Search for massive colored scalars in four-jet final states in sqrt{s}=7 TeV proton-proton collisions with the ATLAS detector

Abstract

A search for pair-produced scalar particles decaying to a four-jet final state is presented. The analysis is performed using an integrated luminosity of 34 pb^-1 recorded by the ATLAS detector in 2010. No deviation from the Standard Model is observed. For a scalar mass of 100 GeV (190 GeV) the limit on the scalar gluon pair production cross section at 95% confidence level is 1 nb (0.28 nb). When these results are interpreted as mass limits, scalar-gluons (hyperpions) with masses of 100 to 185 GeV (100 to 155 GeV) are excluded at 95% confidence level with the exception of a mass window of width about 5 GeV (15 GeV) around 140 GeV.

Figures (3)

• Figure 1: Kinematic variables at different stages of the analysis. Data (dots) are compared to the ALPGEN MC sample (solid line). The solid band corresponds to one standard deviation in the jet energy scale. The ratio data/MC is also shown with its statistical uncertainty, which is dominated by the MC statistics. The dashed line corresponds to a sgluon signal of 100 Ge V. (a) The transverse momentum of the 4$^{th}$ jet is shown. (b) The $\Delta R_{jj}$ distribution for the reconstructed sgluon candidate with the highest transverse momentum jet is shown after requiring the transverse momentum to be greater than 55 Ge V and pairing the four leading jets into two sgluon candidates. (c) The relative mass difference is shown after the criterias on the $p_\mathrm{T}$ and $\Delta R_{jj}$ have been applied. (d) The scattering angle in the 4-jet center-of-mass frame is shown after all other selection criteria have been applied.
• Figure 2: The comparison of the prediction of the background with the data in the signal region is shown. The points are the data in the signal region (region A). The solid (dashed) histogram is the estimated signal in region A (B) for the nominal cross section. The predictions of background in region A based upon the data in region B (rectangles) and upon the result of the fit in region B (line), each normalized using the ABCD method, are shown for: (a) $M_{\mathrm{sgluon}}=100$Ge V, (b) $M_{\mathrm{sgluon}}=140$Ge V, (c) $M_{\mathrm{sgluon}}=160$Ge V and (d) $M_{\mathrm{sgluon}}=190$Ge V. For each, the bin size of the histogram is equal to $0.04\times M_{\mathrm{sgluon}}$.
• Figure 3: Expected and observed 95% CL upper bounds on the product of the scalar pair production cross sections and of the branching ratio to gluons as a function of the scalar mass. The predictions of the sgluon and hyperpion pair production cross section are also shown.