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DrRocket
2010-May-19, 07:51 PM
http://www.fnal.gov/pub/presspass/press_releases/CP-violation-20100518.html

This could become very interesting.

Jens
2010-May-20, 05:45 AM
I don't know if this interpretation is correct, but my feeling is this: the fact that we exist implies that this finding would be made, even if it goes against the standard model. So it was probably expected. So the challenge is just to discover why this happens if the standard model says it shouldn't. If the standard model included a prediction that would make it impossible for us to exist, then clearly there was something wrong. Does this make sense, or am I over-interpreting?

Ken G
2010-May-20, 06:38 AM
This does seem like an extremely important result. However, the article stopped short of saying that the degree of CP violation is what you would need to explain the predominance of matter in our universe. Apparently, you can have either too much or too little CP violation, and you'll have a problem explaining the cosmological results. What is needed is an analysis of whether this resolves the longstanding question of why we live in a universe of matter, or if it just opens up more puzzles. One thing seems clear: the cracks in the Standard Model have opened into chasms. Since this result was already hinted at, theorists must have already begun trying to fix up the Standard Model to account for CP violation at this scale (previous CP violations were quite small, but have led to Nobel prizes in the past).

What's also interesting is that DZero is at Fermilab-- not CERN. The tevatron at Fermilab has a much higher flux of particles, so can see smaller effects than can CERN, even though they can't get up to as high energies. It's likely that CERN will be looking for this too, and may feel a little scooped.

Ken G
2010-May-20, 06:44 AM
I don't know if this interpretation is correct, but my feeling is this: the fact that we exist implies that this finding would be made, even if it goes against the standard model.That seems a reasonable interpretation-- the standard model couldn't explain why we are here, in this predominantly matter universe, so there was probably something wrong with it. By the way, there is a related problem in QCD, but it's kind of the opposite-- QCD looks like it should show lots of CP violation, way more than is actually seen. So either QCD is finely tuned to get just the right amount of CP violation that we need to be here, or else the basic physics underlying the standard model already had a big problem.

DrRocket
2010-May-20, 06:48 AM
This does seem like an extremely important result. However, the article stopped short of saying that the degree of CP violation is what you would need to explain the predominance of matter in our universe. Apparently, you can have either too much or too little CP violation, and you'll have a problem explaining the cosmological results. What is needed is an analysis of whether this resolves the longstanding question of why we live in a universe of matter, or if it just opens up more puzzles. One thing seems clear: the cracks in the Standard Model have opened into chasms. Since this result was already hinted at, theorists must have already begun trying to fix up the Standard Model to account for CP violation at this scale (previous CP violations were quite small, but have led to Nobel prizes in the past).

Yes, that is the point.

It is not a surprise that the universe is mostly ordinary matter. We knew that. For instance I touched the keyboard and did not produce a mushroom cloud. The issue is that the models don't really explain the asymmetry very well. This is a result from a controlled experiment that is not consistent with the model, and therefore ought to help in guiding the development of a better model.

We need something better than the Standard Model, which is really rather ad hoc despite its success. This could be a big help. A little bit of experimental data can go a long way, and experimental support to guide the development of theory has been lacking. There are just too many aesthetically pleasing possibilities. An anchor in reality is needed.

Jens
2010-May-20, 07:35 AM
For instance I touched the keyboard and did not produce a mushroom cloud.

Actually I'm guessing you might have, but that the spores were probably too small to be seen.

trinitree88
2010-May-20, 04:01 PM
As muons eventually decay to electrons, what we also need is a matching asymmetry in production of quarks over anti-quarks, notably in both up and down quark production. For every proton we need an electron for hydrogen to form, but the proton requires two ups and a down. So we need twice the asymmetry in up production as downs to begin with a universe of hot hydrogen, and the ratios need to be perfectly matched to the electron production. So far nothing like that is seen . That's going to require some tricky maneuvering in the Tevatron or the LHC.

What'd really be exciting is to see a muon, and a proton appear out of a jet, violating baryon number and lepton number conservation simultaneously. The muonic hydrogen will decay shortly to normal protium. That has never been seen in cosmic ray emulsions, any of the bubble chambers, spark chambers, wire chambers, or any particle physics lab anywhere. What is seen is conservation laws operating. I'd be interested to see if they screened for gamma rays....the antimuon, like the muon in fusion catalysis, can interact in the nucleus, too, and may be disappearing there.

slang
2010-May-20, 04:18 PM
What is the flux difference between LHC and Tevatron?

GOURDHEAD
2010-May-20, 04:36 PM
Could the results of the linked experiment have arisen from a simple detection error?

Ken G
2010-May-20, 08:36 PM
What is the flux difference between LHC and Tevatron?
Very big at the moment-- I don't recall, maybe a factor of a million. The LHC is not really working to specs yet, for one thing.

trinitree88
2010-May-20, 11:22 PM
Very big at the moment-- I don't recall, maybe a factor of a million. The LHC is not really working to specs yet, for one thing.

Ken G. Fermilab runs at ~ 8 Gev...8 billion electron volts, with a head on collision yielding ~ twice that. SEE:http://www.fnal.gov/pub/science/accelerator/
The LHC's design energy is ~ 7 Tev ...7 trillion electron volts, with a head on collision yielding ~ twice that. So the ratio is about a factor of a thousand. SEE:
Neither machine approaches the energy of cosmic rays

trinitree88
2010-May-20, 11:25 PM
Ken G. Fermilab runs at ~ 8 Gev...8 billion electron volts, with a head on collision yielding ~ twice that. SEE:http://www.fnal.gov/pub/science/accelerator/
The LHC's design energy is ~ 7 Tev ...7 trillion electron volts, with a head on collision yielding ~ twice that. So the ratio is about a factor of a thousand. SEE:http://public.web.cern.ch/public/en/lhc/Facts-en.html
Neither machine approaches the energy of cosmic rays
SEE:http://en.wikipedia.org/wiki/Ultra-high-energy_cosmic_ray ...which at ~ 1020 ev is ~ 100,000,000,000 times more energetic. Despite their sporadic appearance, they may ultimately supply the missing information for some of our mysteries of matter asymmetry and non-Standard Model physics. pete

cjl
2010-May-21, 02:04 AM
Ken G. Fermilab runs at ~ 8 Gev...8 billion electron volts, with a head on collision yielding ~ twice that. SEE:http://www.fnal.gov/pub/science/accelerator/
The LHC's design energy is ~ 7 Tev ...7 trillion electron volts, with a head on collision yielding ~ twice that. So the ratio is about a factor of a thousand. SEE:
Neither machine approaches the energy of cosmic rays

The tevatron definitely runs higher than 8GeV. It's named the tevatron because it hit a trillion eV. Specifically, it hit 980GeV in each direction, with head on collisions at 1.96 TeV. The LHC is only around 7x more powerful than the tevatron, but that's not what was asked if I'm reading the question correctly. The question was about flux, not energy.

Ken G
2010-May-21, 02:22 AM
Right-- LHC gives you a significant energy increase, but it's not even a factor of 10. Right now it is mostly the flux that distinguishes them, which is way way higher for the tevatron. So anything that can happen at < 2 TeV is going to come from Fermilab, not CERN. However, if there are important processes that need more like 10 TeV, then it will be CERN that finds them-- if they can get their machine firing on all cylinders, as it were.

slang
2010-May-21, 09:17 AM
[..] but that's not what was asked if I'm reading the question correctly. The question was about flux, not energy.

You (and Ken) read it correctly. Thanks.

trinitree88
2010-May-21, 01:25 PM
You (and Ken) read it correctly. Thanks.

Yep. CJL's post correctly gives the scoop. my bad, I thought the reference was low on energy, too and that Fermilab had achieved a much higher energy. Somebody should update their stats, and I should've double checked. pete

Ken G
2010-May-21, 06:28 PM
I believe Fermilab is currently running at about 2 TeV per collision, and CERN is running at 3.5 TeV per collision, but with far fewer collisions. I read somewhere that CERN also has a plan to accelerate lead nuclei, which would be at far greater energies given the higher charge of lead nuclei, but I don't know what their current plans are in that direction. Apparently, they are still a bit hesitant to scale up to their full proton-antiproton energy of 7 TeV, for fear of a breakdown, and I guess they just want to see what can happen at 3.5 TeV for the time being.

trinitree88
2010-May-21, 09:43 PM
As I've said before. An asymmetry in meson production ,this time muons, before, B mesons, proves nothing with regards to an asymmetry in baryon production. That remains to be seen. What has historically been seen in all the trillions of collisions measured, is a statistically near perfect symmetry between baryons and anti-baryons (there are no perfect data sets of anything). You see a vertex at a collision point, and from it spring a pair of proton/antiprotons or neutron/antineutrons. It's what made the IMB search for proton decay so interesting. Had they found evidence of the purported X particle....the leptoquark boson....in proton decay in water Cherenkov detectors, then we would have a clear indication of the origin of matter over antimatter. To the limits of ~ 10 31 years, it's unfortunately evidently stable, leaving us other avenues to search. pete

such as SEE:http://www-cdf.fnal.gov/physics/talks_transp/2009/safonov_dis2009.pdf

DrRocket
2010-May-22, 03:21 AM
Yep. CJL's post correctly gives the scoop. my bad, I thought the reference was low on energy, too and that Fermilab had achieved a much higher energy. Somebody should update their stats, and I should've double checked. pete

If that is the biggest mistake that you have made today, you're doing alright.

mugaliens
2010-May-24, 10:11 AM
The tevatron definitely runs higher than 8GeV. It's named the tevatron because it hit a trillion eV. Specifically, it hit 980GeV in each direction, with head on collisions at 1.96 TeV. The LHC is only around 7x more powerful than the tevatron, but that's not what was asked if I'm reading the question correctly. The question was about flux, not energy.

Wow! You've grown over the last five years.

Nice to see. One of these days (you're just up the freakin' road), we'll have to have b/l/d. Your choice. I'll by, but it'll have to be here in the Springs if I'm buying.

Ah, well...