Novel and Updated Bounds on Flavor-Violating Z Interactions in the Quark Sector

Abstract

We derive bounds on the flavor-violating (FV) couplings of the $Z$ boson to quarks and present future sensitivity projections. Our analysis shows that the current bounds on the FV couplings are $\mathcal{O}(10^{-9})$ for the $Z$ couplings to $cu$ and $sd$, $\mathcal{O}(10^{-7})$ for $bd$, $\mathcal{O}(10^{-6})$ for $bs$, and $\mathcal{O}(10^{-3})$ for $tu$ and $tc$. Overall, low-energy flavor experiments provide significantly stronger constraints on these FV couplings than current collider searches.

Figures (4)

• Figure 1: The FV hadronic decays of the $Z$ gauge boson with $i\neq j$, that are originated from the interaction in Eq. (\ref{['eq:FV_Z_cpoupling']}).
• Figure 2: The FV meson oscillations with $i\neq j$, that are originated from the interactions in Eq. (\ref{['eq:FV_Z_cpoupling']}).
• Figure 3: The FV meson Decays, where the meson is made of different flavor quark-antiquark; and it decays into same flavor leptons via the $Z$ gauge boson.
• Figure 4: The current bounds and future projections of the FV $Z$ couplings to quarks ($|g_{L,R}^{ij}|$) given in Eq. (\ref{['eq:FV_Z_cpoupling']}).