Chen, Chuan-HungChuan-HungChenChiang, Cheng-WeiCheng-WeiChiangde la Vega, Leon M. G.Leon M. G.de la Vega2026-01-022026-01-022025-09-05https://scholars.lib.ntu.edu.tw/handle/123456789/734949Right-handed neutrinos νR play a crucial role in flavor-changing neutral-current processes with missing energy, such as (Figure presented.) and (Figure presented.), where Belle-II reports unexpectedly large branching fraction in B→Kνν¯ decays. Assuming νR is the partner of the active neutrino νL in the standard model, a Dirac-type neutrino framework emerges. We investigate a scenario of radiative Dirac neutrino mass generation in a scalar leptoquark (LQ) model with a global U(1)X symmetry to suppress Majorana mass, tree-level Dirac mass, and diquark couplings. The simplest LQ realization consists of two S1 = (3, 1, −1/3) LQs with distinct U(1)X charges. A non-Casas-Ibarra parametrization is proposed to match neutrino data with fewer model parameters. Imposing current experimental constraints from meson mixing and lepton flavor-violating processes, we find that right-handed neutrino effects can significantly enhance B→K∗νν¯ and K+→π+νν¯. Additionally, the model predicts excesses in RD from B→Dτν¯ that remain within 1σ of current experimental data.Non-Standard Neutrino PropertiesRare Decays[SDGs]SDG7journal article10.1007/jhep09(2025)055