Search for New Physics in $\mathrm{\text{Lepton}}+\mathrm{\text{Photon}}+X$ Events with $305{\mathrm{pb}}^{-1}$ of $p\overline{p}$ Collisions at $\sqrt{s}=1.96\mathrm{TeV}$

We present results of a search for anomalous production of events containing a charged lepton ($\ell$, either $e$ or $\mu$) and a photon ($\gamma$), both with high transverse momentum, accompanied by additional signatures $X$, including missing transverse energy (${\mathrm{E̸}}_T$) and additional leptons and photons. We use the same selection criteria as in a previous CDF search but with a substantially larger data set, $305\mathrm{p}{\mathrm{b}}^{-1}$, a $p\overline{p}$ collision energy of 1.96 TeV, and the CDF II detector. We find 42 $\ell \gamma {\mathrm{E̸}}_T$ events versus an expectation of $37.3\pm 5.4$ events. We observe 31 $\ell \ell \gamma +X$ events versus an expectation of $23.0\pm 2.7$ events. We find no events similar to the run I $ee\gamma \gamma {\mathrm{E̸}}_T$ event.

Figure 1

The distributions for events in the $\ell \gamma {\mathrm{E̸}}_T$ sample (points) in (a) the ${\mathrm{E̸}}_T$ of the photon; (b) the $E_T$ of the lepton; (c) the missing transverse energy ${\mathrm{E̸}}_T$; and (d) the transverse mass of the $\ell \gamma {\mathrm{E̸}}_T$ system. The histograms show the expected SM contributions, including estimated backgrounds from misidentified photons and leptons.

Figure 2

The distributions for events in the $\ell \ell \gamma$ sample (points) in (a) the $E_T$ of the photon; (b) the $E_T$ of the leptons (two entries per event); (c) the 2-body mass of the dilepton system; and (d) the 3-body mass $m_{\ell \ell \gamma }$. The histograms show the expected SM contributions.

Figure 3

The distributions in missing transverse energy ${\mathrm{E̸}}_T$ observed in the inclusive search for (a) $\mu \mu \gamma$ events and (b) $ee\gamma$ events. The histograms show the expected SM contributions.