Universal field equations for metric-affine theories of gravity

We show that almost all metric–affine theories of gravity yield Einstein equations with a non–null cosmological constant $\mathrm{\Lambda }$. Under certain circumstances and for any dimension, it is also possible to incorporate a Weyl vector field $W_{\mu }$ and therefore the presence of an anisotropy. The viability of these field equations is discussed in view of recent astrophysical observations.