2015/12/31 by Kaori Fuyuto, W.-S. Hou, Wei-Shu Hou +1 · 57 citations
Physics and Astronomy · #Branching fraction #Coupling (piping) #Dark Matter and Cosmic Phenomena #Meson #Muon #Particle physics #Particle physics theoretical and experimental studies #Physics #Physics beyond the Standard Model #Quantum Chromodynamics and Particle Interactions #Quark #hep-ph
paper · pdf · doi:10.1103/physrevd.93.054021
published in Physical review. D/Physical review. D. 93(5) (American Physical Society) · 18 pages, 12 figures; accepted by PRD, references updated
arxiv created 2016/03/09 · openalex publication_date 2016/03/10 · arxiv updated 2016/03/23 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Anomalous b\ensuremath→s transitions from LHCb data may suggest a new massive gauge boson Z^\ensuremath' that couples to the left-handed b\ensuremath→s current, which in turn implies a coupling to the t\ensuremath→c current. In this paper, we study flavor-changing neutral current (FCNC) decays of the top quark induced by a Z^\ensuremath' boson, namely t\ensuremath→cZ^\ensuremath', based on a model of the gauged L_\ensuremathμ\ensuremath-L_\ensuremathτ symmetry (the difference between the muon and tauon numbers) with vectorlike quarks, which was introduced to explain the anomalous LHCb data. We illustrate that searching for t\ensuremath→cZ^\ensuremath' via Z^\ensuremath'\ensuremath→\ensuremathμ+\ensuremathμ^\ensuremath- with LHC Run 1 data can probe a parameter region that is unexplored by B physics for a Z^\ensuremath' mass of around O(10) GeV or greater. We further extend the model to a very light Z^\ensuremath' with mass below 400 MeV, which is motivated by the muon g\ensuremath-2 anomaly. Taking rare B and K meson decay data into account, we give upper limits on the t\ensuremath→cZ^\ensuremath' branching ratio for the light Z^\ensuremath' case, and discuss about its observability at the LHC. We also scrutinize the possibility that the decay KL\ensuremath→\ensuremathπ0Z^\ensuremath' with Z^\ensuremath'\ensuremath→\ensuremathν\ensuremathν may lead to an apparent violation of the usual Grossman-Nir bound of B(KL\ensuremath→\ensuremathπ0\ensuremathν\ensuremathν)<1.4\ifmmode×\else\texttimes\fi10^\ensuremath-9.