Search for new physics in events with same-sign dileptons and b-tagged jets in pp collisions at sqrt(s) = 7 TeV

TL;DR

The paper reports a CMS search for new physics in events with two like-sign isolated leptons and at least two b-tagged jets, using $4.98\,\

Abstract

A search for new physics is performed using isolated same-sign dileptons with at least two b-quark jets in the final state. Results are based on a 4.98 inverse femtobarn sample of proton-proton collisions at a centre-of-mass energy of 7 TeV collected by the CMS detector. No excess above the standard model background is observed. Upper limits at 95% confidence level are set on the number of events from non-standard-model sources. These limits are used to set constraints on a number of new physics models. Information on acceptance and efficiencies are also provided so that the results can be used to confront additional models in an approximate way.

Figures (9)

• Figure 1: Lepton selection efficiency as a function of $p_{\mathrm{T}}\xspace$ (left); b-jet tagging efficiency as a function of the ${b}$ quark $p_{\mathrm{T}}\xspace$ (right).
• Figure 2: Efficiency for an event to pass a given reconstructed $E_{\mathrm{T}}^{\text{miss}}$ or $H_{\mathrm{T}}\xspace$ threshold as a function of gen-$E_{\mathrm{T}}^{\text{miss}}\xspace$ or gen-$H_{\mathrm{T}}\xspace$. The efficiencies are shown for the thresholds used in defining the signal regions.
• Figure 3: Excluded regions in the parameter spaces of the ${Z}^\prime$ (left) and MxFV models (right). In the case of the ${Z}^\prime\xspace$ model we also show the $m({Z}^\prime\xspace)$ vs. $f_R$ region consistent with the Tevatron ${t}\overline{{t}}\xspace$ forward-backward asymmetry measurements fcnczprime.
• Figure 4: Diagrams for models A1 (left) and A2 (right).
• Figure 5: Left plot: exclusion (95 % CL) in the $m(\widetilde{\chi}^{0}\xspace_1)-m(\widetilde{{g}}\xspace)$ plane for model A1 (gluino decay via virtual top squarks). Right plot: exclusion (95% CL) in the $m(\widetilde{{t}}\xspace_1)-m(\widetilde{{g}}\xspace)$ plane for model A2 (gluino decay to on-shell top squarks). The lines represent the kinematic boundaries of the models. The regions to the left of the bands, and within the kinematic boundaries, are excluded; the thicknesses of the bands represent the theoretical uncertainties on the gluino pair production cross section from scale and parton distribution functions (pdf) variations. In the case of model A2 we show results for $m(\widetilde{\chi}^{0}\xspace_1)=50$$\,\text{Ge\spaceV}$ (red, with dashed lines for the kinematic boundaries) and $m(\widetilde{\chi}^{0}\xspace_1)=150$$\,\text{Ge\spaceV}$ (blue, with solid line for the kinematic boundary).