Slashdot Mirror
LHC Research May Help Explain the Universe's Matter/Antimatter Imbalance
suraj.sun sends this excerpt from the BBC:
"Particles called D-mesons seem to decay slightly differently from their antiparticles, LHCb physicist Matthew Charles told the HCP 2011 meeting on Monday. The result may help explain why we see so much more matter than antimatter. The team stresses that further analysis will be needed to shore up the result. At the moment, they are claiming a statistical certainty of '3.5 sigma' — suggesting that there is less than a 0.05% chance that the result they see is down to chance. The team has nearly double the amount of data that they have analyzed so far, so time will tell whether the result reaches the 'five-sigma' level that qualifies it for a formal discovery."
Is such an imbalance dangerous for a universe this age? Does our universe need medical treatment?
Ha, never did that before
CP violation in weak interactions has been known for some time, specifically in neutral Kaon decay. If I'm understanding this results correctly, the surprise here seems to be the magnitude of the CP violation in this case.
At the moment, they are claiming a statistical certainty of '3.5 sigma' â" suggesting that there is less than a 0.05% chance that the result they see is down to chance.
Seems legit. I mean how many times would one need to take the chance of the results being down to chance for that chance having a chance of happening?
A star made of antimatter would look exactly the same as one made of matter, wouldn't it? What if half of what we can see in the universe is antimatter?
I can't believe I saw this on Yahoo! before I saw it here on Slashdot. I also can't believe I still use Yahoo! either.
Dont article for the public on this kind of stuff need to be simplified for those of us not in the field? At least make the summary partly readable.
What we see is just the observable universe. What if all this missing antimatter happens to be in a non-observable part? You'll never be able to see that! Unless those faster than light particles end the theory of observable universe of course.
Is this sigma terminology coming from some discipline? I've taken plenty of grad statistics and we've always called them alpha-significance levels.
From wikipedia:
The term Six Sigma originated from terminology associated with manufacturing, specifically terms associated with statistical modeling of manufacturing processes
So...the MBAs went and redefined some terms? And we're using them to summarize an empirical physics paper's results...why?
PS: I don't reply to ACs.
Identifying an a real-world mismatch of our models' predictions does not "explain" anything but that our models are incomplete.
When spheres, and spheres on spheres, don't explain planetary motion, let's try another model: the ellipse.
When "classical" mechanics can't explain why "orbiting" electrons don't fall into the nucleus of an atom due to electrostatic attraction, let's come up with a new model (while confusingly calling them "orbitals"): shells and quantum exclusion effects.
When whatever synthesis of strings and quantum gravity and pixie dust (or something very different from all of them) can provide a mathematical basis (that isn't all adjusted parameters) to describe this universe's preference for "matter" vs "anti-matter" (maybe the seventh harmonic of the property of "charge" in 12- (13- ?) dimensional space has a more-natural resonance with the fourth harmonic of the property "mass" for matter than for anti-matter, or something): we'll have a better model, but still, probably, not an "explanation".
If they are able to demonstrate a symmetry breaking strong enough to explain the preponderance of matter in the universe then they are a very good bet for the Nobel price in physics.
All these experiments occured on earth in the vicinity of a lot of matter. How do we know that if we performed the experiments on a anti-earth we would not get an opposite result?
CP violation in Kaon decays can be explained by the Standard Model, but if the magnitude of CP violation they have claimed exists in the D system can not.
The calculations required to predict the amount of CP violation in meson systems are extremely hard to do. When I worked on the NA48 experiment, which measured direct CPV in the kaon system, the theorists were initially adamant that there was no way the parameter we measured (espilon-prime over epsilon) could be above 0.001 in the Standard Model. Several year later after both NA48 and KTeV had published results putting the parameter at well above that I saw a theory talk saying that these results were in perfect agreement with the Standard Model!
Now the discrepancy seems a lot larger here but, nevertheless, even if the result holds I'd give the theorists time to think about this and see whether they find problems in the calculations. I have a huge amount of respect for my theory colleagues but QCD calculations like this are fantastically hard so it is not at all uncommon for the results to change.
The radiation of an antimatter star would be the exact same as a matter star. There is no way of knowing that our visible Universe is mainly matter. That the Universe is made mostly of matter is a myth not really backed up.
Of course there's more matter than anti-matter. If there is a finite amount of matter/antimatter/energy then the only reason there is matter *at all* is that there is some imbalance. Otherwise it would all just be energy. There happens to be more matter than antimatter. Aren't you glad?
A bit off topic but this is very interesting find, just a few weeks after the 'Faster than light neutrinos'. Why can't we put money into projects like these instead of killing people in other countries. Err correction: Bringing democracy to other people.
Unbelievable, the LHC is actually doing what it was (amongst other things) built for! Spread the news, SPREAD THE NEWS!!!!!
Being a physicist myself I am very happy that this topic makes it into the news. But it is important to keep cool and skeptical. The statement that a statistical fluke has a probability of 0.05% implies that it is bound to happen if you let 2000 students do data analyses on independent data sets. There are indeed literally thousands of PhD students doing such analyses LHC data, trying to address hundreds of specific research questions that each require different data selections. So it is very likely that some of them will find a result several standard deviations away from the expectation. Actually 3.5 sigma deviations happen very often, because of all sorts of mistakes and inaccuracies in the analyses, but most of the time these mistakes are scrutinzed away before loud public announcements are made. After all scrutiny a few genuine statistical flukes should still remain, and recognized as such.
(For the xkcd inclined: green jellybeans linked to acne.)
More caveats:
So this is a very interesting result, but more study is needed and in my experience such flukes almost always evaporate in the light of more data and scrutiny. Still, it's not completely excluded that this was indeed the first hint of a real discovery (otherwise no researcher would ever do all that work).
OK, enough for now. Sorry for misinterpretations and other errors I might have made.
Props, you sound like someone worth listening to. What are you doing here?