In this article, we have considered an extension of the inert Higgs doublet model with SU (2)L singlet vector like fermions. Our model is capable of addressing some interesting anomalous results in b → s + − decays (like R(K ( * ) )) and in muon (g − 2). Apart from explaining these anomalies, and being consistent with other flavour data, the model satisfies relevant constraints in the dark matter sector, while remaining within the reach of ongoing direct detection experiments. The model also produces signatures at the large hadron collider (LHC) with final states comprised of dilepton, dijet and missing energy, providing signals to be probed at higher luminosity.

We study a generic leptophilic U(1)X extension of the standard model with a light gauge boson. The U(1)X charge assignments for the leptons are guided by lepton universality violating (LUV) observables in semileptonic b → sℓℓ decays, muon anomalous magnetic moment and the origin of leptonic masses and mixing. Anomaly cancellation conditions require the addition of new chiral fermions in the model, one of which acts as a dark matter (DM) candidate when it is stabilised by an additional $$ {\mathcal{Z}}_2 $$ Z 2 symmetry. From our analysis, we show two different possible models with similar particle content that lead to quite contrasting neutrino mass origin and other phenomenology. The proposed models also have the potential to address the anomalous results in b → cℓνℓ decays like R(D), R(D∗), electron anomalous magnetic moment and the very recent KOTO anomaly in the kaon sector. We also discuss different possible collider signatures of our models which can be tested in future.

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We consider a singlet fermionic dark matter (DM) χ in a gauged U(1) B-3L i extension of the Standard Model (SM), with i ⋲ e, μ, τ, and derive bounds on the allowed parameter space, considering its production via freeze-in mechanism. The DM communicates with the SM only through flavorful vector-portal Z B3L due to its non-trivial charge x under U(1) B-3L i , which also guarantees the stability of the DM over the age of the Universe for x ≠ {±3/2, ±3}. Considering Z B3L to lie within the mass range of a few MeV up to a few GeV, we obtain constraints on the gauge coupling g B3L from the requirement of producing right relic abundance. Taking limits from various (present and future) experimental facilities, e.g., NuCal, NA64, FASER, SHiP into account, we show that the relic density allowed parameter space for the frozen in DM can be probed with g B3L ≳ 10-8 for both mχ < m ZB3L/2 and mχ ≳ m ZB3L, while g B3L ≲ 10-8 remains mostly unconstrained. We also briefly comment on the implications of neutrino mass generation via Type-I seesaw and anomalous (g-2) μ in context with B-3Lμ gauged symmetry.

We study flavor changing neutral current decays of B and K mesons in the dark U(1)D model, with the dark photon/dark Z mass between 10 MeV and 2 GeV. Although the model provides an improved fit (compared to the standard model) to the differential decay distributions of B → K(∗)ℓ+ℓ−, with ℓ = μ, e, and Bs→ ϕμ+μ−, the allowed parameter space is ruled out by measurements of atomic parity violation, K+→ μ+ + invisible decay, and $$ {B}_s-{\overline{B}}_s $$ B s − B ¯ s mixing, among others. To evade constraints from low energy data, we extend the model to allow for (1) additional invisible ZD decay, (2) a direct vector coupling of ZD to muons, and (3) a direct coupling of ZD to both muons and electrons, with the electron coupling fine-tuned to cancel the ZD coupling to electrons via mixing. We find that only the latter case survives all constraints.