Search for the Rare Radiative Decay: $W\rightarrow\pi\gamma$ in \ppbar\ Collisions at $\sqrt{s} = 1.96$ TeV

TL;DR

This paper reports a search for the rare decay W→πγ in proton-antiproton collisions at 1.96 TeV, setting a new upper limit on its branching fraction due to no significant signal being observed.

Contribution

First search for the W→πγ decay in proton-antiproton collisions, providing the most stringent upper limit to date on its branching fraction.

Findings

No significant signal observed for W→πγ decay.

Set a 95% confidence level upper limit of 6.4×10⁻⁵ on the branching ratio.

Improved the previous limit by a factor of 10.

Abstract

We present a search for the rare radiative decay \wpigamma\ using data corresponding to an integrated luminosity of 4.3 \invfb\ of proton-antiproton collisions at a center of mass energy of 1.96 TeV collected by the CDF experiment at Fermilab. As no statistically significant signal is observed, we set a 95% confidence level upper limit on the relative branching fraction \bratio\ at $6.4\times 10^{-5}$, a factor of 10 improvement over the previous limit.