Search for anomalous production of diphoton events with missing transverse energy at CDF and limits on gauge-mediated supersymmetry-breaking models

We present the results of a search for anomalous production of diphoton events with large missing transverse energy using the Collider Detector at Fermilab. In $202\mathrm{p}{\mathrm{b}}^{-1}$ of $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{T}\mathrm{e}\mathrm{V}$ we observe no candidate events, with an expected standard model background of $0.27\pm 0.07(\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t})\pm 0.10(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t})$ events. The results exclude a lightest chargino of mass less than $167\mathrm{G}\mathrm{e}\mathrm{V}/c^2$, and lightest neutralino of mass less than $93\mathrm{G}\mathrm{e}\mathrm{V}/c^2$ at 95% C.L. in a gauge-mediated supersymmetry-breaking model with a light gravitino.

Figure 1

The ${\mathrm{E̸}}_T$ spectrum for events with two isolated central photons with $E_T^{\gamma }>13\mathrm{G}\mathrm{e}\mathrm{V}$ and $|\eta |\lesssim 1.0$ along with the predictions from the GMSB model with a ${\tilde{\chi }}_1^{\pm }$ mass of $175\mathrm{G}\mathrm{e}\mathrm{V}/c^2$, normalized to $202\mathrm{p}{\mathrm{b}}^{-1}$. The diphoton candidate sample data are in good agreement with the background predictions. There are no events above the ${\mathrm{E̸}}_T>45\mathrm{G}\mathrm{e}\mathrm{V}$ threshold. The properties of the two candidates above 40 GeV appear consistent with the expected backgrounds.

Figure 2

The 95% C.L. upper limits on the total production cross section times branching ratio versus ${\mathrm{M}}_{{\tilde{\chi }}_1^{\pm }}$ and ${\mathrm{M}}_{{\tilde{\chi }}_1^0}$ for the light gravitino scenario using the parameters proposed in [18]. The lines show the experimental limit and the LO and NLO theoretically predicted cross sections. We set limits of ${\mathrm{M}}_{{\tilde{\chi }}_1^{\pm }}>167\mathrm{G}\mathrm{e}\mathrm{V}/c^2$ and ${\mathrm{M}}_{{\tilde{\chi }}_1^0}>93\mathrm{G}\mathrm{e}\mathrm{V}/c^2$ at 95% C.L.