what counts as wise? Second, does the public, after considerable thought, think that our society has a moral obligation to pursue lines of research which may benefit present and future generations? I say “moral obligation” because it is sometimes implied by advocates of recombinant D N A research that science would be guilty of a sin of omission if it did not continue and promote research so pr...

The alternative to the standard formulation of the quark-parton model is proposed. Our approach is based on the solution of the master equations relating the structure and distribution functions, which consistently takes into account the intrinsic quark motion in contradistinction to the standard infinite momentum approach, in which this motion is latently suppressed. The model well reproduces ...

The addition of an Abelian family symmetry to the Minimal Supersymmetric Standard Model reproduces the observed hierarchies of quark and lepton masses and quark mixing angles, only if it is anomalous. Green-Schwarz compensation of its anomalies requires the electroweak mixing angle to be sin2 θw = 3/8 at the string scale, without any assumed GUT structure, suggesting a superstring origin for th...

A new relation between ρ-meson mass, weak π-meson decay constant, quark and gluon condensates is derived from the QCD sum rules. As a byproduct an explanation for the dominance of ρρ-decay for the f0(1370)-meson is proposed. Pacs: 12.38.Lg

We study the structure of constituent quarks by dressing bare quarks with the Goldstone bosons and its implications for quark distribution functions of hadrons f1(x), g1(x) and h1(x). In particular we discuss effects of the dressing on the nucleon spin structure, and find that contributions to chiral-odd h1(x) is quite different from those to g1(x), which can be measured in the semi-inclusive p...

Universités Pierre et Marie Curie (Paris 6) et Denis Diderot (Paris 7); Unité associée au CNRS D0 280. Abstract: the scalar composite representations of the electroweak symmetry group of the Standard Model are exhibited in the case of two generations of quarks. The link between 'strong' and 'electroweak' eigenstates is investigated, showing that the quark content commonly attributed to pseudosc...

An azimuthal dependence of pions produced in polarized Deep Inelastic Scattering, γp → πX, has been recently observed and might be related to the so-called Collins effect. We discuss in details, for a general spin configuration of the nucleon, the kinematics of the process and methods of extracting information on the fragmentation properties of a polarized quark. Assuming that the observed azim...

We analyse the phenomenological viability of heterotic Z3 orbifolds with two Wilson lines, which naturally predict three supersymmetric families of matter and Higgs fields. Given that these models can accommodate realistic scenarios for the quark sector avoiding potentially dangerous flavour-changing neutral currents, we now address the leptonic sector, finding that viable orbifold configuratio...

The chiral and heavy quark symmetries of QCD are reviewed. These symmetries are used to predict some low–momentum properties of hadrons containing a single heavy quark. ⋆ Work supported in part by the U.S. Dept. of Energy under Grant no. DE-FG03-92-ER 40701.