R. Mitchell

Observation of a 1750 MeV/c2 state in the peripheral photoproduction of K+K−

Abstract The FOCUS collaboration of Fermilab has observed a clear enhancement at a mass of 1750 MeV/c2 in the exclusive photoproduction of K+K−. The data were obtained using a photon beam with energies from 20 to 160 GeV incident on a BeO target. Mass and width measurements are presented, as well as a search in K ∗ K . This enhancement has not yet been correctly interpreted.

Search for CP Violation in the decays [Formula presented] and [Formula presented]

A high statistics sample of photo-produced charm from the FOCUS(E831) experiment at Fermilab has been used to search for direct CP violation in the decays D+->K_S pi+ and D+ ->K_S K+. We have measured the following asymmetry parameters relative to D+->K-pi+pi+: A_CP(K_S pi+) = (-1.6 +/- 1.5 +/- 0.9)%, A_CP(K_S K+) = (+6.9 +/- 6.0 +/- 1.5)% and A_CP(K_S K+) = (+7.1 +/- 6.1 +/- 1.2)% relative to D+->K_S pi+. The first errors quoted are statistical and the second are systematic. We also measure the relative branching ratios: \Gamma(D+->\bar{K0}pi+)/\Gamma(D+->K-pi+pi+) = (30.60 +/- 0.46 +/- 0.32)%, \Gamma(D+->\bar{K0}K+)/\Gamma(D+->K-pi+pi+) = (6.04 +/- 0.35 +/- 0.30)% and \Gamma(D+->\bar{K0}K+)/\Gamma(D+->\bar{K0}pi+) = (19.96 +/- 1.19 +/- 0.96)%.