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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.
That is a hypothesis used by cosmologists but it isn't part of the Standard Model. The Standard Model predicts particle behavior, not as much the macroscopic stuff. For most purposes the Standard Model agrees with the cosmological observations. This is one example where the Standard Model may be missing something or need tweaking.
Their error, as stated in the linked abstract, is less than 0.3%. So, if you believe they're doing statistics correctly, yes, the signal is greater than the noise. More importantly, even, say 1.0 - 0.3 = 0.7% is HUGE: the common estimate of matter-antimatter asymmetry at the big bang was merely a billion-and-one to a billion. (linky: http://livefromcern.web.cern.ch/livefromcern/antimatter/academy/AM-travel02c.html). And that extra one in a billion is all the matter we have today.
Assuming that what the conclusion (p. 21) reports as "like-sign dimuon charge asymmetry of semileptonic b-hadron decays" is the number we're looking for, they do give a margin of error that's smaller than the asymmetry observed. They report the asymmetry as:
A = -0.00957 +/- 0.00251 (stat) +/- 0.00146 (syst)
I believe the two errors are there because they breaking out the statistical margin of error (due to sampling) and systemic margin of error (due to accuracy of apparatus and setup).
10 PRINT CHR$(205.5+RND(1)); : GOTO 10
It would be so funny to discover now that the laws of physics ... be uneven in time. Maybe every 54.12 years the relation between produced matter/antimatter switches from 1:1.01 to 1.01:1.
You're not the first to think this (specifically the fundamental constants like the speed of light might be changing over time):
http://www.space.com/scienceastronomy/generalscience/constant_changing_010815.html
no, this is doesn't fit the physics i know of.
in quantum field theory, you can describe the phenomena of a photon splitting into a particle-antiparticle pair that then anihilates to recreate the initial photon. these are the pairs that appear and disappear all the time (because of virtual photons that appear and disappear). However, a photon splitting into a particle-particle pair doesn't fit QFT.
new sig
Had you read the abstract, you'd know that Fermilab's result is b+anti-b decay, not p+anti-p, so LHC is fine as long as they can specifically track which muons came from b quark decays.
As a matter of fact, they have a special detector just for that (it's not general-purpose, because b+anti-b pairs decay within centimetres from their creation point, so they actually drop particle tracker 5mm from the beam). See LHCb experiment.
I refuse to use
It's been known for a long time that the standard model has problems.
To continue your analogy.
The earth is flat works really well as a model. If you're in a hilly terrain, you might suspect early on that the flat earth model isn't quite right.
To find out that earth is actually a slightly disorted sphere with a radius of some 6000km means that you have to go quite far (distance wise) to realise that the errors in the flat-earth model actually add up to a coherent alternative theory - a spherical earth.
It's much like this in physics.
Saying 'the standard model is wrong' - and giving plausible arguments - doesn't give much for alternative theorists to get their teeth into.
If however, you can produce a concrete measurement that can say 'The standard model is off by 0.3% here, 0.6% here, 1.2% here, and this looks _really_ like a curve of 0.5x+x^2 in the energy/bias ratio' - this can eliminate whole classes of alternate theories.
At the moment, string theory (and the descendant fields) suffer from an embarrasment of possibilities. ...
There are people arguing that the world is flat, round, toroidal, duck-shaped,
These theories are generally internally consistent, and can only be proved wrong with measurements of the real world. Without these measurements, the theories are interesting maths that you can make a career in maths about, but not predict the world in a useful way.
This is yet another reason why you shouldn't read mainstream media to get your physics news. Just reading the article summary makes me shiver all over.
Please, there are no fireballs at a particle collider and we are many many orders of magnitude in energy away from recreating the conditions after the Big Bang.
There is no miniature universe anywhere. Nothing went from being neutral to more matter than antimatter. Given that the (anti)matter in question here are (anti)muons
that would imply violation of charge conservation, which is not what they observed. This has nothing (well almost nothing, I'll explain in a sec) to do with why there is
so much more matter than antimatter in the universe, and the Standard Model does not suggest that there should be equal amounts either. The only correct
representation of facts in there is that the paper is indeed from the D0 collaboration and it has to do with seeing 1% more muons than antimuons.
Okay, so what did they do? They looked at decays of neutral B-mesons. These are curious mesons, because they oscillate back and forth between being a ..."), in this case direct evidence of new physics beyond the ...
B and an anti-B. If you ever took quantum mechanics: The propagating energy eigenstates are |B> +/ |anti-B> while |B> and |anti-B> are eigenstates of charge-conjugation+parity (CP).
The B can decay into a mu+ (antimuon) + other stuff, the anti-B can decay into a mu- (muon) + other stuff. (In both cases the other stuff has the opposite charge, so total
charge is conserved.) They saw a 1% asymmetry in the amount of mu+ vs. mu- which means that during the oscillation back and forth they end up 1% more often in one
than the other state which means there is a matter-anti-matter asymmetry in their behavior (technically there is CP violation in the mixing). The newsworthy fact is that in
the Standard Model this particular asymmetry (CP violation in mixing) is predicted to be about 25times smaller. With the uncertainties they quote that makes a 3-sigma discrepancy
which is regarded enough to claim "evidence of something" (you need 5 sigma to claim "observation of
Standard Model, which is what particle physicists have eagerly been looking for for the last decades. Personally, I'm holding my breath until I see the same measurement
from CDF (the other experiment at Fermilab). There have been many 3-sigma descrepancies in the past
As far as the universe is concerned, today we only have matter (forget about particle colliders, the point is there are no stars or huge clouds of anti-hydrogen out there).
As the theory goes after the Big Bang there were equal amounts of matter and antimatter, which would eventually have all annihilated into radiation and we wouldn't be here.
The matter we see today is from a tiny, 1 in 10^9, asymmetry in the amount of matter vs. anti-matter that was generated dynamically by particle reactions after the Big Bang.
When the universe cooled down and all the anti-matter got annihialted the tiny excess of matter was left over, which is the matter we see today. To generate this asymmetry one
needs (among other things) CP violation. There is CP violation in the Standard Model, it's just not nearly enough (several orders of magnitude) to generate the required asymmetry in the early
universe. It is totally not straightforward what the 1% asymmetry in the B-anti-B mixing from above translates into in the early universe, although I'm quite sure people are looking at
it right as I speak. I would be very surprised if it was enough though.
Because good theories always make fundamental predictions that need to be contradicted by reality and then tweaked later in an ad-hoc fashion without ever revising their underlying principles. That's great science! Ah well, whatever gets you grants and funding right? In that case, status quo it is! We must always be openly hostile to all competing theories, refuse to publish them so they can be peer-reviewed, etc. That's progress.
In a generic sense it's a quite easy to publish a new, competing theory. That's the kind of thing most encouraged by the current peer review culture, as long as it's self consistent and matches observations.
"I zero-index my hamsters" - Willtor (147206)