Abstract
This paper presents a search for new particles in events with one lepton (electron or muon) and missing transverse momentum using 20.3 $fb^{-1}$ of proton-proton collision data at $\sqrt{s}=8$ TeV recorded by the ATLAS experiment at the Large Hadron Collider. No significant excess beyond Standard Model expectations is observed. A $W'$ with Sequential Standard Model couplings is excluded at the 95% confidence level for masses up to 3.24 TeV. Excited chiral bosons ($W^{*}$) with equivalent coupling strengths are excluded for masses up to 3.21 TeV. In the framework of an effective field theory limits are also set on the dark matter-nucleon scattering cross-section as well as the mass scale $M_{*}$ of the unknown mediating interaction for dark matter pair production in association with a leptonically decaying $W$.
Highlights
Paper the search region is expanded to higher masses and the sensitivity is considerably improved in the region covered by the previous search
This paper presents a search for new particles in events with one lepton and missing transverse momentum using 20.3 fb−1 of proton-proton collision data at s = 8 TeV recorded by the ATLAS experiment at the Large Hadron Collider
Limits are reported for the dark matter (DM)-nucleon scattering cross-section as well as the mass scale, M∗, of a new SM-DM interaction expressed in an effective field theory (EFT) as a fourpoint contact interaction [22,23,24,25,26,27]
Summary
The ATLAS detector [30] is a multi-purpose particle physics detector with a forwardbackward symmetric cylindrical geometry and nearly 4π coverage in solid angle. Tracks and vertices of charged particles are reconstructed with silicon pixel and silicon microstrip detectors covering |η| < 2.5 and straw-tube transition radiation detectors covering |η| < 2.0, all immersed in a homogeneous 2 T magnetic field provided by a superconducting solenoid. The ID is surrounded by a hermetic calorimeter that covers |η| < 4.9 and provides three-dimensional reconstruction of particle showers. The electromagnetic calorimeter is a liquid argon (LAr) sampling calorimeter, which uses lead absorbers for |η| < 3.2 and copper absorbers in the very forward region. The hadronic sampling calorimeter uses plastic scintillator tiles as the active material and iron absorbers in the region |η| < 1.7. In the region 1.5 < |η| < 4.9, liquid argon is used as the active material, with copper and/or tungsten absorbers. The MS surrounds the calorimeters and consists of three large superconducting toroid systems (each with eight coils) together with multiple layers of trigger chambers up to |η| < 2.4 and tracking chambers, providing precision track measurements, up to |η| < 2.7
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