Supplemental Material：Strong coupling of excitons in a two-dimensional atomic crystal with quasi bound state in the continuum supported by a single nanoparticle

details on the fitting absorption corss-section by using Fano modified Formula, the multipole decomposition of the far-field scattering, the artificial permittivity of WS2 monolayer described by a sum of Lorentzian oscillators, the affection of WS2 monolayer position on the coupling behavior, and the quantitative analysis of mode volume V and the number of excitons involved in coupling N