ATLAS Collaboration(Aad, G. et al), Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Cabrera Urban, S., Cantero, J., et al. (2023). Measurements of Higgs boson production by gluon-gluon fusion and vector-boson fusion using H -> WW* -> eνμν decays in pp collisions at root s=13 TeV with the ATLAS detector. Phys. Rev. D, 108(3), 032005–41pp.
Abstract: Higgs boson production via gluon-gluon fusion and vector-boson fusion in proton-proton collisions is measured in the H & RARR; WW* & RARR; ev & mu;v decay channel. The Large Hadron Collider delivered proton-proton collisions at a center-of-mass energy of 13 TeV between 2015 and 2018, which were recorded by the ATLAS detector, corresponding to an integrated luminosity of 139 fb-1. The total cross sections for Higgs boson production by gluon-gluon fusion and vector-boson fusion times the H & RARR; WW* branching ratio are measured to be 12.0 1 1.4 and 0.75 thorn 0.19 -0.16 pb, respectively, in agreement with the Standard Model predictions of 10.4 1 0.6 and 0.81 1 0.02 pb. Higgs boson production is further characterized through measurements of Simplified Template Cross Sections in a total of 11 kinematic fiducial regions.
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ATLAS Collaboration(Aad, G. et al), Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Bouchhar, N., Cabrera Urban, S., et al. (2023). Measurements of differential cross sections of Higgs boson production through gluon fusion in the H → WW *→ eνμν final state at √s=13 TeV with the ATLAS detector. Eur. Phys. J. C, 83(9), 774–40pp.
Abstract: Higgs boson production via gluon-gluon fusion is measured in the WW *-> e nu μnu decay channel. The dataset utilized corresponds to an integrated luminosity of 139 fb(-1) collected by the ATLAS detector from root s = 13TeV proton-proton collisions delivered by the Large Hadron Collider between 2015 and 2018. Differential cross sections are measured in a fiducial phase space restricted to the production of at most one additional jet. The results are consistent with Standard Model expectations, derived using different Monte Carlo generators.
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ATLAS Collaboration(Aad, G. et al), Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Bouchhar, N., Cabrera Urban, S., et al. (2023). Measurement of Z γ γ production in pp collisions at √s=13 TeV with the ATLAS detector. Eur. Phys. J. C, 83(6), 539–30pp.
Abstract: Cross-sections for the production of a Z boson in association with two photons are measured in proton-proton collisions at a centre-of-mass energy of 13 TeV. The data used correspond to an integrated luminosity of 139 fb(-1) recorded by the ATLAS experiment during Run 2 of the LHC. The measurements use the electron and muon decay channels of the Z boson, and a fiducial phase-space region where the photons are not radiated from the leptons. The integrated Z(-> ll)gamma gamma cross-section is measured with a precision of 12% and differential cross-sections are measured as a function of six kinematic variables of the Z gamma gamma system. The data are compared with predictions from MC event generators which are accurate to up to next-to-leading order in QCD. The cross-section measurements are used to set limits on the coupling strengths of dimension-8 operators in the framework of an effective field theory.
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ATLAS Collaboration(Aad, G. et al), Aikot, A., Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Bouchhar, N., et al. (2024). Measurement of the tt cross section and its ratio to the Z production cross section using pp collisions at √s=13.6 TeV with the ATLAS detector. Phys. Lett. B, 848, 138376–25pp.
Abstract: The inclusive top-quark-pair production cross section rrtt and its ratio to the Z-boson production cross section have been measured in proton-proton collisions at root s = 13.6 TeV, using 29 fb-1 of data collected in 2022 with the ATLAS experiment at the Large Hadron Collider. Using events with an opposite-charge electron-muon pair and b-tagged jets, and assuming Standard Model decays, the top-quark-pair production cross section is measured to be rrtt = 850 +/- 3(stat.) +/- 18(syst.) +/- 20(lumi.) pb. The ratio of the ttand the Z-boson production cross sections is also measured, where the Z-boson contribution is determined for inclusive e+e- and mu+mu- events in a fiducial phase space. The relative uncertainty on the ratio is reduced compared to the ttcross section, thanks to the cancellation of several systematic uncertainties. The result for the ratio, Rtt/Z = 1.145 +/- 0.003(stat.) +/- 0.021(syst.) +/- 0.002(lumi.) is consistent with the Standard Model prediction using the PDF4LHC21 PDF set.
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ATLAS Collaboration(Aad, G. et al), Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Cabrera Urban, S., Cantero, J., et al. (2023). Measurement of the total cross section and ρ-parameter from elastic scattering in pp collisions at √s=13 TeV with the ATLAS detector. Eur. Phys. J. C, 83(5), 441–49pp.
Abstract: In a special run of the LHC with beta star=2.5 km, proton-proton elastic-scattering events were recorded at root s=13 TeV with an integrated luminosity of 340 μb(-1) using the ALFA subdetector of ATLAS in 2016. The elastic cross section was measured differentially in the Mandelstam t variable in the range from -t=2.5 center dot 10(-4) GeV2 to -t=0.46 GeV2 using 6.9 million elastic-scattering candidates. This paper presents measurements of the total cross section sigma(tot), parameters of the nuclear slope, and the rho-parameter defined as the ratio of the real part to the imaginary part of the elastic-scattering amplitude in the limit t -> 0. These parameters are determined from a fit to the differential elastic cross section using the optical theorem and different parameterizations of the t-dependence. The results for sigma(tot) and rho are sigma(tot) (PP -> X ) =104.7 +/- 1.1 mob , rho=0.098 +/- 0.011. The uncertainty in sigma(tot) is dominated by the luminosity measurement, and in rho by imperfect knowledge of the detector alignment and by modelling of the nuclear amplitude.
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