Abstract
A measurement is presented of the phi times mathcal {BR}(phi rightarrow K^{+}K^{-}) production cross section at sqrt{s} = 7 TeV using pp collision data corresponding to an integrated luminosity of 383 mathrm {upmu b^{-1}}, collected with the ATLAS experiment at the LHC. Selection of phi (1020) mesons is based on the identification of charged kaons by their energy loss in the pixel detector. The differential cross section is measured as a function of the transverse momentum, p_{mathrm {T,phi }}, and rapidity, y_{phi }, of the phi (1020) meson in the fiducial region 500 <p_{mathrm {T,phi }}< 1200 MeV, |y_{phi }|< 0.8, kaon p_{mathrm {T},K}> 230 MeV and kaon momentum p_{K}< 800 MeV. The integrated phi (1020)-meson production cross section in this fiducial range is measured to be sigma _{phi } times mathcal {BR}(phi rightarrow K^{+}K^{-}) = 570 pm 8 (stat) pm 66 (syst) pm 20 (lumi) mathrm {upmu b}.
Highlights
Perturbative quantum chromodynamics (QCD) successfully describes physics of hadronic interactions at high momentum transfer (Q2 1 GeV2), while phenomenological models are needed for soft interactions at lower momentum transfers.An accurate description of these soft interactions is required to model so-called underlying events present in hard scattering events
The differential φ × BR(φ → K + K −) cross section in the fiducial region 500 < pT,φ < 1200 MeV, |yφ| < 0.8, kaon transverse momentum pT,K > 230 MeV and kaon momentum pK < 800 MeV is shown in Fig. 4 a) as a function of pT,φ and in Fig. 4 b) as a function of |yφ| and compared to simulation
This determination is less sensitive to mismodelling of the pT,φ distribution than a determination based on the sum of the differential cross sections as a function of |yφ| and is measured to be σφ × BR(φ → K + K −) = 570 ± 8 ± 68 ± 20 μb
Summary
Perturbative quantum chromodynamics (QCD) successfully describes physics of hadronic interactions at high momentum transfer (Q2 1 GeV2), while phenomenological models are needed for soft interactions at lower momentum transfers. This paper presents a measurement with the ATLAS detector [1] of the φ interactions at (√1020)-meson s = 7 TeV, production cross section using the φ → K + K −. To avoid model-dependent extrapolations outside the detector acceptance, the cross section is measured in the fiducial region, defined as 500 < pT,φ < 1200 MeV, |yφ| < 0.8, kaon transverse momentum pT,K > 230 MeV and kaon momentum pK < 800 MeV. The fiducial range is limited to the region where the differential cross section can be measured and where correcting for the losses due to the requirements on kaon momentum is reliable. The φ(1020) production cross section presented in this paper is compared to the measurement by ALICE and to MC predictions
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