2018/11/30 by Chuan-Hung Chen, Takaaki Nomura · 1 citation
Physics and Astronomy · #Boson #Diquark #High-Energy Particle Collisions Research #Particle physics #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #Quark #hep-ex #hep-ph
paper · pdf · doi:10.1103/physrevd.99.115006
published as Phys. Rev. D 99, 115006 (2019) · 28 pages, 10 figures, version accepted for publication in PRD
arxiv created 2019/06/05 · openalex publication_date 2019/06/06 · arxiv updated 2019/06/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We investigate whether a color-sextet scalar diquark (H6) coupling to the left-handed quarks contributes to the \mathrm\ensuremathΔS=2 process. It is found that the box diagrams mediated by W and H6 bosons have no contributions to \mathrm\ensuremathΔS=2 when the limit of mt=0 is used, and the flavor mixing matrices for diagonalizing quark mass matrices are introduced at the same time. When the heavy top-quark mass effects are taken into account, it is found that in addition to the W\text\ensuremath-H6 box diagrams significantly contributing to \mathrm\ensuremathΔS=2, their effects can be as large as those from the H6\text\ensuremath-H6 box diagrams. Using the parameters that are constrained by the K0\ensuremath-K0 mixing parameter \mathrm\ensuremathΔMK and the kaon indirect CP violation \ensuremathεK, we find that the left-handed color-sextet diquark can lead to the kaon direct CP violation being Re(\ensuremathε^\ensuremath'/\ensuremathε)\ensuremath∼0.3\ifmmode×\else\texttimes\fi10^\ensuremath-3. In the chosen scheme, although the diquark contribution to KL\ensuremath→\ensuremathπ0\ensuremathν\ensuremathν is small, the branching ratio of K+\ensuremath→\ensuremathπ+\ensuremathν\ensuremathν can reach the current experimental upper bound.