A measurement of the strange quark forward-backward asymmetry at the Z pole has been performed by the DELPHI Collaboration at LEP. The sbars asymmetry has been measured from the asymmetry of fast charged kaons identified using Ring Imaging CHerenkov (RICH) detectors. The kaon production asymmetry, measured in the momentum range from 10 to 18 GeV/c, has been found to be A_FB(K) = 0.044 ± 0.005 (stat.) ± 0.004 (sys.). From this value the strange quark asymmetry has been measured: A_FB(s) = 0.111 ± 0.019 (stat.) ± 0.020 (sys.). This result updates the previous measurements published by DELPHI. An analysis based on the asymmetry of high momentum Λ's has also been performed, providing a consistent value for the sbars asymmetry.
