Abstract
This paper describes a measurement of fiducial and differential cross sections of gluon-fusion Higgs boson production in the $H{\rightarrow\,}WW^{\ast}{\rightarrow\,}e\nu\mu\nu$ channel, using 20.3 fb$^{-1}$ of proton-proton collision data. The data were produced at a centre-of-mass energy of $\sqrt{s} = 8$ TeV at the CERN Large Hadron Collider and recorded by the ATLAS detector in 2012. Cross sections are measured from the observed $H{\rightarrow\,}WW^{\ast}{\rightarrow\,}e\nu\mu\nu$ signal yield in categories distinguished by the number of associated jets. The total cross section is measured in a fiducial region defined by the kinematic properties of the charged leptons and neutrinos. Differential cross sections are reported as a function of the number of jets, the Higgs boson transverse momentum, the dilepton rapidity, and the transverse momentum of the leading jet. The jet-veto efficiency, or fraction of events with no jets above a given transverse momentum threshold, is also reported. All measurements are compared to QCD predictions from Monte Carlo generators and fixed-order calculations, and are in agreement with the Standard Model predictions.
Highlights
Background rejectionvector-boson fusion (VBF) veto H→ WW∗→ ν ν topology Njet = 0 Njet ≥ 2Two isolated leptons ( = e, μ) with opposite charge plTead > 22 GeV, psTublead > 15 GeV m > 10 GeV pm T iss > 20 GeV Nb-jet = 0∆φ(, pmTiss) > 1.57 max(mT) > 50 GeV - pT > 30 GeV mττ < mZ − 25 GeV mττ < mZ − 25 GeV mjj < 600 GeV or ∆yjj < 3.6 m < 55 GeV ∆φ < 1.885 GeV < mT < 125 GeVUpper bounds on m and the azimuthal angle between the leptons ∆φ take advantage of the unique kinematics of the H → W W ∗ decay to discriminate between these signal events and the continuum W W background
This paper describes a measurement of fiducial and differential cross sections of gluon-fusion Higgs boson production in the H→ W W ∗→ eνμν channel, using 20.3 fb−1 of proton-proton collision data
Each control region is designed for the calculation of a normalisation factor (NF) for a particular target process, The NF is defined as (N − B )/B, where N is the number of data events observed in the control region, B is the expected background yield in the CR for the target process based on the predicted cross section and acceptance from Monte Carlo (MC) simulation, and B is the predicted yield from other processes in the control region
Summary
The ATLAS detector [20] at the LHC covers nearly the entire solid angle around the collision point. It consists of an inner tracking detector surrounded by a thin superconducting solenoid, electromagnetic and hadronic calorimeters, and a muon spectrometer incorporating three large superconducting toroid magnets. The silicon-microstrip tracker surrounding it typically provides four additional two-dimensional measurement points per track. Within the region |η| < 3.2, electromagnetic calorimetry is provided by a high-granularity lead/liquid-argon (LAr) sampling calorimeter. The solid-angle coverage is completed with forward copper/LAr and tungsten/LAr calorimeter modules optimised for electromagnetic and hadronic measurements respectively. Cathode-strip chambers provide additional high-granularity coverage in the forward (2 < |η| < 2.7) region. The two subsequent trigger levels, collectively referred to as the High-Level Trigger (HLT), are implemented in software
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