Search results for "basis"
showing 10 items of 760 documents
Effects of pseudoscalar-baryon channels in the dynamically generated vector-baryon resonances
2012
We study the interaction of vector mesons with the octet of stable baryons in the framework of the local hidden gauge formalism using a coupled channels unitary approach, including also the pseudoscalar-baryon channels which couple to the same quantum numbers. We examine the scattering amplitudes and their poles, which can be associated to known $J^P=1/2^-,3/2^-$ baryon resonances, and determine the role of the pseudoscalar-baryon channels, changing the width and eventually the mass of the resonances generated with only the basis of vector-baryon states.
On the variational approach to Jastrow correlations in nuclei
1973
The variational equation determining the Jastrow correlation function is investigated with particular emphasis on the healing problem for both nuclear matter and finite nuclei. The consequences of several healing conditions are discussed. Furthermore, influences from the choice of the single particle basis and from long range correlations are studied and are found to be small in the short range region.
Nuclear structure of 157Gd
2003
Abstract The energy levels of 157 Gd have been investigated using the (n, γ ) and (n, n′ γ ) reactions. As a result of the analysis of the γ -ray spectra from 16 isolated neutron resonances, a level scheme with a complete set of levels with spins J =1/2, 3/2 has been established up to 1.86 MeV excitation energy. A part of the level scheme is interpreted in more detail on the basis of Coriolis and Δ N =2 coupled Nilsson configurations. Slightly different sets of shape parameters are deduced for negative- and positive-parity levels. A large excess of unassigned 1/2 and 3/2 levels evidently requires an explanation in terms of inclusion of new additional degrees of freedom.
Isospin Violation inϵ′
2003
On the basis of a next-to-leading-order calculation in chiral perturbation theory, the first complete analysis of isospin breaking for direct $CP$ violation in ${K}^{0}\ensuremath{\rightarrow}2\ensuremath{\pi}$ decays is performed. We find a destructive interference between three different sources of isospin violation in the $CP$ violation parameter ${ϵ}^{\ensuremath{'}}$. Within the uncertainties of large-${N}_{c}$ estimates for the low-energy constants, the isospin violating correction for ${ϵ}^{\ensuremath{'}}$ is below 15%.
Photoproduction of pions at low energy
1980
Presented in this paper is a field theory model for photoproduction of pions at low energy. In particular, it is shown that certain interaction terms, which were previously considered to be essential in order to explain the experimental situation corresponding to the spin-3/2 resonances, are really unnecessary and that the presence of these terms are not justifiable from the theoretical point of view. Further, the free parameters in the theory representing the off-mass-shell effects of the spin-3/2 particles are fixed on the basis of theoretical considerations.
Photoelectric effect from a metal surface: a revisited theoretical model
1992
The Sommerfeld model extended to include radiation–electron interaction in the regime of highly intense fields is taken as the basis for studying theoretically the laser multiphoton photoelectric effect from a metal surface. Numerical analysis is carried out without approximations other than those inherent in the model itself; the study of the multiphoton aspect of the problem is based on a scheme that is nonperturbative in an essential way. The numerical analysis facilitates insight into the potential and the limits of the model in the interpretation of recent experiments and into the similarities and differences between the metal multiphoton effect and atomic multiphoton ionization. The r…
Method specific Cholesky decomposition : Coulomb and exchange energies
2008
We present a novel approach to the calculation of the Coulomb and exchange contributions to the total electronic energy in self consistent field and density functional theory. The numerical procedure is based on the Cholesky decomposition and involves decomposition of specific Hadamard product matrices that enter the energy expression. In this way, we determine an auxiliary basis and obtain a dramatic reduction in size as compared to the resolution of identity (RI) method. Although the auxiliary basis is determined from the energy expression, we have complete control of the errors in the gradient or Fock matrix. Another important advantage of this method specific Cholesky decomposition is t…
A Temperature Dependent Non-Linear Inductor Model for a DC/DC Boost Converter
2018
This paper is focused on the use of non-linear inductors in DC/DC switching converters, as well as their behaviour due to changes in current and temperature. The model of an inductor is set up on the basis of experimental data, which are automatically acquired by a virtual instrument; from those data, a polynomial curve describing the inductance variations is obtained. The analysis of the converter, performed by including the proposed model, is validated by experimental tests.
From self-adjoint to non self-adjoint harmonic oscillators: physical consequences and mathematical pitfalls
2013
Using as a prototype example the harmonic oscillator we show how losing self-adjointness of the hamiltonian $H$ changes drastically the related functional structure. In particular, we show that even a small deviation from strict self-adjointness of $H$ produces two deep consequences, not well understood in the literature: first of all, the original orthonormal basis of $H$ splits into two families of biorthogonal vectors. These two families are complete but, contrarily to what often claimed for similar systems, none of them is a basis for the Hilbert space $\Hil$. Secondly, the so-called metric operator is unbounded, as well as its inverse. In the second part of the paper, after an extensio…
Quantum Computation with Generalized Binomial States in Cavity Quantum Electrodynamics
2008
We study universal quantum computation in the cavity quantum electrodynamics (CQED) framework exploiting two orthonormal two-photon generalized binomial states as qubit and dispersive interactions of Rydberg atoms with high-$Q$ cavities. We show that an arbitrary qubit state may be generated and that controlled-NOT and 1-qubit rotation gates can be realized via standard atom-cavity interactions.