Constraining scalar dark matter with Big Bang nucleosynthesis and atomic spectroscopy

Scalar dark matter can interact with Standard Model (SM) particles, altering the fundamental constants of Nature in the process. Changes in the fundamental constants during and prior to Big Bang nucleosynthesis (BBN) produce changes in the primordial abundances of the light elements. By comparing the measured and calculated (within the SM) primordial abundance of $^{4}$He, which is predominantly determined by the ratio of the neutron-proton mass difference to freeze-out temperature at the time of weak interaction freeze-out prior to BBN, we are able to derive stringent constraints on the mass of a scalar dark matter particle $\phi$ together with its interactions with the photon, light quarks and massive vector bosons via quadratic couplings in $\phi$, as well as its interactions with massive vector bosons via linear couplings in $\phi$. We also derive a stringent constraint on the quadratic interaction of $\phi$ with the photon from recent atomic dysprosium spectroscopy measurements.