Abstract

Inclusive and differential fiducial cross sections of the Higgs boson are measured in the H rightarrow ZZ^{*} rightarrow 4ell (ell = e,mu ) decay channel. The results are based on proton-proton collision data produced at the Large Hadron Collider at a centre-of-mass energy of 13 TeV and recorded by the ATLAS detector from 2015 to 2018, equivalent to an integrated luminosity of 139 hbox {fb}^{-1}. The inclusive fiducial cross section for the H rightarrow ZZ^{*} rightarrow 4ell process is measured to be sigma _mathrm {fid} = 3.28 ,{pm }, 0.32 fb, in agreement with the Standard Model prediction of sigma _mathrm {fid, SM} = 3.41 pm 0.18 fb. Differential fiducial cross sections are measured for a variety of observables which are sensitive to the production and decay of the Higgs boson. All measurements are in agreement with the Standard Model predictions. The results are used to constrain anomalous Higgs boson interactions with Standard Model particles.

Highlights

  • Background estimationNon-resonant SM (Z (∗)/γ ∗)(Z (∗)/γ ∗) production via qqannihilation and gluon–gluon fusion, referred to as Z Z ∗, can result in four prompt leptons in the final state and constitutes the largest background for this analysis

  • The uncertainty in the prediction is shown by the hatched band, which includes the theoretical uncertainties of the SM cross section for the signal and the Z Z ∗ background

  • The combined inclusive fiducial cross section is extrapolated to the full phase space, as shown in the right panel of Fig. 18, using the fiducial acceptance as well as the branching ratios, with the uncertainties described in Sect

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Summary

The ATLAS detector

The ATLAS detector [32] is a multipurpose particle detector with a forward–backward symmetric cylindrical geometry and a near 4π coverage in solid angle. It consists of an inner tracking detector (ID) surrounded by a thin superconducting solenoid, which provides a 2 T axial magnetic field, electromagnetic (EM) and hadron calorimeters, and a muon spectrometer. The inner tracking detector covers the pseudorapidity range |η| < 2.5. Lead/liquid-argon (LAr) sampling calorimeters provide electromagnetic energy measurements with high. Software algorithms with access to the full detector information are used in the high-level trigger to yield a recorded event rate of about 1 kHz [35]

Theoretical predictions and event simulation
Event reconstruction and selection
Fiducial phase space and unfolded observables
Background estimation
Signal extraction and unfolding
Systematic uncertainties
Experimental uncertainties
Theoretical uncertainties
Results
Measured data yields
Statistical analysis
Inclusive fiducial cross-section measurements
Differential cross-section measurements
10 Interpretation of differential distributions
10.1 Constraints on BSM effects within the pseudo-observables framework
10.2 Constraints on Yukawa couplings
11 Summary
A Results with regularised unfolding

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