The hypothetical "X" particle recently suggested as a dark matter candidate by scientists at Brookhaven isn't the only exotic particle that physicists have proposed in recent years.
In fact, Fermilab's CMS collaboration has an "exotica hotline" staffed by about 10 physicists who review the previous day's collisions looking for anything that might break the rules or expectations of the Standard Model. And with its unprecedented energies, the Large Hadron Collider is hot on Fermilab's heels. It could turn up some exciting new physics, too: mini black holes, large extra dimensions, and a host of exotic subatomic particles, just to name a few.
Here's a sampling of some of the weirder hypothetical particles that could turn up at the LHC:
Squarks and Sleptons: Supersymmetry (SUSY) attempts to go beyond the Standard Model to help correct some of its shortcomings: namely, that the Standard Model's calculations for the masses of certain particles predict far heavier masses than found in nature.
SUSY addresses this by predicting a host of mirror particles (superpartners, or shadow particles) that match up with the various known regular particles: for instance, quarks and leptons pair up with squarks and sleptons. It's like Bizarro World for subatomic particles.
SLIDE SHOW: Top 5 Misconceptions About The LHC
We don't see superpartners around us today, but the theory goes that they dominated during the earliest stages of the universe, just after the inflationary period. And since the LHC is designed to recreate conditions in the early universe, physicists hope to see evidence of squarks and sleptons in the fallout from those collisions.
CHAMPs: Short for CHArged Massive stable Particles, this is a type of long-lived, very heavy particle also predicted by supersymmetry theory. Fermilab's DZero collaboration has been searching for signs of CHAMPs, thus far with no success.
They are expected to have an unusual decay signature, and a strong one, since they decay much more slowly than many subatomic particles. But they could also be easily mistaken for the far more common muon.
The most recent data indicates that the proposed supersymmetric partner of the top quark (dubbed a "stop") must have a mass greater than 249 GeV, and has some limits as to how it can interact with other particles. It's helped physicists rule out certain supersymmetry models that predict otherwise. But finding an honest-to-goodness CHAMP signature would be very exciting, indeed.
String Balls: Stringballs would probably look a lot like mini-black holes, except for an unusually wide range of possible decay patterns. That's understandable, because the idea behind string balls is that they start with a black hole that evaporates away due to Hawking radiation.
ANALYSIS: Man-Made (But Very Tiny) Black Holes Possible
Enter string theory, which suggests that if such a black hole gets small enough -- and we're talking very tiny, indeed -- it will turn into a "highly excited vibrating string state" and then disintegrate into radiation.
It's possible those telltale jets of radiation, shooting in every direction, would be detectable by the LHC. Oh, and if the LHC does find evidence for stringballs, this would also provide support for extra dimensions.
SUSY Q Balls: Remember those squarks and sleptons predicted by SUSY? Several years ago, a physicist at UCLA named Alexander Kusenko suggested that this early "sea" of squarks and sleptons would show tiny ripples, or variations in density, and this would likely lead to clumping.
If those clumps grew large enough, you'd have a Q ball on your hands: a teensy blob of exotic matter roaming the universe in search of regular matter to assimilate.
Q balls are speedy, zipping through a planet or star like our Sun in less than four minutes. (Kusenko likens it to "a bullet passing through a cloud of vapor.") And if it runs into a neutron star? The Q-ball will slowly eat its heart out (very slowly, over millions or billions of years), because it finds neutrons so very tasty.
If Q balls did form in the early universe, they should still be lurking around somewhere. We just have to figure out how to spot them.
Image credits: CERN, ATLAS, iStockPhoto
Tags: Cosmology, Large Hadron Collider, Particle Physics, Physics, Quantum Physics
comments ( )