Hit-and-run

March 22, 2006

hep-ex/0603035 reports on the CDF Run I limits on large extra dimensions, in searches for high-energy diphoton and dielectron events. The production channel is via a virtual graviton. These analyses were, as far as I can tell, the Ph.D. theses of Simona Murgia and John Carlson. I have no idea why this paper is being posted now, and why it doesn’t have a full CDF author list on it. I don’t know if the analyses were ever made final (certainly, unlike DØ’s version, it doesn’t seem that the analyses were published before).

hep-ex/0603041 is a new measurement of the branching fraction of KL → π+ π from the KLOE experiment. This is the famous decay that established CP violation in the kaon system, since a pure CP-odd scalar is forbidden from decaying to two pions. The KTeV experiment fairly recently redetermined the branching fractions of the major KL decays, and their B(KL → π+ π) disagreed strongly with the PDG fit central value. The new KLOE result agrees with KTeV.

An aside: I find KLOE rather neat because it has similarities to CLEO, and not just from similar-sounding names. KLOE uses φ mesons produced in electron-positron collisions from the DAΦNE accelerator, which decays to pairs of kaons in a way very analogous to how we at CLEO use ψ” decays to pairs of charmed mesons. Neutral kaons are always produced as a KS KL pair, which allows tagging techniques to be used on the KL. Because the φ basically just falls apart, there is a good chance the KL will decay within the detector, with a displaced vertex. This event display shows a candidate CP-violating event.

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