Diboson at the LHC vs LEP

TL;DR

This paper demonstrates that current diboson production data at the LHC can set competitive bounds on new physics operators, comparable to LEP-1, and explores the impact of modified quark couplings on these bounds, with projections for the HL-LHC.

Contribution

It provides the first comprehensive analysis comparing LHC diboson bounds with LEP-1, including the effects of flavor assumptions and modified Z-quark couplings, and projects future sensitivities.

Findings

LHC diboson data already constrains new physics similarly to LEP-1.

Modified Z-quark couplings significantly affect anomalous gauge coupling bounds.

HL-LHC can improve bounds, but global fits are necessary for robustness.

Abstract

We use the current CMS and ATLAS data for the leptonic $pp \to WW, WZ$ channels to show that diboson production is, for a broad class of flavour models, already competitive with LEP-1 measurements for setting bounds on the dimension six operators parametrising the anomalous couplings between the quarks and the electroweak gauge bosons, at least under the assumption that any new particle is heavier than a few TeV. We also make an estimate of the HL-LHC reach with $3$ ab$^{-1}$. We comment on possible BSM interpretations of the bounds, and show the interplay with other searches for a simplified model with vector triplets. We further study the effect of modified $Z$-quark-quark couplings on the anomalous triple gauge coupling bounds. We find that their impact is already significant and that it could modify the constraints on $\delta g_{1z}$ and $\delta \kappa_\gamma$ by as much as a factor two at the end of HL-LHC ($\lambda_\gamma$ is only marginally affected), requiring a global fit to extract robust bounds. We stress the role of flavour assumptions and study explicitly flavour universal and minimal flavour violation scenarios, illustrating the differences with results obtained for universal theories.