We present results of dynamical simulations with 2 flavours of degenerate Wilson twisted mass quarks at maximal twist in the range of pseudo scalar masses from 300 to 550 MeV. The simulations are performed at one value of the lattice spacing a \lesssim 0.1 fm. In order to have O(a) improvement and aiming at small residual cutoff effects, the theory is tuned to maximal twist by requiring the vanishing of the untwisted quark mass. Precise results for the pseudo scalar decay constant and the pseudo scalar mass are confronted with chiral perturbation theory predictions and the low energy constants F, \bar{l}_3 and \bar{l}_4 are evaluated with small statistical errors.
@article{arxiv.hep-lat/0701012,
title = {Dynamical Twisted Mass Fermions with Light Quarks},
author = {Ph. Boucaud and P. Dimopoulos and F. Farchioni and R. Frezzotti and V. Gimenez and G. Herdoiza and K. Jansen and V. Lubicz and G. Martinelli and C. McNeile and C. Michael and I. Montvay and D. Palao and M. Papinutto and J. Pickavance and G. C. Rossi and L. Scorzato and A. Shindler and S. Simula and C. Urbach and U. Wenger and ETM collaboration},
journal= {arXiv preprint arXiv:hep-lat/0701012},
year = {2010}
}