Lattice QCD  (LQCD123)


The research activity of the LQCD123 group in Tor Vergata concerns the study of the strong interactions in the non-perturbative regime and their effects in certain processes (decays, meson-antimeson oscillations, vacuum polarization) of utmost relevance for the phenomenology of the Standard Model (SM) of Particle Physics. Monte Carlo simulations of the basic theory (QCD, recently also including QED corrections at the leading order in alpha_em) cleverly regulated on spacetime lattices of sufficiently large volume allow for a rigorous and systematically improvable study of the non-perturbative observables of interest, e.g. masses

and widths of the lightest hadrons as well as matrix elements of the effective electroweak Hamiltonian (in the SM and beyond) between hadron states. Besides providing a first-principle test of QCD as the correct theory of strong interactions, these computations enable extraction of the free parameters of the SM and its possible extensions from the experimental data with a controlled accuracy at the level of few-percents or better, which is the precision required to detect possible signals of New Physics.

Among the main current research topics we recall:

1) renormalized charm and bottom quark masses and leptonic decays constants f_D, f_Ds, f_B, f_Bs;

2) oscillation parameters of K-Kbar, D-Dbar and B-Bbar and constraints on SM extensions;

3) leading isospin breaking effects (LIBE) in meson masses and leptonic decay rates;

4) QED+QCD with strict locality and C* boundary conditions: from constructive quantum field theory to LIBE computations with reduced finite size effects;

5) advanced methods for non-perturbative renormalization.

Staff members involved in this research activity: G.M. de Divitiis, R. Frezzotti, N. Tantalo - in collaboration with prof. G.C. Rossi, dr. A. Vladikas, dr. P. Dimopoulos and many other researchers in the Rome area and in several European research institutions.