58 research outputs found
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
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
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 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.
Trinification phenomenology and the structure of Higgs bosons
The extension of the Standard Model to (the trinification group) augmented by the flavor group is
considered. In our phenomenological treatment partly known and partly proposed
vacuum expectation values of the scalar Higgs fields play a dominant role. All
Higgs fields are taken to be flavor singlets, all flavon fields trinification
singlets. We need two flavor (generation) matrices. One determines the mass
hierarchy of all fermions, the second one is responsible for all mixings
including the CP-violating phase in the CKM matrix. The mixing with higher
states contained in the group representation provides for an understanding of
the difference between the up quark and the down quark spectrum. There is a
close connection between charged and neutral fermions. An inverted neutrino
hierarchy is predicted. Examples for the tree-level potential of the Higgs
fields are given. To obtain an acceptable spectrum of scalar states, the
construction of the potential requires the combination of matrix fields that
differ with respect to fermion couplings and flavor-changing properties. As a
consequence bosons with fermiophobic components or, alternatively,
flavor-changing components are predicted in this model. Nevertheless, the Higgs
boson at 125 GeV is very little different from the Standard Model Higgs boson
in its couplings to fermions but may have self-coupling constants larger by a
factor 2.Comment: 12 pages, minor corrections, version accepted for publication in JHE
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