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January 29, 2006
Particle Physics on Ice: Constraints on Neutrino Interactions Far above the Weak Scale
Abstract: Ultrahigh energy cosmic rays and neutrinos probe energies far above the weak scale. Their usefulness might appear to be limited by astrophysical uncertainties; however, by simultaneously considering up- and down-going events, one may disentangle particle physics from astrophysics. We show that present data from the AMANDA experiment in the South Pole ice already imply an upper bound on neutrino cross sections at energy scales that will likely never be probed at man-made accelerators. The existing data also place an upper limit on the neutrino flux valid for any neutrino cross section. In the future, similar analyses of IceCube data will constrain neutrino properties and fluxes at the (10%) level.
Comments from PhysOrg.Com explain.
PhysOrg notes that the current detector has registered about a dozen neutrino events.
PhysOrg.Com provides the following description
In recent decades, new theories have developed – such as string theory, extra dimensions and supersymmetry – to bridge the gap between the two most successful theories of the 20th century, general relativity and quantum mechanics. Quantum mechanics describes three of the fundamental forces of nature: electromagnetism, strong forces (binding atomic nuclei) and weak forces (seen in radioactivity). It is, however, incompatible with Einstein's general relativity, the leading description of the fourth force, gravity. Scientists hope to find one unified theory to provide a quantum description of all four forces.
Clues to unification, scientists say, lie at extreme energies. On Earth, human-made particle accelerators have already produced energies at which electromagnetic forces and weak forces are indistinguishable. Scientists have ideas about how the next generation of accelerators will reveal that strong forces are indistinguishable from the weak and electromagnetic at yet higher energies. Yet to probe deeper to see gravity's connection to the other three forces, still higher energies are needed.
Anchordoqui and his colleagues say that extragalactic sources can serve as the ultimate cosmic accelerator, and that neutrinos from these sources smacking into protons can release energies in the realm where the first clues to string theory could be revealed.
Neutrinos are elementary particles similar to electrons, but they are far less massive, have neutral charge, and hardly interact with matter. They are among the most abundant particles in the universe; untold billions pass through our bodies every second. Most of the neutrinos reaching Earth are lower-energy particles from the sun.
Source: South Pole Neutrino Detector Could Yield Evidences of String Theory, Physics : January 26, 2006. http://physorg.com/news10295.html
Original article: Particle Physics on Ice: Constraints on Neutrino Interactions Far above the Weak Scale
Luis A. Anchordoqui,(1) Jonathan L. Feng,(2) and Haim Goldberg(1)
(1) Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA
(2) Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
Physics Letters, January 20, 2006.
URL: http://link.aps.org/abstract/PRL/v96/e021101
Posted by sjc at January 29, 2006 6:39 AM
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