2020/10/31 by Leendert Hayen, L. Hayen · 1 citation
Physics and Astronomy · #Hadron #High-Energy Particle Collisions Research #Isoscalar #Isovector #Mathematical physics #Nucleon #Particle physics #Particle physics theoretical and experimental studies #Physics #Physics beyond the Standard Model #Quantum Chromodynamics and Particle Interactions #Quantum chromodynamics #Sum rule in quantum mechanics #hep-lat #hep-ph #nucl-ex #nucl-th
paper · pdf · doi:10.1103/physrevd.103.113001
published as Phys. Rev. D 103, 113001 (2021) · 27 pages, 6 figures
openalex created_date 2020/10/22 · openalex publication_date 2021/06/01 · arxiv created 2021/06/15 · arxiv updated 2021/06/16 · openalex updated_date 2026/08/06
We present an O(\ensuremathα) Standard Model calculation of the inner radiative corrections to Gamow-Teller \ensuremathβ decays. We find that a priori contributions arise from the photonic vertex correction and \ensuremathγW box diagram. Upon evaluation most elastic contributions vanish due to crossing symmetry or cancellation between isoscalar and isovector photonic contributions, leaving only the polarized parity-odd contribution, i.e., the Gamow-Teller equivalent of the well-known axial \ensuremathγW box contribution for Fermi decays. We show that weak magnetism contributes significantly to the Born amplitude, and consider additional hadronic contributions at low energy using a holomorphic continuation of the polarized Bjorken sum rule constrained by experimental data. We perform the same procedure for the Fermi inner radiative correction through a combination of the running of Bjorken and Gross-Llewellyn Smith sum rules. We discuss heavy flavor, higher-twist, and target mass corrections and find a significant increase at low momentum from the latter. We find \mathrm\ensuremathΔRA=0.02532(22) and \mathrm\ensuremathΔRV=0.02473(27) for axial and vector inner radiative corrections, respectively, resulting in \mathrm\ensuremathΔRA\ensuremath-\mathrm\ensuremathΔRV=0.60(5)\ifmmode×\else\texttimes\fi10^\ensuremath-3, which allows us to extract gA0 for the first time to our knowledge. We discuss consequences for comparing experimental data to lattice calculations in beyond Standard Model fits. Further, we show how some traditional \ensuremathβ decay calculations contain part of this effect but fail to account for cancellations in the full O(\ensuremathα) result. Finally, we correct for a double-counting instance in the isospin T=1/2 mirror decay extraction of |Vud|, the up-down matrix element of the Cabibbo-Kobayashi-Maskawa matrix element, resolving a long-standing tension and leading to increased precision.