  We have explored twisted mass LQCD (tmLQCD) analytically using chiral
perturbation theory, including discretization effects up to O(a^2), and working
at next-to-leading (NLO) order in the chiral expansion. In particular we have
studied the vacuum structure, and calculated the dependence of pion masses and
decay constants on the quark mass, twisting angle and lattice spacing. We give
explicit examples for quantities that both are and are not automatically
improved at maximal twisting.
