AXION - Neutron interferometry as Test for Standard Model and Newton Gravitational Forces

The proposal addresses some important questions, which are at the forefront of particle and nuclear physics and concern the analysis of possible deviations from the Standard Model (SM) of particle physics. As a tool for the test of the SM we propose to use quantum interference experiments with the neutron. The deviations are expected to be the phenomenological outcome of more fundamental theories, unifying all forces induced shortly after the Big Bang. Such a grand unification is an extension of the SM, containing new symmetry concepts based on supersymmetric and super-gravitational interactions. In turn, supersymmetric theories, describing interactions of point-like particles, can be part of more general theories such as string, superstring and D-brane theories. These theories predict new extra dimensions less than a millimeter in size, which can be picked up in the neutron interferometry q-bouncing experiments, measuring the phase shift of the wave function of the neutron, induced by the Newton gravitational potential generalised by the inclusion of a Yukawa term. The neutron interferometry experiments allow to probe Newton gravity at the micron scale. This is important for the check of the theoretical assertion that deviations of Newton`s gravitational law at the micron scales can be induced by supersymmetric extra dimensions and related to the smallness of the cosmological constant. The aim of the experimental part of this project is to search for these specific deviations from Newton`s gravity law provoked by axion or axion-like couplings. For that purpose a newly developed technique called "Gravity Resonance Technique" will be used, which allows for the first time to probe the energy states of bound neutrons in the gravity potential of the earth. A hypothetical axion coupling leads to a potential which is proportional to the 5th force potential and will change the energy states as a function of the range of this coupling. A second motivation for this search is that at the short range part of this "axion window" up to 10 -4 m, this neutron experiment places the only existing limit. With the new resonance technique improvement by at least two orders of magnitude can be reached. The aim of the theoretical part of this project is the analysis of all reliable candidates for physics beyond the Standard Model, which effectively induce a deviation of Newton`s gravity law at short distances with hindsight of the special setup of this experiment as well as the investigations of the obtained results concerning their relation to other fundamental properties of particle physics. These theories can also be selected according to their predictions for the electric dipole moment of the neutron, the appearance of which is a direct consequence of the violation of CP-invariance.

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