Effects of ground-state correlations on 2??? decay rates and limitations of the QRPA approach

1989 ◽  
Vol 334 (2) ◽  
pp. 177-186 ◽  
Author(s):  
K. Muto ◽  
E. Bender ◽  
H. V. Klapdor
Keyword(s):  
Ground State ◽  
Decay Rates ◽  
Qrpa Approach

scholarly journals Recent results for the logarithmic Keller-Segel-Fisher/KPP System

2019 ◽  
Vol 38 (7) ◽  
pp. 37-48
Author(s):  
Yanni Zeng ◽  
Kun Zhao
Keyword(s):  
Ground State ◽  
Decay Rates ◽  
Optimal Time ◽  
Logistic Growth ◽  
Time Behavior ◽  
Long Time Behavior ◽  
Chemotaxis Model ◽  
Time Decay Rates ◽  
Long Time ◽  
Logarithmic Sensitivity

We consider a Keller-Segel type chemotaxis model with logarithmic sensitivity and logistic growth. It is a 2 by 2 system describing the interaction of cells and a chemical signal. We study Cauchy problem with finite initial data, i.e., without the commonly used smallness assumption on  initial perturbations around a constant ground state. We survey a sequence of recent results by the authors on  the existence of global-in-time solution,  long-time behavior, vanishing coefficient limit and optimal time decay rates of the solution.

Evaluation of Luminescence Decay Measurements Probed on Pure and Doped Pt(IV) Hexahalogeno Complexes. II. Molecular Properties Obtained from Temperature Dependent Lifetime Curves

1997 ◽  
Vol 52 (5) ◽  
pp. 447-456
Author(s):  
Ingo Biertümpel ◽  
Hans-Herbert Schmidtke
Keyword(s):  
Excited States ◽  
Ground State ◽  
Energy Levels ◽  
Decay Rates ◽  
Rate Equations ◽  
Temperature Dependent ◽  
Lifetime Measurements ◽  
Thermally Activated ◽  
Ground State Energies ◽  
Higher Excited States

Abstract Lifetime measurements down to nearly liquid helium temperatures are used for determining energy levels and transition rates between excited levels and relaxations into the ground state. Energies are obtained from temperature dependent lifetimes by fitting experimental curves to model functions pertinent for thermally activated processes. Rates are calculated from solutions of rate equations. Similar parameters for pure and doped Pt(IV) hexahalogeno complexes indicate that excited levels largely belong to molecular units. Some of the rates between excited states are only somewhat larger than decay rates into the ground state, which is a consequence of the polyexponential decay measured also at low temperature (2 K). In the series of halogen complexes, the rates between spinorbit levels resulting from 3T1g increase from fluorine to bromine, although energy splittings become larger. Due to the decreasing population of higher excited states in this series, K^PtFö shows a tri-exponential, K2PtCl6 a bi-exponential and FoPtBr6 a mono-exponential decay. In the latter case the population density of higher excited states relaxes so fast that emission occurs primarily from the lowest excited Γ3(3T1g) level. Phase transitions and emission from chromophores on different sites can also be observed.

scholarly journals Two-phonon structures for beta-decay theory

2018 ◽  
Vol 194 ◽  
pp. 02008
Author(s):  
A.P. Severyukhin ◽  
N.N. Arsenyev ◽  
I.N. Borzov ◽  
R.G. Nazmitdinov ◽  
S. Åberg
Keyword(s):  
Random Matrix ◽  
Single Particle ◽  
Ground State ◽  
Matrix Theory ◽  
Decay Rates ◽  
Total Probability ◽  
Phonon Coupling ◽  
Skyrme Interaction ◽  
Β Decay ◽  
Gamow Teller

The β-decay rates of 60Ca have been studied within a microscopic model, which is based on the Skyrme interaction T45 to construct single-particle and phonon spaces. We observe a redistribution of the Gamow–Teller strength due to the phonon-phonon coupling, considered in the model. For 60Sc, the spin-parity of the ground state is found to be 1+. We predict that the half-life of 60Ca is 0.3 ms, while the total probability of the βxn emission is 6:1%. Additionally, the random matrix theory has been applied to analyze the statistical properties of the 1+ spectrum populated in the β-decay to elucidate the obtained results.

Ground-state scalarq¯qnonet: SU(3) mass splittings and strong, electromagnetic, and weak decay rates

2004 ◽  
Vol 69 (1) ◽  
Author(s):  
Michael D. Scadron ◽  
George Rupp ◽  
Frieder Kleefeld ◽  
Eef van Beveren
Keyword(s):  
Ground State ◽  
Weak Decay ◽  
Decay Rates

MAGNETIC RELAXATION OF SUPERCONDUCTING QUANTUM DOT AND TUNNELING OF ELECTRON IN A MAGNETIC FIELD

2009 ◽  
Vol 23 (20n21) ◽  
pp. 4422-4447
Author(s):  
D. R. GULEVICH ◽  
F. V. KUSMARTSEV
Keyword(s):  
Magnetic Field ◽  
Quantum Dot ◽  
Ground State ◽  
Quantum Tunneling ◽  
Quantum Particle ◽  
High Temperature Superconductors ◽  
Decay Rates ◽  
Method Of Images ◽  
Mesoscopic Superconductors ◽  
Low Temperature Creep

Quantum tunneling of vortices had been found to be an important novel phenomena for description of low temperature creep in high temperature superconductors (HTSCs). We speculate that quantum tunneling may be also exhibited in mesoscopic superconductors due to vortices trapped by the Bean-Livingston barrier. The London approximation and method of images is used to estimate the shape of the potential well in superconducting HTSC quantum dot. To calculate the escape rate we use the instanton technique. We model the vortex by a quantum particle tunneling from a two-dimensional ground state under magnetic field applied in the transverse direction. The resulting decay rates obtained by the instanton approach and conventional WKB are compared revealing complete coincidence with each other.

scholarly journals Electromagnetic transition form factors and Dalitz decays of hyperons

2021 ◽  
Vol 57 (6) ◽  
Author(s):  
Nora Salone ◽  
Stefan Leupold
Keyword(s):  
Form Factor ◽  
Decay Width ◽  
Ground State ◽  
Composite Structure ◽  
Relative Phase ◽  
Form Factors ◽  
Decay Rates ◽  
Transition Form ◽  
Type Approximation ◽  
Hyperon Resonance

AbstractDalitz decays of a hyperon resonance to a ground-state hyperon and an electron-positron pair can give access to some information about the composite structure of hyperons. We present expressions for the multi-differential decay rates in terms of general transition form factors for spin-parity combinations $$J^P = \frac{1}{2}^\pm , \frac{3}{2}^\pm $$ J P = 1 2 ± , 3 2 ± of the hyperon resonance. Even if the spin of the initial hyperon resonance is not measured, the self-analyzing weak decay of the “final” ground-state hyperon contains information about the relative phase between combinations of transition form factors. This relative phase is non-vanishing because of the unstable nature of the hyperon resonance. If all form factor combinations in the differential decay formulae are replaced by their respective values at the photon point, one obtains a QED type approximation, which might be interpreted as characterizing hypothetical hyperons with point-like structure. We compare the QED type approximation to a more realistic form factor scenario for the lowest-lying singly-strange hyperon resonances. In this way we explore which accuracy in the measurements of the differential Dalitz decay rates is required in order to distinguish the composite-structure case from the pointlike case. Based on the QED type approximation we obtain as a by-product a rough prediction for the ratio between the Dalitz decay width and the corresponding photon decay width.

scholarly journals On continuum- and bound-state ℓ−-decay rates of pionic and kaonic hydrogen in the ground state

2009 ◽  
Vol 36 (7) ◽  
pp. 075009 ◽  
Author(s):  
M Faber ◽  
A N Ivanov ◽  
V A Ivanova ◽  
J Marton ◽  
M Pitschmann ◽  
...  
Keyword(s):  
Ground State ◽  
Bound State ◽  
Decay Rates ◽  
Kaonic Hydrogen

scholarly journals Nuclear Weak Processes in Presupernova Stars

1996 ◽  
Vol 145 ◽  
pp. 165-172
Author(s):  
A. Ray ◽  
T. Kar ◽  
S. Sarkar ◽  
S. Chakravarti
Keyword(s):  
Excited States ◽  
Beta Decay ◽  
Ground State ◽  
Strength Function ◽  
Supernova Explosion ◽  
Decay Rates ◽  
Distribution Method ◽  
The Core ◽  
Weak Transition ◽  
Late Stages

The structure and the size of the core of massive presupernova stars are determined by the electron fraction and entropy of the core during its late stages of evolution; these in turn affect the subsequent evolution during gravitational collapse and supernova explosion phases. Beta decay and electron capture on a number of neutron rich nuclei can contribute substantially towards the reduction of the entropy and possibly the electron fraction in the core. Methods for calculating the weak transition rates for a number of nuclei for which no reliable rates exist (particularly for A > 60) are outlined. The calculations are particularly suited for presupernova matter density (p = 107 - 109 g/cc) and temperature (T = 2 - 6 × 109 °K). We include besides the contributions from the ground state and the known excited states, the Gamow-Teller (GT) resonance states (e.g. for beta decay rates, the GT+ states) in the mother nucleus which are populated thermally. For the GT strength function for transitions from the ground state (as well as excited states) we use a sum rule calculated by the spectral distribution method where the centroid of the distribution is obtained from experimental data on (p,n) reactions. The contribution of the excited levels and GT+ resonances turn out to be important at high temperatures which may prevail in presupernova stellar cores.

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