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LHCb experiment discovers a new pentaquark

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Re: LHCb experiment discovers a new pentaquark

#11

Post by andrepd »

drilldrive wrote: post #9
andrepd wrote: post #8

Earlier quoted context omitted.

Usually quarks are confined in composite particles of two (mesons) or three (baryons) quarks. However they can also in certain conditions form particles of 5 quarks (the pentaquarks).

Oh, so quarks can only be composites of two, three, and five? Any reason that could be stated in layman's terms?

Quantum chromodynamics (the theory which describes the strong interaction) has a feature called colour confinement, which says that quarks will favour being in colourless configuration (where colourless = zero colour charge). The two easiest ways for this to happen are in mesons (two quarks: one quark and one antiquark of the same colour, like red + antired = colourless), or in baryons (three quarks: 1 red + 1 green + 1 blue = colourless) like the familiar proton and neutron. However other configurations are possible, these are just the simplest ones. In certain incredibly difficult to attain conditions, we can avoid producing either a two- or three-quark composite particle but produce instead a five-quark particle (e.g. 1 red + 1 green + 1 blue + 1 red + 1 antired = colourless).

This "colour" means colour charge, it doesn't have any relation to the regular meaning of "colour of light".

Re: LHCb experiment discovers a new pentaquark

#12

Post by Retra »

drilldrive wrote: post #9
andrepd wrote: post #8

Earlier quoted context omitted.

Usually quarks are confined in composite particles of two (mesons) or three (baryons) quarks. However they can also in certain conditions form particles of 5 quarks (the pentaquarks).

Oh, so quarks can only be composites of two, three, and five? Any reason that could be stated in layman's terms?

Basically, take the numbers 1/3, -1/3, and count how many terms you need to produce something that sums to a whole number. You can get four with (1/3 + 1/3 - 1/3 - 1/3), so it's not an impossible configuration.

Re: LHCb experiment discovers a new pentaquark

#13

Post by [deleted] »

andrepd wrote: post #11
drilldrive wrote: post #9

Earlier quoted context omitted.

Oh, so quarks can only be composites of two, three, and five? Any reason that could be stated in layman's terms?

Quantum chromodynamics (the theory which describes the strong interaction) has a feature called colour confinement, which says that quarks will favour being in colourless configuration (where colourless = zero colour charge). The two easiest ways for this to happen are in mesons (two quarks: one quark and one antiquark of the same colour, like red + antired = colourless), or in baryons (three quarks: 1 red + 1 green…

[deleted]

Re: LHCb experiment discovers a new pentaquark

#14

Post by xelxebar »

drilldrive wrote: post #9
andrepd wrote: post #8

Earlier quoted context omitted.

Usually quarks are confined in composite particles of two (mesons) or three (baryons) quarks. However they can also in certain conditions form particles of 5 quarks (the pentaquarks).

Oh, so quarks can only be composites of two, three, and five? Any reason that could be stated in layman's terms?

If you're willing to dive in a bit, Matt Strassler has a nice blog aimed at the lay reader. His mini-series on the structure of the proton is quite excellent:

https://profmattstrassler.com/articles-and-posts/largehadron...

Re: LHCb experiment discovers a new pentaquark

#15

Post by dragonwriter »

Retra wrote: post #12
drilldrive wrote: post #9

Earlier quoted context omitted.

Oh, so quarks can only be composites of two, three, and five? Any reason that could be stated in layman's terms?

Basically, take the numbers 1/3, -1/3, and count how many terms you need to produce something that sums to a whole number. You can get four with (1/3 + 1/3 - 1/3 - 1/3), so it's not an impossible configuration.

> Basically, take the numbers 1/3, -1/3, and count how many terms you need to produce something that sums to a whole number.

Any whole number of terms greater than 1 will allow this, by the way.

Re: LHCb experiment discovers a new pentaquark

#16

Post by Ygg2 »

andrepd wrote: post #11
drilldrive wrote: post #9

Earlier quoted context omitted.

Oh, so quarks can only be composites of two, three, and five? Any reason that could be stated in layman's terms?

Quantum chromodynamics (the theory which describes the strong interaction) has a feature called colour confinement, which says that quarks will favour being in colourless configuration (where colourless = zero colour charge). The two easiest ways for this to happen are in mesons (two quarks: one quark and one antiquark of the same colour, like red + antired = colourless), or in baryons (three quarks: 1 red + 1 green…

> This "colour" means colour charge.

Color charge is essentially as charge. I.e. instead of having +/- you have A/B/C. Except you also have Anti A/B/C.

Re: LHCb experiment discovers a new pentaquark

#17

Post by sand500 »

sanxiyn wrote: post #5
afraca wrote: post #4

This is both entertainment and information, so to justify it I'll ask a question about this: https://www.youtube.com/watch?v=j50ZssEojtM (Large Hadron Rap) Are these goals still accurate or has new knowledge and engineering changed the goals of the detectors?

The rap is pretty bad. It lists four questions: dark matter, matter-antimatter asymmetry (aka baryogenesis, related to CP violation), Higgs boson, and hierarchy problem (why gravity is so weak; rap alludes extra dimension). We found Higgs boson, which is great. We are no closer to answer other three questions, and frankly, there was no reason to expect LHC to help there, it was all wishful thinking. Sure, it was poss…

As I see it, we are basically putting more and more energy into these particle collisions and hoping something unexpected happens.

Re: LHCb experiment discovers a new pentaquark

#18

Post by JadeNB »

dragonwriter wrote: post #10
drilldrive wrote: post #9

Earlier quoted context omitted.

Oh, so quarks can only be composites of two, three, and five? Any reason that could be stated in layman's terms?

> Oh, so quarks can only be composites of two, three, and five? They can also be in fours. Possibly other configurations; the four and five quark configurations were theorized in 1964 but only confirmed in 2014 & 2015. > Any reason that could be stated in layman's terms? None at all, in fact, the source article does so: “In the conventional quark model, composite particles can be either mesons formed of quark–antiqua…

> > Any reason that could be stated in layman's terms?

> None at all, in fact, the source article does so ….

Did you really mean "None at all"? The rest of your post seems to say the opposite.

Re: LHCb experiment discovers a new pentaquark

#19

Post by JadeNB »

Retra wrote: post #12
drilldrive wrote: post #9

Earlier quoted context omitted.

Oh, so quarks can only be composites of two, three, and five? Any reason that could be stated in layman's terms?

Basically, take the numbers 1/3, -1/3, and count how many terms you need to produce something that sums to a whole number. You can get four with (1/3 + 1/3 - 1/3 - 1/3), so it's not an impossible configuration.

> Basically, take the numbers 1/3, -1/3, and count how many terms you need to produce something that sums to a whole number.

Shouldn't there be +2/3 and -2/3 charges as well? Otherwise the only way to do this is with an equal number of +1/3 and -1/3 charges (so not 5 total, for example).

Re: LHCb experiment discovers a new pentaquark

#20

Post by Retra »

JadeNB wrote: post #19
Retra wrote: post #12

Earlier quoted context omitted.

Basically, take the numbers 1/3, -1/3, and count how many terms you need to produce something that sums to a whole number. You can get four with (1/3 + 1/3 - 1/3 - 1/3), so it's not an impossible configuration.

> Basically, take the numbers 1/3, -1/3, and count how many terms you need to produce something that sums to a whole number. Shouldn't there be +2/3 and -2/3 charges as well? Otherwise the only way to do this is with an equal number of +1/3 and -1/3 charges (so not 5 total, for example).

You can get five with (1/3 + 1/3 + 1/3 + 1/3 - 1/3). Note that I'm not really talking about charges directly so they don't need to be equal, but rather I'm using these numbers as a proxy for charges. So this configuration might be something like (red, green, blue, red, antired).

It's just a quick rule for showing how many quarks can fit together, not what kinds of quarks they are.

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