Unified framework for <em>B</em>-anomalies, muon <em>g</em> – 2 and neutrino masses

We present a model of radiative neutrino masses which also resolves anomalies reported in <em>B</em>-meson decays, <span class="mathjax-tex">\( {R}_{D^{\left(\ast \right)}} \)</span> and <span class="mathjax-tex">\( {R}_{K^{\left(\ast \right)}} \)</span>, as well as in muon <em>g –</em> 2 measurement, Δ<em>a</em>_<em>μ</em>. Neutrino masses arise in the model through loop diagrams involving TeV-scale leptoquark (LQ) scalars <em>R</em>₂ and <em>S</em>₃. Fits to neutrino oscillation parameters are obtained satisfying all flavor constraints which also explain the anomalies in <span class="mathjax-tex">\( {R}_{D^{\left(\ast \right)}} \)</span>, <span class="mathjax-tex">\( {R}_{K^{\left(\ast \right)}} \)</span> and Δ<em>a</em>_<em>μ</em> within 1 <em>σ</em>. An isospin-3/2 Higgs quadruplet plays a crucial role in generating neutrino masses; we point out that the doubly-charged scalar contained therein can be produced in the decays of the <em>S</em>₃ LQ, which enhances its reach to 1.1 (6.2) TeV at <span class="mathjax-tex">\( \sqrt{s} \)</span> = 14 TeV high-luminosity LHC (<span class="mathjax-tex">\( \sqrt{s} \)</span> = 100 TeV FCC-hh). We also present flavor-dependent upper limits on the Yukawa couplings of the LQs to the first two family fermions, arising from non-resonant dilepton (<em>pp → ℓ</em>⁺<em>ℓ</em>^<em>–</em>) processes mediated by <em>t</em>-channel LQ exchange, which for 1 TeV LQ mass, are found to be in the range (0<em>.</em>15 <em>–</em> 0<em>.</em>36). These limits preclude any explanation of <span class="mathjax-tex">\( {R}_{D^{\left(\ast \right)}} \)</span> through LQ-mediated <em>B</em>-meson decays involving <em>ν</em>_<em>e</em> or <em>ν</em>_<em>μ</em> in the final state. We also find that the same Yukawa couplings responsible for the chirally-enhanced contribution to Δ<em>a</em>_<em>μ</em> give rise to new contributions to the SM Higgs decays to muon and tau pairs, with the modifications to the corresponding branching ratios being at (2–6)% level, which could be tested at future hadron colliders, such as HL-LHC and FCC-hh.