D - charmed mesons



After charmionium, another class of interesting charmed mesons are those mixed with "ligher", like u or s quarks 
An experiment run in Fermilab aims to validate or not the Standard Model of elementary particles, and also check other phenomena, like CP parity violation.

Ds+ and Do  have unique  non-spectator decays
d-charm d-charm

The experiment is called FOCUS and run at Fermilab
High energy photon beam (~300 GeV) impinges on beryllium oxide target, producing the charm quarks by “fusing” with a gluon in the target
Theory predicts: the lifetime ratio (Ds+) /(Do) =1.07-1.20

The preliminary experimental result is:  (Ds+) /(Do) = 1.214 ± 0.017

i.e. within the error bar in agreement with the Standard Model Theory !



[the final comment by GK, based on http://lexus.physics.indiana.edu/~focus/project/pptfiles/iu_focus_intro.ppt,  document, as read in 01/02/2004]            

see more details at:

Introduction to the FOCUS Experiment 

for the full document see:
http://lexus.physics.indiana.edu/~focus/project/pptfiles/iu_focus_intro.ppt