A New Interpretation of Einstein's Cosmological Constant
  A new approach to the cosmological constant problem is proposed by modifying Einstein's theory of general relativity, using instead a scalar-tensor theory of gravitation. This theory of gravity crucially incorporates the concept of quantum symmetry breaking. The role of the cosmological constant $\lambda$ as a graviton mass in the weak-field limit is necessarily utilized. Because $\lambda$ takes on two values as a broken symmetry, so does the graviton mass -- one of which cannot be zero. Gravity now exhibits both long- and short-range forces, by introducing hadron bags into strong interaction physics using a nonlinear, self-interacting scalar $\sigma$-field coupled to the gravitational Lagrangian. 
Thomas L. Wilson
gr-qc hep-th