Probing anomalous $WW\gamma$ Triple Gauge Bosons Coupling at LHeC

TL;DR

This paper explores how the future LHeC collider can precisely measure the $WW\gamma$ vertex, using novel angular and polarization analyses to improve constraints on anomalous gauge couplings beyond current collider capabilities.

Contribution

It proposes new measurement channels and analysis methods at LHeC to enhance sensitivity to anomalous $WW\gamma$ couplings, surpassing existing experimental limits.

Findings

Potential to constrain $\lambda_{\gamma}$ and $\Delta\kappa_{\gamma}$ to the order of 10^{-3} with 2-3 ab$^{-1}$ data.

Angular variable analysis enhances sensitivity to anomalous couplings.

Full reconstruction of $W$ polarization provides additional probing capability.

Abstract

The precision measurement of the $WW\gamma$ vertex at the future Large Hadron electron Collider (LHeC) at CERN is discussed in this paper. We propose to measure this vertex in the $e^{-} p\to e^{-}W^{\pm}j$ channel as a complement to the conventional charged current $\nu_{e}\gamma j$ channel. In addition to the cross section measurement, $\chi^{2}$ method studies of angular variables provide powerful tools to probe the anomalous structure of triple gauge boson couplings. We study the distribution of the well-known azimuthal angle between the final state forward electron and jet in this vector-boson fusion (VBF) process. On the other hand, full reconstruction of leptonic $W$ decay opens a new opportunity to measure $W$ polarization that is also sensitive to the anomalous triple gauge boson couplings. Taking into consideration the superior determination of parton distribution functions~(PDFs) based on future LHeC data, the constraints of $\lambda_{\gamma}$ and $\Delta\kappa_{\gamma}$ might reach up to $\mathcal{O}(10^{-3})$ level in the most ideal case with the 2--3~ab$^{-1}$ data set, which shows a potential advantage compared to those from LHC and LEP data.