A simple scheme for masses and mixings of quarks and neutrinos

The mass matrices of charged fermions have a simple structure if expressed in powers of the small parameter sigma=(m_c/m_t)^{1/2}. It is suggested that the mass matrix of the three heavy neutrinos occuring in grand unified theories can be expressed in terms of the same parameter. The requirement that these heavy neutrinos carry different U(1) generation quantum numbers gives rise to an almost unique form for this matrix. By applying the see-saw mechanism, the mass splitting of the two lightest neutrinos comes out to be tiny, favoring the vacuum oscillation solution for solar neutrinos. The mixing matrix is of the bimaximal type but contains also CP violating phases.Comment: 9 pages, references added and minor correction

Pentaquarks in the Chiral Symmetry Limit

We demonstrate that a five quark state of positive parity with an internal P-wave structure - usually pictured as a composite of an antiquark and two diquarks in a P-wave state - can couple to nucleons and Goldstone particles in a chirally invariant way. The corresponding decay width is generally not suppressed. A pentaquark of positive or negative parity with an internal S-wave structure, which may be viewed as a composite of an antiquark and two chirally different diquarks in an S-state, does not couple to nucleons and light mesons in the limit of an unbroken chiral symmetry. It is stable in this limit. However, such states can decay via the effect of the spontaneous breaking of chiral symmetry. This breaking is strong because of the sizeable magnitude of the quark condensate. Thus, chiral symmetry cannot be the cause of a tiny decay amplitude, even for pentaquarks stable in a strict chiral symmetry limit.Comment: Modified version. We added a discussion of the effect of spontaneous breaking of chiral symmetry on the pentaquark. This has changed part of our conclusions: we argue that the effect is large indicating that chiral symmetry cannot be the origin of the small width of the pentaquar

Exclusive Hadronic B-Decays

Exclusive non-leptonic two-body decays are discussed on the basis of a generalized factorization approach which also includes non-factorizeable contributions. Numerous decay processes can be described satisfactorily. The success of the method makes possible the determination of decay constants from non-leptonic decays. In particular, we obtain f_{D_s}=(234+-25) MeV and f_{D^*_s}=(271+-33) MeV. The observed constructive and destructive interference pattern in charged B- and D-decays, respectively, can be understood in terms of the different alpha_s-values governing the interaction among the quarks. The running of alpha_s is also the cause of the observed strong increase of the amplitude of lowest isospin when going to low energy transitions.Comment: 11 pages, LaTeX, uses epsf.sty, one eps figure, plenary talk at the b20 Symposium, Chicago, July 199

The mass of the Higgs boson in the trinification subgroup of E6

The extension of the standard model to SU(3)_L x SU(3)_R x SU(3)_C is considered. Spontaneous symmetry breaking requires two Higgs field multiplets with a strong hierarchical structure of vacuum expectation values. These vacuum expectation values, some of them known from experiment, are used to construct invariant potentials in form of a sum of individual potentials relevant at the weak scale. As in a previous suggestion one may normalize the most important individual potentials such that their mass eigenvalues agree with their very large vacuum expectation values. In this case (for a wide class of parameters) the scalar field corresponding to the standard model Higgs turns out to have the precise mass value m_Higgs = v/sqrt(2) = 123 GeV at the weak scale. The physical mass (pole mass) is larger and found to be 125 +/- 1.4 GeV.Comment: 5 pages, version appearing in Phys. Rev.

Non-Leptonic Weak Decays of B Mesons

We present a detailed study of non-leptonic two-body decays of B mesons based on a generalized factorization hypothesis. We discuss the structure of non-factorizable corrections and present arguments in favour of a simple phenomenological description of their effects. To evaluate the relevant transition form factors in the factorized decay amplitudes, we use information extracted from semileptonic decays and incorporate constraints imposed by heavy-quark symmetry. We discuss tests of the factorization hypothesis and show how unknown decay constants may be determined from non-leptonic decays. In particular, we find f_{Ds}=(234+-25) MeV and f_{Ds*}=(271+-33) MeV.Comment: two references added and one entry in Table 9 corrected; to appear in the Second Edition of "Heavy Flavours", edited by A.J. Buras and M. Lindner (World Scientific, Singapore

The systematic position of Gradsteinia andicola Ochyra (Donrichardsiaceae, Bryopsida) : evidence from nrDNA internal transcribed spacer sequences

Nuclear ribosomal DNA internal transcribed spacer (ITS) 1/2 sequences of the Colombian endemic Gradsteinia andicola were determined and compared with those of 16 other species of the Hypnales (Amblystegiaceae, Brachytheciaceae, Hypnaceae, Plagiotheciaceae and Rhytidiaceae). In a maximum parsimony tree Gradsteinia andicola belongs to a well supported clade consisting of Amblystegium, Cratoneuron, Cratoneuropsis, Hypnobartlettia and Palustriella, and seems to be closely related to Cratoneuropsis relaxa from New Zealand. Gradsteinia andicola is therefore transferred to Amblystegiaceae, but the genus Gradsteinia is maintained. The systematic relationship of Amblystegiaceae and Donrichardsiaceae is discussed