The effect of trace-anomaly on ω = −1 crossing in f(R,T) gravity

• The phantom-divide line crossing in f(R,T) gravity is studied.
• Quantum corrections via the account of trace anomaly is considered.
• Crossing of ω = −1 in f(R,T) gravity occurs by adding the trace anomaly effect to the theory.

We study the phantom-divide line crossing in f(R,T) gravity theories, where the gravitational Lagrangian is described by an arbitrary function of the Ricci scalar R and of the trace of the energy-momentum tensor T. Although crossing of ω = −1 does not occur at classical level, quantum contributions induce such a crossing for particular classes of f(R,T) models obtained by explicitly specifying the functional form of f. The quantum effects are considered via the account of trace (conformal) anomaly. Our results coincide with the results obtained for well-known modified theories of gravity such as f(R) and f(G) models.