Abstract
A measurement of the four-lepton invariant mass spectrum is made with the ATLAS detector, using an integrated luminosity of 36.1 fb−1 of proton-proton collisions at sqrt{s} = 13 TeV delivered by the Large Hadron Collider. The differential cross-section is measured for events containing two same-flavour opposite-sign lepton pairs. It exhibits a rich structure, with different mass regions dominated in the Standard Model by single Z boson production, Higgs boson production, and Z boson pair production, and non-negligible interference effects at high invariant masses. The measurement is compared with state-of-the-art Standard Model calculations, which are found to be consistent with the data. These calculations are used to interpret the data in terms of gg → ZZ → 4ℓ and Z → 4ℓ subprocesses, and to place constraints on a possible contribution from physics beyond the Standard Model.
Highlights
Vector-boson fusion and associated production with vector bosons or top-quark pairs
It exhibits a rich structure, with different mass regions dominated in the Standard Model by single Z boson production, Higgs boson production, and Z boson pair production, and nonnegligible interference effects at high invariant masses
The off-shell Higgs production rate may be affected by beyond-the-SM (BSM) processes involving additional heavy particles, or modifications of the Higgs couplings, even if there is no effect on on-shell Higgs boson production [4]
Summary
The ATLAS experiment [11,12,13] at the LHC is a multipurpose particle detector with a forward-backward symmetric cylindrical geometry and a near 4π coverage in solid angle.. The ATLAS experiment [11,12,13] at the LHC is a multipurpose particle detector with a forward-backward symmetric cylindrical geometry and a near 4π coverage in solid angle.1 It consists of an inner tracking detector surrounded by a thin superconducting solenoid providing a 2 T axial magnetic field, electromagnetic and hadron calorimeters, and a muon spectrometer. The MS is based on a system of precision chambers providing tracking information up to |η| = 2.7 and fast detectors for triggering in the region |η| < 2.4. This is followed by the software-based high-level trigger, which reduces the accepted event rate to 1 kHz on average depending on the data-taking conditions
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