Isotope shift (IS) in atomic spectra is sensitive to a new interaction between the electron and the neutron. In the standard model (SM) of particle physics, the finite nuclear mass and size varying from one isotope to another cause the IS. Since the theoretical calculation of IS is not easy, even in the SM, we introduce a new method to search for the new interaction. Our method employs a generalization of the King linearity of IS, the generalized IS linearity.
We apply various generalized linearities to recent IS data of Ytterbium (Yb) and illustrate constraints on the new interaction.

References
K. Mikami, MT, Y.Yamamoto, EPJC 77, 896 (2017)
K. Ono, MT et al. PRX 12, 021033 (2022)