scholarly journals CLUSTER RADIOACTIVITY OF TH ISOTOPES IN THE MEAN-FIELD HFB THEORY

2008 ◽  
Vol 17 (01) ◽  
pp. 204-211 ◽  
Author(s):  
L. M. ROBLEDO ◽  
M. WARDA
Keyword(s):  
Experimental Data ◽  
Symmetry Breaking ◽  
Quadrupole Moment ◽  
Mean Field ◽  
Reflection Symmetry ◽  
Fission Process ◽  
Cluster Radioactivity ◽  
The Mean ◽  
The Masses ◽  
Asymmetric Fission

Cluster radioactivity is described as a very mass asymmetric fission process. The reflection symmetry breaking octupole moment has been used in a mean field HFB theory as leading coordinate instead of the quadrupole moment usually used in standard fission calculations. The procedure has been applied to the study of the "very mass asymmetric fission barrier" of several even-even Thorium isotopes. The masses of the emitted clusters as well as the corresponding half-lives have been evaluated on those cases where experimental data exist.

BARYON MASSES IN COLOR DIELECTRIC MODEL

1994 ◽  
Vol 03 (02) ◽  
pp. 801-810 ◽  
Author(s):  
SARIRA SAHU
Keyword(s):  
Projection Method ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Quantum Mechanical ◽  
Quantum Mechanical Treatment ◽  
State Approximation ◽  
Dielectric Model ◽  
The Mean ◽  
The Masses

The non-scaling version of the Color Dielectric Model is used to calculate the SU(3) baryon octet and decuplet masses with the mean-field approximation and momentum projection method of Peierls and Yoccoz. Quantum mechanical treatment of the dielectric field is done by taking the coherent state approximation. For suitable set of parameters it is observed that the masses in the momentum projection method are in better agreement with the observed values than those of the mean-field ones.

SYMMETRY BREAKING PHENOMENA IN MESOSCOPIC SYSTEMS: QUANTUM DOTS AND ROTATING NUCLEI

2009 ◽  
Vol 18 (04) ◽  
pp. 1014-1021
Author(s):  
R. G. NAZMITDINOV ◽  
A. PUENTE
Keyword(s):  
Quantum Dots ◽  
Symmetry Breaking ◽  
Rotational Symmetry ◽  
Random Phase ◽  
Mean Field ◽  
Rotating Frame ◽  
Octupole Deformation ◽  
The Mean ◽  
Symmetry Breaking Phenomena ◽  
Rotating Nuclei

A brief description of excited and ground states in two-dimensional quantum dots and rotating nuclei is presented within a mean field approach and a random-phase approximation (RPA). We discuss the procedure to restore the rotational symmetry broken at the mean field, which can be extended for other symmetry breaking cases. We propose to consider a disappearance of collective excitations in the rotating frame as a manifestation of symmetry breaking phenomena of the rotating mean field. In particular, we demonstrate that the disappearance of a collective octupole mode in the rotating frame in 162 Yb gives rise to the nonaxial octupole deformation.

THE EMISSION OF HEAVY CLUSTERS DESCRIBED IN THE MEAN-FIELD HFB THEORY: THE CASE OF 242Cm

2008 ◽  
Vol 17 (10) ◽  
pp. 2275-2282 ◽  
Author(s):  
L. M. ROBLEDO ◽  
M. WARDA
Keyword(s):  
Mean Field ◽  
Zero Point ◽  
Point Energy ◽  
Cluster Emission ◽  
Field Techniques ◽  
Hartree Fock ◽  
Moment Operator ◽  
Collective Coordinate ◽  
The Mean ◽  
Asymmetric Fission

The emission of a nucleus of 34 Si by the parent [Formula: see text] is a process in the diffuse borderline between cluster emission and standard mass asymmetric fission. In this paper we analyze in a microscopic framework such process using the standard mean field techniques used to describe cluster emission. They include Hartree-Fock-Bogoliubov constrained calculations with the Gogny D1S interaction and the octupole moment operator as the collective coordinate to describe the process. Collective masses and all kind of zero point energy corrections are considered which allows for a parameter free estimation of the process' half-life. The agreement with experiment is quite satisfactory.

scholarly journals Mean-field parameters of some PrxTb(1-x)Al2 compounds found via searching for the best magnetic heat capacity fitting

2021 ◽  
Vol 2090 (1) ◽  
pp. 012081
Author(s):  
J. C. G. Tedesco ◽  
V.J. Monteiro ◽  
A. M. G. Carvalho ◽  
L.P. Cardoso ◽  
A. A. Coelho
Keyword(s):  
Experimental Data ◽  
Heat Capacity ◽  
Magnetocaloric Effect ◽  
Mean Field ◽  
Heat Capacities ◽  
Field Approach ◽  
Physical Limitations ◽  
The Mean ◽  
Good Agreement

Abstract Simulations of the magnetic heat capacity of some (Pr, Tb)Al2 compounds were performed using the mean-field approach. The developed routine aims to optimize the set of mean-field parameters. The proposed algorithm calculates the sum of squared differences between the experimental points and the simulated curve and then changes the parameters in order to minimize this sum. This searching leads to consistent values that can reproduce the experimental data. The parameters found in this work reproduced the heat capacities curves of the PrxTb(1−x)Al2 compounds, x=0.25, x=0.50 and x=0.75, with good agreement. The physical limitations of the mean-field approach do not preclude analysing the results. These parameters are important because they can help to understand and calculate the magnetocaloric effect these materials can present.

scholarly journals ISOSPIN MIXING OF ISOSPIN-PROJECTED SLATER DETERMINANTS: FORMALISM AND PRELIMINARY APPLICATIONS

2009 ◽  
Vol 18 (04) ◽  
pp. 958-964 ◽  
Author(s):  
M. RAFALSKI ◽  
W. SATUŁA ◽  
J. DOBACZEWSKI
Keyword(s):  
Symmetry Breaking ◽  
Harmonic Oscillator ◽  
Mean Field ◽  
Isospin Symmetry ◽  
Harmonic Oscillator Basis ◽  
Field Approach ◽  
Mixing Parameter ◽  
Oscillator Basis ◽  
Isospin Symmetry Breaking ◽  
The Mean

We report on the development of a new theoretical tool that allows for isospin projection of Slater determinants and we present its first applications. In particular, we determine the isospin mixing in ground states of N = Z nuclei and discuss its dependence on the size of the harmonic-oscillator basis used in the calculations. We also discuss the unphysical contribution to the isospin mixing caused by the spurious isospin-symmetry breaking inherent to the mean-field approach. We show that these contributions may be as large as 30% of the value of the isospin-mixing parameter.

Calculation of the Spontaneous Polarization and the Dielectric Constant for the Ferroelectric N(CH3)4HSO4 Using the Mean Field Model

2017 ◽  
Vol 36 (9) ◽  
pp. 863-869
Author(s):  
H. Yurtseven ◽  
M. Celik ◽  
H. Karacali
Keyword(s):  
Experimental Data ◽  
Dielectric Constant ◽  
Spontaneous Polarization ◽  
Field Model ◽  
Mean Field ◽  
Mean Field Model ◽  
Temperature Dependences ◽  
Inverse Susceptibility ◽  
The Mean ◽  
Fitting Parameters

AbstractThe temperature dependences of the spontaneous polarization and the dielectric constant (susceptibility) are calculated using the mean field model for the ferroelectric N(CH3)4HSO4. Expressions derived from the mean field model for the spontaneous polarization and the inverse susceptibility are fitted to the experimental data from the literature. The fitting parameters in the expansion of the free energy in terms of the spontaneous polarization are determined within the temperature intervals in the ferroelectric and paraelectric phases of N(CH3)4HSO4. Our results show that the temperature dependences of the spontaneous polarization and the dielectric constant as predicted from our mean field model, describe adequately the observed behavior of N(CH3)4HSO4 in the ferroelectric and paraelectric phases.

scholarly journals Formalizing the gene centered view of evolution

1999 ◽  
Vol 02 (03) ◽  
pp. 277-281 ◽  
Author(s):  
Yaneer Bar-Yam
Keyword(s):  
Symmetry Breaking ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Trait Divergence ◽  
The Mean ◽  
Dynamic Version ◽  
Evolving Populations

A historical dispute in the conceptual underpinnings of evolution is the validity of the gene centered view of evolution (Dawkins, 1989; Sober and Lewontin, 1982). We transcend this debate by formalizing the gene centered view as a dynamic version of the mean field approximation. This establishes the conditions under which it is applicable and when it is not. In particular, it breaks down for trait divergence which corresponds to symmetry breaking in evolving populations.

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