Saturday, December 26, 2009

Parity Invariance

The Mystery of Parity
"And should I not take pity on Nineveh, that great city, with more than a hundred and twenty thousand inhabitants who do not know their right hand from their left, and many beasts besides?" [Jonah 4:11]
In this article we shall be concerned with microscopic parity invariance and a mystery which it presents. This consists of a marriage of internal and space-time symmetries, forbidden when the space-time symmetry consists of the whole Poincare group but permitted in this case because of the discrete nature of the parity transformation. We will argue that this marriage could point to regularities underlying the nature of quarks and leptons, and to extensions of particle interactions beyond those known today.

time reversal invariance violation

Large scale physical effects of T violation in mesons
An increasing number of experiments at the Belle, BNL, CERN and SLAC accelerators are confirming the violation of time reversal invariance (T). The violation signifies a fundamental asymmetry between the past and future and calls for a major shift in the way we think about time. Here we show that processes which violate T symmetry induce destructive interference between different paths that the universe can take through time. The interference eliminates all paths except for two that represent continuously forwards and continuously backwards time evolution. Evidence from the accelerator experiments indicates which path the universe is effectively following. This work resolves the long-standing problem of modeling the dynamics of T violation processes. It shows that T violation has previously unknown, large-scale physical effects and that these effects underlie the origin of the unidirectionality of time. It also provides a view of the quantum nature of time itself.

Missing Baryons

The Baryon Content of Cosmic Structures
We make an inventory of the baryonic and gravitating mass in structures ranging from the smallest galaxies to rich clusters of galaxies. We find that the fraction of baryons converted to stars reaches a maximum between M500 = 1E12 and 1E13 Msun, suggesting that star formation is most efficient in bright galaxies in groups. The fraction of baryons detected in all forms deviates monotonically from the cosmic baryon fraction as a function of mass. On the largest scales of clusters, most of the expected baryons are detected, while in the smallest dwarf galaxies, fewer than 1% are detected. Where these missing baryons reside is unclear.

Flavor Physics

Brief Introduction to Flavor Physics
We consider the standard model (SM) quark flavor sector. We study its structure in a spurionic, symmetry oriented approach. The SM picture of flavor and CP violation is now experimentally verified, hence strong bounds on beyond the SM flavor structure follow. We show how to parametrically derive such bounds, in a model independent manner, via minimal flavor violation power counting. This min-review summarizes lectures given at the ISSCSMB '08 international school. It aims to give basic tools to understand how flavor and CP violation occur in the SM and its extensions. It should be particularly useful for non-expert students who have mastered other aspects of the SM dynamics.

Note: A spurion is the name given to a "particle" inserted mathematically into an isospin-violating decay in order to analyze it as though it conserved isospin. --- Wikipedia