Matter-Antimatter Bias Seen In Fermilab Collisions

ubermiester writes "The New York Times is reporting that scientists at Fermilab have found evidence of a very small (about 1%) average difference between the amount of matter/antimatter produced in a series of particle collisions. Quoting: '[T]he team, known as the DZero collaboration, found that the fireballs produced pairs of ... muons ... slightly more often than they produced pairs of anti-muons. So the miniature universe inside the accelerator went from being neutral to being about 1 percent more matter than antimatter.' This finding invites theorists to explain why there is so much more matter than antimatter in the universe, when the Standard Model suggests that there should be equal amounts of each." Here is the paper as submitted to Physical Review (PDF). The DZero team is looking forward to getting detailed data from the LHC once it ramps up operationally.

Comments

Is 1% significant?

[gman003]

For some experiments, 1% might be attributable to error. I've never done practical particle physics, though. Does this fall under experimental error, or is stuff like this usually re-creatable to seventeen decimal places?

I may not know much science, but I do know that margin of error is important.

Uneven laws

[Thanshin]

It would be so funny to discover now that the laws of physics are uneven in space...

That the same experiment gets you different results depending on which sid of the Milky Way you are...

Or they could be uneven in time. Maybe every 54.12 years the relation between produced matter/antimatter switches from 1:1.01 to 1.01:1.

Re:Uneven laws

[silentcoder]

That would not be a "discovery" but a confirmation. Many physicists have suggested such hypothesis in the past. Even more have suggested asymetry in time -t that at various ages of the universe the fundamental constants may have been different to what they are now.

There are a few pieces of evidence suggesting this (the rate of decay of Oklo's uranium COULD be explained that way - though a natural fission reactor is a more plausible one), and several physicists have conjectured that the fine-structure-constant may have changed over time, and that would be an explanation for the wrong speed of galaxies that wouldn't require cold-dark-matter.

Our estimates on the age of the universe have changed 4 times in the past 2 decades - generally, it got younger with the current consensus at about 13-Billion years.
Of course if any of the fundamental constants had changed over time or in different regions of space - in the end, it's simply a matter of how you travel through space-time, then that means all bets are off. The fundamental constants determine the laws of physics. Thus far, outside of singularities like the big bang or black holes (and Stephen Hawking thinks we don't even need THOSE to be singularities) there is no really strong evidence for it. It's possible, but unlikely - and if true, means it's mathematically impossible for us to understand the universe.

Re:Uneven laws

[Black Gold Alchemist]

If the laws are uneven in time, that could lead to perpetual motion among other interesting consequences.

For example, pretend that the speed of light is variable over time and remember that E=mc^2. On earth, we build a matter-antimatter annihilation laser and point it at a base in space. When the speed of light speeds up to c=1.1 the normal value, we fire off the laser, converting 10 g of matter into 1.08749377 petajoules. The light energy travels for a time, during which the speed of light slows back down to c. It hits a set up in the space base that converts the light back into matter. We divide by normal c, and are left with 12.1 grams of matter. We mail it back to earth, and send 10 g grams back to the laser (to repeat the process). The other 2.1 g is used as starship fuel, worth over 180 terajoules. Don't rinse, but repeat.

Re:Uneven laws

[silentcoder]

Hypothesis are a dime a dozen, theories are supposed to be hypotheses that have stood the test of time for a while, but the terminology often gets mixed up to the detriment of science (even by scientists).

That said, in this case - the people who made these hypothesis are highly respected phycisists who had genuine puzzles they were attempting to explain. In most cases so far - there ended up being other more plausible explanations, but I just don't imagine serious physicists proposing an alteration to a fundamental constant lightly.

Right now there is some puzzles in cosmology that suggest that the fine structure constant may have been slightly lower in the past, there is further very strong evidence that supports the possibility (notably - the energy of the background cosmic radiation is slightly lower, by almost exactly the amount it would be if this was true).
BUT - and this is a big but, in the meantime, two other explanations for the cosmic radiation difference have been proposed. In both cases they don't rely on a different fine structure constant shortly after the big bang. But their supporting evidence is still being tested. In the meantime - neither explains the puzzles that led to the proposal in the first place, so if either is shown to be accurate - cosmology still can't answer those.
That puts the weight of evidence currently on the side of a change over time in the FSC, if only because it explains more observations than any other available hypotheses.
Downside - if the FSC was different, that means a LOT of other differences, because the FSC is an amalgamation of several other fundamental constants including Planck's. Change that in the past, and it means the physics of the early universe was slightly different to ours, and such a difference is a mathematical singularity, it's impossible from our side of it, to predict what was on the other side.

Re:Uneven laws

[Myopic]

That is indeed interesting. My inference is that you just explained why C must be constant. You did a physical proof by reduction to the absurd.

new matter?

[kix]

I'm probably misunderstanding something here, but it seems that they have discovered that when the big bang happened, then because of this property, a bit more matter was created than anti-matter out of wherever they came in the first place, the rest of it annihilated with each other and everything else is made up from the "extra bits". This seems fairly reasonable.

Now, it is also known that new matter-antimatter element pairs are being created and annihilated all the time everywhere, this is where Hawking radiation comes from.

Does this new discovery mean, that it would be possible, that instead of an antimatter-matter pair a matter-matter pair is created sometimes instead and therefore the amount of matter in the universe is increasing (even if by a tiny amount)? Or are the conditions needed for this to happen too extreme to ever take place outside of big bangs and accelerators? Although as I understand some cosmic rays have far greater energies than accelerators.

Real physicists - please help me make sense of it all!

They fight for survival

[Laxator2]

The Tevatron is so thoroughly outclassed by the LHC that they have to take advantage of every opportunity to make a press release and show that they are still relevant. Once the LHC starts producing science data there will be impossible to justify funding for the Tevatron. The whole of Fermi Lab. (which uses about half the science money given by the D.O.E.) will be in danger of being closed, so they are fighting for survival. During the Bush administration they had to get private funding to avoid lay-offs. http://tierneylab.blogs.nytimes.com/2008/07/02/good-news-or-less-bad-news-for-american-science/