Assuming three light neutrinos and the seesaw mechanism we present a semiquantitative model of fermion masses based on (SUSY) SU(5) and abelian horizontal charges. A good description of the observed pattern of quark and lepton masses is obtained. For neutrinos we naturally obtain widely split masses and large atmospheric neutrino mixing as a consequence of SU(5)-related asymmetric mass matrices...

This paper is a review of recent lattice determinations of the light quark masses. It describes the method employed to calculate quark masses in the lattice formulation, and the extrapolations required to reach the physical regime. This review is designed to be accessible to a general audience, not specifically lattice theorists.

The available experimental information is consistent with the Weinberg predictions for the threshold parameters of ππ-scattering. The data, however, only test those relations that are insensitive to the quark masses mu and md. Recent theoretical progress leads to remarkably sharp predictions for the behaviour of the Sand P-wave phase shifts in the elastic region – one of the very few low energy...

It is presented a critical consideration of all unusual properties of the scalar a 0 (980) and f 0 (980)-mesons in the four-quark, two-quark and molecular models. The arguments are adduced that the four-quark model is more preferable. It is discussed the complex of experiments that could finally resolve this issue.

The bottomonium and charmonium systems have long proved to be a rich source of QCD physics. Recent CLEO contributions in three disparate areas are presented: (1) the study of quark and gluon hadronization using Υ decays; (2) the interpretation of heavy charmonium states, including non-cc candidates; and (3) the exploration of light quark physics using the decays of narrow charmonium states as a...