barrier to seeing triple-charm, top, or bottom is the energy needed to make them, and the probability that they will decay very quickly, making them hard to see. In fact you "see" them by recognizing their decay products, which have to be predicted ahead of time. That's harder that "predicting" the existence of the particles themselves.

The only 2-quark particles that cannot exist are those where a quark is paired with another one, and not an anti-quark as in a meson. For instance, up/up, up/down, are illegal in the Standard Model, but up/anti-up is just the familiar neutral pi-meson.

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Re: "are there any 2 or 3 quark particles that are not predicted?"

@Daedalus

"Since all quarks have a charge that is a multiple of 1/3, any three-quark particle has a whole number charge."

You mention the necessity of mesons having one quark and one anti-quark but skip that baryons are the opposite: they must have ONLY quarks or ONLY anti-quarks.

For example, if you start with a strange (-1/3) and an anti-charm (-2/3), you have -1 charge but no third quark or anti-quark you can add will leave the resulting 3-quark particle with a whole charge.

NOW, it is my understanding that the requirement of a whole charge is not what governs the combination of quarks but is instead 'merely' a result of some deeper rule. But that is a layman's understanding and when words like 'gauge' and 'symmetry' and 'iso-spin' and 'group' get thrown around, Dan is sorely out of his depth.

Of course, when you come to the charge of an electron being exactly (so far as is known) the same as that of a proton, things get profounding amazing and I am in awe of this wonderful universe (and those unravelling its secrets). But even then, if there is some 'grand unified theory' then there are real connections between the forces at play and so this is all, perhaps, to be expected.

Hence using the result of whole charges as a rule for me : )

The question I suppose at the heart of my earlier question is: do these underlying rules of combination preclude any combinations that would otherwise create a particle with a whole charge multiple?

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And I thought school was a forced day care centre.

These guys and girls were the ones listening and learning.

A+

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Anonymous Coward

Re: And I thought school was a forced day care centre.

P J O'Rourke once described South Korea as a country full of people who stayed in on Friday evening to do their school homework.

Figures.

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The XICC++ baryon?

Clearly this baryon has class, unlike the XiCC baryon.

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Re: The XICC++ baryon?

Baryons with inheritance? Perhaps quantum effects are the kids fighting over the assets.

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Anonymous Coward

Re: The XICC++ baryon?

Yes, but the problem is multiple inheritance. All because of that old up quark who becomes attached to two charming ones in the heat of the collision...

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Re: The XICC++ baryon?

Is there a posh quark?

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Joke

Re: The XICC++ baryon?

No......a quark is what a posh duck says!

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Re: The XICC++ baryon?

"Is there a posh quark?"

Only when there's a Becks quark. They appear spontaniously together whenever large numbers of photons are emitted by a photographic flash.

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XICC - how do you pronounce that?

XICC = chic?

Chic++

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Re: XICC - how do you pronounce that?

I must admit that I read it as "Xi (as in the Greek character Ξ/ξ)-double-charm-two-plus" but I'm no expert on this kind of stuff.

That said, "chic-plus-plus" has a certain ring to it (and is a darn sight easier to say). Doesn't sound sufficiently particley to me, though. New programming language with a focus on style, perhaps?

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Anonymous Coward

Re: XICC - how do you pronounce that?

But Nature is functional, not object-oriented.

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Headmaster

“In contrast to other baryons, in which the three quarks perform an elaborate dance around each other, a doubly heavy baryon is expected to act like a planetary system, where the two heavy quarks play the role of heavy stars orbiting one around the other, with the lighter quark orbiting around this binary system”.

This is apparently not the right image to have in mind.

Check this nice stack overflow entry: How (or when) do gluons change the color of a quark?

Why does the universe infrastructure perform these crazy girations with complex probabilities tacked onto everything? Lattice QCD simulations of a simple nuclean on 16×16×16×32 grids eat CPU cycles raw.

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When does it all go wrong?

Is there an energy level for these types of collisions where the Standard Model predicts something drastic happens?

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