Friday, September 28, 2007

Unknown Symmetry in Mesons?

Towards understanding broad degeneracy in non-strange mesons
Authors: S.S. Afonin
Abstract: The spectroscopic regularities of modern empirical data on the non-strange mesons up to 2.4 GeV can be summarized as a systematic clustering of states near certain values of energy. It is getting evident that some unknown X-symmetry triggers the phenomenon. We review the experimental status of this symmetry and recent theoretical attempts put forward for explanation of broad degeneracy.


By the way, a meson is a strongly interacting particle composed of a quark-antiquark pair.

A bright millisecond radio burst of extragalactic origin

D. R. Lorimer, M. Bailes, M. A. McLaughlin, D. J. Narkevic, F. Crawford
(Submitted on 27 Sep 2007)
Abstract: Pulsar surveys offer one of the few opportunities to monitor even a small fraction (~0.00001) of the radio sky for impulsive burst-like events with millisecond durations. In analysis of archival survey data, we have discovered a 30-Jy dispersed burst of duration <5 ms located three degrees from the Small Magellanic Cloud. The burst properties argue against a physical association with our Galaxy or the Small Magellanic Cloud. Current models for the free electron content in the Universe imply a distance to the burst of <1 Gpc No further bursts are seen in 90-hr of additional observations, implying that it was a singular event such as a supernova or coalescence of relativistic objects. Hundreds of similar events could occur every day and act as insightful cosmological probes.

A bright millisecond radio burst of extragalactic origin

A pulsar is thought to be a rotating neutron star.

The Small Magellanic Cloud is a satellite galaxy of our Milky Way, it's visible in the Southern Hemisphere.

The Sun is Peculiarly Deficient in Lithium

According to the preprint below, the sun has a strangely low amount of Lithium.

"For example, the depletion in the
observed solar Li abundance by about a factor of 200
relative to that found in meteorites is not explained by
standard stellar evolution models. Since more physically
realistic models, calculated from basic principles, cannot
be computed yet, non-standard stellar evolution models
have to introduce free parameters to reproduce the ob-
served Li depletion"

"The Sun appears to be lithium-poor by a factor of 10 com-
pared to similar solar type disk stars"

HIP 56948: A Solar Twin With a Low Lithium Abundance

Sun's 'twin' an ideal hunting ground for alien life in New Scientist.