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Addressing the CKM unitarity problem with a vector-like up quark

2021/03/31 by G.C. Branco, G. C. Branco, J. T. Penedo +3
Physics and Astronomy · #B meson #CP violation #Cabibbo–Kobayashi–Maskawa matrix #High-Energy Particle Collisions Research #Meson #Mixing (physics) #Order (exchange) #Particle physics #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #Quark #Unitarity #Vector meson #hep-ph

paper · pdf · doi:10.1007/jhep07(2021)099

24 pages, 4 figures, 2 tables; comments and references added

arxiv created 2021/04/01 · openalex publication_date 2021/07/01 · arxiv updated 2021/08/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

A bstract We point out that hints of deviations from unitarity in the first row of the CKM matrix may be explained by the presence of a single vector-like top. We study how the stringent experimental constraints arising from CP Violation in the kaon sector and from meson mixing such as D0\hbox- D0,K0\hbox- K0 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mi>D</mml:mi><mml:mn>0</mml:mn></mml:msup><mml:mo>‐</mml:mo><mml:msup><mml:mover><mml:mi>D</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mn>0</mml:mn></mml:msup><mml:mo>,</mml:mo><mml:msup><mml:mi>K</mml:mi><mml:mn>0</mml:mn></mml:msup><mml:mo>‐</mml:mo><mml:msup><mml:mover><mml:mi>K</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mn>0</mml:mn></mml:msup></mml:math> and Bd,s0\hbox- Bd,s0 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mi>B</mml:mi><mml:mrow><mml:mi>d</mml:mi><mml:mo>,</mml:mo><mml:mi>s</mml:mi></mml:mrow><mml:mn>0</mml:mn></mml:msubsup><mml:mo>‐</mml:mo><mml:msubsup><mml:mover><mml:mi>B</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mrow><mml:mi>d</mml:mi><mml:mo>,</mml:mo><mml:mi>s</mml:mi></mml:mrow><mml:mn>0</mml:mn></mml:msubsup></mml:math> can be satisfied in the proposed framework. In order for the deviations from unitarity to be of the required size while keeping the theory perturbative, the new top quark should have a mass m T ≲ 7 TeV which could be probed in upcoming experiments at the energy frontier.

Citations