Abstract
We demonstrate that an atom placed in a constant background interacting with the electronic axial-vector current exhibits a new type of parity-breaking transverse magnetoelectric polarizability. Within beyond-Standard-Model (BSM) frameworks, such as the Lorentz-violating Standard Model Extension, such constant backgrounds are considered to be condensates of Planck-scale fields, thus, precision measurements of the magnetoelectric polarizability is able to constrain non-trivial BSM physics. Indeed, we demonstrate that the contribution to this effect within the Standard Model due to weak interaction is strongly suppressed, the effect virtually being purely exotic. We calculate magnetoelectric polarizability for a simple atom and discuss its observability.
Highlights
Lorentz invariance has been an underlying principle of virtually all modern physical theories since their emergence, including quantum field theory and high-energy physics
With the advent of the string theory and other attempts to find a consistent description of quantum gravity, it turned out that this symmetry could be spontaneously broken on an energy scale close to the Planck energy [1]
Quite recently, Petr Horava presented an example of a field theory, whose non-Lorentzian behavior in the highenergy regime results in power-counting renormalizability, whereas in the low-energy regime, the conventional SO(1, 3) symmetry group is restored and the theory reproduces General Relativity [3]
Summary
Lorentz invariance has been an underlying principle of virtually all modern physical theories since their emergence, including quantum field theory and high-energy physics. Quite recently, Petr Horava presented an example of a field theory, whose non-Lorentzian behavior in the highenergy regime results in power-counting renormalizability, whereas in the low-energy regime, the conventional SO(1, 3) symmetry group is restored and the theory reproduces General Relativity [3]. These discoveries have triggered interest in precision tests of Lorentz invariance one could perform at attainable energies, as a window into beyond-Standard-Model (BSM) physics. The paper is organized as follows: in Sec. 2, we introduce the setup of the problem in question and evaluate the magnetoelectric polarizability of an atom; Sec. 3 discusses Standard-Model contributions to the ME effect due to weak interaction; the concluding Sec. 4 summarizes the results obtained
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