Systematic study of giant quadrupole resonances with the subtracted second random-phase approximation: Beyond-mean-field centroids and fragmentation

2018 ◽  
Vol 98 (4) ◽  
Author(s):  
O. Vasseur ◽  
D. Gambacurta ◽  
M. Grasso
Keyword(s):  
Systematic Study ◽  
Random Phase Approximation ◽  
Random Phase ◽  
Mean Field ◽  
Phase Approximation

σ AND ω, WITH ∆-BARYON, AT HIGH TEMPERATURE

1996 ◽  
Vol 05 (03) ◽  
pp. 511-520
Author(s):  
ABHIJIT BHATTACHARYYA
Keyword(s):  
High Temperature ◽  
Temperature Dependence ◽  
Random Phase Approximation ◽  
Random Phase ◽  
Mean Field ◽  
Meson Mass ◽  
Phase Approximation ◽  
Effective Masses ◽  
The Mean ◽  
Walecka Model

The temperature dependence of σ and ω meson effective masses due to the presence of Δ-baryon has been studied. Starting from the Walecka model, containing both nucleon and Δ, the temperature dependence of effective masses of nucleon and Δ have been calculated at the Mean Field (MF) level. These results have been used to calculate the contribution to the effective masses of σ and ω from both [Formula: see text]- and [Formula: see text]-loops in Random Phase Approximation (RPA). The results are quite interesting. The σ-meson mass increases due to the [Formula: see text] loop whereas it decreases due to [Formula: see text]-loop with temperature. Further, the change in σ-meson mass due to [Formula: see text]-loop is much more compared to that due to [Formula: see text]-loop. For the ω-meson, both the loops are responsible for the increase in mass with temperature.

scholarly journals Spurious finite-size instabilities with Gogny-type interactions

2019 ◽  
Vol 55 (9) ◽  
Author(s):  
M. Martini ◽  
A. De Pace ◽  
K. Bennaceur
Keyword(s):  
Nuclear Matter ◽  
Linear Response ◽  
Random Phase Approximation ◽  
Continued Fraction ◽  
Random Phase ◽  
Mean Field ◽  
Finite Size ◽  
Phase Approximation ◽  
Response Functions ◽  
First Time

Abstract. Recently, a new parameterization of the Gogny interaction suitable for astrophysical applications, named D1M*, has been presented. We investigate the possible existence of spurious finite-size instabilities of this new Gogny force by repeating a study that we have already performed for the most commonly used parameterizations (D1, D1S, D1N, D1M) of the Gogny force. This study is based on a fully antisymmetrized random phase approximation (RPA) calculation of the nuclear matter response functions employing the continued fraction technique. It turns out that this new Gogny interaction is affected by spurious finite-size instabilities in the scalar isovector channel; hence, unphysical results are expected in the calculation of properties of nuclei, like neutron and proton densities, if this D1M* force is used. The conclusions from this study are then, for the first time, tested against mean-field calculations in a coordinate representation for several nuclei. Unphysical results for several nuclei are also obtained with the D1N parameterization of the Gogny force. These observations strongly advocate for the use of the linear response formalism to detect and avoid finite-size instabilities during the fit of the parameters of Gogny interactions as it is already done for some Skyrme forces.

scholarly journals The time-dependent relativistic mean-field theory and the random phase approximation

2001 ◽  
Vol 694 (1-2) ◽  
pp. 249-268 ◽  
Author(s):  
P. Ring ◽  
Zhong-yu Ma ◽  
Nguyen Van Giai ◽  
D. Vretenar ◽  
A. Wandelt ◽  
...  
Keyword(s):  
Field Theory ◽  
Random Phase Approximation ◽  
Mean Field Theory ◽  
Random Phase ◽  
Mean Field ◽  
Time Dependent ◽  
Phase Approximation ◽  
Relativistic Mean Field Theory ◽  
Relativistic Mean Field

scholarly journals Scattering of multicomponent polymer blends

2021 ◽  
Author(s):  
Henrich Frielinghaus
Keyword(s):  
Polymer Blends ◽  
Random Phase Approximation ◽  
Repeat Unit ◽  
Mean Field Theory ◽  
Random Phase ◽  
Mean Field ◽  
Phase Approximation ◽  
Field Phase ◽  
Phase Boundaries ◽  
Multicomponent Polymer

AbstractThe random phase approximation for polymer blends was developed by H. Benoît and described small angle scattering functions as well as mean field phase boundaries. It is a pure mean field theory that loses validity close to the real phase boundaries due to strong fluctuations. However, it gives a very clear roadmap about phase diagrams and scattering functions. A simplification of the random phase approximation is discussed that comes into effect when several polymers are mixed that involve a rather low number of chemically different repeat units. Then, the correlation functions of the same repeat unit pairs can be added up in a specific way such that the overall complexity for the calculations is reduced. The scattering functions and mean field phase boundaries are discussed within this concept. Graphical abstract

Finite nucleus Dirac mean field theory and random phase approximation using finiteBsplines

1989 ◽  
Vol 40 (1) ◽  
pp. 399-406 ◽  
Author(s):  
J. A. McNeil ◽  
R. J. Furnstahl ◽  
E. Rost ◽  
J. R. Shepard
Keyword(s):  
Field Theory ◽  
Random Phase Approximation ◽  
Mean Field Theory ◽  
Random Phase ◽  
Mean Field ◽  
Phase Approximation ◽  
Finite Nucleus
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