MDPI - Publisher of Open Access Journals

14 pages, 317 KiB

Open AccessArticle

Beta Decay Properties of Waiting-Point N = 50 and 82 Isotopes

by Necla Çakmak and Najm Abdullah Saleh

Particles 2025, 8(2), 56; https://doi.org/10.3390/particles8020056 - 6 May 2025

Viewed by 757

We performed the microscopic calculation of

β

-decay properties for waiting-point nuclei with neutron-closed magic shells. Allowed Gamow–Teller (GT) and first-forbidden (FF) transitions were simulated using a schematic model (SM) for waiting-point N =

50, 82

isotopes in the framework of a [...] Read more.

We performed the microscopic calculation of

β

-decay properties for waiting-point nuclei with neutron-closed magic shells. Allowed Gamow–Teller (GT) and first-forbidden (FF) transitions were simulated using a schematic model (SM) for waiting-point N =

50, 82

isotopes in the framework of a proton–neutron quasiparticle random phase approximation (

p n

-QRPA). The Woods–Saxon (WS) potential basis was used in our calculations. The

p n

-QRPA equations of allowed (GT) and (FF) transitions were utilized in both the particle–hole (

p h

) and particle–particle (

p p

) channels in the SM. We solved the secular equations of the GT and FF transitions for eigenvalues and eigenfunctions of the corresponding Hamiltonians. A spherical shape was assigned to each waiting-point nucleus in all simulations. Significantly, this study marks the first time that

β

-decay analysis has been applied to certain nuclei, including ⁸²Ge₅₀, ⁸³As₅₀, ⁸⁴Se₅₀, ⁸⁵Br₅₀ and ⁸⁷Rb₅₀ with

N = 50

isotones, and ¹³²Sn₈₂, ¹³³Sb₈₂, ¹³⁴Te₈₂, ¹³⁵I₈₂ and ¹³⁷Cs₈₂ with

N = 82

isotones. Since there is no prior theoretical research on these nuclei, this work is a unique addition to the field. We compared our results with the previous calculations and measured data, and our calculations agree with the experimental data and the other theoretical results. Full article

12 pages, 304 KiB

Open AccessArticle

The Quenched g_A in Nuclei and Infrared Fixed Point in QCD

by Mannque Rho and Long-Qi Shao

Symmetry 2024, 16(12), 1704; https://doi.org/10.3390/sym16121704 - 22 Dec 2024

Cited by 1 | Viewed by 535

Abstract

The possible consequence of an infrared (IR) fixed point in QCD for

N_{f} = 2, 3

in nuclear matter is discussed. It is shown in terms of d(ilaton)-

χ

effective field theory (d

χ

EFT) incorporated in a generalized effective [...] Read more.

The possible consequence of an infrared (IR) fixed point in QCD for

N_{f} = 2, 3

in nuclear matter is discussed. It is shown in terms of d(ilaton)-

χ

effective field theory (d

χ

EFT) incorporated in a generalized effective field theory implemented with hidden local symmetry and hidden scale symmetry that the superallowed Gamow–Teller transition in the doubly magic-shell nucleus ¹⁰⁰Sn recently measured at RIKEN indicates a large anomaly-induced quenching identified as a fundamental renormalization of

g_{A}

from the free-space value of 1.276 to ≈0.8. Combined with the quenching expected from strong nuclear correlations “snc”, the effective coupling in nuclei

g_{A}^{eff}

would come to ∼1/2. If this result were reconfirmed, it would impact drastically not only nuclear structure and dense compact-star matter—where

g_{A}

figures in

π

-N coupling via the Goldberger-Treiman relation—but also in search for physics Beyond the Standard Model (BSM), e.g.,

0 ν β β

decay, where the fourth power of

g_{A}

figures. Full article

(This article belongs to the Special Issue Nuclear Symmetry Energy: From Finite Nuclei to Neutron Stars)

26 pages, 643 KiB

Open AccessArticle

Re-Examination of the Effect of Pairing Gaps on Gamow–Teller Strength Distributions and β-Decay Rates

by Jameel-Un Nabi, Muhammad Riaz and Arslan Mehmood

Universe 2024, 10(3), 128; https://doi.org/10.3390/universe10030128 - 6 Mar 2024

Cited by 3 | Viewed by 1545

Abstract

β

-decay is one of the key factors for understanding the r-process and evolution of massive stars. The Gamow–Teller (GT) transitions drive the

β

-decay process. We employ the proton–neutron quasiparticle random phase approximation (pn-QRPA) model to calculate terrestrial and stellar

β

[...] Read more.

β

-decay is one of the key factors for understanding the r-process and evolution of massive stars. The Gamow–Teller (GT) transitions drive the

β

-decay process. We employ the proton–neutron quasiparticle random phase approximation (pn-QRPA) model to calculate terrestrial and stellar

β

-decay rates for 50 top-ranked nuclei possessing astrophysical significance according to a recent survey. The model parameters of the pn-QRPA model affect the predicted results of

β

-decay. The current study investigates the effect of nucleon–nucleon pairing gaps on charge-changing transitions and the associated

β

decay rates. Three different values of pairing gaps, namely TF, 3TF, and 5TF, were used in our investigation. It was concluded that both GT strength distributions and half-lives are sensitive to pairing gap values. The 3TF pairing gap scheme, in our chosen nuclear model, resulted in the best prediction with around 80% of the calculated half-lives within a factor 10 of the measured ones. The 3TF pairing scheme also led to the calculation of the biggest

β

-decay rates in stellar matter. Full article

(This article belongs to the Special Issue Recent Advances in Double Beta Decay Investigations: In Honor of Prof. Sabin Stoica at His 70th Anniversary)

► Show Figures

Figure 1

15 pages, 1167 KiB

Open AccessFeature PaperArticle

Gamow–Teller Beta Decay and Pseudo-SU(4) Symmetry

by Piet Van Isacker, Alejandro Algora, András Vitéz-Sveiczer, Gábor Gyula Kiss, Sonja Elena Agata Orrigo, Berta Rubio and Pablo Aguilera

Symmetry 2023, 15(11), 2001; https://doi.org/10.3390/sym15112001 - 31 Oct 2023

Cited by 2 | Viewed by 1445

Abstract

We report on recent experimental results on

β

decay into self-conjugate (

N = Z

) nuclei with mass number

58 \leq A \leq 70

. Super-allowed

β

decays from the

J^{π} = 0^{+}

ground state of a [...] Read more.

We report on recent experimental results on

β

decay into self-conjugate (

N = Z

) nuclei with mass number

58 \leq A \leq 70

. Super-allowed

β

decays from the

J^{π} = 0^{+}

ground state of a

Z = N + 2

parent nucleus are to the isobaric analogue state through so-called Fermi transitions and to

J^{π} = 1^{+}

states by way of Gamow–Teller (GT) transitions. The operator of the latter decay is a generator of Wigner’s SU(4) algebra and as a consequence GT transitions obey selection rules associated with this symmetry. Since SU(4) is progressively broken with increasing A, mainly as a consequence of the spin–orbit interaction, this symmetry is not relevant for the nuclei considered here. We argue, however, that the pseudo-spin–orbit splitting can be small in nuclei with

58 \leq A \leq 70

, in which case nuclear states exhibit an approximate pseudo-SU(4) symmetry. To test this conjecture, GT decay strength is calculated with use of a schematic Hamiltonian with pseudo-SU(4) symmetry. Some generic features of the GT

β

decay due to pseudo-SU(4) symmetry are pointed out. The experimentally observed GT strength indicates a restoration of pseudo-SU(4) symmetry for

A = 70

. Full article

(This article belongs to the Special Issue Role of Symmetries in Nuclear Physics)

► Show Figures

Figure 1

11 pages, 603 KiB

Open AccessArticle

The St. Benedict Facility: Probing Fundamental Symmetries through Mixed Mirror β-Decays

by William S. Porter, Daniel W. Bardayan, Maxime Brodeur, Daniel P. Burdette, Jason A. Clark, Aaron T. Gallant, Alicen M. Houff, James J. Kolata, Biying Liu, Patrick D. O’Malley, Caleb Quick, Fabio Rivero, Guy Savard, Adrian A. Valverde and Regan Zite

Atoms 2023, 11(10), 129; https://doi.org/10.3390/atoms11100129 - 11 Oct 2023

Cited by 2 | Viewed by 1962

Abstract

Precise measurements of nuclear beta decays provide a unique insight into the Standard Model due to their connection to the electroweak interaction. These decays help constrain the unitarity or non-unitarity of the Cabibbo–Kobayashi–Maskawa (CKM) quark mixing matrix, and can uniquely probe the existence [...] Read more.

Precise measurements of nuclear beta decays provide a unique insight into the Standard Model due to their connection to the electroweak interaction. These decays help constrain the unitarity or non-unitarity of the Cabibbo–Kobayashi–Maskawa (CKM) quark mixing matrix, and can uniquely probe the existence of exotic scalar or tensor currents. Of these decays, superallowed mixed mirror transitions have been the least well-studied, in part due to the absence of data on their Fermi to Gamow-Teller mixing ratios (

ρ

). At the Nuclear Science Laboratory (NSL) at the University of Notre Dame, the Superallowed Transition Beta-Neutrino Decay Ion Coincidence Trap (St. Benedict) is being constructed to determine the

ρ

for various mirror decays via a measurement of the beta–neutrino angular correlation parameter (

a_{β ν}

) to a relative precision of 0.5%. In this work, we present an overview of the St. Benedict facility and the impact it will have on various Beyond the Standard Model studies, including an expanded sensitivity study of

ρ

for various mirror nuclei accessible to the facility. A feasibility evaluation is also presented that indicates the measurement goals for many mirror nuclei, which are currently attainable in a week of radioactive beam delivery at the NSL. Full article

(This article belongs to the Special Issue Advances in Ion Trapping of Radioactive Ions)

► Show Figures

Figure 1

9 pages, 277 KiB

Open AccessArticle

Anomaly-Induced Quenching of g_A in Nuclear Matter and Impact on Search for Neutrinoless ββ Decay

by Mannque Rho

Symmetry 2023, 15(9), 1648; https://doi.org/10.3390/sym15091648 - 25 Aug 2023

Cited by 9 | Viewed by 1086

Abstract

How to disentangle the possible genuine quenching of

g_{A}

caused by scale anomaly of QCD parameterized by the scale-symmetry-breaking quenching factor

q_{s s b}

from nuclear correlation effects is described. This is accomplished by matching the Fermi-liquid fixed point theory to [...] Read more.

How to disentangle the possible genuine quenching of

g_{A}

caused by scale anomaly of QCD parameterized by the scale-symmetry-breaking quenching factor

q_{s s b}

from nuclear correlation effects is described. This is accomplished by matching the Fermi-liquid fixed point theory to the “Extreme Single Particle (shell) Model” (acronym ESPM) in superallowed Gamow–Teller transitions in heavy doubly-magic shell nuclei. The recently experimentally observed indication for

(1 - q_{s s b}) \neq 0

—that one might identify as “fundamental quenching (FQ)”—in certain experiments seems to be alarmingly significant. I present arguments for how symmetries hidden in the matter-free vacuum can emerge and suppress such FQ in strong nuclear correlations. How to confirm or refute this observation is discussed in terms of the superallowed Gamow–Teller transition in the doubly-magic nucleus

^{100}

Sn and in the spectral shape in the multifold forbidden

β

decay of

^{115}

In. Full article

(This article belongs to the Special Issue Symmetries and Ultra Dense Matter of Compact Stars II: Emergence of Symmetries in Strong Nuclear Correlations)

8 pages, 259 KiB

Open AccessArticle

Multifarious Roles of Hidden Chiral-Scale Symmetry: “Quenching” g_A in Nuclei

by Mannque Rho

Symmetry 2021, 13(8), 1388; https://doi.org/10.3390/sym13081388 - 30 Jul 2021

Cited by 8 | Viewed by 1566

Abstract

I discuss how the axial current coupling constant

g_{A}

renormalized in scale symmetric chiral EFT defined at a chiral matching scale impacts on the axial current matrix elements on beta decays in nuclei with and without neutrinos. The “quenched”

g_{A}

observed [...] Read more.

I discuss how the axial current coupling constant

g_{A}

renormalized in scale symmetric chiral EFT defined at a chiral matching scale impacts on the axial current matrix elements on beta decays in nuclei with and without neutrinos. The “quenched”

g_{A}

observed in nuclear superallowed Gamow–Teller transitions, a long-standing puzzle in nuclear physics, is shown to encode the emergence of chiral-scale symmetry hidden in QCD in the vacuum. This enables one to explore how trace-anomaly-induced scale symmetry breaking enters in the renormalized

g_{A}

in nuclei applicable to certain non-unique forbidden processes involved in neutrinoless double beta decays. A parallel is made between the roles of chiral-scale symmetry in quenching

g_{A}

in highly dense medium and in hadron–quark continuity in the EoS of dense matter in massive compact stars. A systematic chiral-scale EFT, presently lacking in nuclear theory and potentially crucial for the future progress, is suggested as a challenge in the field. Full article

(This article belongs to the Special Issue Chiral Symmetry in Physics)

8 pages, 364 KiB

Open AccessArticle

β⁻-Decay Half-Lives of Even-Even Nuclei Using the Recently Introduced Phase Space Recipe

by Jameel-Un Nabi, Mavra Ishfaq, Ovidiu Niţescu, Mihail Mirea and Sabin Stoica

Universe 2020, 6(1), 5; https://doi.org/10.3390/universe6010005 - 26 Dec 2019

Cited by 2 | Viewed by 3215

Abstract

In this paper, we present the

β

-decay half-lives calculation for selected even-even nuclei that decay through electron emission. The kinematical portion of the half-life calculation was performed using a recently introduced technique for computation of phase space factors (PSFs). The dynamical portion [...] Read more.

In this paper, we present the

β

-decay half-lives calculation for selected even-even nuclei that decay through electron emission. The kinematical portion of the half-life calculation was performed using a recently introduced technique for computation of phase space factors (PSFs). The dynamical portion of our calculation was performed within the proton-neutron quasiparticle random phase approximation (pn-QRPA) model. Six nuclei (

^{20}

O,

^{24}

Ne,

^{34}

Si,

^{54}

Ti,

^{62}

Fe and

^{98}

Zr) were selected for the present calculation. We compare the calculated PSFs for these cases against the traditionally used recipe. In our new approach, the Dirac equation was numerically solved by employing a Coulomb potential. This potential was adopted from a more realistic proton distribution of the daughter nucleus. Thus, the finite size of the nucleus and the diffuse nuclear surface corrections are taken into account. Moreover, a screened Coulomb potential was constructed to account for the effect of atomic screening. The power series technique was used for the numerical solution. The calculated values of half-lives, employing the recently developed method for computation of PSFs, were in good agreement with the experimental data. Full article

(This article belongs to the Special Issue Relativistic Astrophysics)

► Show Figures

Figure 1

12 pages, 686 KiB

Open AccessArticle

The Investigation of the log(ft) Values for the Allowed Gamow-Teller Transitions of Some Deformed Nuclei

by C. Selam, T. Babacan, H. A. Aygör, H. Bircan, A. Küçübursa and I. Maraş

Math. Comput. Appl. 2004, 9(1), 79-90; https://doi.org/10.3390/mca9010079 - 1 Apr 2004

Cited by 6 | Viewed by 1572

Abstract

The log(ft) values of allowed β^± decay between odd-A nuclei for 125 < A < 180 mass region are investigated. Single particle energies and wave functions are calculated by making use of a deformed Woods-Saxon potential. The calculations are performed in the [...] Read more.

The log(ft) values of allowed β^± decay between odd-A nuclei for 125 < A < 180 mass region are investigated. Single particle energies and wave functions are calculated by making use of a deformed Woods-Saxon potential. The calculations are performed in the framework of proton-neutron quasi particle random phase approximation (QRPA) including the schematic residual spin-isospin interaction among the nucleons in the particle hole channel. The calculations indicated that the results obtained through using the χ_GT=5.2/A^0.7 are more in agreement with experimental observations. Full article

Search Results (9)

Further Information

Guidelines

MDPI Initiatives

Follow MDPI

Saved Queries

Search Filter Reset All

Years

Feature Papers

Subjects

Journals

Article Types

Countries / Regions

Search Results (9)

Further Information

Guidelines

MDPI Initiatives

Follow MDPI