%0 Journal Article %T Probing Physics beyond the Standard Model with He/Xe clock comparison experiments %A U. Schmidt %A F. Allmendinger %A W. Heil %A S. Karpuk %A A. Scharth %A Y. Sobolev %A K. Tullney %A S. Zimmer %J Physics %D 2013 %I arXiv %X The comparison of the free precession of co-located 3He-129Xe spins (clock comparison) enables us to search for very tiny nonmagnetic spin interactions. With our setup we could establish new limits for Lorentz invariance violating interactions of spins with a relic background field which permeates the Universe and points in a preferred direction in space. %U http://arxiv.org/abs/1307.5604v1