ILD benchmark: Quartic Gauge Couplings

Abstract

The quartic gauge coupling (QGC) of the electroweak interaction can be used as a probe for physics beyond the Standard Model and has been previously measured at the Large Hadron Collider. However, to achieve sensitivity to small deviations the couplings must be measured with precision beyond the capability of a hadron collider. An electron-positron collider with center-of-mass energies in the TeV range can precisely probe the QGC and test a variety of models. The International Linear Collider is such a collider project with a possible extension to $1\,$TeV. In this note the critical reconstruction aspects of a QGC analysis in the vector boson scattering (VBS) channel of $e^+e^- \rightarrow ν\barν q\bar{q} q\bar{q}$ at $\sqrt{s}=1\,$TeV are identified for the International Large Detector. Generator level information from the event generator and simulation is used to gain access to influence of separate reconstruction effects. The separation of hadronic $WW$ and $ZZ$ decays by their invariant mass is chosen to quantify the strength of the effects. In the current simple reconstruction scheme the main obstacles are observed to be the removal of beam backgrounds, the jet clustering, and semi-leptonic decays within jets. At high center-of-mass energies of the VBS interaction jet clustering is found to no longer be a limiting factor. Points of optimizations are laid out for these aspects. In the case of semi-leptonic decays, proof-of-principal tests for corrections are performed and found to be challenging. A full analysis which includes the extraction of limits on anomalous QGCs remains open. Sensitivities similar to those achieved in generator level studies with approximated detector effects are expected.