Search for squarks and gluinos in events with jets and missing transverse energy using 2.1 fb-1 of ppbar collision data at sqrt(s)=1.96 TeV

Abstract

A data sample corresponding to an integrated luminosity of 2.1 fb-1 collected by the D0 detector at the Fermilab Tevatron Collider was analyzed to search for squarks and gluinos produced in ppbar collisions at a center-of-mass energy of 1.96 TeV. No evidence for the production of such particles was observed in topologies involving jets and missing transverse energy, and 95% C.L. lower limits of 379 GeV and 308 GeV were set on the squark and gluino masses, respectively, within the framework of minimal supergravity with tan(beta)=3, A0=0, and mu<0. The corresponding previous limits are improved by 54 GeV and 67 GeV.

Figures (4)

• Figure 1: Distributions of $\hbox{$\,\slash emE_{T}$}$ after applying all analysis criteria except the one on $\hbox{$\,\slash emE_{T}$}$ for the "dijet" (a), "3-jets" (b), and "gluino" (c) analyses; for data (points with error bars), for SM background (full histogram), and for signal MC (dotted histogram on top of SM). The signal drawn corresponds to $(m_0,m_{1/2})=(25,175)$ GeV, $m_{\tilde{q}}=m_{\tilde{g}}=410$ GeV, and $(m_0,m_{1/2})=(500,110)$ GeV from left to right. The fitted QCD background contribution is also shown.
• Figure 2: For $\tan\beta = 3$, $A_0 = 0$, $\mu < 0$, observed (closed circles) and expected (opened triangles) 95% C.L. upper limits on squark-gluino production cross sections combining the analyses for $m_0=25$ GeV (a), $m_{\tilde{q}}=m_{\tilde{g}}$ (b), and $m_0=500$ GeV (c). The nominal production cross sections are also shown, with shaded bands corresponding to the PDF and renormalization-and-factorization scale uncertainties.
• Figure 3: In the gluino and squark mass plane, excluded regions at the 95% C.L. by direct searches in the mSUGRA framework with $\tan\beta = 3$, $A_0 = 0$, $\mu < 0$. The region excluded by this analysis and previous D0 Run II results Abazov:2006bj in the most conservative hypothesis ($\sigma_{\mathrm{min}}$) is shown in dark shading. The thick (dotted) line is the limit of the observed (expected) excluded region for the $\sigma_{\mathrm{nom}}$ hypothesis. The band delimited by the two dashed lines shows the effect of the PDF choice and of the variation of $\mu_{\mathrm{r,f}}$ by a factor of two. Regions excluded by previous experiments are indicated in light shading prevexp. The two thin lines indicate the indirect limits inferred from the LEP2 chargino and slepton searches lepindirect. The region where no mSUGRA solution can be found is shown hatched.
• Figure 4: In the $(m_{0},m_{1/2})$ plane, the region excluded by this analysis at the 95% C.L. in the mSUGRA framework for $\tan\beta = 3$, $A_0 = 0$, $\mu < 0$ is shown in dark shading. The thick line is the limit of the excluded region for the $\sigma_{\mathrm{nom}}$ hypothesis. The corresponding expected limit is the dashed line. The band delimited by the two dotted lines shows the effect of the PDF choice and of the variation of $\mu_{\mathrm{r,f}}$ by a factor of two. Regions excluded by the LEP2 chargino and slepton searches are indicated in light shading lepindirect. The region where there is no electroweak symmetry breaking is shown in black.