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New 'Mystery Meson' Sub-Atomic Particle Discovered
securitas writes "The BBC reports that scientists in Japan have discovered a new sub-atomic particle that defies current theories of matter and energy. The 'mystery meson' X(3872) was revealed while studying beauty quarks at the KEK High Energy Accelerator Research Organization Tsukuba meson factory. 'It weighs about the same as a single atom of helium and exists for only about one billionth of a trillionth of a second before it decays into other longer-lived, more familiar particles.' Scientists say the lifespan 'is nearly an eternity for a sub-atomic particle this heavy' and may require a change in current theory. Possible explanations for this include the particle being comprised of two quarks and two antiquarks, instead of the usual one-one pairing. More explanation and illustrations at KEK."
from the Institute of Physics
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No, they think it is most likely to be a combination of four quarks - charm/anti-charm and up/anti-up. This hasn't been seen before but is perfectly valid under the standard model... they've already seen pentaquark states after all.
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Actually, June's Scientific American had an interesting article on The Dawn of Physics beyond the Standard Model.
:(
It's too bad the full text of this article is available only for subscribers
"When a ball dreams, it dreams it's a frisbee"
Years back, IBM had an advertisement in Scientific American. It showed a stop-motion picture of a hammer smashing a watch, and pieces flying out. The text said something to the effect of, "Imaging learning how a watch works by smashing it and examining the pieces as they fly out. That's how we do subatomic physics." The gist of the ad was that IBM computers helped in that daunting process.
The living have better things to do than to continue hating the dead.
That's a deep question, and I guess in some sense we don't know. As with most of science, you accumulate evidence and test your theory. If the theory always gives the right answer, even when you try to prove it wrong a million different ways, then you assume you're on to something (or, at least, you start believing it will probably give you the right answer to your next question). Physicists currently believe that the Standard Model is only an approximation to something a bit deeper - the things we think of as particles might be strings, or something much weirder. But we have such detailed evidence of particle behavior to so many decimal places that we don't think we're far off.
Thats muons, not protons.
"We have got to make Stan understand the importance of voting, because he'll definitely vote for our guy." - South Park
Probably not very much, but who knows? String theory generally deals with phenomena at energy scales MUCH higher than these accelerators are dealing with, so high in fact that it really doesn't make any useful predictions about ordinary phenomena (even particle accelerator phenomena!) It's sort of like trying to predict the shape of a snowflake if all you've ever seen is steam. That's one of the main complaints about the theory - it may be right, it may be wrong, but it doesn't have any major prospects for predictions we could even test!
That's the way things are done for lower-mass particles (muons, pions, etc.), but heavier ones with even shorter lifetimes still don't travel a measurable distance and have to have their lifetimes measured as in my post above.
Wow, I've learnt how to answer my own questions..
Question
Is time quantized?
Asked by: Chris Ingram
Answer
I guess that the simplest answer to this would be: 'Yes, everything is quantized.' However, unfortunately this is one of the biggest problems in modern physics. No-one is really sure how it should be quantized but the idea of quantized time as well as quantized space and quantized gravity is part of the elusive theory of quantum gravity.
Some of the best minds in the world have been tackling the problem for years now. Einstein failed to united quantum theory with his own relativity, Richard Feynman couldn't do it (although QED was a definite step forwards) and even today some of our most famous physicists such as Kip Thorne, Stephen Hawking and Roger Penrose are still unable to unite quantum theory and relativity.
In answer to your question then. Yes, time is theoretically quantized and in an ultimate field theory it would be a quantized field much the same as the particle fields that we can already see in unified field theories. However, no-one has yet been able to come up with a consistent theory of space, time, fields and matter which shows exactly how time is quantized.
Answered by: Edward Rayne, Physics Undergraduate Student, Cambridge UK
The standard model is pretty well fucked anyway. It's not a revolution, it's a kick in the ass that's going to force us to re-examine a large amount of our basic assumptions/research done in the Standard Model.
Already outstanding issues include pentaquarks (5-quark exotic baryons), the inability to find the Higgs boson (not so much finding it, but having the found mass be correct), muon g-factor anomalies, and kaon decay, to name but a few.
I guess what I'm saying is: it's going to be a long time. Don't hold your breath.
blog |
For those of you interested in reading the actual paper, have a look at http://arxiv.org/abs/hep-ex/0309032 Warning: Contains sentenses like "We determine a ratio of product branching fractions" and "measurement of the width for this decay channel" - scary stuff!
.....link.........
"That said, how do you detect particles that exist for this short a period of time anyway?"
I would guess based either on the distance it travels and/or the momentum of it's decay particles.
It is by the juice of the coffee bean that thoughts acquire speed, the teeth acquire stains. The stains become a warning
No. Its been a while since 1 billion = 1 million million was common usage in Britain.
We use 1000 Million like the US now. Well, I'm sure there are *some people* who don't. You know how people get attached to archaic measurements. But the common usage is 1000 Million.
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A little bigger on the inside than out
Actually, we can narrow it down quite a bit using indirect observation. Thanks to Bjorken and Feynman, we have a way of showing that quarks (the subatomic constituents of matter) _must_ be point particles, at least to the smallest length scales we can probe with today's accelerators, e.g. by verifying experimentally that proton cross-sections are the sum of point-particle cross sections for particles with charge 2/3 e, 2/3 e, -1/3 e.
We also have shown that electrons are point particles down to a very small length scale (this is one of the most precisely tested theories in all of science.) In other words, the particles may not be true point particles, and instead have some finite size, but if they are, they are exceedingly small---so small that, as far as we care today, they may as well be point particles.
String theorists say that they are not point particles, but only at length scales that are so small there is no possibility of observing the difference; we'd have to build an accelerator the size of the universe to check.
Sure, quark-antiquark pairs are fine (mesons). Triplets are fine (baryons). And Pentaquarks are (anti :-)strange, but fine (u,u,d,d,!s).
My "WTF happened to QCD" was in regards to a comment implying that X(3872) was a four-quark static configuration, which I thought was unkosher.
Did someone find the Jaffe tetraquark or hexaquark and I've just been in a cave for the past decade? :) It's been a long time since I seriously studied any of this, and most of the papers I just googled were dated within the last 5 years, so I won't be at all embarassed to be proven dead wrong.
Belive it or not thats actualy the way that the model works. Like I said earlier, it is a very patch-work afair becuase of our lack of understanding of the way it all fits together. So in fact the name Standard Model is an oxymoron because it is nothing more than our best guess at how it works, and a guess that does hold exparimentaly true for now.
As a student of physics I don't like that standard model. It seems more like classification than theory to me
The hope of the Standard Model is that if enough things get listed and categorized, some clever person will come along, see a pattern which we will later all consider obvious, and write down where all those categories come from in the first place.
That's how we discovered quarks in the first place. Patterns were noticed in the categories of baryons, and invoking a few quarks explained all those particles.
neutrons are stabilized by protons
it's the other way around. neutrons form a neutral insulator in the nucleus so the protons don't all push away from each other because of their positive charges.
Just one more sensation out of misunderstood
//charge +1 //charge -1 //charge 0 //charge 0 //charge 0
//charge +1 //charge 0 //charge -1
scientific paper.
I work with the team which confirmed it at Fermi in X(3872) -> J/Psi Pion Pion.
Some background on quarks first:
There are six quarks d, u, s, c, b, t. The heaviest are on the right.
And six antiquarks d(bar), u(bar), s(bar)... you've got the idea.
d, s, b have charge -1/3.
u, c, t have charge 2/3,
antiquarks and quarks have opposite charge.
All the matter consist of the particles which
are combinations of quarks. There are several
types of observed combinations: Mesons, Barions,
Tetraquarks, Pentaquarks. They are correspondingly
consist from 2, 3, 4 or 5 quarks.
All the Mesons consist of quark and antiquark. Examples:
Pion = (u, d(bar));
Kaon =(s, u(bar));
J/Psi =(c, c(bar));
D =(c, u(bar));
D(bar)=(c(bar), u);
Barions consist of 3 quarks. Examples:
Proton =(u, u, d );
Neutron =(d, d, u );
Antiproton =(u(bar), u(bar), d(bar));
You may continue it yourself for Tetraquarks and Pentaquarks.
Make sure the total charge of the particle is integer.
Heavy quarks want to decay to a ligter ones.
Eventually to u, d, u(bar), d(bar) and also
leptons (electron, muon) neutrinos and photons.
Some people think that X(3872) is one of the exited states of (c, c(bar)). Some people think
that it could be a tetraquark (c, c(bar), u, u(bar)). We should observe other modes
to know for sure. I am looking for X(3872) -> DD (bar).
No luck so far.
It is definitely very exiting to see a new particle like it would be exiting
to see a new chemical element. As far as I know it fit quite nicely
in the standard model - the analog of the Mendeleev table for particle physics.
Basically, it is possible to know how fast it's going (simple mechanics) and it is possible to see (or deduce) where it came into being and where it disintegrated into bits-- measure the distance between them and you have time.
It's a really really short time, but particles ejected from a collision in a particle accelerator are going really really fast-- they get to cover some distance in that short interval.
-- MG
All the matter consist of the particles which
are combinations of quarks.
Ordinary matter (like you and me) is composed of barions and leptons. Leptons are not composed of quarks. Same for neutrinos, which are a bit less ordinary, but still count as matter.
As barions provide most of the total mass of an atom, the best you can say is that most of the matter is made of quarks.
Agree. I just tried to provide a minimum of information required to understand the issue. for more info on Standard Model: http://www2.slac.stanford.edu/vvc/theory/model.htm l
"exists for only about one billionth of a trillionth of a second"
Remember, people: "billion" and "trillion" mean very different things to people in different English-speaking parts of the world. Exponents and/or SI prefixes are the proper way to express numbers like this.