New Type of Particle May Have Been Found
An anonymous reader writes "The LHC is out of commission, but the Tevatron collider at Fermilab is still chugging along, and may have just discovered a new type of particle that would signal new physics. New Scientist reports that the Tevatron's CDF detector has found muons that seem to have been created outside of the beam pipe that confines the protons and anti-protons being smashed together. The standard model can't explain the muons, and some speculate that 'an unknown particle with a lifetime of about 20 picoseconds was produced in the collision, traveled about 1 centimeter, through the side of the beam pipe, and then decayed into muons.' The hypothetical particle even seems to have the right mass to account for one theory of dark matter."
I just find it odd that with the introduction of a new collider this one has finally found something.
The hypothetical particle even seems to have the right mass to account for one theory of dark matter."
Not to ask the blatantly obvious, but if it's the right mass for one theory of dark matter, I can't help but wonder where they are all being produced. Given a life of 20 picoseconds, I can't imagine that there would be monstrous factories of these things all over the universe to account for the stupidly large amount of mass they are supposed to account for. How come we haven't found them before?
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I conjecture that it's the same old physics, and that we only understand it a bit better.
In order to be applicable to Dark Matter theories, the particle would need to be traveling at near light-speed for the lifetime to be long enough to matter. But if it's traveling that fast, the mass would have changed and no longer fit the theory. However, if the relative velocity is low enough for the mass to be right, it simply isn't going to last long enough to have any impact.
Besides which, I suspect further discoveries in cosmology will reduce - and eventually eliminate - any need for dark matter. Galaxy formation already got something of a re-write not too long ago, and it was galaxy formation that was one of the areas that "needed" dark matter to explain. Grabity - err, gravity - didn't seem to be sufficient in the earlier models. Other models, such as the forming of particles and any biases that might apply, have also been modified. We also know more about the distribution of new stars in a galaxy than we did back then. One can assume the dark matter theorists have redone the calculations to see how all of these different effects alter the models, but when was the last time you saw an article on such a recalculation?
Needless to say, I do not believe in dark matter. I'm willing to be convinced, if it can be shown that all these adjustments are asymptotic to values that still cannot describe what we observe to be true, or if this "dark matter" can be observed in the laboratory. But until then, it seems prudent to be skeptical once you know that the calculations used to predict dark matter were incorrect and there is no clear-cut evidence of recalculations being done with better data.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
an unknown particle with a lifetime of about 20 picoseconds was produced in the collision, traveled about 1 centimeter
That is 16000 times faster than light..!
There are several mysterious particles that aren't easily identified by the Standard Model. One in particular is the X(3872) particle, which was discovered by Japanese scientists and confirmed by other laboratories. It might be a tetraquark particle or even a meson molecule, but scientists are just guessing for now.
http://www.symmetrymagazine.org/breaking/2008/04/13/the-charming-case-of-x3872/
He who lights his taper at mine, receives light without darkening me.
1) 20 picoseconds is a half life (so it has a 50% chance of decaying every 20 picoseconds).
2) Time slows down for a fast moving particle. This was one of the first pieces of evidence for special relativity:
http://hyperphysics.phy-astr.gsu.edu/hbase/Relativ/muon.html