3,159 research outputs found

    Ethyl 1-(4-meth­oxy­benz­yl)-3-p-tolyl-1H-pyrazole-5-carboxyl­ate

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    In the title compound, C21H22N2O3, the pyrazole ring makes dihedral angles of 12.93 (8) and 69.38 (8)°, respectively, with the tolyl and meth­oxy­benzyl rings

    Momentum-dependence of ρω\rho-\omega mixing in the pion vector form factor and its effect on (g2)μ(g-2)_\mu

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    The inclusion of the ρω\rho-\omega mixing effect is crucial for a good description of the pion electromagnetic form factor in the e+eπ+πe^+e^- \rightarrow \pi^+\pi^- process, which quantifies the two-pion contribution to the anomalous magnetic moment of the muon aμa_\mu. In this paper, we try to analyze the impact of the momentum-dependence of the ρω\rho-\omega mixing within the framework of resonance chiral theory. The momentum-dependence of the ρω\rho-\omega mixing is incorporated due to the calculation of loop contributions at the next-to-leading order in the 1/NC1/N_C expansion. The work of {[}Y. H. Chen, D. L. Yao, and H. Q. Zheng, Commun. Theor. Phys. 69 (2018) 1{]} is revisited taking into account the contribution due to the kaon mass splitting in the kaon loops and the latest experimental data. We perform two kinds of fits (with momentum-independent or momentum-dependent ρω\rho-\omega mixing amplitude) describing the e+eπ+πe^+e^-\rightarrow \pi^+\pi^- and τντ2π\tau\rightarrow \nu_{\tau}2\pi data in the energy region of 600\sim900 MeV and the decay width of ωπ+π\omega \rightarrow \pi^+\pi^-, and compare their results. It is found that taking account of the momentum-dependence of ρω\rho-\omega mixing can describe the pion vector form factor data a little better. For the contribution to the anomalous magnetic moment of the muon aμππ[0.6,0.9]GeVa_\mu^{\pi\pi}|_{[0.6,0.9]\text{GeV}}, the values of the results in the fits considering the momentum-dependent ρω\rho-\omega mixing amplitude are agree well with those in the fits without including the momentum-dependence of the ρω\rho-\omega mixing within errors. In addition, based on the fitted values of the involved parameters, we find that in the decay width of ωπ+π\omega \rightarrow \pi^+\pi^- the contribution from the direct ωIππ\omega_I\pi\pi coupling is comparable with the contribution due to the ρω\rho-\omega mixing.Comment: 21 pages, 4 figures. arXiv admin note: text overlap with arXiv:1710.1144
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