Type: Article
Publication Date: 1995-11-01
Citations: 25
DOI: https://doi.org/10.1103/physrevd.52.4929
We show from general principles that there must be a center-of-mass energy \ensuremath{\surd}${\mathit{s}}_{0}$ where the polarization asymmetry A=\ensuremath{\Delta}\ensuremath{\sigma}(\ensuremath{\gamma}e\ensuremath{\rightarrow}W\ensuremath{\nu})/\ensuremath{\sigma}(\ensuremath{\gamma}e\ensuremath{\rightarrow}W\ensuremath{\nu}) for circularly polarized photon and electron beams vanishes. In the case of the standard model, the crossing point where the asymmetry changes sign occurs in Born approximation at \ensuremath{\surd}${\mathit{s}}_{\ensuremath{\gamma}\mathit{e}}$ =3.1583. . .${\mathit{M}}_{\mathit{W}}$\ensuremath{\simeq}254 GeV. We demonstrate the sensitivity of the position of the polarization asymmetry zero to modifications of the SM trilinear \ensuremath{\gamma}WW coupling. Given reasonable assumptions for the luminosity and energy range for the Next Linear Collider with a backscattered laser beam, we show that the zero point, \ensuremath{\surd}${\mathit{s}}_{0}$ , of the polarization asymmetry may be determined with sufficient precision to constrain the anomalous couplings of the W to better than the 1% level at 95% C.L. In addition to the fact that only a limited range of energy is required, the polarization asymmetry measurements have the important advantage that many of the systematic errors cancel in taking cross section ratios. The position of the zero thus provides an additional weapon in the arsenal used to probe anomalous trilinear gauge couplings.