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Search for scalar bottom pair production with the ATLAS detector in pp collisions at sqrt(s) = 7 TeV

ATLAS Collaboration

TL;DR

This letter reports a search for direct sbottom pair production in pp collisions at sqrt(s) = 7 TeV using 2.05 fb^-1 of ATLAS data, targeting events with two b-tagged jets and large missing transverse momentum under the MSSM framework with BR(tilde{b}_1 -> b tilde{chi}^0_1) = 100%. Three signal regions defined by m_CT thresholds of 100, 150, and 200 GeV maximize sensitivity across the tilde{b}_1–tilde{chi}^0_1 mass plane, with backgrounds estimated from data-driven transfer factors and MC simulations and systematic uncertainties including JES, b-tagging, and theoretical modeling. The results set 95% CL upper limits on the effective cross section using the CLs method and translate these into exclusions in the tilde{b}_1–tilde{chi}^0_1 mass plane; neutralino masses below 60 GeV lead to sbottom mass exclusions up to 390 GeV (sigma_min) to 420 GeV (sigma_max), with 120 GeV neutralinos excluded for 275 < m_{tilde{b}_1} < 350 GeV. Overall, the analysis extends previous sbottom mass limits at 7 TeV and demonstrates the power of jet identification and missing energy techniques in SUSY searches.

Abstract

The results of a search for pair production of the scalar partners of bottom quarks in 2.05 fb^-1 of pp collisions at sqrt{s} = 7 TeV using the ATLAS experiment are reported. Scalar bottoms are searched for in events with large missing transverse momentum and two jets in the final state, where both jets are identified as originating from a b-quark. In an R-parity conserving minimal supersymmetric scenario, assuming that the scalar bottom decays exclusively into a bottom quark and a neutralino, 95% confidence-level upper limits are obtained in the tilde{b}_1 - tilde{chi}^0_1 mass plane such that for neutralino masses below 60 GeV scalar bottom masses up to 390 GeV are excluded.

Search for scalar bottom pair production with the ATLAS detector in pp collisions at sqrt(s) = 7 TeV

TL;DR

This letter reports a search for direct sbottom pair production in pp collisions at sqrt(s) = 7 TeV using 2.05 fb^-1 of ATLAS data, targeting events with two b-tagged jets and large missing transverse momentum under the MSSM framework with BR(tilde{b}_1 -> b tilde{chi}^0_1) = 100%. Three signal regions defined by m_CT thresholds of 100, 150, and 200 GeV maximize sensitivity across the tilde{b}_1–tilde{chi}^0_1 mass plane, with backgrounds estimated from data-driven transfer factors and MC simulations and systematic uncertainties including JES, b-tagging, and theoretical modeling. The results set 95% CL upper limits on the effective cross section using the CLs method and translate these into exclusions in the tilde{b}_1–tilde{chi}^0_1 mass plane; neutralino masses below 60 GeV lead to sbottom mass exclusions up to 390 GeV (sigma_min) to 420 GeV (sigma_max), with 120 GeV neutralinos excluded for 275 < m_{tilde{b}_1} < 350 GeV. Overall, the analysis extends previous sbottom mass limits at 7 TeV and demonstrates the power of jet identification and missing energy techniques in SUSY searches.

Abstract

The results of a search for pair production of the scalar partners of bottom quarks in 2.05 fb^-1 of pp collisions at sqrt{s} = 7 TeV using the ATLAS experiment are reported. Scalar bottoms are searched for in events with large missing transverse momentum and two jets in the final state, where both jets are identified as originating from a b-quark. In an R-parity conserving minimal supersymmetric scenario, assuming that the scalar bottom decays exclusively into a bottom quark and a neutralino, 95% confidence-level upper limits are obtained in the tilde{b}_1 - tilde{chi}^0_1 mass plane such that for neutralino masses below 60 GeV scalar bottom masses up to 390 GeV are excluded.

Paper Structure

This paper contains 1 section, 2 figures, 1 table.

Table of Contents

  1. Acknowledgements

Figures (2)

  • Figure 1: Measured $m_\mathrm{CT}$ (left) and $E_{\mathrm{T}}^{\mathrm{miss}}$ (right) distributions before the $m_\mathrm{CT}$ selection compared to the SM predictions (solid line) and SM+MSSM predictions (dashed lines). The dashed grey band represents the total systematic uncertainties.
  • Figure 2: Expected and observed exclusion limits, as well as $\pm 1 \sigma$ variation on the expected limit, in the $\tilde{b}^{}_{1}-\tilde{\chi}^{0}_{1}$ mass plane. The band around the observed limit delimited by the two dashed lines shows the effect of renormalization and factorization scale variation. The reference point indicated on the plane corresponds to the MSSM scenario with sbottom and neutralino masses of 300 GeV and 100 GeV, respectively. Results are compared to previous exclusion limits from Tevatron experiments. Results from LEP cover the region with sbottom mass below 100 GeV.