A cosmological model based on two scalar fields is proposed. The first of these, phi, has mass mu, while the second, chi, is massless. The pair are coupled through a "Higgs portal". First, we show how the model reproduces the Friedmann equations if the square of the mass of the phi field is proportional to the cosmological constant and chi represents the quintessence field. Quantum corrections break the conformal symmetry, and the chi field acquires a mass equal to root 3g Lambda The perturbative approach with g << 1 is consistent with the bounds for m(chi); moreover, by using dimensional analysis, we estimate m(chi) << H-0 approximate to 10(-33) eV, which is in accordance with what is expected in the quintessence scenario. The acceleration of the universe is proportional to chi(2), we conclude that for very long times, the solution of the equation of motion approaches <chi > similar to m(chi)/root lambda and the universe continues to accelerate, with a constant acceleration.