LHCb experiment discovers a new pentaquark

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?

Re: LHCb experiment discovers a new pentaquark

#5

Post by sanxiyn » Wed, Mar 27, 2019, 12:39 PM UTC

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 possible, LHC would do what has never been done, but not very probable.

Re: LHCb experiment discovers a new pentaquark

#6

Post by TheAdamist » Wed, Mar 27, 2019, 1:01 PM UTC

drilldrive wrote: post #2

So, what is a pentaquark exactly? The article doesn't say.

if you click through on the 'read more' to: http://lhcb-public.web.cern.ch/lhcb-public/Welcome.html#Pent...

including the detail that the quark state content is: "duucc: four quarks and one antiquark. "

Theres a further 'read more' link to a powerpoint, http://moriond.in2p3.fr/QCD/2019/TuesdayMorning/Skwarnicki.p... which is way out of my understanding

Re: LHCb experiment discovers a new pentaquark

#7

Post by Hattes » Wed, Mar 27, 2019, 1:03 PM UTC

drilldrive wrote: post #2

So, what is a pentaquark exactly? The article doesn't say.

Penta = five. There's a picture of a ball with five balls in it. It decays to a proton (which as mentioned has three quarks) and another pair of a quark and an anti-quark. I'd say it's there.

Re: LHCb experiment discovers a new pentaquark

#8

Post by andrepd » Wed, Mar 27, 2019, 1:27 PM UTC

drilldrive wrote: post #2

So, what is a pentaquark exactly? The article doesn't say.

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).

Re: LHCb experiment discovers a new pentaquark

#9

Post by drilldrive » Wed, Mar 27, 2019, 1:41 PM UTC

andrepd wrote: post #8

drilldrive wrote: post #2

So, what is a pentaquark exactly? The article doesn't say.

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?

Re: LHCb experiment discovers a new pentaquark

#10

Post by dragonwriter » Wed, Mar 27, 2019, 1:49 PM UTC

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?

> 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–antiquark pairs or baryons formed of three quarks. Particles not classified within this scheme are known as exotic hadrons. When Murray Gell-Mann proposed the quark model in his fundamental 1964 paper, he mentioned the possibility of exotic hadrons such as pentaquarks, but it took 50 years to demonstrate their existence experimentally.”

(There is slightly more detail on the read more link, too.)