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71.
N. D. Christensen P. de Aquino N. Deutschmann C. Duhr B. Fuks C. Garcia-Cely O. Mattelaer K. Mawatari B. Oexl Y. Takaesu 《The European Physical Journal C - Particles and Fields》2013,73(10):1-23
Support for interactions of spin- $\frac{3}{2}$ particles is implemented in the FeynRules and ALOHA packages and tested with the MadGraph 5 and CalcHEP event generators in the context of three phenomenological applications. In the first, we implement a spin- $\frac{3}{2}$ Majorana gravitino field, as in local supersymmetric models, and study gravitino and gluino pair-production. In the second, a spin- $\frac{3}{2}$ Dirac top-quark excitation, inspired from compositeness models, is implemented. We then investigate both top-quark excitation and top-quark pair-production. In the third, a general effective operator for a spin- $\frac{3}{2}$ Dirac quark excitation is implemented, followed by a calculation of the angular distribution of the s-channel production mechanism. 相似文献
72.
R. Bonin G. Bertotti C. Serpico I. D. Mayergoyz M. d’Aquino 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,68(2):221-231
An analytical approach is presented for the study of synchronization effects in spin-transfer-driven nanomagnets subjected
to radio-frequency magnetic fields. The conditions are derived and discussed under which the current-induced magnetization
precession is synchronized by the radio-frequency field. Exact analytical results are obtained for the case when the problem
exhibits uniaxial symmetry around the axis perpendicular to the device plane. It is demonstrated that the magnetization dynamics
under nonzero current and nonzero rf field is identical in structure to that under zero current. On this basis, analytical
predictions are obtained for: the existence of phase-locking between current-induced magnetization precession and rf field
oscillations; the frequency pulling effect in proximity of phase locking; the occurrence of hysteresis effects in phase-locking
as a function of the spin-polarized current. The proposed approach is valid for arbitrary rf field amplitude and current intensity. 相似文献
73.
74.
Carbonell SA de Aquino Neto FR Cardoso JN dos Santos Pereira A Amaral AC Barnes RA 《Journal of chromatographic science》2000,38(6):234-240
The crude ethanol extracts from the leaves of three Croton hemiargyrus hemiargyreus plants are fractionated by thin-layer chromatography, yielding five fractions. The fractions and the crude extract are analyzed by high-temperature high-resolution gas chromatography coupled with mass spectrometry (HT-HRGC-MS). Several natural products, including thermolabile components, can be characterized directly in the samples, such as alkaloids, terpenes, flavonoids, acids, alcohols, etc. The cold on-column technique proves to be appropriate for the injection of these thermolabile compounds. HT-HRGC-MS is shown to be a valuable tool and an alternative technique to classical phytochemical procedures for the simple and fast routine analysis of natural products in crude extracts. 相似文献
75.
J. F. Rivas‐Silva A. Flores‐Riveros J. S. Durand‐Niconoff N. Aquino 《International journal of quantum chemistry》2004,97(3):815-825
Doping effects are analyzed by means of the ab initio perturbed ion (aiPI) method via substitution of the fluorides and oxides of zirconium, hafnium, and thorium. Lattice relaxation is simulated through the calculation of vibrational breathing modes and substitutional effects on the compound are thereby analyzed. In addition, the band gaps (in the pure species) and impurity levels (where substitutional ions Pr+4 and Yb+3 are considered in the doped species) of the fluorides are estimated via the transition energy calculated at the aiPI‐optimized geometry of the pure and doped crystal clusters by means of the configuration interaction with single excitations (CIS) method that accounts for electronic correlation. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004 相似文献
76.
F. M. Aquino D. M. A. Melo R. C. Santiago M. A. F. Melo A. E. Martinelli J. C. O. Freitas L. C. B. Araújo 《Journal of Thermal Analysis and Calorimetry》2011,104(2):701-705
Thermogravimetric data using the non-isothermal kinetic models of Flynn and Wall and “Model-free Kinetics” were used to determine
the activation energy to study the decomposition kinetics of the ligand groups with system’s metallic ions that takes part
in the synthesis of PrMO3 (M = Ni or Co). This activation energy was determined for the stage of highest decomposition of the organic matter to establish
parameters in synthesis condition optimization and application of the proposed material. 相似文献
77.
We calculate Shannon and Fisher entropies in the position and momentum space, and some complexity measures for a variationally described hydrogen atom confined in soft and hard spherical boxes of varying dimension and selected values of strength . We include calculations for a free particle trapped in impenetrable boxes. It is found that the Shannon entropy becomes negative for small cavity radii and large values of , due to the highly localized nature of the particle. For soft confinement and small cavity dimensions, the entropies change very rapidly over short radial intervals. 相似文献
78.
C. R. Estañón H. E. Montgomery Jr. J. C. Angulo N. Aquino 《International journal of quantum chemistry》2024,124(4):e27358
In this article, we study the helium atom confined in a spherical impenetrable cavity by using informational measures. We use the Ritz variational method to obtain the energies and wave functions of the confined helium atom as a function of the cavity radius . As trial wave functions we use one uncorrelated function and five explicitly correlated basis sets in Hylleraas coordinates with different degrees of electronic correlation. We computed the Shannon entropy, Fisher information, Kullback–Leibler entropy, Tsallis entropy, disequilibrium and Fisher–Shannon complexity, as a function of . We found that these entropic measures are sensitive to electronic correlation and can be used to measure it. As expected these entropic measures are less sensitive to electron correlation in the strong confinement regime ( a.u.). 相似文献
79.
Xavier Calmet Priscila de Aquino 《The European Physical Journal C - Particles and Fields》2010,68(1-2):305-311
We study the production of massless gravitons at the LHC and compare our results to those obtained in extra-dimensional models. The signature in both cases is missing energy plus jets. In case of non-observation, the LHC could be used to put the tightest limit to date on the value of the Planck mass. 相似文献
80.
We study an ensemble of two-level systems interacting with a thermal bath. This is a well-known model for glasses. The origin of memory effects in this model is a quasistationary but nonequilibrium state of a single two-level system, which is realized due to a finite-rate cooling and slow thermally activated relaxation. We show that single-particle memory effects, such as negativity of the specific heat under reheating, vanish for a sufficiently disordered ensemble. In contrast, a disordered ensemble displays a collective memory effect [similar to the Kovacs effect], where nonequilibrium features of the ensemble are monitored via a macroscopic observable. An experimental realization of the effect can be used to further assess the consistency of the model. 相似文献