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51.
William A. Ponce Arnulfo Zepeda Jesús M. Mira 《Zeitschrift fur Physik C Particles and Fields》1996,69(4):683-686
We analyze U(1)H as a horizontal symmetry and its possibilities to explain the known elementary-fermion masses. We find that only two candidates, in the context of SU(3)c ? SU(2)L ? U(1)Y ? U(1)H nonsuper-symmetric, are able to fit the experimental result mb«mt. identity, but it is a common prejudice to assume that the appropriate family symmetry may explain this fact as a consequence of (i) and (ii). In what follows we will enlarge the SM gauge group with an extra U(1)H horizontal local gauge symmetry (the simplest multi-family continuous symmetry we can think of). We then show that the structure SU(3)c ? SU(2)L ? U(1)Y ? U(1)H by itself is able to explain (ii), and that the simplest supersymmetric (SUSY) extension of this model without a μ-term can not cope with (ii). 相似文献
52.
53.
Albino Hernández-Galeana William A. Ponce Arnulfo Zepeda 《Zeitschrift fur Physik C Particles and Fields》1992,55(3):423-434
Electroweak and horizontal interactions are unified with the groupSU(6)
L
U(1)
Y
for three generations. The horizontal gauge group suggested from low energy phenomenology isSU(2)
H
. This model does not contain exotic quarks, but exotic leptons are needed in order to make it anomaly-free. The breaking of the symmetry gives, in a natural way, heavy masses for exotic leptons and a BCS mass matrix for the up quarks, which implies that at tree level only the top quark gets a mass of orderM
W
. The see-saw mechanism generates tiny masses for the three known neutrinos. The remaining of the known fermion masses are light, because they can be generated only as radiative corrections. 相似文献
54.
Carlos E. Kenig Gustavo Ponce Luis Vega 《Transactions of the American Mathematical Society》1996,348(8):3323-3353
This paper is concerned with 1-D quadratic semilinear
Schrödinger equations. We study local well posedness in classical Sobolev space of the associated initial value problem and periodic boundary value problem. Our main interest is to obtain the lowest value of which guarantees the desired local well posedness result. We prove that at least for the quadratic cases these values are negative and depend on the structure of the nonlinearity considered.
Schrödinger equations. We study local well posedness in classical Sobolev space of the associated initial value problem and periodic boundary value problem. Our main interest is to obtain the lowest value of which guarantees the desired local well posedness result. We prove that at least for the quadratic cases these values are negative and depend on the structure of the nonlinearity considered.
55.
56.
ter Steege DH Smits M de Lange CA Westwood NP Peel JB Visscher L 《Faraday discussions》2000,(115):259-69; discussion 303-30
A (2 + 1) one-colour resonance-enhanced multiphoton ionisation study is carried out on the C 2 sigma- state of the ClO radical in the one-photon energy range 29,500-31,250 cm-1. The ClO radical is produced by one-photon photolysis of ClO2 employing 359.2 nm photons derived from a separate laser. In this way a significant concentration of vibrationally excited ClO in its spin-orbit split X 2 pi omega (omega = 3/2 or 1/2) electronic ground state is produced. In addition to mass-resolved excitation spectra, kinetic-energy resolved photoelectron spectra for the X 3 sigma-(v+)<--C 2 sigma-(v' = 3-5) transitions are measured. These transitions are not completely Frank-Condon diagonal, and indicate a decrease in bond length on removal of the Rydberg electron from the C 2 sigma- state. In addition to an unambiguous assignment of the C 2 sigma- state, valuable information is obtained on the degree of vibrational excitation with which the nascent ClO radical is formed in the photolysis of ClO2. Analysis of the photoelectron spectra is supported by Franck-Condon calculations based on potential energy curves either from experimental spectroscopic parameters, or obtained by theoretical ab initio methods. 相似文献
57.
J. Ponce de Leon 《General Relativity and Gravitation》1993,25(11):1123-1137
The energy conditions of general relativity are satisfied by all experimentally detected fields. We discuss their interpretation and application to charged spheres. It is found that they prevent the existence of naked singularities, and demand that the effective gravitational mass be everywhere non-negative. We focus on the emergence of limiting configurations-sources of the Reissner-Nordström field that have vanishing effective mass everywhere within the sphere. These configurations have a number of interesting features. Among them we find that, near the center, the limiting form of the equation of state is+3p=0. Notably this is the only equation of state consistent with the existence of zero-point electromagnetic field, and it has been considered in different contexts, in discussions of cosmic strings and in derivations of (3+1) properties of matter from (4+1) geometry. The consistency of these configurations with the Einstein-Maxwell equations is shown by means of explicit examples. These configurations can be interpreted as due to selfinteracting gravitational effects of the zero-point electromagnetic field. 相似文献
58.
Ysaías J. Alvarado Néstor Cubillán María G. Leal Paola H. Labarca Elba Michelena Yovani Marrero Ponce 《Journal of solution chemistry》2007,36(9):1139-1155
The values of electronic polarizability of quinoline and isoquinoline in extremely diluted liquid solution are reported in this paper. These were obtained by means of three new strategies based on UV-visible-NIR spectroscopy, the Kramers-Krönig relations, high precision densitometry and high exactitude refractometry, which are called here Arakawa’s Approximation (AA), Optical Substractive Approximation (OSA) and Optical Differential Approximation (ODA). In general the static electronic polarizability values of solute molecules obtained by ODA and OSA are in excellent agreement with the reported theoretical values at the Density Functional Theory (DFT) level and the Atom monopole-dipole model, but strong discrepancies were observed with the experimental values previously reported for quinoline and isoquinoline using refractometric and electro-optic methods. These differences were interpreted and analyzed in terms of dielectric intermolecular forces, resonant and pre-resonant effects. The AA method is shown to fail in predicting the polarizability of the quinoline and isoquinoline molecules. 相似文献
59.
Lazaro J. Yamin Carlos A. Ponce Mario R. Estrada Francisco Tomas Vert 《Journal of Molecular Structure》1996,360(1-3):109-117
Ab initio molecular orbital calculations with 4-31G//4-31G, 6-31G*//4-31G and 6-31+G//4-31G basis sets have been used to examine the structure, relative energy, protonation and deprotonation of a series of seven hydroxamic acids in the gas phase. The results show that hydroxamic acids are predominantly in the E-TS form and that the most probable protonation site is the carbonyl oxygen atom, while deprotonation proceeds by loss of NH hydrogen. 相似文献
60.
使用含时密度泛函理论(TDDFT)B3LYP方法计算了IB, IIB, VIIIB过渡金属与8-羟基喹啉络合(MQ)后, 配合物的电子光谱以及二阶非线性光学性质. 结果表明, 掺杂过渡金属后, 形成络合物的能隙值减小100~150 kJ/mol, 最大吸收波长红移150~200 nm左右. 电子从基态到激发态的跃迁主要为p→p*, n→p*跃迁, 属于LLCT, MLCT过程. IB的络合物MQ以及VIIIB的络合物MQ3表现出良好的非线性光学性质. 相似文献