Measurement of the $p arp o WZ _s16 X$ cross-section at $sqrts$ = 1.96-TeV and limits on WWZ trilinear gauge couplings

Abstract

We present measurements of the process $pbar{p} to WZ_s16X to ell^{prime} nu_{ell^{prime}} ell bar{ell}$ at $sqrt{s}=1.96$ TeV, where $ell$ and $ell^{prime}$ are electrons or muons. Using 1 fb$^{-1}$ of data from the D0 experiment, we observe 13 candidates with an expected background of $4.5pm0.6$ events and measure a cross section $sigma(WZ)=2.7^{_s161.7}_{-1.3}$ pb. From the number of observed events and the $Z$ boson transverse momentum distribution, we limit the trilinear $WWZ$ gauge couplings to $-0.17 le lambda_Z le 0.21$ $(Delta kappa_Z = 0)$ at the 95% C.L. for a form factor scale $Lambda=2$ TeV. Further, assuming that $Delta g^Z_1 = Deltakappa_Z$, we find $-0.12 le Deltakappa_Z le 0.29$ $(lambda_Z=0)$ at the 95% C.L. These are the most restrictive limits on the $WWZ$ couplings available to date.