KTeV Results: Re($ε' / ε$) and Rare Decay Results

Abstract

The KTeV physics program encompasses many goals including a precision measurement of the direct CP violation parameter Re($ε' / ε$) in $K \to ππ$ decays, and studies of rare neutral kaon decays. The KTeV detector collected data during the Fermilab fixed-targed runs of 1996-97 and 1999. This article focuses on the precision measurement of the direct CP violation parameter Re($ε' / ε$) using the 1996-97 data set. In addition, measurements of the neutral kaon parameters $τ_S$, $Δm$, $ϕ_{+-}$, $Δϕ$ from that data set and a new measurement of the branching fraction of $K_L \to e^+ e^- μ^+ μ^-$ from the 1997 and 1999 data also are presented.