Abstract
The process e+e−→K+K−η has been studied in the center-of-mass energy range from 1.59 to 2.007 GeV using the data sample of 59.5 pb−1, collected with the CMD-3 detector at the VEPP-2000 e+e− collider in 2011, 2012 and 2017. The K+K−η final state is found to be dominated by the contribution of the ϕ(1020)η intermediate state. The cross section of the process e+e−→ϕ(1020)η has been measured with a systematic uncertainty of 5.1% on the base of 3009 ± 67 selected events. The obtained cross section has been used to calculate the contribution to the anomalous magnetic moment of the muon: aμϕη(E<1.8GeV)=(0.321±0.015stat±0.016syst)×10−10, aμϕη(E<2.0GeV)=(0.440±0.015stat±0.022syst)×10−10. From the cross section approximation the ϕ(1680) meson parameters have been determined with better statistical precision, than in previous studies.
Highlights
A high-precision measurement of the cross section of e+e− → hadrons has numerous applications including, e.g., a calculation of the hadronic contribution to the muon anomalous magnetic moment (g − 2)μ and running fine structure constant
In this paper we report the results of the study of the process e+e−→K + K −η, based on 59.5 pb−1 of integrated luminosity collected by the CMD-3 detector in 2011, 2012 and 2017 in the Ec.m. range from 1.59 to 2.007 GeV
To study a detector response and determine a detection efficiency, we have developed a code for Monte Carlo (MC) simulation of our detector based on the GEANT4 [17] package so that all simulated events are subjected to the same reconstruction and selection procedures as the data
Summary
A high-precision measurement of the cross section of e+e− → hadrons has numerous applications including, e.g., a calculation of the hadronic contribution to the muon anomalous. In the BaBar study [6] it was found that the dominant intermediate mechanism in this process is e+e−→φ(1680)→φ(1020)η (in what follows φ(1020)≡φ, φ(1680)≡φ and natural units h = c = 1 are used), so the total cross section σ (e+e−→K + K −η) was subdivided into two parts: σ (e+e−→φη)·BφK + K − (for the invariant masses of kaons minv, 2K < 1045 MeV) and σNON−φ (e+e−→K + K −η) (for minv, 2K > 1045 MeV). We observe the contribution of the φη intermediate state only, and from the approximation of the e+e−→φη cross section determine the parameters of the φ meson
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