Feeds

back to article New ATLAS particle part of 'everyday mass'

While we’ve been paying all our attention to the elusive Higgs boson, the ATLAS experiment has turned up another particle which researchers say could be responsible for shed light on* much of the mass of “everyday objects”. The new object, known as chi-b(3P), is the first confirmed brand-new particle discovered at the Large …

COMMENTS

This topic is closed for new posts.
Silver badge
Holmes

Three quarks for Muster Mark!

"the release doesn’t tell El Reg how that binding takes place without annihilation, which is a pity"

Should be similar to positronium - a proton and an antiproton bound by the electromagnetic force "orbiting each other" -- in the rather inappropriate classical imagery, Here, a b-quark and a b-bar quark bound by the color force are "orbiting each other". Don't ask for the probability density function over the states which happens to exclude the "mutual annihilation" state (a description less apt to lead you astray I would think), I don't know anything about that.

“a lot of the mass of everyday objects comes from the strong interaction we are investigating using the chi-b”

What he means to say is that most of the mass of nucleons is not in the quarks (with masses in the MeV range for standard stuff) but in the energetic color force (quantizable to massless gluons) that holds them together - around 99% IIRC. Interestingly, when tightly confined the quarks are only lightly touched by this force, which is the opposite of what one see with the electromagnetic force.

Elementary!

2
0
Silver badge
Unhappy

Wuff ... positronium is of course an e+ / e- composite. Yeah, yeah writing while having beer.

1
0
Anonymous Coward

Bottomonium

Left alone in a bound state the bottom and antibottom (bottomonium) quarks would annihilate eventually (eventually = fractions of picoseconds here), but except for the lowest energy bound states (the eta_b and Upsilon(1S)) they are likely to decay by other means before annihilation can occur.

The states above a certain threshold are likely to decay into 2 B mesons (a bottom (anti-)quark, and a light (anti-)quark (u, d, or s)). Those below the threshold are likely to decay to lower energy states, by emitting pions or photons, until they reach one of the lowest energy states, or annihilate, or one of the bottom quarks decays.

The difference between positronium, and bottomonium is as you suggest that in positronium the binding energy has vary little effect on the mass, whereas for mesons it makes up a major component of the mass, and thus the different bound states appear as particles with different masses.

For the light particles (nucleons, pions...) the binding energy is most of the mass of the particle, but for particles made of heavier quarks, the effect is less, e.g. bottom (anti-) quarks have a mass of about 4.5GeV/c2, and their bound states have masses from about 9.4 to ~11GeV/c2. As the effect is less on these particles, they can be less complicated to understand and model than the lighter mesons. Finding more of the bottomonium bound states (and their masses/transition energies) thus allows for a greater understanding of (the way composite particle masses are generated by) the strong force.

5
0

I'm sorry, but did you say "bottomonium"?

3
0
Happy

elem

Wouldn't that be alimentary ?

0
0

Not sure how this is different to the bottom eta meson:

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

0
0
Silver badge

Same components - different (higher) energy state, inaccessible to the SLAC.

2
0
Stop

Not "responsible" for mass.

From the press release: "a lot of the mass of everyday objects comes from the strong interaction we are investigating using the chi b.’

It's like saying "A lot of the mass of people comes from meat, which we are investigating using mice"; meat's involved in both cases, but that doesn't mean we're made of mice.

4
0
Black Helicopters

Anihilation

If I remember my physics correctly, annihilation is actually a misnomer. It is usual for particles in "annihilation" events to decay into different particles. The particle discovered is a Meson not a Hadron, and mesons are made from a quark/artiquark pair. They aren't usually log lived and break down to other particles in short order. The annihilation you are referring to is the breakdown when a hadron meets its anti-hadron, or meson meets its anti-meson, or lepton (eg electron) meets its anti-lepton. Quarks are a bit more gregarious with anti-quarks - probably something to do with the differing colour charge (see quantum chromodynamics) - it makes the pairing of a green quark and antigreen antiquark possible because they aren't the same colour charge.

1
0

Is this the "fat bottom" meson?

0
0
Pint

To mis-quote Queen...

As in "fat-bottomed mesons, you make the rocking world go 'round"?

2
0
Trollface

Re: DD

Squeak Squeak Squeak Squeak!

Er, I mean, of course! Made of mice... ridiculous!

Squeak!

0
0

Post-Christmas I appear to be made of cheese.

2
0
Boffin

So they say the Higgs is...

...supposed to be a single indivisible particle? Isn't that the same problem as the Greeks had?

So they gave us "atom" as the label for the smallest indivisible component of matter in the Universe ("un-i-verse". Mr Dent-Arthur-Dent!).

1
1
Ru
Boffin

Much like the photon, yes

Strange things, gauge bosons.

0
0
Silver badge
WTF?

I still have a problem here;

Is it a hadron collider that is very large,

a collider of large hadrons

or does it make large collisions of hadrons?

We need to be told!

0
0

@will

Actually, it is all 3 a large collider for large collisions of large hadrons

5
0
Silver badge

I've always imagined that the adjective was needed because under a desk somewhere, perhaps pedal powered, was a 'small hadron collider'

7
0
Headmaster

Small Hadron Collider? http://sascha.mehlhase.info/physics.php?open=atlaslego

0
0

I'm probably going to regret asking, but.....

How is it a new "particle" if it is made up of two particles?

Isn't that a bit like saying Sodium Chloride is an element?

0
1
Gold badge

Re: ..gret asking

I think "particle" is used fairly generally to describe things that aren't fields. This one isn't a fundamental particle, but it's related to things found before WW2 which were called particles then (because we didn't know what they were made of) and so even though the quark model (1960s) lets us talk about the make-up of these particles, they're still particles.

4
0
jai
Silver badge

chi-b?

Are all the particles short, with cute faces and big eyes?

3
0
Silver badge
Childcatcher

I think you're getting confused

Pi-plings are the short ones with the cute faces and big eyes.

I'm being brainwashed by kids' tv...

0
0
Silver badge
Angel

...Yes

However they are *so* short, you would need a scanning string microscope to see these details.

0
0
rcs

most of visible mass of universe has nothing to do with higgs particle

Actually, most of the mass of the proton and neutron and therefore essentially all other visible mass in the universe is mostly coming from the strong interaction. A proton consists of three valence quarks which make up just about a % of the proton's mass and the interaction - Quantum chromo dynamics QCD makes up the rest. The Higgs gives the quarks its mass, but QCD is responsible for the whole rest. That's why I am actually studying the structure of the Proton which is currently studied also at accelerators at CERN, BNL and JLAB.

1
0
Alert

From another LHC experiment looking for cheap eastern labour at CERN, also about B mesons and b quarks, for those wondering:

"The cost [...] has been evaluated, taking into account realistic labor prices in different countries. The total cost is X (with a western equivalent value of Y)" [where Y>X]

source: LHCb calorimeters : Technical Design Report

ISBN: 9290831693 http://cdsweb.cern.ch/record/494264

0
0

@will

Exiting stuff! Vexing questions. I have a large Hadron!

0
0
Bronze badge

but...

Nobody has mentioned Jesus yet. Surely an omission!

I'll have a little pray to thank our lord for... er, oh I'll just make something up.

0
0
This topic is closed for new posts.