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ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Barranco Navarro, L., Cabrera Urban, S., Castillo Gimenez, V., Cerda Alberich, L., et al. (2017). Measurement of the W+ W- production cross section in pp collisions at a centre-of-mass energy of root s=13 TeV with the ATLAS experiment. Phys. Lett. B, 773, 354–374.
Abstract: The production of opposite-charge W-boson pairs in proton-proton collisions at root s = 13 TeV is measured using data corresponding to 3.16 fb(-1) of integrated luminosity collected by the ATLAS detector at the CERN Large Hadron Collider in 2015. Candidate W-boson pairs are selected by identifying their leptonic decays into an electron, a muon and neutrinos. Events with reconstructed jets are not included in the candidate event sample. The cross-section measurement is performed in a fiducial phase space close to the experimental acceptance and is compared to theoretical predictions. Agreement is found between the measurement and the most accurate calculations available.
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ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Barranco Navarro, L., Cabrera Urban, S., Castillo Gimenez, V., Cerda Alberich, L., et al. (2016). Measurement of the W-+/- Z boson pair-production cross section in pp collisions at root s=13 TeV with the ATLAS detector. Phys. Lett. B, 762, 1–22.
Abstract: The production of W-+/- Z events in proton-proton collisions at a centre-of-mass energy of 13 TeV is measured with the ATLAS detector at the LHC. The collected data correspond to an integrated luminosity of 3.2 fb(-1). The W-+/- Z candidates are reconstructed using leptonic decays of the gauge bosons into electrons or muons. The measured inclusive cross section in the detector fiducial region for leptonic decay modes is sigma(fid.)(W +/- Z -> L'vll) = 63.2 +/- 3.2 (stat.) +/- 2.6 (sys.) +/- 1.5 (lumi.) fb. In comparison, the next-to-leading-order Standard Model prediction is 53.4(-2.8)(+3.6) fb. The extrapolation of the measurement from the fiducial to the total phase space yields sigma(tot.)(W +/- Z) = 50.6 +/- 2.6 (stat.) +/- 2.0 (sys.) +/- 0.9 (th.) +/- 1.2 (lumi.) pb, in agreement with a recent next-to-next-to-leading-order calculation of 48.2(-1.0)(+1.1) pb. The cross section as a function of jet multiplicity is also measured, together with the charge-dependent W+ Z and W- Z cross sections and their ratio.
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ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Barranco Navarro, L., Cabrera Urban, S., Castillo Gimenez, V., Cerda Alberich, L., et al. (2018). Measurement of the W-boson mass in pp collisions at root s=7 TeV with the ATLAS detector. Eur. Phys. J. C, 78(2), 110–61pp.
Abstract: A measurement of the mass of the W boson is presented based on proton-proton collision data recorded in 2011 at a centre-of-mass energy of 7 TeV with the ATLAS detector at the LHC, and corresponding to 4.6 fb(-1) of integrated luminosity. The selected data sample consists of 7.8 x 10(6) candidates in the W -> μnu channel and 5.9 x 10(6) candidates in the W -> e nu channel. The W-boson mass is obtained from template fits to the reconstructed distributions of the charged lepton transverse momentum and of the W boson transverse mass in the electron and muon decay channels, yielding m(W) = 80370 +/- 7 (stat.) +/- 11(exp. syst.) +/- 14 (mod. syst.) MeV = 80370 +/- 19 MeV, where the first uncertainty is statistical, the second corresponds to the experimental systematic uncertainty, and the third to the physics-modelling systematic uncertainty. A measurement of the mass difference between the W+ and W- bosons yields m(W+) – m(W-) = -29 +/- 28 MeV.
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ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Aparisi Pozo, J. A., Bailey, A. J., Barranco Navarro, L., Cabrera Urban, S., et al. (2018). Measurement of the Z gamma ->nu nu gamma production cross section in pp collisions at root s=13 TeV with the ATLAS detector and limits on anomalous triple gauge-boson couplings. J. High Energy Phys., 12(12), 010–42pp.
Abstract: The production of Z bosons in association with a high-energy photon (Z production) is studied in the neutrino decay channel of the Z boson using pp collisions at =13 TeV. The analysis uses a data sample with an integrated luminosity of 36.1fb(-1) collected by the ATLAS detector at the LHC in 2015 and 2016. Candidate Z events with invisible decays of the Z boson are selected by requiring significant transverse momentum (p(T)) of the dineutrino system in conjunction with a single isolated photon with large transverse energy (E-T). The rate of Z production is measured as a function of photon E-T, dineutrino system p(T) and jet multiplicity. Evidence of anomalous triple gauge-boson couplings is sought in Z production with photon E-T greater than 600 GeV. No excess is observed relative to the Standard Model expectation, and upper limits are set on the strength of ZZ and Z couplings
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ATLAS Collaboration(Aad, G. et al), Alvarez Piqueras, D., Aparisi Pozo, J. A., Bailey, A. J., Cabrera Urban, S., Castillo, F. L., et al. (2020). Measurement of the Z(-> l(+)l(-))gamma production cross-section in pp collisions at root s=13 TeV with the ATLAS detector. J. High Energy Phys., 03(3), 054–52pp.
Abstract: The production of a prompt photon in association with a Z boson is studied in proton-proton collisions at a centre-of-mass energy s = 13 TeV. The analysis uses a data sample with an integrated luminosity of 139 fb(-1) collected by the ATLAS detector at the LHC from 2015 to 2018. The production cross-section for the process pp -> l(+)l(-)gamma + X (l = e, mu) is measured within a fiducial phase-space region defined by kinematic requirements on the photon and the leptons, and by isolation requirements on the photon. An experimental precision of 2.9% is achieved for the fiducial cross-section. Differential cross-sections are measured as a function of each of six kinematic variables characterising the l(+)l(-)gamma system. The data are compared with theoretical predictions based on next-to-leading-order and next-to-next-to-leading-order perturbative QCD calculations. The impact of next-to-leading-order electroweak corrections is also considered.
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