1,767 research outputs found
Analysis of the quark sector in the 2HDM-III with a four-zero Yukawa texture using the most recent data on the CKM matrix
In this letter we analyse, in the context of the general 2-Higgs Doublet
Model, the structure of the Yukawa matrices, , by assuming a four-zero texture ansatz for their definition. In this
framework, we obtain compact expressions for , which are reduced to the Cheng and Sher ansatz with the difference that
they are obtained naturally as a direct consequence of the invariants of the
fermion mass matrices. Furthermore, in order to avoid large flavour violating
effects coming from charged Higgs exchange, we consider the main flavour
constraints on the off-diagonal terms of Yukawa texture {{}} (). We perform a -fit
based on current experimental data on the quark masses and the
Cabibbo-Kobayashi-Maskawa mixing matrix . Hence, we obtain
the allowed ranges for the parameters at
1 for several values of . The results are in complete
agreement with the bounds obtained taking into account constraints on Flavour
Changing Neutral Currents reported in the literature.Comment: 12 pages, 1 figure. Version accepted in Phys. Lett.
Quark lepton complementarity and renormalization group effects
We consider a scenario for the Quark-Lepton Complementarity relations between
mixing angles in which the bi-maximal mixing follows from the neutrino mass
matrix. According to this scenario in the lowest order the angle \theta_{12} is
\sim 1\sigma (1.5 - 2^\circ) above the best fit point coinciding practically
with the tri-bimaximal mixing prediction. Realization of this scenario in the
context of the seesaw type-I mechanism with leptonic Dirac mass matrices
approximately equal to the quark mass matrices is studied. We calculate the
renormalization group corrections to \theta_{12} as well as to \theta_{13} in
the standard model (SM) and minimal supersymmetric standard model (MSSM). We
find that in large part of the parameter space corrections \Delta \theta_{12}
are small or negligible. In the MSSM version of the scenario the correction
\Delta \theta_{12} is in general positive. Small negative corrections appear in
the case of an inverted mass hierarchy and opposite CP parities of \nu_1 and
\nu_2 when leading contributions to \theta_{12} running are strongly
suppressed. The corrections are negative in the SM version in a large part of
the parameter space for values of the relative CP phase of \nu_1 and \nu_2:
\phi > \pi/2.Comment: version as published in PRD, 14 pages, 12 figure
A ’feasibility space’ as a goal to be achieved in the development of new technologies for converting renewable energies
This method article proposes the establishment of a feasibility space as an objective to be achieved during the development of new technologies to convert energy from renewable resources. The feasibility space can also be a reference when designing an energy system based on renewable resources. The feasibility space is a set of parameter values for the design stage that define the economic and technical feasibility of an energy system or a new technology, which must be satisfied when the energy system comes into operation or when the new technology for converting power goes into operation. The study of possible feasibility spaces allows characterizing energy systems or new technologies as attractive investments, or on the other hand, as unfeasible ventures. - The method proposes to establish a goal to achieve during the development of technologies for energy conversion. - The method provides a benchmark for both the stages of design and development of generation systems and new technologies. - The feasibility space constitutes a planning tool for power systems based on renewable resources of any size
Farm Efficiency and Productivity Growth: The Effect of Commodity Prices
Crop prices can affect farm productivity through input- output decisions. This study assesses the relationship between crop prices and productivity changes among a sample of Kansas farms. The changes in total factor productivity are evaluated using a nonparametric approach with a Malmquist productivity index and potential drivers of technical efficiency and productivity change are analyzed. Farms with higher leverage and greater diversification are likely to be more efficient and experience productivity change. Lower productivity occurred during years with higher crop prices, suggesting that innovation is more likely to occur when margins are tight
Optical study of archetypical valence-fluctuating Eu-systems
We have investigated the optical conductivity of the prominent valence
fluctuating compounds EuIr2Si2 and EuNi2P2 in the infrared energy range to get
new insights into the electronic properties of valence fluctuating systems. For
both compounds we observe upon cooling the formation of a renormalized Drude
response, a partial suppression of the optical conductivity below 100 meV and
the appearance of a mid-infrared peak at 0.15 eV for EuIr2Si2 and at 0.13 eV
for EuNi2P2. Most remarkably, our results show a strong similarity with the
optical spectra reported for many Ce- or Yb-based heavy fermion metals and
intermediate valence systems, although the phase diagrams and the temperature
dependence of the valence differ strongly between Eu- and Ce-/Yb-systems. This
suggests that the hybridization between 4f- and conduction electrons, which is
responsible for the properties of Ce- and Yb-systems, plays an important role
in valence fluctuating Eu-systems
Searching for the Balance Between Flexibility and Workers\u27 Security (Is it Time to Reform Labor Market Policies?)
The protection of labor and the regulation of labor-capital relations are fundamental elements of Philippine labor policy. This protective posture is enshrined in the Constitution (Art. XIII), and reaffirmed in the Labor Code of the Philippines which provides the legal basis for all existing labor market policies and regulations
Exploring high temperature magnetic order in CeTi_1-xSc_xGe
Most of magnetic transitions related to Ce ordering are found below
T_ord~12K. Among the few cases exceeding that temperature, two types of
behaviors can be distinguished. One of them is related to the rare cases of Ce
binary compounds formed in BCC structures, with a quartet ground state, whose
degeneracy is reduced by undergoing different types of transitions mostly
structural. The other group shows evidences of itinerant character with the
outstanding example of CeRh_3B_2 showing the highest T_ord=115K. The second
highest ordering temperature has been reported for CeScGe with T_ord=47K, but
the nature of this magnetic state has not been investigated very deeply. In
order to shed more light into this unusual high temperature ordering we studied
the structural, magnetic, transport and thermal properties of CeTi_1-xSc_xGe
alloys in the stability range of the CeScSi-type structure 0.25<x<1 This system
presents a rich variety of magnetic behaviors along this concentration range,
with the magnetic ordering growing from ferromagnetic (FM) T_C~7K up to an
antiferromagnetic (AFM) transition at T_N=47K. The different regions show the
following characteristics: i) on the Ti rich side (0.25<x<0.50) it exhibits a
FM ground state (GS) with large saturation magnetization values M_sat up to
~1.15 mu_B. ii) Around x=0.60, the first crystal electric field excited doublet
starts to contribute to the GS magnetic properties. Furthermore an AFM
component with a connected metamagnetic transition appears. iii) At x=0.65 a
clear change in the GS nature is associated to a critical point above which the
GS properties can be described like for an itinerant system (with decreasing
M_sat) and an effective GS degeneracy N_eff=4. iv) For x>0.65, the magnetic
phase boundary splits into two transitions, with an intermediate phase
presenting incommensurate spin density waves features.Comment: 8 pages, 10 figure
Benign Bilateral Adenomyoepithelioma of the Mammary Gland in a Ring-tailed Lemur (Lemur catta)
Naturally occurring mammary tumours are uncommon in prosimians. A 20-year-old female ring-tailed lemur (Lemur catta) developed bilateral enlargement of the mammary glands. Surgical removal revealed that both masses were comprised of multiple nodules and cystic areas that entirely replaced the normal glands. Histologically, a benign neoplastic biphasic cellular proliferation, composed of luminal–epithelial and basal–myoepithelial components, was identified. Immunohistochemical analysis for expression of cytokeratin (CK) AE1/AE3, CK7, CK5 + 8, CK14, vimentin, p63 and 14-3-3σ highlighted the biphasic nature of the neoplasm. A low mitotic count, low Ki67 labelling index, expression of oestrogen receptor-α, lack of expression of human epidermal growth factor receptor and a 3-year disease-free period without recurrence supported the benign nature of the tumour. Macroscopically, histologically and immunohistochemically this neoplasm resembled benign adenomyoepithelioma of the breast in women. This is the first complete report of a naturally occurring mammary tumour in a ring-tailed lemur
Huge First-Order Metamagnetic Transition in the Paramagnetic Heavy-Fermion System CeTiGe
We report on the observation of large, step-like anomalies in the
magnetization (\,/Ce), in the magnetostriction
(), and in the magnetoresistance in
polycrystals of the paramagnetic heavy-fermion system CeTiGe at a critical
magnetic field 12.5\,T at low temperatures. The size of
these anomalies is much larger than those reported for the prototypical
heavy-fermion metamagnet CeRuSi. Furthermore, hysteresis between
increasing and decreasing field data indicate a real thermodynamic, first-order
type of phase transition, in contrast to the crossover reported for
CeRuSi. Analysis of the resistivity data shows a pronounced decrease of
the electronic quasiparticle mass across . These results establish CeTiGe
as a new metamagnetic Kondo-lattice system, with an exceptionally large,
metamagnetic transition of first-order type at a moderate field.Comment: 5 pages, 4 figure
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