Searching for Flavored Gauge Bosons

Abstract

Standard Model may allow an extended gauge sector with anomaly-free flavored gauge symmetries, such as $L_i-L_j$, $B_i-L_j$, and $B-3L_i$, where $i,j=1,2,3$ are flavor indices. We investigate phenomenological implications of the new flavored gauge boson $Z^{\prime }$ in the above three classes of gauge symmetries. Focusing on the gauge boson mass above 5 GeV, we use the lepton universality test in the $Z$ and $\tau /\mu$ decays, LEP searches, LHC searches, neutrino trident production bound, and LHC $Z\to 4\mu$ searches to put constraints on the $g^{\prime }-M_{Z^{\prime }}$ plane. When $L_1$ is involved, the LEP bounds on the $e^{-}{e}^{+}\to {\ell }^{-}{\ell }^{+}$ processes give the most stringent bounds, while the LHC bound becomes the strongest constraints in the large $M_{Z^{\prime }}$ region when $B_i$ is involved. The bound from $Z\to 4\mu$ productions, which is applicable for $L_2$-involved scenarios, provides stringent bounds in the small $M_{Z^{\prime }}$ region. One exception is the $B-3L_2$ scenario, in which case only a small region is favored due to the lepton universality.

Comments: v3: updated LHC bounds for B-3L_i models