Violation of the equivalence principle from light scalar dark matter

Abstract

Tensor-scalar theory is a wide class of alternative theory of gravitation that can be motivated by higher dimensional theories, by models of dark matter or dark ernergy. In the general case, the scalar field will couple non-universally to matter producing a violation of the equivalence principle. In this communication, we review a microscopic model of scalar/matter coupling and its observable consequences in terms of universality of free fall, of frequencies comparison and of redshifts tests. We then focus on two models: (i) a model of ultralight scalar dark matter and (ii) a model of scalarized black hole in our Galactic Center. For both these models, we present constraints using recent measurements: atomic clocks comparisons, universality of free fall measurements, measurement of the relativistic redshift with the short period star S0-2 orbiting the supermassive black hole in our Galactic Center.

Emergent long-range interactions in Bose-Einstein condensates

“…In particular, in any theory where dark matter is an ultralight (and weakly self-interacting) scalar particle, a long-range force between baryons should emerge whenever there is s a contact interaction (however weak) between baryons and dark matter. In a broad class of scalar dark matter models, the emergent force can be of comparable strength to gravity provided that parameters satisfy (37).…”

“…Comment added -While putting the finishing touches to this paper we came across some recent works [36,37] on the subject. In particular, the effect of the emergent long range force of [1] was rediscovered using classical field theory techniques, in the case of a nonself-interacting, massive, real scalar field with nonlinear interaction with a source.…”

“…Specifically, it was shown in [36] that if the scalar field has an oscillating background with a frequency equal to the mass of the scalar field (i.e., if the BEC is formed), the mass term cancels out, resulting in the scalar field mediating a long-range force, albeit with an oscillating pre-factor. Furthermore, the approach of [36] was used in [37] to calculate the scalar profile created by the extended distribution of baryons. There it was shown that, depending on the compactness of the source, the scalar density could get significantly screened or amplified, depending on the sign of the coupling between the scalar field and baryons.…”

Detectability of ultralight scalar field dark matter with gravitational-wave detectors

“…The oscillation of the scalar field that couples with the SM particles causes time variations of physical constants such as the proton mass and the fine-structure constant. They produce the time variations of the atomic transitions as well as oscillatory force on bodies from which the constraint on the coupling to the SM particles can be obtained [18][19][20][21][22][23][24][25][26][27]. For example, hyperfine frequency comparison of 87 Rb and 133 Cs atoms has been used for this purpose [22].…”

Accurate Prediction of Clock Transitions in a Highly Charged Ion with Complex Electronic Structure

“…A particular attraction of HCI clock transitions is their exceptionally high sensitivity to a variation of the fine-structure constant α and, subsequently to dark matter searches [2][3][4].In many theories beyond the standard model, in particular those involving light scalar fields that naturally appear in cosmological models, the fundamental constants become dynamical (i.e. varying) [9][10][11][12][13][14]. If the fundamental constants, such as α, exhibit space-time variation, so are atomic spectra and clock frequencies, which is potentially detectable with atomic clocks.…”