The exploration of fundamental interactions between subatomic particles led to the particle physics Standard Model which remains unchallenged by any lab experiment. However, some serious theoretical and cosmological clues reveal shortcomings in the Standard Model and deviations are expected. This new physics is searched for at large colliders with energies of the order of the electroweak scale and beyond. With a different philosophy, one can expect the new physics to show up at very low energy using atypical experimental techniques. This thesis deals with short-range spin-dependent new forces which are at the heart of the low energy precision physics. A hyperpolarized helium 3 gas was used as a probe of this new sub-mm interaction. This manuscript present the best exclusion limit on the strength of a scalar-pseudoscalar coupling gsgp for ranges between 1 μm and 100 μm, which correspond to sub-eV masses.

Contact : blanc@ill.fr