Giles Barr

Abstract:

A measurement of the KS lifetime is presented using data recorded by the NA48 experiment at the CERN-SPS during 1998 and 1999. The KS lifetime is derived from the ratio of decay time distributions in simultaneous, collinear KS and KL beams, giving a result which is approximately independent of the detector acceptance and with reduced systematic errors. The result obtained is τS = (0.89598 ± 0.00048 ± 0.00051) × 10-10 s, where the first error is statistical and the second systematic. © 2002 Published by Elsevier Science B.V.

Abstract:

The decay rate of KL → π⁰ γγ has been measured with the NA48 detector at the CERN SPS. A total of 2558 KL π⁰γγ candidates have been observed with a residual background of 3.2%. The branching ratio is determined to be (1.36 ± 0.03(stat) ± 0.03(syst) ± 0.03(norm)) × 10^-6 and the vector coupling constant av = -0.46 ± 0.03(stat) ± 0.04(syst). This result suggests that the CP-violation effects are dominating in the KL → π⁰e⁺e^- decay. An upper limit for the KL → π⁰γγ decay rate in the two photon mass region mγγ < mπ0 is also given. © 2002 Published by Elsevier Science B.V.

Abstract:

New measurements of the η and K⁰ masses have been performed using decays to 3π⁰ with the NA48 detector at the CERN SPS. Using symmetric decays to reduce systematic effects, the results M(η) = 547.843 ± 0.051 MeV/c² and M(K⁰) = 497.625 ± 0.031 MeV/c² were obtained. © 2002 Elsevier Science B.V. All rights reserved.

Abstract:

The origin and source of CP violation in fundamental fermion interactions was discussed. The CP violation in Lepton decay was analyzed in the context of a model where the CP symmetry was broken. No evidence of violation was found in lepton decays into the final state. Limits on the imaginary part of the coupling constant were provided describing a relative contribution of the CP violating processes with respect to the standard model. Systematic errors were estimated in order to estimate the limits on CP violating parameter.