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← LHC reports discovery of its first new particle

LHC reports discovery of its first new particle - Comments

Jos Gibbons's Avatar Comment 1 by Jos Gibbons

Let me put this discovery into its context in physics.
Mesons are quark-antiquark pairs analogous to a very simple atom of a nucleus and an electron. Like an atom, it can occupy discrete energy levels. Because a nucleus is much heavier than an electron, the nucleus in an atom can be approximated as stationary, so we usually summarise the energ levels as those of an electron. Mesons don't allow us this approximation unless the quark and antiquark differ greatly in mass, and chi mesons are examples of "quarkonium" mesons, in which the masses don't differ at all. (Another "like an atom where the nucleus is as light as the electron" system is positronium, a positron-electron system.) However, the discrete-energies phenomenon is still applicable. Some mesons are made of the same quark-antiquark pair, but the energies are different. This "new particle" is essentially an excited state of a more familiar meson. Imagine we had only just discovered the highest yet known excitation of a hydrogen atom's electron. That's basically what this discovery is like.
It's significant because our theories predict both the existence and properties of this state, and spotting it lets us verify that.

Thu, 22 Dec 2011 20:53:51 UTC | #902028

ridelo's Avatar Comment 2 by ridelo

Thanks, Jos Gibbons. This helps. I know a bit chemistry, but the subatomic particles jungle is "terra incognita" for me.

Thu, 22 Dec 2011 21:52:28 UTC | #902043

Neodarwinian's Avatar Comment 3 by Neodarwinian

Thanks, Josh, but I hope that the name ' Chi_b (3P) ' is temporary!! Need some quarky like names, such as, my suggestion, ' weird! '

Thu, 22 Dec 2011 22:00:25 UTC | #902045

Cook@Tahiti's Avatar Comment 4 by Cook@Tahiti

The headline is misleading. It's not really a new particle. As I understand it, it's an old particle in a different state.

Thu, 22 Dec 2011 23:24:06 UTC | #902058

QuestioningKat's Avatar Comment 5 by QuestioningKat

Note to scientists: Please do not name discoveries anything that can be misinterpreted as woo. Chi as in life force - Tai Chi...

Thu, 22 Dec 2011 23:35:39 UTC | #902061

God fearing Atheist's Avatar Comment 6 by God fearing Atheist

Comment 5 by QuestioningKat :

Note to scientists: Please do not name discoveries anything that can be misinterpreted as woo. Chi as in life force - Tai Chi...

Its also the 22nd letter of the Greek alphabet, and pops up all over the place in stats. maths, and obviously physics.

Thu, 22 Dec 2011 23:48:46 UTC | #902063

Anaximander's Avatar Comment 7 by Anaximander

The headline is misleading. It's not really a new particle. As I understand it, it's an old particle in a different state.

A new particle or not a new particle? That is a difficult question.

Fri, 23 Dec 2011 00:21:34 UTC | #902070

Steve Zara's Avatar Comment 8 by Steve Zara

Comment 1 by Jos Gibbons

Thank you. That was an extremely clear and informative summary. Most helpful!

Fri, 23 Dec 2011 01:14:40 UTC | #902089

QuestioningKat's Avatar Comment 9 by QuestioningKat

Comment 6 by God fearing Atheist :

Comment 5 by QuestioningKat :

Note to scientists: Please do not name discoveries anything that can be misinterpreted as woo. Chi as in life force - Tai Chi...

Its also the 22nd letter of the Greek alphabet, and pops up all over the place in stats. maths, and obviously physics.

oooo! oooo! ouch! my bad. Rest assured that the majority of the world is more scientifically literate and intelligent than I am and will not make the mistake confusing woo - Chi, the life force, with the 22nd letter of the Greek alphabet! Well, I learned something new today.

Fri, 23 Dec 2011 02:08:19 UTC | #902096

AnthropicConstance's Avatar Comment 10 by AnthropicConstance

@QuestioningKat Understandable. Several young persons around my community did not know 'the God particle' was so named by the media, not by physicists (who more properly call it the Higgs boson.)

Comment by Jos Gibbons

...I wonder if I may ask something somewhat off-topic: Wherever I look up the mass of a photon, listed with other particles, the reply is that it has none. Why then, should there be such a thing as gravitational lensing?

(I wanted to ask in the 'Smart answers to dumb physics questions' thread but got lost amid all the other great questions.)

Fri, 23 Dec 2011 05:20:16 UTC | #902123

JuJu's Avatar Comment 11 by JuJu

Chi particle? God particle? Whats next the "Homeopathic dilution particle" or maybe the "Vaccines cause autism particle" How about the "Astrology particle"?

Fri, 23 Dec 2011 07:00:25 UTC | #902128

urn's Avatar Comment 12 by urn

@ AnthropicConstance.

from the photons perspective its traveling in a straight line, but gravity is warping the spacetime its traveling through.

its kinda like drawing a straight line on a piece of paper, and then warping the paper. the trajectory of the line appears to be redirected. (at least thats my understanding)

Fri, 23 Dec 2011 07:06:33 UTC | #902130

mmurray's Avatar Comment 13 by mmurray

Comment 11 by JuJu :

Chi particle? God particle? Whats next the "Homeopathic dilution particle" or maybe the "Vaccines cause autism particle" How about the "Astrology particle"?

It's not the life-force chi. It's the greek letter chi. No stranger than alpha particle, beta decay, gamma ray etc.

Michael

Fri, 23 Dec 2011 07:24:00 UTC | #902132

Jos Gibbons's Avatar Comment 14 by Jos Gibbons

Comment 3 by Neodarwinian - (1) it's Jos, (2) if these are anything to go by, the name is permanent.
Comments 5 et al re: chi - incidentally, while the Chi in Tai Chi is pronounced like the first four letters of cheese, the Greek letter is pronounced like the first three letters of chiropractor.
Comments 10 & 11 re: photons - one shouldn't confuse inertial mass (energy/c squared) with rest mass. Gravity acts on the former. The energy E is related to the rest mass m0 by E squared = (m0 c squared) squared + (pc) squared, p being the momentum, which in turn is velocity times the inertial (not rest) mass.

Fri, 23 Dec 2011 08:15:20 UTC | #902143

mmurray's Avatar Comment 15 by mmurray

A quick look at the actual preprint

http://arxiv.org/pdf/1112.5154v1

and you can see what chi looks like. Second "word" of the abstract.

Michael

Fri, 23 Dec 2011 08:59:27 UTC | #902156

thebaldgit's Avatar Comment 16 by thebaldgit

Perhaps this discovery will be more important than the Higgs but whether it is or not it is nice for the LHC to get one under its belt pity about the name though.

Fri, 23 Dec 2011 10:42:56 UTC | #902184

Schrodinger's Cat's Avatar Comment 17 by Schrodinger's Cat

"The new particle is made up of a 'beauty quark' and a 'beauty anti-quark'.....

Chi_b (3P)..........with scientifically proven beauty enhancement. From our laboratories in France.

Because you're worth it.

Fri, 23 Dec 2011 10:55:03 UTC | #902186

Jos Gibbons's Avatar Comment 18 by Jos Gibbons

16 - nope.

Fri, 23 Dec 2011 11:40:56 UTC | #902195

mmurray's Avatar Comment 19 by mmurray

Comment 16 by thebaldgit :

Perhaps this discovery will be more important than the Higgs but whether it is or not it is nice for the LHC to get one under its belt pity about the name though.

There are lots of particle states with names like this

http://en.wikipedia.org/wiki/Quarkonium

Michael

Fri, 23 Dec 2011 12:31:19 UTC | #902205

Mr DArcy's Avatar Comment 20 by Mr DArcy

This an old chesnut but probably worth a repeat.

What do you call a female crew member of an atomic submarine who likes discos?

A sub-atomic party girl!

Fri, 23 Dec 2011 12:54:21 UTC | #902210

drumdaddy's Avatar Comment 21 by drumdaddy

Particle physics is well beyond my depth. I just hope they don't ever find the 'Devil Particle'.

Fri, 23 Dec 2011 17:05:09 UTC | #902260

Daryl 's Avatar Comment 22 by Daryl

I looked at the Abstract. Well, it's Greek to me (please feel free to groan heartily). It's coupled with my watching the BluRay of the Hubble movie last night; what an extraordinary universe we live in. Can you imagine how dull and small it would be if we really were at the center?

Fri, 23 Dec 2011 20:14:56 UTC | #902283

mmurray's Avatar Comment 23 by mmurray

Comment 22 by Daryl :

I looked at the Abstract. Well, it's Greek to me (please feel free to groan heartily).

Done :-) and to Mr Darcy for the sub-atomic party girl. You both deserve my 15 year old son's highest praise: "lame".

Michael

Sat, 24 Dec 2011 00:41:44 UTC | #902311

Rara192's Avatar Comment 24 by Rara192

Every time I'm reminded of the LHC it makes me sad. American physics seems to be earnestly running in the opposite direction, and Australian physics probably doesn't even exist. It's not that I'm jealous that it's all happening in Switzerland; "good on 'em," I say, and I would gladly move there if I could. But such instruments like the LHC and the Hubble represent the few threads of evidence we have that our species is trying to push the frontier, and with proposals for their successors rejected — even terminated mid-construction — it just highlights how vulnerable our science and future exploration still is.

Sat, 24 Dec 2011 13:06:24 UTC | #902376