Improved constraints on exotic interactions between electron and proton in hydrogen

Atomic spectroscopy can be used to search for new bosons that carry exotic forces between elementary fermions. A comparison of a recent precise measurement [Bullis \textit{et al.}, Phys. Rev. Lett. \textbf{130}, 203001 (2023)] of the hyperfine splitting of the 2S$_{1/2}$ electronic levels of hydrogen and up-to-date bound-state quantum electrodynamics theory yields improved constraints on electron-proton exotic interactions of the dimensionless coupling strengths $g_Ag_A$, $g_pg_p$, and $g_Vg_V$ corresponding to the exchange of a axial-vector, pseudoscalar (axionlike) or vector boson, respectively.