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 $\mathit{\text{et}}\mathit{\text{al.}}$, Phys. Rev. Lett. $\mathbf{\text{130}}$, 203001 (2023)] of the hyperfine splitting of the 2S${}_{1\mathrm{/}2}$ 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 $g_A{g}_A$, $g_p{g}_p$, and $g_V{g}_V$ corresponding to the exchange of a axial-vector, pseudoscalar (axionlike) or vector boson, respectively.