New Spectroscopy with Charm and Beauty Multiquark States

Exotic charmonium and bottonomium resonances recently discovered are discussed and interpreted as diquark-antidiquark states containing a pair of charm quarks and a pair of light, up and down, quarks. Successes, shortcomings and predictions of the model are illustrated.Comment: Talk given at the Erice School of Subnuclear Physics, June 30, 2013, Ettore Majorana Foundation and Center for Science and Culture, Erice, Ital

The GIM Mechanism: origin, predictions and recent uses

The GIM Mechanism was introduced by Sheldon L. Glashow, John Iliopoulos and Luciano Maiani in 1970, to explain the suppression of Delta S=1, 2 neutral current processes and is an important element of the unified theories of the weak and electromagnetic interactions. Origin, predictions and uses of the GIM Mechanism are illustrated. Flavor changing neutral current processes (FCNC) represent today an important benchmark for the Standard Theory and give strong limitations to theories that go beyond ST in the few TeV region. Ideas on the ways constraints on FCNC may be imposed are briefly described.Comment: Opening Talk, Rencontres de Moriond, EW Interactions and Unified Theories, La Thuile, Valle d'Aosta, Italia, 2-9 March, 201

Non-Perturbative Renormalisation and Kaon Physics

A general review is presented on the problem of non perturbative computation of the $K\to\pi\pi$ transition amplitude.Comment: 8 pages, Latex, uses espcrc2.sty, Talk given at LATTICE9

Concluding Remarks: the Scientist that Lived Three Times

The highlights of the conference: The Legacy of Bruno Pontecorvo: the Scientist and the Man, held in Roma, Universit\`a La Sapienza, 11-12 September, 2013, are summarised and illustrated

The Charm of Theoretical Physics (1958-1993)

Personal recollections on theoretical particle physics in the years when the Standard Theory was formed. In the background, the remarkable development of Italian theoretical physics in the second part of the last century, with great personalities like Bruno Touschek, Raoul Gatto, Nicola Cabibbo and their schools.Comment: 53 pages, 12 figures, to be published in The European Physical Journal H. New version with added text and figure

More loosely bound hadron molecules at CDF?

In a recent paper we have proposed a method to estimate the prompt production cross section of X(3872) at the Tevatron assuming that this particle is a loosely bound molecule of a D and a D*bar meson. Under this hypothesis we find that it is impossible to explain the high prompt production cross section found by CDF at sigma(X(3872)) \sim 30-70 nb as our theoretical prediction is about 300 times smaller than the measured one. Following our work, Artoisenet and Braaten, have suggested that final state interactions in the DD*bar system might be so strong to push the result we obtained for the cross section up to the experimental value. Relying on their conclusions we show that the production of another very narrow loosely bound molecule, the X_s=D_s D_s*bar, could be similarly enhanced. X_s should then be detectable at CDF with a mass of 4080 MeV and a prompt production cross section of sigma(X_s) \sim 1-3 nb.Comment: Minor revisions made. To appear in Phys Lett

Bounds to the Higgs Sector Masses in Minimal Supersymmetry from LHC Data

We update our analysis of the Higgs sector masses in Minimal Supersymmetry and in the Two-Higgs Doublet Model to the final ATLAS and CMS data from the 2011-2012 LHC run.Comment: 5 pages, 5 figures, comments added, references update

Further discussions on a possible lattice chiral gauge theory

In a possible $SU_L(2)$ lattice chiral gauge theory with a large multifermion coupling, we try to further clarify the threshold phenomenon: the possibility that the right-handed three-fermion state turns into the virtual states of its constituents (free chiral fermions) in the low-energy limit. Provided this phenomenon occurs, we discuss the chiral gauge coupling, Ward identities and the gauge anomaly within the gauge-invariant prescription of the perturbative chiral gauge theory.Comment: LaTex 14 pages, to appear in Phys. Lett.