Reconciling dark matter, $$ {R}_{K^{\left(\ast \right)}} $$ anomalies and (g − 2)μ in an Lμ − Lτ scenario

Abstract

We propose an anomaly free unified scenario by invocation of an extra local U(1) Lµ−Lτ gauge symmetry. This scenario simultaneously resolves the R K (*) anomalies, the dark matter puzzle and the long-standing discrepancy in muon's anomalous magnetic moment. A complex scalar (η) having nonzero L µ − L τ charge has been introduced to break this new U(1) symmetry spontaneously. Moreover, for the purpose of studying dark matter phenomenology and R K (*) anomalies in a correlated manner, we introduce an inert SU(2) L scalar doublet (Φ), a Z 2-odd real singlet scalar (S) and a Z 2-odd coloured fermion (χ) which transforms vectorially under the U(1) Lµ−Lτ symmetry. This extra gauge symmetry provides a new gauge boson Z µτ which not only gives additional contribution to both b → s transition and (g − 2) µ but also provides a crucial annihilation channel for dark matter candidate ρ 1 of the present scenario. This ρ 1 is an admixture of CPeven neutral component of Φ and S. Our analysis shows that the low mass dark matter regime (M ρ 1 60 GeV) is still allowed by the experiments like XENON1T, LHC (via Higgs invisible branching) and Fermi-LAT, making the dark matter phenomenology drastically different from the standard Inert Doublet and the Scalar Singlet models. Furthermore, the present model is also fairly consistent with the observed branching ratio of B → X s γ in 3σ range and is quite capable of explaining neutrino masses and mixings via Type-I seesaw mechanism if we add three right handed neutrinos in the particle spectrum. Finally, we use the latest ATLAS data of non-observation of a resonant + − signal at the 13 TeV LHC to constrain the mass-coupling plane of Z µτ .

Solar neutrino probes of the muon anomalous magnetic moment in the gauged $$ \mathrm{U}{(1)}_{L_{\mu }-{L}_{\tau }} $$

“…Since gauging the difference between two leptonflavour numbers is anomaly-free within the SM, these constructions provide a minimal extension of the SM gauge group without the need for extra fermions [24,25]. It has been noted that such a model can simultaneously account for the observed discrepancy in (g−2) µ and even accommodate dark matter with the correct relic abundance [18,[26][27][28][29][30][31]. Furthermore, as suggested in ref.…”

Low scale U(1)X gauge symmetry as an origin of dark matter, neutrino mass and flavour anomalies

“…The one way of cancelling the anomaly without adding more fermions is to consider equal and opposite charges for any two generations of leptons and let the charge of the third generation be zero. These are the symmetries like U(1) Le−Lµ , U(1) Lµ−Lτ which has been discussed earlier in the references [31,33,35,50]. However, if we want to consider non-zero charges for all the three lepton generations, then we need to have additional chiral fermions in our model for anomaly cancellation.…”

New Physics Probes: Atomic Parity Violation, Polarized Electron Scattering and Neutrino-Nucleus Coherent Scattering

“…Models based on the L µ − L τ gauge symmetry have recently brought a lot of attention due to some flavor anomaly [69][70][71][72][73][74][75]. The Z boson can be quite light and has no interactions with quarks at tree-level.…”