322 research outputs found

### 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.

### Mixing and Decay Constants of Pseudoscalar Mesons: The Sequel

We present further tests and applications of the new eta-eta' mixing scheme
recently proposed by us. The particle states are decomposed into orthonormal
basis vectors in a light-cone Fock representation. Because of flavor symmetry
breaking the mixing of the decay constants can be identical to the mixing of
particle states at most for a specific choice of this basis. Theoretical and
phenomenological considerations show that the quark flavor basis has this
property and allows, therefore, for a reduction of the number of mixing
parameters. A detailed comparison with other mixing schemes is also presented.Comment: 9 page

### Width of the J^P=1/2^+ pentaquark in the quark-diquark model

We analyse the width of the $\theta(\frac12^+)$ pentaquark assuming that it
is a bound state of two extended spin-zero $ud$-diquarks and the $\bar s$
antiquark (the Jaffe-Wilczek scenario). The width obtained when the size
parameters of the pentaquark wave function are taken to be close to the
parameters of the nucleon is found to be $\simeq 150$ MeV, i.e. it has a normal
value for a $P$-wave hadron decay with the corresponding energy
release.However, we found a strong dynamical suppression of the decay width if
the pentaquark has an asymmetric "peanut" structure with the strange antiquark
in the center and the two diquarks rotating around. In this case a decay width
of $\simeq$ 1 MeV is a natural possibility.Comment: 3 new references added, version accepted to Physics Letters

### Fermion Masses and Coupling Unification in E6. Life in the Desert

We present an $E_6$ Grand Unified model with a realistic pattern of fermion
masses. All standard model fermions are unified in three fundamental 27-plets
(i.e. supersymmetry is not invoked), which involve in addition right handed
neutrinos and three families of vector like heavy quarks and leptons. The
lightest of those can lie in the low TeV range, being accessible to future
collider experiments. Due to the high symmetry, the masses and mixings of all
fermions are closely related. The new heavy fermions play a crucial role for
the quark and lepton mass matrices and the bilarge neutrino oscillations. In
all channels generation mixing and ${\cal CP}$ violation arise from a single
antisymmetric matrix. The $E_6$ breaking proceeds via an intermediate energy
region with SU(3)_L\tm SU(3)_R\tm SU(3)_C gauge symmetry and a discrete
left-right symmetry. This breaking pattern leads in a straightforward way to
the unification of the three gauge coupling constants at high scales, providing
for a long proton lifetime. The model also provides for the unification of the
top, bottom and tau Yukawa couplings and for new interesting relations in
flavor and generation space.Comment: RevTex4, three ps figures, some correction

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