### Light quarks

Using lattice QCD, D. Becirevic has worked on several aspects of kaon physics :

the semileptonic form factor of the K, crucial to assess precisely the Cabbibo angle,

the `K_0`-`\bar{K}_0` mixing and the decay `K \to \pi \pi`, in collaboration with Roma, Southampton and Valencia. This study required to solve some
problems realted to weak non-leptonic interactions (renormalisation of 4-quark operators on the lattice).

In addition, S. Descotes-Genon has studied the radiative corrections affecting semi-leptonic processes for pseudoscalar mesons at low energy.

### Heavy quarks

A team (D. Becirevic, S. Descotes-Genon, A. Le Yaouanc, L. Oliver, O. Pène et J.C. Raynal) is interested in the decays of B mesons. These mesons, containing a b quark, are particularly convenient to study CP violation in the quark sector. Very accurate results come from the current B factories (BaBar and Belle) and others are expected from the experiments at hadronic colliders (CDF/D0, LHCb). This group collaborates regularly with experimental teams (LAL, DAPNIA).

A. Le Yaouanc, L. Oliver, O. Pène and J.C. Raynal
have developed a quark model for semi-leptonic form factors that satisfies heavy-quark symmetry explicitly and enables computations for B and D mesons. They have established relations among heavy-to-light form factors when the light meson is very energetic.

S. Descotes-Genon and O. Pène étudient les applications possibles et les limitations de formules de factorisation des effets de QCD dans les transitions électrofaibles dans la limite d’un quark b lourd.

These issues are also studied under their numerical aspect by the lattice QCD group in collaboration with the University of Roma.

### Higgs

A. Djouadi is interested in the phenomenology of the Higgs boson, in particular the signatures of its production in hadronic and leptonic colliders, as well as its fundamental
properties.
s’intéresse

### Neutrinos

A. Abada has investigated verious aspects of neutrino physics in relation with current and forthcoming experimental constraints :

their properties : masses, mixings, magnetic moments...

their role in astrophysics : photon-neutrino interaction, star cooling...

their behaviour in high-density media : neutron stars, white dwarves...