Conformal anomaly and large-scale gravitational coupling

We present a model in which the breakdown of conformal symmetry of a quantum stress-tenser due to the trace anomaly is related to a cosmological effect in a gravitational model. This is done by characterizing the traceless part of the quantum stress-tenser in terms of the stress-tensor of a conformal invariant classical scalar field. We introduce a conformal frame in which the anomalous trace is identified with a cosmological constant. In this conformal frame we establish the Einstein field equations by connecting the quantum stress-tenser with the large-scale distribution of matter in the universe.