Measurements of luminosity and leptonic partial widths of the Z(0) boson at Mark II/SLC.

Abstract

A luminosity measurement using the Small Angle Monitor (SAM) at Mark II/SLC is presented. The method using both the tracking and the calorimeter sections gives the integrated luminosity of 19.71 $\pm$ 0.88 nb$\sp{-1}$. The previous method using only the calorimeter section results in the integrated luminosity of 19.82 $\pm$ 0.97 nb$\sp{-1}$. This improvement is expected to be bigger with more data. We also extract leptonic partial widths of the $Z\sp\circ$ boson using a maximum likelihood method and an analytical form of the cross section which takes into account higher than first-order initial-state radiation effects. Assuming the universality of leptons, we obtain the leptonic partial width of 91$\sbsp{-7}{+7}$ MeV with 56 lepton events. This result agrees with the Standard Model prediction of 83.3 MeV and with more measurements from LEP which give an average of 83.2 $\pm$ 1.2 MeV.