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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."
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.
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?
If you really want to contribute to the narrative, you should program one of your function keys to emit the string "Frosty Piss". You'll save valuable time when composing your groundbreaking first post.
Nullius in verba
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 such an imbalance dangerous for a universe this age? Does our universe need medical treatment?
Further, don't expect a balanced universe amendment any time soon.
A feeling of having made the same mistake before: Deja Foobar
s this sigma terminology coming from some discipline? I've taken plenty of grad statistics and we've always called them alpha-significance levels.
Surely if you've taken plenty of grad statistics, you've seen sigma used for the standard deviation.
They're saying something like the observed difference is 3.5 times sigma. That corresponds to an alpha=0.05% (or is it 99.95%?); they're not saying that sigma itself is 0.05%.
Yes. 3.5 standard deviations on the normal curve (gaussian distribution, I assume).
- The race is not [always] to the swift, nor the battle to the strong. -
No, this is not MBA-speak, sigma is standard statistical terminology for "standard deviation":
In some fields, for example nuclear and particle physics, it is common to express statistical significance in units of the standard deviation of a normal distribution.
Ok, here we go again:
LHCb sees where the antimatter's gone
ALICE looks at collisions of lead ions
CMS and ATLAS are two of a kind
They're looking for whatever new particles they can find.
The LHC accelerates the protons and the lead
And the things that it discovers will rock you in the head.
>>>>At the moment, they are claiming a statistical certainty of '3.5 sigma' Ã" 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?
My plan for runs on the LHC is to run 1000 experiments and then pick the result that most supports some media-attention-grabbing theory that I'll just make up on the spot. /sacrasm off
In all honestly, a sigma of 0.05 isn't especially good for experiments like this. You don't have the confounding effects that make social "science" so hard to trust.
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?
Funny that you mention alpha, since Wikipedia says: "In some fields, for example nuclear and particle physics, it is common to express statistical significance in units of the standard deviation Ïf of a normal distribution."
Avantslash: low-bandwidth mobile slashdot.
How in the world do you take even ONE grad class and never hear of sigma or standard deviation? This is like the intro to the intro to statistics class and everything builds on it. You would have seen sigma dozens of times in each class...
See my journal for slashdot ID's by year. Mine created in 2005. http://slashdot.org/journal/289875/slashdot-ids-by-year
Any medical treatment given the universe would most certainly not be good for sub-microscopic lifeforms living on planets...
GrpA
Enjoy science fiction? "Turing Evolved" - AI, Mecha, Androids and rail-gun battles. What more could you want?
The universe we can see is primarily made up of matter. We know because there are characteristics of antimatter that would allow us to know if we were looking at an anti-galaxy, for example. But we don't know why there is so much matter, and not anti-matter, because the laws of physics we understand so far are neutral. So to explain the universe we see, there must be some rule we don't know about yet, which explains why the universe heavily favors matter.
This story is about a high-energy physics experiment which revealed a result which will help to explain the discrepancy if it can be confirmed. It will guide us towards that new rule to explain this particular mystery of the universe.
"Who is the Journal of Quantum Physics going to believe?" --Stephen Hawking
Sounds like he had a brain-fart. RIgth now, he's smacking his forehead and calling himself an idiot because he didn't put together this sigma with the sigma he knows about as the standard deviation.
This sort of thing happens to me all the time. (Sometimes I feel really old.) I hate it when it makes me look stupid in front of someone. Like the day I was in the office of a Linguistics professor and asked a really stupid question about the fridge magnet letters that just happened to be IPA characters. I know IPA like the back of my hand, so I don't know what I was thinking.
I do other things that make me look stupider than I really am. Recently, I did a doozie in a slashdot comment. But this time, I was just being lazy. They were talking about Bulldozer, and I said a bunch of things that were wrong, mostly because I had forgotten, and I didn't take the time to look it up. I'm getting a Ph.D. specializing in computer architecture, but my lazyness made me look like a total idiot.
Fortunately, my dissertation committee won't be looking at my slashdot comments. :)
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.
They are averaging the results of many collisions, which are presumed to be independent and identically distributed of finite variance. Thus the central limit theorem dictates that the measured average is normally distributed about the mean of the true distribution of the statistics of a single collision. As they repeat the experiment n times the variance of the mean reduces at order n (hence std dev. the square root of the variance reduces at order sqrt(n)) Once they have repeated the experiment sufficient times the observed mean will be resolvable from a theoretical calculation (that is, if the theory is in error). They are waiting to verify that the expected (theoretical) result differs from the observed (measured average of many experiments) by at least six standard deviations (more experiments will lower the standard deviation while keeping the difference between theory and observation relatively static, or not). Then they will be certain that the theory is in error by however much they measure, then it is time to revise the theory to match the observation (without breaking any other observations and being able to predict new results that can be tested experimentally).
How many more galaxies must suffer before we build a universal healthcare system?!?
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Oh, I knew they were trying to refer to the second parameter of a normal distribution. But, whatever symbol we *use* for the variance (std dev) is just a symbol. We could call it: "a", "alpha", "sigma", "theta", all with various subscripts, and so on and so forth. Ever heard of six-theta_2 ? Six-theta_2 refers to 6 times the standard deviation of an estimated, normal curve. The term six-theta_2 only makes sense because we filled in the crucial parts (that shouldn't be left out).
Saying "sigma" without any qualifications leaves much to be assumed. I'm being persnickety about terms because the terminology lacked definiteness.
PS: I don't reply to ACs.
But as found out by Professor Murphy, we are likely to live in parallel world #2000.
What if the planet this result isn't true is #42?
units of the standard deviation Ïf of a normal distribution
Now how'd that get in there?
The question is why. Physicists are still trying to figure out why at the creation of the universe there wasn't complete uniformity. This lack of uniformity also allowed galaxies to form, but just because something is good that doesn't mean it makes sense.
you only make yourself sound like a douche regardless.
Pot? I'd like to introduce you to Kettle. Oh, you say Kettle is black? Why yes, yes it is....
The second central moment is the variance, not the standard deviation.
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.
Supernovas are universal antibiotics.
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.
I noted in a reply further up that 3sigma events many times end up going away as more statistics are taken. Google "3 sigma bump" for examples.
Ok, here we go again:
LHCb sees where the antimatter's gone
ALICE looks at collisions of lead ions
CMS and ATLAS are two of a kind
They're looking for whatever new particles they can find
The LHC accelerates the protons and the lead
And the things that it discovers will rock you in the head.
Or, for the full version: http://www.youtube.com/watch?v=j50ZssEojtM
units of the standard deviation Ïf of a normal distribution
Now how'd that get in there?
Pair production? Maybe now there's an anti-Ïf floating around somewhere.
Hah, that's hilarious.
Well, the MBAs apply Six Sigma to all kinds of stuff that it really doesn't fit. However, the definition of six sigma is pretty straightforward:
A six sigma process is one whose specification limits are at least six standard deviations away from the mean.
So, if a space shuttle part needs to be 1 meter long, and if bad things happen if it is more than one cm off, then a six sigma process would need to produce parts that are 1 meter long with a standard deviation of 1/6th of a centimeter (and a normal distribution of sizes). If the process can do that then the chances of a part ever coming off the line that is off by a centimeter is VERY low - so low that you don't really need to check them all.
Statistical process control is how the Japanese clobbered US industry after WWII. The US was stuck on outdated models where you test every part and reject the bad ones. The pioneer of SPC (an American) realized that you could ditch the testing, and take all that saved money and instead put it into improving your manufacturing process so that you don't make the bad parts to begin with. Modern process control is about randomly monitoring critical parameters and ensuring they all stay in range so that the final product is VERY likely to have the desired attributes.
Alpha is used in hypothesis testing - as in, we can all be sure that 5% of all the clinical trial conclusions ever reached are downright wrong, and most likely those that are actually are reported are wrong much more often than that.
Yahoo? You seem to be confusing antimatter with doesn't matter...
Not everything that can be measured matters; Not everything that matters can be measured.