Measurement of the $WW+WZ$ cross section and limits on anomalous triple gauge couplings using final states with one lepton, missing transverse momentum, and two jets with the ATLAS detector at $\sqrt{\mathrm{s}}=7$ TeV

The production of a $W$ boson decaying to $e\nu$ or $\mu \nu$ in association with a $W$ or $Z$ boson decaying to two jets is studied using $4.6 $\mathrm{f}\mathrm{b}$^{-1}$ofproton--protoncollisiondataat$\sqrt{\rm{s}} = 7$ TeV recorded with the ATLAS detector at the LHC. The combined $WW+WZ$ cross section is measured with a significance of 3.4$\sigma$ and is found to be $68 \pm 7
$(\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}\mathrm{.})$ \pm 19 \ $(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{.})$ \ pb$, in agreement with the Standard Model expectation of $61.1\pm 2.2\mathrm{p}\mathrm{b}$. The distribution of the transverse momentum of the dijet system is used to set limits on anomalous contributions to the triple gauge coupling vertices and on parameters of an effective-field-theory model.