QCDにおけるリノーマロンの除去：理論的定式化とαs決定への応用

Tohoku University隅野行成課

UV contribution and power dependence on ΛQCD\Lambda_\mathrm{QCD} of Adler function

We formulate a way to separate UV and IR contributions to the Adler function and discuss how $\Lambda_\mathrm{QCD}^2/Q^2$ dependence is encoded in the UV contribution within perturbative QCD.Comment: 10 pages, 5 figures. v3: minor modification

QED on the lattice and numerical perturbative computation of g−2g-2

We compute the electron $g$ factor to the $\mathcal{O}(\alpha^5)$ order on the lattice in quenched QED. We first study finite volume corrections in various IR regularization methods to discuss which regularization is optimal for our purpose. We find that in QED$_L$ the finite volume correction to the effective mass can have different parametric dependences depending on the size of Euclidean time $t$ and match the `naive on-shell result' only at very large $t$ region, $t \gg L$. We adopt finite photon mass regularization to suppress finite volume effects exponentially and also discuss our strategy for selecting simulation parameters and the order of extrapolations to efficiently obtain the $g$ factor. We perform lattice simulation using small lattices to test feasibility of our calculation strategy. This study can be regarded as an intermediate step toward giving the five-loop coefficient independently of the preceding studies.Comment: 27 pages, 6 figures, 1 table, version to appear in PTE

Gradient-flow renormalon subtraction and the hadronic tau decay series

The inconsistency between the fixed-order (FO) and contour-improved (CI) representation of the QCD corrections to the inclusive hadronic tau decay width limits the precision to which the strong coupling can be determined from this process. It has recently been shown that subtracting the infrared renormalon divergence related to the gluon condensate resolves the discrepancy. Here we suggest to employ the gradient flow to define gauge-invariant regularized operators and to use the corresponding condensates in the operator product expansion. The associated rearrangement of the perturbative series results in automatic renormalon subtraction without the need to determine explicitly the Stokes constants that normalize the divergent asymptotic series. Applying this method to the gluon condensate, we find that the CI series is modified and now agrees with the (unmodified) FO series. This conclusively demonstrates the preference for the fixed-order approach, as has been advocated long ago.Comment: 10 pages, contribution to the Proceedings of the 16th International Symposium on Radiative Corrections: Applications of Quantum Field Theory to Phenomenology (RADCOR2023), 28th May - 2nd June, 2023, Crieff, Scotland, U

Determination of HQET nonperturbative matrix elements with renormalon subtraction using Fourier transform

As higher order perturbative series are available, it is becoming necessary to include nonperturbative effects in QCD calculations using the OPE. In order to systematically determine nonperturbative effects and to incorporate them into theoretical calculations, the renormalon problem should be resolved. We use a renormalon subtraction method utilizing Fourier transform to determine nonperturbative matrix elements of HQET, ⊼ and μ2π. This is the first determination performed with subtraction of the u = 1 renormalon