scholarly journals Nuclear form factors and closure approximation in the study of the (μ-,e-) conversion in nuclei

2020 ◽  
Vol 1 ◽  
pp. 27
Author(s):  
T. S. Kosmas ◽  
J. D. Vergados
Keyword(s):  
Shell Model ◽  
Periodic Table ◽  
Transition Rate ◽  
Form Factors ◽  
Matrix Elements ◽  
Closure Approximation ◽  
Coherent Process

The methods of studying the exotic (μ-,e-) conversion in nuclei are discussed. For the coherent process the dependence of the rate on the nuclear parameters is obtained by using shell model nuclear form factors. For the noncoher­ent processes the relevant matrix elements are calculated in the framework of the closure approximation. Finally the fraction of the transition rate of the coherent process throughout the periodic table is calculated.

scholarly journals Large Scale Shell Model Calculations of the Negative-Parity States Structure in 24Mg Nucleus

2021 ◽  
Vol 66 (4) ◽  
pp. 293
Author(s):  
A.A. Al-Sammarraie ◽  
F.A. Ahmed ◽  
A.A. Okhunov
Keyword(s):  
Shell Model ◽  
Large Scale ◽  
Transition Probabilities ◽  
Transition Probability ◽  
Energy Levels ◽  
Form Factors ◽  
Model Space ◽  
Negative Parity ◽  
Matrix Elements ◽  
Model Calculations

The negative-parity states of 24Mg nucleus are investigated within the shell model. We are based on the calculations of energy levels, total squared form factors, and transition probability using the p-sd-pf (PSDPF) Hamiltonian in a large model space (0 + 1) hW. The comparison between the experimental and theoretical states showed a good agreement within a truncated model space. The PSDPF-based calculations successfully reproduced the data on the total squared form factors and transition probabilities of the negative-parity states in 24Mg nucleus. These quantities depend on the one-body density matrix elements that are obtained from the PSDPF Hamiltonian. The wave functions of radial one-particle matrix elements calculated with the harmonic-oscillator potential are suitable to predict experimental data by changing the center-of-mass corrections.

scholarly journals Double beta decay without invoking closure

2020 ◽  
Vol 1 ◽  
pp. 45
Author(s):  
G. Pantis ◽  
J. D. Vergados
Keyword(s):  
Shell Model ◽  
Beta Decay ◽  
Nuclear Matrix ◽  
Model Space ◽  
Double Beta Decay ◽  
Matrix Elements ◽  
Model Calculations ◽  
Closure Approximation ◽  
The Matrix

The nuclear matrix elements of PU operators entering in the 0v ßß-decay of 76Ge-->76Se have been calculated explicitly  in the context of QRPA within the model space 0f7/2 - 0h11/2. T h e validity of the closure approximation has been tested and seems to be quite satisfactory for those matrix elements which are not usually suppressed. Our results indicate that they are dominated by multipoles other than 0+ and 1+ and that the matrix elements are comparable to those of shell model calculations.

scholarly journals Light-cone sum rules for proton decay

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Ulrich Haisch ◽  
Amando Hala
Keyword(s):  
Lattice Qcd ◽  
Light Cone ◽  
Sum Rules ◽  
State Of The Art ◽  
Form Factors ◽  
Baryon Number ◽  
Proton Decay ◽  
Matrix Elements ◽  
Decay Channels ◽  
Systematic Uncertainties

Abstract We estimate the form factors that parametrise the hadronic matrix elements of proton-to-pion transitions with the help of light-cone sum rules. These form factors are relevant for semi-leptonic proton decay channels induced by baryon-number violating dimension-six operators, as typically studied in the context of grand unified theories. We calculate the form factors in a kinematical regime where the momentum transfer from the proton to the pion is space-like and extrapolate our final results to the regime that is relevant for proton decay. In this way, we obtain estimates for the form factors that show agreement with the state-of-the-art calculations in lattice QCD, if systematic uncertainties are taken into account. Our work is a first step towards calculating more involved proton decay channels where lattice QCD results are not available at present.

scholarly journals Neutrinoless double beta nuclear matrix elements around mass 80 in the nuclear shell-model

2015 ◽  
Vol 93 ◽  
pp. 01055
Author(s):  
N. Yoshinaga ◽  
K. Higashiyama ◽  
D. Taguchi ◽  
E. Teruya
Keyword(s):  
Shell Model ◽  
Nuclear Matrix ◽  
Nuclear Shell Model ◽  
Matrix Elements ◽  
Nuclear Shell

Bc → J/ψ tensor form factors at large momentum recoil

2021 ◽  
pp. 2150135
Author(s):  
Dandan Shen ◽  
Huimin Ren ◽  
Fan Wu ◽  
Ruilin Zhu
Keyword(s):  
Form Factors ◽  
Distance Matrix ◽  
Relativistic Correction ◽  
Large Momentum ◽  
Matrix Elements ◽  
Leading Order ◽  
Lattice Data ◽  
Tensor Form ◽  
Long Distance ◽  
Current Form

We present a next-to-leading order (NLO) relativistic correction to [Formula: see text] tensor form factors within nonrelativistic QCD (NRQCD). We also consider complete Dirac bilinears [Formula: see text] with [Formula: see text] matrices [Formula: see text] in the [Formula: see text] transition. The relation among different current form factors is given and it shows that symmetries emerge in the heavy bottom quark limit. For a phenomenological extension, we propose to extract the long-distance matrix elements (LDMEs) for [Formula: see text] meson from the recent HPQCD lattice data and the NLO form factors at large momentum recoil.

scholarly journals Study of nuclear structure for carbon isotopes using local scale transformation technique in shell model

2019 ◽  
Vol 16 (39) ◽  
pp. 103-116
Author(s):  
Saja H. Mohammed
Keyword(s):  
Shell Model ◽  
Carbon Isotopes ◽  
Form Factors ◽  
Local Scale ◽  
Scale Transformation ◽  
Calculated Density ◽  
Radial Wave ◽  
Density Distributions ◽  
Proton Charge ◽  
Core Part

This work is devoted to study the properties of the ground states such as the root-mean square ( ) proton, charge, neutron and matter radii, nuclear density distributions and elastic electron scattering charge form factors for Carbon Isotopes (9C, 12C, 13C, 15C, 16C, 17C, 19C and 22C). The calculations are based on two approaches; the first is by applying the transformed harmonic-oscillator (THO) wavefunctions in local scale transformation (LST) to all nuclear subshells for only 9C, 12C, 13C and 22C. In the second approach, the 9C, 15C, 16C, 17C and 19C isotopes are studied by dividing the whole nuclear system into two parts; the first is the compact core part and the second is the halo part. The core and halo parts are studied using the radial wave functions of HO and THO radial wavefunctions, respectively. For 9C, 12C and 13C isotopes, the no-core shell model (NCSM) are studied using the Warburton-Brown interaction. Very good agreements are obtained for the calculated density distributions and form factors in comparison with experimental data.

scholarly journals The Electro-Excitation Form Factors for Low-Lying States of 7Li Nucleus

2010 ◽  
Vol 7 (1) ◽  
pp. 105-112
Author(s):  
Baghdad Science Journal
Keyword(s):  
Shell Model ◽  
Electron Scattering ◽  
Form Factors ◽  
Model Space ◽  
Theoretical Models ◽  
Inelastic Electron ◽  
Oscillator Shell ◽  
21.60 Cs ◽  
Configuration Mixing ◽  
Transverse Electron

The transverse electron scattering form factors have been studied for low –lying excited states of 7Li nucleus. These states are specified by J? T= (0.478MeV), (4.63MeV) and (6.68MeV). The transitions to these states are taking place by both isoscalar and isovector components. These form factors have been analyzed in the framework of the multi-nucleon configuration mixing of harmonic oscillator shell model with size parameter brms=1.74fm. The universal two-body of Cohen-Kurath is used to generate the 1p-shell wave functions. The core polarization effects are included in the calculations through effective g-factors and resolved many discrepancies with experiments. A higher configuration effect outside the 1p-shell model space, such as the 2p-shell, enhances the form factors for q-values and reproduces the data. The present results are compared with other theoretical models. PACS: 25.30.Bf Elastic electron scattering - 25.30.Dh Inelastic electron scattering to specific states – 21.60.Cs Shell model – 27.20. +n 5? A ?19

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