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...

Many of the classic problems of particle physics appear in a very different light when viewed from the perspective of the multiverse. Most importantly the two great “fine tuning” problems that motivate the field are far less serious when one accounts for the required anthropic constraints which exist in a multiverse. However, the challenge then becomes to construct a realistic physical theory o...

We present some recent developments on model building for neutrino masses and mixings. In particular, we review tri-bimaximal neutrino mixing derived from discrete groups, notably A4. We discuss the problems encountered with extending the symmetry to the quark sector and with Grand Unification.

It is suggested that the narrow meson state seen in the the SELEX experiment is a (cs̄ss̄) tetraquark state. Characteristics of other possible tetraquarks formed out of c and s quarks and antiquarks are considered. SELEX experiment has reported [1] a puzzling narrow meson state at a mass of 2632.6± 1.6 MeV/c which decays preferentially to D s (cs̄) + η(548) rather than to D(cd̄)+K or D(cū)+K. In th...

Small momentum transfer elastic pion-proton cross-section at high energies is calculated assuming the proton is composed of two constituents, a quark and a diquark. We find that it is possible to fit very precisely the data when (i) the pion acts as a single entity (no constituent quark structure) and (ii) the diquark is rather large, comparable to the size of the proton.

The high energy physics program (Ecms ≤ 8.6GeV ) at DORIS was initiated by the PLUTO collaboration which sent its proposal to the Forschungskollegium June 30, 1977 [1]. The same day the observation of the Υ(9.46) resonance was announced to the public in a seminar at FNAL [2]. The physics program proposed by PLUTO included the measurement of σtot and the search for charm and τ . The search for a...

A seesaw mass matrix model is reviewed as a unification model of quark and lepton mass matrices. The model can understand why topquark mass mt is so singularly enhanced compared with other quark masses, especially, why mt ≫ mb in contrast to mu ∼ md, and why only top-quark mass is of the order of the electroweak scale ΛW , i.e., mt ∼ O(ΛW ). The model predicts the fourth up-quark t′ with a mass...

One of the central questions in theoretical particle physics, since already several decades, has been that of " masses and mixings of the quarks. With the entry of neutrino oscillations into the field, the issue of lepton masses has added a new dimension to the problem. In the literature one finds many models of quark and lepton mass matrices. However, the mass and mixing problems remain unsolv...

We review the present status of QCD corrections to weak decays beyond the leading logarithmic approximation including particle-antiparticle mixing and rare and CP violating decays. After presenting the basic formalism for these calculations we discuss in detail the effective hamiltonians for all decays for which the next-to-leading corrections are known. Subsequently, we present the phenomenolo...

We illustrate the current status of heavy quark physics on the lattice. Special emphasis is paid to the question of systematic uncertainties and to the connection of lattice computations to continuum physics. Latest results are presented and discussed with respect to the progress in methods, statistical accuracy and reliability.