Luciano Maiani

Bounds on the number and masses of quarks and leptons

Abstract We assume weak, electromagnetic and strong interactions to be asymptotically divergent, and to become strong at very large energies, of the order of the Plank mass. In this picture, the “low-energy” couplings (i.e. in the 102 GeV region) must be near the infrared stable point, and this allows us to put bounds on the number of elementary fermions (quarks and leptons). Similar assumptions on the Higgs couplings give bound on the fermion and on the Higgs boson masses. We consider the cases where weak and electromagnetic interactions are described by the gauge groups SU(2) ⊗ U(1) or SU(2)R ⊗ U(1). The weak neutral current mixing angle is computed in both cases.

The Lifetime of Charmed Particles

Abstract We present a computation of the semileptonic decay rate of charmed particles, including the first order gluon corrections and the final quark mass corrections. Taking into account these corrections, the lifetime of charmed particles is estimated to be: τ ≈ 0.7 × 10 −12 s.

The structure of parity violating strangeness conserving weak non-leptonic amplitudes in an asymptotically free theory

Abstract We study the structure of parity violating ΔS = 0 weak non-leptonic amplitudes in a gauge theory of strong, weak and electromagnetic interactions based on the Weinberg-Salam theory with three quartets of fractionally charged quarks. It is shown, that, similarly to what happens for ΔS = 1 non-leptonic amplitudes, a definite pattern of enhanced terms emerges. The enhanced operators have isospin zero and one, while isospin-two components are suppressed. The enhancement factors are comparable to those found in the same model for ΔS = 1 transitions and can account for at least a part of the present disagreement between experimental findings and theoretical estimates for the photon polarization in the process n + p → d + γ at thermal energies.

Enhancement of non-leptonic decays of charmed particles

We suggest that non-leptonic decays of charmed particles are enhanced over semi-leptonic decays by a sizeable factor, in analogy with the situation encountered in strange particle decays. This conjecture is verified in a model octet enhancement based on asymptotically-free gauge theories of strong interactions. Arguments are given to support a specific SU(3) behavior of the enhanced part of the non-leptonic Hamiltonian for charmed particle decays. Consequent selection and intensity rules are discussed.

Weak non leptonic decays of charmed hadrons

Abstract Weak non leptonic decays of charmed hadrons are studied in the SU(4) quark model with color. Relations for baryon decays following from a specific SU(3) behaviour of the effective hamiltonian, proposed in a previous paper, are presented and discussed. Consideration of the exact SU(4) limit leads to an estimate of the absolute widths of charmed baryons, and to a new relation among hyperon decay S-wave amplitudes, found to be violated to approximately 40%.

Soft pion emission in pp resonance formation

Abstract The differential cross section is given for the process p p → X + π 0 in the soft pion limit, X being a charmonium state. The result depends only on the partial width for the decay X → p p and on the spin-orbit wave function of the resonating system. p p

Relativistic quantum mechanics : an introduction to relativistic quantum fields

THE SYMMETRIES OF SPACE-TIME THE PRINCIPLE OF RELATIVITY PROPER AND ORTHOCHRONOUS LORENTZ TRANSFORMATIONS CAUSAL STRUCTURE OF SPACE-TIME CONTRAVARIANT AND COVARIANT VECTORS THE CLASSICAL FREE PARTICLE SPACE-TIME MOTION PARTICLE OF ZERO MASS ACTION PRINCIPLE FOR THE FREE PARTICLE THE MASS-ENERGY RELATION THE LAGRANGIAN THEORY OF FIELDS THE ACTION PRINCIPLE HAMILTONIAN AND CANONICAL FORMALISM TRANSFORMATION OF FIELDS CONTINUOUS SYMMETRIES NOETHERS THEOREM ENERGY-MOMENTUM TENSOR KLEIN-GORDON FIELD QUANTISATION THE REAL SCALAR FIELD GREENS FUNCTIONS OF THE SCALAR FIELD QUANTISATION OF THE SCALAR FIELD ELECTROMAGNETIC FIELD QUANTISATION MAXWELLS EQUATIONS IN COVARIANT FORM GREENS FUNCTIONS OF THE ELECTROMAGNETIC FIELD THE MAXWELL-LORENTZ EQUATIONS HAMILTON FORMALISM AND MINIMAL SUBSTITUTION QUANTISATION OF THE ELECTROMAGNETIC FIELD IN VACUUM THE SPIN OF THE PHOTON THE DIRAC EQUATION FORM AND PROPERTIES OF THE DIRAC EQUATION THE RELATIVISTIC HYDROGEN ATOM TRACES OF THE gamma MATRICES QUANTISATION OF THE DIRAC FIELD PARTICLES AND ANTIPARTICLES SECOND QUANTISATION: HOW IT WORKS CANONICAL QUANTISATION OF THE DIRAC FIELD THE REPRESENTATION OF THE LORENTZ GROUP MICROCAUSALITY THE RELATION BETWEEN SPIN AND STATISTICS FREE FIELD PROPAGATORS THE TIME-ORDERED PRODUCT PROPAGATORS OF THE SCALAR FIELD PROPAGATORS OF THE DIRAC FIELD THE PHOTON PROPAGATOR INTERACTIONS QUANTUM ELECTRODYNAMICS THE FERMI INTERACTION FOR ss DECAY STRONG INTERACTIONS HADRONS, LEPTONS AND FIELDS OF FORCE TIME EVOLUTION OF QUANTUM SYSTEMS THE SCHRODINGER REPRESENTATION THE HEISENBERG REPRESENTATION THE INTERACTION REPRESENTATION SYMMETRIES AND CONSTANTS OF THE MOTION RELATIVISTIC PERTURBATION THEORY THE DYSON FORMULA CONSERVATION LAWS COLLISION CROSS SECTION AND LIFETIME THE DISCRETE SYMMETRIES: P, C, T PARITY CHARGE CONJUGATION TIME REVERSAL TRANSFORMATION OF THE STATES SOME APPLICATIONS THE CPT THEOREM WEYL AND MAJORANA NEUTRINOS THE WEYL NEUTRINO THE MAJORANA NEUTRINO RELATIONSHIPS BETWEEN WEYL, MAJORANA AND DIRAC NEUTRINOS APPLICATIONS: QED SCATTERING IN A CLASSICAL COULOMB FIELD ELECTROMAGNETIC FORM FACTORS THE ROSENBLUTH FORMULA COMPTON SCATTERING COMPTON SCATTERING ON RELATIVISTIC ELECTRONS THE PROCESSES gammagamma --> e+e- and e+e- --> gammagamma e+ e- --> mu+ mu- ANNIHILATION APPLICATIONS: WEAK INTERACTIONS NEUTRON DECAY MUON DECAY UNIVERSALITY, CURRENT x CURRENT THEORY TOWARDS A FUNDAMENTAL THEORY NEUTRINO OSCILLATIONS OSCILLATIONS IN VACUUM NATURAL AND ARTIFICIAL NEUTRINOS INTERACTION WITH MATTER: THE MSW EFFECT ANALYSIS OF THE EXPERIMENTS OPEN PROBLEMS APPENDIX: BASIC ELEMENTS OF QUANTUM MECHANICS THE PRINCIPLE OF SUPERPOSITION LINEAR OPERATORS OBSERVABLE QUANTITIES AND HERMITIAN OPERATORS THE NON-RELATIVISTIC SPIN 0 PARTICLE THE NON-RELATIVISTIC HYDROGEN ATOM Some end-of-chapter problems are included.