ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., Fiorini, L., et al. (2015). Measurement of the WW plus WZ cross section and limits on anomalous triple gauge couplings using final states with one lepton, missing transverse momentum, and two jets with the ATLAS detector at root s=7 TeV. J. High Energy Phys., 01(1), 049–42pp.
Abstract: The production of a W boson decaying to ev or μv in association with a W or Z boson decaying to two jets is studied using 4.6 fb(-1) of proton-proton collision data at root s = 7 TeV recorded with the ATLAS detector at the LHC. The combined WW + WZ cross section is measured with a significance of 3.4 sigma and is found to be 68 +/- 7 (stat.) +/- 19 (syst.) pb, in agreement with the Standard Model expectation of 61.1 +/- 2.2 pb. The distribution of the transverse momentum of the dijet system is used to set limits on anomalous contributions to the triple gauge coupling vertices and on parameters of an effective-field-theory model.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2017). Measurement of the Y(nS) polarizations in pp collisions at root s=7 and 8 TeV. J. High Energy Phys., 12(12), 110–60pp.
Abstract: The polarization of the (sic) (1S), (sic) (2S) and (sic) (3S) mesons, produced in pp collisions at centre-of-mass energies root s = 7 and 8TeV, is measured using data samples collected by the LHCb experiment, corresponding to integrated luminosities of 1 and 2 fb(-1), respectively. The measurements are performed in three polarization frames, using (sic) -> μμdecays in the kinematic region of the transverse momentum p(T)((sic)) < 30 GeV/c and rapidity 2.2 < y((sic)) < 4.5. No large polarization is observed.
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LHCb Collaboration(Aaij, R. et al), Jaimes Elles, S. J., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Rebollo De Miguel, M., et al. (2024). Measurement of the Z boson production cross-section in pp collisions at √s=5.02 TeV. J. High Energy Phys., 02(2), 070–38pp.
Abstract: The first measurement of the Z boson production cross-section at centre-of-mass energy v s = 5.02TeV in the forward region is reported, using pp collision data collected by the LHCb experiment in year 2017, corresponding to an integrated luminosity of 100 +/- 2 pb-1. The production cross-section is measured for final-state muons in the pseudorapidity range 2.0 <. < 4.5 with transverse momentum pT > 20 GeV/c. The integrated cross-section is determined to be sZ.mu+mu- = 39.6 +/- 0.7(stat) +/- 0.6(syst) +/- 0.8(lumi) pb for the di-muon invariant mass in the range 60 < M μμ< 120 GeV/c2. This result and the differential cross-section results are in good agreement with theoretical predictions at next-to-next-to-leading order in the strong coupling constant. Based on a previous LHCb measurement of the Z boson production cross-section in pPb collisions at v sNN = 5.02TeV, the nuclear modification factor RpPb is measured for the first time at this energy. The measured values are 1.2+0.5 -0.3(stat) +/- 0.1(syst) in the forward region (1.53 < y* μ< 4.03) and 3.6+1.6 -0.9(stat)+/- 0.2(syst) in the backward region (-4.97 < y* μ< -2.47), where y* μrepresents the muon rapidity in the centre-of-mass frame.
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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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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2015). Measurement of the Z plus b-jet cross-section in pp collisions at root s=7 TeV in the forward region. J. High Energy Phys., 01(1), 064–15pp.
Abstract: The associated production of a Z boson or an off-shell photon gamma* with a bottom quark in the forward region is studied using proton-proton collisions at a centre-of-mass energy of 7TeV. The Z bosons are reconstructed in the Z/gamma* -> mu(+)mu(-) final state from muons with a transverse momentum larger than 20 GeV, while two transverse momentum thresholds are considered for jets (10 GeV and 20 GeV). Both muons and jets are reconstructed in the pseudorapidity range 2.0 < eta < 4.5. The results are based on data corresponding to 1.0 fb(-1) recorded in 2011 with the LHCb detector. The measurement of the Z+b-jet cross-section is normalized to the Z+jet cross-section. The measured cross-sections are (Z/ (mu+ mu-) + b-jet) = 295 60 (stat) 51 (syst) 10 (lumi) fb (0.1) for p T(jet) > 10 GeV, and (Z/ (mu+ mu-) + b-jet) = 128 36 (stat) 22 (syst) 5 (lumi) fb (0.2) for p T(jet) > 20 GeV.
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