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.
Width of the J^P=1/2^+ pentaquark in the quark-diquark model
We analyse the width of the pentaquark assuming that it
is a bound state of two extended spin-zero -diquarks and the
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 MeV, i.e. it has a normal
value for a -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 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 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 violation arise from a single
antisymmetric matrix. The 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
Bio-Optical Modeling in a Tropical Hypersaline Lagoon Environment
In this chapter, we attempted to present an overview of the use of remote sensing to monitor water quality parameters, mainly chlorophyll-a (chl-a) and turbidity. We summarized the main concepts of bio-optical modeling and presented a case study of the application of the Hyperspectral Imager for the Coastal Ocean (HICO) for the monitoring of water quality in a tropical hypersaline aquatic environment. Using HICO, we evaluated a set of different semi-empirical bio-optical algorithms for chl-a and turbidity estimation developed for inland and oceanic waters in the Araruama Lagoon, RJ, Brazil, which is an extreme environment due to its high salinity values. We also developed an empirical algorithm for both water quality parameters and compared the performances. Results showed that for chl-a estimation all models have a low performance with a normalized root mean square error (NRMSE) varying from 24.13 to 30.46. For turbidity, the bio-optical algorithms showed a better performance with the NRMSE between 15.49 and 28.04. Overall, these results highlight the importance of including extreme environments, such as the Araruama Lagoon, on the validation of bio-optical algorithms as well as the need for new orbital hyperspectral sensors which will improve the development of the field
Non-local anomaly of the axial-vector current for bound states
We demonstrate that the amplitude does not vanish in the limit of zero quark masses. This
represents a new kind of violation of the classical equation of motion for the
axial current and should be interpreted as the axial anomaly for bound states.
The anomaly emerges in spite of the fact that the one loop integrals are
ultraviolet-finite as guaranteed by the presence of the bound-state wave
function. As a result, the amplitude behaves like in the limit of
a large momentum of the current. This is to be compared with the amplitude
which remains
finite in the limit .
The observed effect leads to the modification of the classical equation of
motion of the axial-vector current in terms of the non-local operator and can
be formulated as a non-local axial anomaly for bound states.Comment: revtex, 4 pages, numerical value for in Eq. (19) is
corrected, Eqs. (22) and (23) are modified. New references added. Results
remain unchange
Leading twist moments of the neutron structure function F2n
We perform a global analysis of neutron F2n structure function data, obtained
by combining proton and deuteron measurements over a large range of kinematics.
From these data the lowest moments (n <= 10) of the leading twist neutron F2n
structure function are extracted. Particular attention is paid to nuclear
effects in the deuteron, which become increasingly important for the higher
moments. Our results for the nonsinglet, isovector (p - n) combination of the
leading twist moments are used to test recent lattice simulations. We also
determine the lowest few moments of the higher twist contributions, and find
these to be approximately isospin independent, suggesting the possible
dominance of ud correlations over uu and dd in the nucleon.Comment: 34 pages, 13 figures. Minor changes. Version to appear in NP
Influence of summertime mesoscale convective systems on the heat balance and surface mixed layer dynamics of a large Amazonian hydroelectric reservoir
We evaluated the impacts of summertime mesoscale convective systems (MCS) on the heat balance and diel surface mixed layer (SML) dynamics of the Brazilian Amazon's TucuruĂ Hydroelectric Reservoir (THR). We used a synergistic approach that combines in situ data, remote sensing data, and three-dimensional (3-D) modeling to investigate the typical behavior of the components of the heat balance and the SML dynamics. During the study period (the austral summer of 2012â2013), 22 days with MCS activity were identified. These events occurred approximately every 4 days, and they were most frequent during January (50% of the observations). An analysis of local meteorological data showed that when MCS occur, the environmental conditions at THR change significantly (p-valueâ<â0.01). The net longwave flux, which was the heat balance component most strongly impacted by MCS, increased more than 32% on days with MCS activity. The daily integrated heat balance became negative (â54 W mâ2) on MCS days, while the balance was positive (19 W mâ2) on non-MCS days. In response to the changes in the heat balance, the SML dynamics changed when a MCS was over the THR. The SML depth was typically 28% higher on the days with MCS (âŒ1.6 m) compared with the days without MCS (âŒ1.3 m). The results indicate that MCS are one of the main meteorological disturbances driving the heat balance and the mixing dynamics of Amazonian hydroelectric reservoirs during the summer. These events may have implications for the water quality and greenhouse gas emissions of Amazonian reservoirs
On-chip automation of cell-free protein synthesis: new opportunities due to a novel reaction mode
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