On (g − 2)μ from gauged U(1)X

We investigate an economical explanation for the (g − 2)μ anomaly with a neutral vector boson from a spontaneously broken U(1)X gauge symmetry. The Standard Model fermion content is minimally extended by 3 right-handed neutrinos. Using a battery of complementary constraints, we perform a thorough investigation of the renormalizable, quark flavor-universal, vector-like U(1)X models, allowing for arbitrary kinetic mixing. Out of 419 models with integer charges not greater than ten, only 7 models are viable solutions, describing a narrow region in model space. These are either Lμ − Lτ or models with a ratio of electron to baryon number close to −2. The key complementary constraints are from the searches for nonstandard neutrino interactions. Furthermore, we comment on the severe challenges to chiral U(1)X solutions and show the severe constraints on a particularly promising such candidate.