Probing $WW\gamma$ coupling through $e^{-}\gamma \to {\nu }_e{W}^{-}$ at ILC

Abstract

The anomalous $WW\gamma$ coupling is probed through $e\gamma \to \nu W$ at the ILC. With a spectacular single lepton final state, this process is well suited to study the above coupling. Cross section measurements can probe $\delta {\kappa }_{\gamma }$ to about $\pm 0.004$ for a luminosity of 100 fb${}^{-1}$ at $500$ GeV center-of-mass energy with unpolarized electron beam. The limits derivable on ${\lambda }_{\gamma }$ from the total cross section are comparatively more relaxed. Exploiting the energy-angle double distribution of the secondary muons, kinematic regions sensitive to these couplings are identified. The derivable limit on ${\lambda }_{\gamma }<0$ could be improved to a few per-mil, focusing on such regions. More importantly, the angular distributions at fixed energy values, and energy distribution at fixed angles present very interesting possibility of distinguishing the case of ${\lambda }_{\gamma }<0$ and ${\lambda }_{\gamma }\ge 0$.

Comments: 16 page, 11 figure, pdflatex (revtex4). previous conf version: arXiv:1103.4036