2020/06/23 by H. M. Asatrian, Hrachia M. Asatrian, H. H. Asatryan +7 · 25 citations
Physics and Astronomy · #High-Energy Particle Collisions Research #Order (exchange) #Particle physics #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #Quantum chromodynamics #Quark #hep-ph
paper · pdf · doi:10.1103/physrevd.102.033007
published in Physical review. D/Physical review. D. 102(3) (American Physical Society) · 11 pages, 1 figure
arxiv created 2020/06/23 · openalex created_date 2020/07/02 · openalex publication_date 2020/08/31 · arxiv updated 2020/09/09 · openalex updated_date 2026/08/05
We present new contributions to the decay matrix element \mathrm\ensuremathΓ12q of the Bq\ensuremath-Bq mixing complex, where q=d or s. Our new results constitute the order \ensuremathαs2Nf corrections to the penguin contributions to the Wilson coefficients entering \mathrm\ensuremathΓ12q with full dependence on the charm quark mass. This is the first step toward the prediction of the CP asymmetry afsq quantifying CP violation in mixing at next-to-next-to-leading logarithmic order (NNLO) in quantum chromodynamics (QCD) and further improves the prediction of the width difference \mathrm\ensuremathΔ\mathrm\ensuremathΓq between the two neutral-meson eigenstates. We find a sizable effect from the nonzero charm mass and our partial NNLO result decreases the NLO penguin corrections to afsq by 37% and those to \mathrm\ensuremathΔ\mathrm\ensuremathΓq by 16%. We further update the Standard-Model NLO predictions for afsq and the ratio of the width and mass differences of the Bq eigenstates: If we express the results in terms of the pole mass of the bottom quark, we find afss=(2.07\ifmmode±\else\textpm\fi0.10)\ifmmode×\else\texttimes\fi10^\ensuremath-5, afsd=(\ensuremath-4.71\ifmmode±\else\textpm\fi0.24)\ifmmode×\else\texttimes\fi10^\ensuremath-4, \mathrm\ensuremathΔ\mathrm\ensuremathΓs/\mathrm\ensuremathΔMs=\phantom\rule0ex0ex(4.33\ifmmode±\else\textpm\fi1.26)\ifmmode×\else\texttimes\fi10^\ensuremath-3, and \mathrm\ensuremathΔ\mathrm\ensuremathΓd/\mathrm\ensuremathΔMd=(4.48\ifmmode±\else\textpm\fi1.19)\ifmmode×\else\texttimes\fi10^\ensuremath-3. In the MS scheme these numbers read afss=(2.04\ifmmode±\else\textpm\fi0.11)\ifmmode×\else\texttimes\fi10^\ensuremath-5, afsd=(\ensuremath-4.64\ifmmode±\else\textpm\fi0.25)\ifmmode×\else\texttimes\fi10^\ensuremath-4, \mathrm\ensuremathΔ\mathrm\ensuremathΓs/\mathrm\ensuremathΔMs=(4.97\ifmmode±\else\textpm\fi1.02)\ifmmode×\else\texttimes\fi10^\ensuremath-3, and \mathrm\ensuremathΔ\mathrm\ensuremathΓd/\mathrm\ensuremathΔMd=(5.07\ifmmode±\else\textpm\fi0.96)\ifmmode×\else\texttimes\fi10^\ensuremath-3.