Strong interactions, driven by Quantum Chromodynamics (QCD), are a key subject in order to disentangle effects beyond the Standard Model in low-energy hadron dynamics. While at high energies strong interactions are described by the scattering of quarks and gluons, and perturbative methods apply because the strong coupling is small, hadron dynamics, on the other side, is ruled by QCD in its non-perturbative regime.
Perturbative QCD is one of the key topics of this line of research. Its main task is to determine the study of multipartonic processes relevant for hadron colliders like LHC. It also determines the scale evolution of non-perturbative quantities like parton dristribution functions.
The study of processes involving hadrons requires an appropriate treatment of strong interactions at low-energies. Several approaches are the goal of the researchers of this line: 1) Effective field theories, like Chiral Perturbation Theory or phenomenological Lagrangians, like Resonance Chiral Theory, involve analytical treatments for the study of low-energy processes with the help of working schemes like the large-Nc expansion (Nc is short for number of colours); 2) Lattice QCD is the only known non-perturbative method that can, in principle, solve QCD from first principles. The field has made enormous progress recently concerning the treatment of light quarks; 3) The study of Schwinger-Dyson equations is a very helpful tool to analyse the infrared domain of QCD; 4) Models based on QCD symmetries and dynamics with effective quark and gluon degrees of freedom constitute an excellent workbench for hadron dynamics.
At present the main research lines and topics are the followings:
- Theoretical and phenomenological studies of QCD at hadron colliders in the TeV energy range, the Tevatron at FNAL and the LHC at CERN.
- Study of hadron phenomenology in the resonance energy region: hadronic decays of the tau lepton, semileptonic decays of D mesons.
- Development of matching techniques from the study of 3 and 4 point Green functions of QCD currents in order to obtain information on strong low-energy constants of the chiral Lagrangian and the resonance chiral Lagrangian.
- Determination of the strong and weak low-energy couplings from correlation functions computed in lattice QCD.
- Study of the properties of hadrons in the Standard Model and beyond by performing realistic numerical simulations of QCD with maximally twisted mass fermions including dynamical strange and charm quark effects.
- Study of the interplay between hadrons (mesons and baryons) and their description in terms of the underlying quarks and gluons.
- To obtain from the Schwinger-Dyson equations of QCD the infrared behaviour of gluon and ghost propagators, and comparison with lattice simulations.
