Search for contact interactions in dimuon events from $pp$ collisions at $\sqrt{s}=7\mathrm{TeV}$ with the ATLAS detector

A search for contact interactions has been performed using dimuon events recorded with the ATLAS detector in proton-proton collisions at $\sqrt{s}=7\mathrm{TeV}$. The data sample corresponds to an integrated luminosity of $42{\mathrm{pb}}^{-1}$. No significant deviation from the standard model is observed in the dimuon mass spectrum, allowing the following 95% C.L. limits to be set on the energy scale of contact interactions: $\Lambda >4.9\mathrm{TeV}$ (4.5 TeV) for constructive (destructive) interference in the left-left isoscalar compositeness model. These limits are the most stringent to date for $\mu \mu qq$ contact interactions.

Figure 1

Dimuon invariant mass distribution for data (points) and Monte Carlo simulations (histograms). The red (blue) line corresponds to the distribution expected in the presence of contact interactions with ${\Lambda }^{-}=3\mathrm{TeV}$ (5 TeV) for constructive interference. The dashed blue line corresponds to ${\Lambda }^{+}=5\mathrm{TeV}$ for destructive interference.

Figure 2

Distribution of the number of events with dimuon mass above $m_{\mu \mu }^{\min }$ for data (points) and Monte Carlo simulations (histograms). The SM prediction is shown as the shaded grey histogram, whereas the solid (dashed) histograms correspond to the expected distributions in the presence of contact interactions with various scales $\Lambda$ for constructive (destructive) interference.