scholarly journals Coupling constant and quark-loop expansion for corrections to the valence approximation

1999 ◽  
Vol 59 (9) ◽  
Author(s):  
W. Lee ◽  
D. Weingarten
Keyword(s):  
Coupling Constant ◽  
Quark Loop ◽  
Loop Expansion ◽  
Valence Approximation

scholarly journals Self-Consistent Pushing and Cranking Corrections to the Meson Fields of the Chiral Quark-Loop Soliton

1998 ◽  
Vol 07 (01) ◽  
pp. 121-138 ◽  
Author(s):  
M. Schleif ◽  
R. Wünsch ◽  
T. Maissner
Keyword(s):  
Constituent Quark ◽  
Magnetic Moments ◽  
Axial Vector ◽  
Mass Splitting ◽  
Energy Functional ◽  
Coupling Constant ◽  
Quark Loop ◽  
Vector Coupling ◽  
Quark Masses ◽  
Axial Vector Coupling

We study translational and spin-isospin symmetry restoration for the two-flavor chiral quark-loop soliton. Instead of a static soliton at rest we consider a boosted and rotating hedgehog soliton. Corrected classical meson fields are obtained by minimizing a corrected energy functional which has been derived by semi-classical methods (variation after projection). We evaluate corrected meson fields in the region 300 MeV ≤ M≤ 600 MeV of constituent quark masses M and compare them with the uncorrected fields. We study the effect of the corrections on various expectation values of nuclear observables such as the root-mean square radius, the axial-vector coupling constant, magnetic moments and the delta-nucleon mass splitting.

scholarly journals Radial anharmonic oscillator: Perturbation theory, new semiclassical expansion, approximating eigenfunctions. I. Generalities, cubic anharmonicity case

2019 ◽  
Vol 34 (26) ◽  
pp. 1950143 ◽  
Author(s):  
J. C. del Valle ◽  
A. V. Turbiner
Keyword(s):  
Perturbation Theory ◽  
Anharmonic Oscillator ◽  
Logarithmic Derivative ◽  
Variational Calculus ◽  
Strong Coupling Regime ◽  
Coupling Constant ◽  
Dimension Formula ◽  
Loop Expansion ◽  
Exact Ground State ◽  
Semiclassical Expansion

For the general [Formula: see text]-dimensional radial anharmonic oscillator with potential [Formula: see text] the perturbation theory (PT) in powers of coupling constant [Formula: see text] (weak coupling regime) and in inverse, fractional powers of [Formula: see text] (strong coupling regime) is developed constructively in [Formula: see text]-space and in [Formula: see text]-space, respectively. The Riccati–Bloch (RB) equation and generalized Bloch (GB) equation are introduced as ones which govern dynamics in coordinate [Formula: see text]-space and in [Formula: see text]-space, respectively, exploring the logarithmic derivative of wave function [Formula: see text]. It is shown that PT in powers of [Formula: see text] developed in RB equation leads to Taylor expansion of [Formula: see text] at small [Formula: see text] while being developed in GB equation leads to a new form of semiclassical expansion at large [Formula: see text]: it coincides with loop expansion in path integral formalism. In complementary way PT for large [Formula: see text] developed in RB equation leads to an expansion of [Formula: see text] at large [Formula: see text] and developed in GB equation leads to an expansion at small [Formula: see text]. Interpolating all four expansions for [Formula: see text] leads to a compact function (called the Approximant), which should uniformly approximate the exact eigenfunction at [Formula: see text] for any coupling constant [Formula: see text] and dimension [Formula: see text]. As a concrete application, the low-lying states of the cubic anharmonic oscillator [Formula: see text] are considered. 3 free parameters of the Approximant are fixed by taking it as a trial function in variational calculus. It is shown that the relative deviation of the Approximant from the exact ground state eigenfunction is [Formula: see text] for [Formula: see text] for coupling constant [Formula: see text] and dimension [Formula: see text] In turn, the variational energies of the low-lying states are obtained with unprecedented accuracy 7–8 s.d. for [Formula: see text] and [Formula: see text]

Exchange-Correlation Energy Densities and Response Potentials: Connection Between Two Definitions and Analytical Model for the Strong-Coupling Limit of a Stretched Bond

2019 ◽  
Author(s):  
S. Giarrusso ◽  
Paola Gori-Giorgi
Keyword(s):  
Density Functional Theory ◽  
Strong Coupling ◽  
Density Functional ◽  
Correlation Energy ◽  
Order Term ◽  
Strong Coupling Limit ◽  
Local Form ◽  
Coupling Constant ◽  
Functional Theory ◽  
Exchange Correlation

We analyze in depth two widely used definitions (from the theory of conditional probablity amplitudes and from the adiabatic connection formalism) of the exchange-correlation energy density and of the response potential of Kohn-Sham density functional theory. We introduce a local form of the coupling-constant-dependent Hohenberg-Kohn functional, showing that the difference between the two definitions is due to a corresponding local first-order term in the coupling constant, which disappears globally (when integrated over all space), but not locally. We also design an analytic representation for the response potential in the strong-coupling limit of density functional theory for a model single stretched bond.<br>

Assessing the Calculation of Exchange Coupling Constants and Spin Crossover Gaps Using the Approximate Projection Model to Improve Density Function Calculations

2019 ◽  
Author(s):  
Xianghai Sheng ◽  
Lee Thompson ◽  
Hrant Hratchian
Keyword(s):  
Density Functional Theory ◽  
Exchange Coupling ◽  
Density Functional ◽  
Spin Crossover ◽  
Coupling Constants ◽  
Spin Projection ◽  
Coupling Constant ◽  
Projection Model ◽  
Functional Theory

This work evaluates the quality of exchange coupling constant and spin crossover gap calculations using density functional theory corrected by the Approximate Projection model. Results show that improvements using the Approximate Projection model range from modest to significant. This study demonstrates that, at least for the class of systems examined here, spin-projection generally improves the quality of density functional theory calculations of J-coupling constants and spin crossover gaps. Furthermore, it is shown that spin-projection can be important for both geometry optimization and energy evaluations. The Approximate Project model provides an affordable and practical approach for effectively correcting spin-contamination errors in molecular exchange coupling constant and spin crossover gap calculations.

Meconium peritonitis: review of literature and own clinical observations

2020 ◽  
Author(s):  
E.N. Glavatskaya , O.V. Pribushenya , N.A. Venchikova
Keyword(s):  
Prenatal Diagnosis ◽  
Premature Birth ◽  
Surgical Care ◽  
Intestinal Wall ◽  
Meconium Peritonitis ◽  
Review Of Literature ◽  
Review Of The Literature ◽  
Clinical Observations ◽  
Loop Expansion ◽  
The Impact

Two clinical cases of meconium peritonitis in the fetuses are presented. The diagnosis was made prenatally at 30+5 and 20+1 weeks of gestation. The main ultrasound signs were ascites, loop expansion and thickening of the intestinal wall, peritoneal calcifications, meconium pseudocysts. In one case, pregnancy was complicated by polyhydramnios. In both cases, the pregnancy ended in premature birth, followed by surgical treatment during the first days of life. A review of the literature on the topic are discussed the etiology, the spectrum and frequency of ultrasound signs suggesting this condition in the fetus, the effectiveness of prenatal diagnosis, the prognosis for the life and health of the newborn, as well as the impact of the quality and timeliness of the prenatal diagnosis on the management of pregnancy and timeliness of surgical care for the newborn.

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