Search for Supersymmetry in $pp$ Collisions at $\sqrt{s}=7\mathrm{TeV}$ in Events with Two Photons and Missing Transverse Energy

A search for supersymmetry in the context of general gauge-mediated breaking with the lightest neutralino as the next-to-lightest supersymmetric particle and the gravitino as the lightest is presented. The data sample corresponds to an integrated luminosity of $36{\mathrm{pb}}^{-1}$ recorded by the CMS experiment at the LHC. The search is performed by using events containing two or more isolated photons, at least one hadronic jet, and significant missing transverse energy. No excess of events at high missing transverse energy is observed. Upper limits on the signal cross section for general gauge-mediated supersymmetry between 0.3 and 1.1 pb at the 95% confidence level are determined for a range of squark, gluino, and neutralino masses, excluding supersymmetry parameter space that was inaccessible to previous experiments.

Figure 1

$E_T^{\mathrm{miss}}$ distribution for $\gamma \gamma$ data, including the jet requirement, compared with backgrounds and a possible GGM SUSY signal. The solid circles with error bars represent the data. The double-hatched blue band represents the contribution of the electroweak background. The single-hatched red band shows the sum of the electroweak background with the QCD $E_T^{\mathrm{miss}}$ prediction obtained from the $Z\to ee$ sample. The widths of the bands correspond to the sum of the statistical and systematic uncertainties on the backgrounds. The prediction of the GGM SUSY sample point described in the text is shown in the plot as the solid line histogram.

Figure 2

The $E_T^{\mathrm{miss}}$ distribution of the $e\gamma$ candidates (solid circles with error bars) is compared to the QCD expectation for this spectrum from $Z\to ee$ events (solid histogram). The $W\gamma$ and $W$ plus jet (with the jet misidentified as a photon) contributions are shown as dashed and dash-dotted histograms, respectively. The hatched red band represents the sum of all expected background components, and its width corresponds to the sum of the statistical and systematic uncertainties on the backgrounds.

Figure 3

95% C.L. upper limits for GGM production cross section as a function of squark ($\tilde{q}$) and gluino ($\tilde{g}$) masses for a neutralino mass of 150 GeV.

Figure 4

Lower 95% C.L. exclusion limits on the squark ($\tilde{q}$) and gluino ($\tilde{g}$) masses in the GGM benchmark model for 50, 150, and 500 GeV neutralino (${\tilde{\chi }}_1^0$) masses. The areas below and to the left of the lines are excluded. The expected exclusion limit for 150 GeV neutralino mass is shown by the dashed line. The shaded band represents $\pm 1$ standard deviation of theoretical uncertainty on the GGM cross section.