A recently re-discovered variant of the Backus-Gilbert algorithm for spectral reconstruction enables the controlled determination of smeared spectral densities from lattice field theory correlation functions. A particular advantage of this approach is the \emph{a priori} specification of the kernel with which the underlying spectral density is smeared, allowing for variation of its peak position, smearing width, and functional form. If the unsmeared spectral density is sufficiently smooth in the neighborhood of a particular energy, it can be obtained from an extrapolation to zero smearing-kernel width at fixed peak position. A natural application for this approach is scattering processes summed over all hadronic final states. As a proof-of-principle test, an inclusive rate is computed in the two-dimensional O(3) sigma model from a two-point correlation function of conserved currents. The results at finite and zero smearing radius are in good agreement with the known analytic form up to energies at which 40-particle states contribute, and are sensitive to the 4-particle contribution to the inclusive rate. The straight-forward adaptation to compute the $R$-ratio in lattice QCD from two-point functions of the electromagnetic current is briefly discussed.
Study on the systematic effects on $b \to c$ inclusive semileptonic decays
University of Southampton（南安普顿大学）；STAG Research Center, University of Southampton（南安普顿大学STAG研究中心）；High Energy Accelerator Research Organization (KEK)（高能加速器研究机构（KEK））；SOKENDAI (The Graduate University for Advanced Studies)（综合研究大学院大学）；CERN（欧洲核子研究中心）
本文通过格点QCD计算$B_s \to X_c l ν_l$衰变，探讨系统误差来源，包括雅各比平滑的影响、源-汇分离变化及包络重建方法的固有不确定性，并展示如何通过将地面态贡献视为排除性衰变来抑制系统误差。
Universität Heidelberg（海德堡大学）；ExtreMe Matter Institute EMMI, GSI（GSI极端物质研究所（EMMI））；University of Stavanger（斯塔万格大学）；Perimeter Institute for Theoretical Physics（圆周理论物理研究所）
