Detailed Discussion of a linear electric field frequency shift induced   in confined gases by a magnetic field gradient: Implications for neutron   electric dipole moment experiments
  The search for particle electric dipole moments (edm) is one of the best places to look for physics beyond the standard model because the size of time reversal violation predicted by the standard model is incompatible with present ideas concerning the creation of the Baryon-Antibaryon asymmetry. As the sensitivity of these edm searches increases more subtle systematic effects become important. We develop a general analytical approach to describe a systematic effect recently observed in an electric dipole moment experiment using stored particles \cite{JMP}. Our approach is based on the relationship between the systematic frequency shift and the velocity autocorrelation function of the resonating particles. Our results, when applied to well-known limiting forms of the correlation function, are in good agreement with both the limiting cases studied in recent work that employed a numerical/heuristic analysis. Our general approach explains some of the surprising results observed in that work and displays the rich behavior of the shift for intermediate frequencies, which has not been previously studied. 
S.K. Lamoreaux, R. Golub