Precision tests of the J/ψ from full lattice QCD: mass, leptonic width and radiative decay rate to η_c
G. C. Donald, C. T. H. Davies, R. J. Dowdall, E. Follana, K. Hornbostel, J. Koponen, G. P. Lepage, C. McNeile
备注：
20 pages, 16 figures. Added some text plus a figure and two tables comparing the time moments of the charmonium vector correlator to results extracted from experiment for the charm contribution to e^+e^- -> hadrons. This allows a 1.5% test of QCD. Further minor amendments to the text. Version accepted for publication by Physical Review D
首次计算了海中u、d、s夸克的格点量子色动力学的J/π质量、轻子宽度和辐射衰变率γ η c。我们使用高度改进的交错夸克形式主义和非微扰归一化矢量流的轻子和辐射衰变率。计算结果为：M_{J/ψ} - M_{η_c} = 116.5（3.2）MeV，Γ（J/ε to e^+e^-）= 5.48（16）keV，Γ（J/ε to γη_c）= 2.49（19）keV.前两个结果与实验符合得很好，其中的Γ（J/ε to e^+e^-）提供了对QCD中衰变矩阵元的检验，与CKM的不确定度无关，误差为2%。同时，关联函数的时间矩的结果可以与粲对Γ（e^+e^-对强子）的贡献值进行比较，给出QCD的1.5%检验。我们的结果表明，改进的实验误差将使得从Γ（J/ω到γη_c）的类似强检验成为可能。
英文摘要：
We calculate the J/ψ mass, leptonic width and radiative decay rate to γη_c from lattice QCD including u, d and s quarks in the sea for the first time. We use the Highly Improved Staggered Quark formalism and nonperturbatively normalised vector currents for the leptonic and radiative decay rates. Our results are: M_{J/ψ} -M_{η_c} = 116.5(3.2) MeV; Γ(J/ψ to e^+e^-) = 5.48(16) keV; Γ(J/ψ to γη_c) = 2.49(19) keV. The first two are in good agreement with experiment, with Γ(J/ψ to e^+e^-) providing a test of a decay matrix element in QCD, independent of CKM uncertainties, to 2%. At the same time results for the time moments of the correlation function can be compared to values from the charm contribution to Γ(e^+e^- to hadrons), giving a 1.5% test of QCD. Our results show that an improved experimental error would enable a similarly strong test from Γ(J/ψ to γη_c).
Lattice Calculation of Light Meson Radiative Leptonic Decays
Physics Department, Brookhaven National Laboratory（布鲁克海文国家实验室物理系）；School of Physics and Astronomy, The University of Edinburgh（爱丁堡大学物理与天文学院）；Physics Department, Columbia University（哥伦比亚大学物理系）；School of Physics, Peking University（北京大学物理学院）；Collaborative Innovation Center of Quantum Matter（量子物质协同创新中心）；Center for High Energy Physics, Peking University（北京大学高能物理中心）；RIKEN-BNL Research Center, Brookhaven National Laboratory（布鲁克海文国家实验室理研-BNL研究中心）；Physics Department, University of Connecticut（康涅狄格大学物理系）；School of Physics and Astronomy, University of Southampton（南安普顿大学物理与天文学院）
