Search for Supersymmetry at the LHC in Events with Jets and Missing Transverse Energy

A search for events with jets and missing transverse energy is performed in a data sample of $pp$ collisions collected at $\sqrt{s}=7\mathrm{TeV}$ by the CMS experiment at the LHC. The analyzed data sample corresponds to an integrated luminosity of $1.14{\mathrm{fb}}^{-1}$. In this search, a kinematic variable ${\alpha }_{\mathrm{T}}$ is used as the main discriminator between events with genuine and misreconstructed missing transverse energy. No excess of events over the standard model expectation is found. Exclusion limits in the parameter space of the constrained minimal supersymmetric extension of the standard model are set. In this model, squark masses below 1.1 TeV are excluded at 95% C.L. Gluino masses below 1.1 TeV are also ruled out at 95% C.L. for values of the universal scalar mass parameter below 500 GeV.

Figure 1

The distribution of ${\alpha }_{\mathrm{T}}$, described in the text, for events in data with two or more jets (black dots with error bars representing the statistical uncertainties), after all event selection criteria except ${\alpha }_{\mathrm{T}}$ are applied and $H_{\mathrm{T}}>375\mathrm{GeV}$. For illustrative purposes only, expected yields from simulation are also shown for QCD multijet events (dot-dashed line), associated production of top quarks, $W$, or $Z$ with jets (long-dashed line), the sum of all aforementioned SM processes (solid line) and the SUSY LM6 model (dotted line). The uncertainties for the SM expectation, due to the limited accuracy of the available simulation data sets and jet energy calibrations, are represented by the hatched area. The highest bin contains the overflows.

Figure 2

The ratio $R_{{\alpha }_{\mathrm{T}}}$ as a function of $H_{\mathrm{T}}$, as measured in the hadronic data samples (black dots with error bars representing the statistical uncertainties). The ratios using the direct predictions from the $\mu +\mathrm{\text{jets}}$ and $\gamma +\mathrm{\text{jets}}$ samples are shown as open squares (offset for clarity, with error bars representing the statistical and systematic uncertainties). Also shown is the result of the simultaneous fit to the three data samples (solid line); the analogous result when assuming a $H_{\mathrm{T}}$-independent hypothesis (dotted line); and, for illustrative purposes only, the expectation from the SUSY LM6 model when superimposed on the nominal fit result (long-dashed line).

Figure 3

The observed event yields versus $H_{\mathrm{T}}$ in the hadronic signal sample (black dots with error bars representing the statistical uncertainties). Also shown are the expectations given by the simultaneous fit for the $Z\to \nu \overline{\nu }+\mathrm{\text{jets}}$ process (dot-dashed line); the associated production of top, $W$, or $Z$ with jets (long-dashed line); the sum of QCD and all aforementioned processes (solid line); and, for illustrative purposes only, the SUSY LM6 model superimposed on the SM expectation (dotted line).

Figure 4

Observed and expected 95% C.L. exclusion contours in the CMSSM ($m_0$, $m_{1/2}$) plane ($\tan \beta =10$, $A_0=0$, $\mu >0$) using NLO signal cross sections with the $\mathrm{C}.{\mathrm{L}.}_s$ method. The expected limit is shown with its 68% C.L. range. The SUSY benchmark model LM6 is also shown.