Nonanalytic metric in the presence of gravitomagnetic monopoles
  The nonanalytic property of metric resulting from the presence of gravitomagnetic monopoles is considered. The curvature tensors, dual curvature tensors, dual Einstein tensor (and hence the gravitational field equation of gravitomagnetic matter) expressed in terms of nonanalytic metric are analyzed. It is shown that the spinor gravitomagnetic monopole may be one of the potential origins of the cosmological constant. An alternative approach to the cosmological constant problem is thus proposed based on the concept of gravitomagnetic monopole. 
Jian Qi Shen