Nuclear Theory·nucl-th

Tuesday·August 8, 2023

20 papers—11 primary·9 cross-listed

01
Radiative neutron capture reaction rates for stellar nucleosynthesis
Vinay Singh · Debasis Bhowmick · D. N. Basu
There is a high demand for nuclear data in multidisciplinary subject like nuclear astrophysics. The two areas of nuclear physics which are most clearly related to one another are stellar evolution and nucleosynthesis. The necessity for nuclear data for astrophysical applications puts experimental methods as well as reliability and predicative ability of current nuclear models to the test. Despite recent, considerable advances, there are still significant issues and mysteries. Only a few characteristics of nuclear astrophysics are covered in the current work which include $^{20}$ Ne(n, $γ$ ) $^{21}$ Ne, $^{52}$ Fe(n, $γ$ ) $^{53}$ Fe, $^{53}$ Fe(n, $γ$ ) $^{54}$ Fe, $^{54}$ Fe(n, $γ$ ) $^{55}$ Fe and $^{55}$ Fe(n, $γ$ ) $^{56}$ Fe reactions which are important in stellar nucleosynthesis. The reaction rates are calculated using nuclear statistical model. These rates are subsequently fitted to polynomials of temperature T $_{9}$ in order to facilitate calculations for stellar nucleosynthesis.
nucl-thastro-ph.SRIndian J.Phys.(2025)·0 citations
02
Triplet-odd pairing in finite nuclear systems: Even-even singly closed nuclei
Nobuo Hinohara · Tomohiro Oishi · Kenichi Yoshida
Background: The appearance of the pairing condensate is an essential feature of many-fermion systems. There are two possible types of pairing: spin-singlet and spin-triplet. However, an open question remains as to whether the spin-triplet pairing condensate emerges in finite nuclei. Purpose: The aim of this work is to examine the coexistence of the spin-singlet and spin-triplet like-particle pairing condensates in nuclei. We also discuss the dependence on the type of pairing functional. Method: The Hartree-Fock-Bogoliubov calculations with a Skyrme $+$ local-pair energy-density functional (EDF) are performed to investigate the pairing condensate in the spherical ground states of Ca and Sn isotopes. Results: The spin-singlet pair EDF induces not only the spin-singlet but also the spin-triplet pairing condensates due to a strong spin-orbit splitting. By discarding the spin-orbit EDF, only the spin-singlet pairing condensate appears. The spin-triplet pair EDF, however, induces the spin-orbit splitting and accordingly the spin-singlet pairing condensate. Conclusions: The spin-orbit splitting plays an essential role in the coexistence of the spin-singlet and spin-triplet pairing condensates in nuclei.
nucl-thcond-mat.supr-conPRC(2024)·11 citations
03
Neutron matter: The unitary limit and its far-reaching impact
Francesca Sammarruca
We explore low-density neutron matter and its behavior in proximity to the unitary limit. To that end, we construct unitary nucleon-nucleon potentials with infinite 1S0 neutron-neutron scattering lengths. We discuss the Berstch parameter in relation to results from ultra-cold atomic gases. Unitarity as a constraint for neutron matter and the symmetry energy has been discussed in the literature. We revisit some of those arguments and emphasize the relevance of keeping a firm link with low-energy nuclear physics for robust predictions of neutron-rich systems. Our predictions are obtained from realistic few-nucleon forces based on chiral effective field theory at N3LO.
nucl-thPRC(2023)·2 citations
04
Candidates for three-quasiparticle $K$ -isomers in odd-even Md-Rg nuclei
P. Jachimowicz · M. Kowal · J. Skalski
We performed a search for three-quasiparticle high- $K$ isomer candidates in odd-even Md - Rg nuclei by considering the lowest lying 1 $π$ 2 $ν$ and 3 $π$ excitations. Our approach involves calculating the energies of different nuclear configurations using a microscopic-macroscopic model with the Woods-Saxon potential. We explore three pairing scenarios: blocking, quasi-particle BCS method, and particle number projection formalism. The optimal deformations for both ground-states and high- $K$ configurations are determined through a four-dimensional energy minimization process. By analyzing the obtained excitation energies, we discuss the most promising candidates for high- $K$ isomers and compare them, where possible, with existing experimental data. We also discuss a possible isomer $α$ -decay hindrance using calculated $Q_{α}$ -hindrances.
nucl-thPRC(2023)·2 citations
05
The charge and mass symmetry breaking in the $K K K ˉ$ system
Igor Filikhin🇺🇸 · Roman Ya. Kezerashvili🇺🇸 · Branislav Vlahovic🇺🇸
In the framework of the Faddeev equations in configuration space, we investigate the $K$ (1460) meson as a resonant state of the $K K K ˉ$ kaonic system. We perform calculations for the particle configurations $K^{0} K^{+} K^{-}$ and $K^{0} K^{+} K^{0}$ within two models: the $A B C$ model, in which all three particles are distinguishable, and the $AA C$ model when two particles are identical. The models differ in their treatment of the kaon mass difference and the attractive Coulomb force between the $K^{+} K^{-}$ pair. We found that the Coulomb shift adds over 1 MeV to the three-body binding energy. The expected correction to the binding energy due to mass redistribution from $AA$ to $A B$ is found to be negligible, up to a maximum of 6\% of the relative mass correction. At the same time, the symmetry of the wave function is distorted depending on the mass ratio value. We found that the repulsive $K K$ interaction plays essential role in the binding energy of the $K K K ˉ$ system and report the mass of 1461.8 or 1464.1 MeV for the neutral $K^{0}$ (1460) and 1466.5 or 1468.8 MeV for the charged $K^{+}$ (1460) resonances, respectively, depending on the parameter sets for $K K$ and $K K ˉ$ interactions.
nucl-thquant-phJ.Phys.G(2024)·9 citations
06
Effect of cluster transfer on neutron-rich nuclide production around N=126 in multinucleon transfer reactions
Zhao-Qing Feng
The cluster transfer in multinucleon transfer reactions near Coulomb barrier energies is implemented into the master equations in dinuclear system model, in which the deuteron, triton, $^{3}$ He and $α$ are taken into account. The effects of cluster transfer and dynamical deformation on the formation of primary and secondary fragments are systematically investigated. It is found that the inclusion of cluster transfer is favorable the fragment formation with increasing the transferring nucleons and leads to a broad mass distribution. The isotopic cross sections of elements W, Os, Rn and Fr in the reaction of $^{136}$ Xe+ $^{208}$ Pb at the incident energy of E $_{c . m .}$ = 450 MeV are nicely consistent with the Argonne data. The new neutron-rich isotopes of wolfram and osmium are predicted with cross sections above 10 nb. The production mechanism of neutron-rich heavy nuclei around N = 126 in the reactions of $^{58, 64, 72}$ Ni + $^{198}$ Pt is investigated thoroughly. The cross sections for producing the neutron-rich isotopes of platinum, iridium, osmium and rhenium in the multinucleon transfer reactions of $^{64}$ Ni + $^{198}$ Pt and $^{72}$ Ni + $^{198}$ Pt at the center of mass energies of 220 MeV and 230 MeV are estimated and proposed for the future experiments.
nucl-thPRC(2023)·10 citations
07
Cluster radioactivity from trans-tin to superheavy region using an improved empirical formula
G. Saxena · A. Jain
A simple relation $(a Z_{c} + b) (Z_{d} / Q)^{1/2} + (c Z_{c} + d)$ of estimation of the half-life of cluster emission is further improved for cluster and $α$ -decays, separately, by incorporating isospin of parent nucleus as well as angular momentum taken away by the emitted particle. This improved version is not only found robust in producing experimental half-lives belonging to the trans-tin and trans-lead regions but also elucidates cluster emission in superheavy nuclei over the usual $α$ -decay. Considering daughter nuclei around the doubly magic $^{100}$ Sn and $^{208}$ Pb nuclei for trans-tin and trans-lead (including superheavy) parents, respectively, a systematic and extensive study of 56 $\leq$ Z $\leq$ 120 isotopes is performed for the light and heavy cluster emissions. A fair competition among cluster emission, $α$ -decay, spontaneous fission, and $β$ -decay is observed in this broad range resulting in a substantial probability of C to Sr clusters from several nuclei, which demonstrates the adequacy of shell effects. The present article proposes a single, improved, latest-fitted, and effective formula of cluster radioactivity that can be used to estimate precise half-lives for a wide range of the periodic chart from trans-tin to superheavy nuclei.
nucl-thnucl-exEPJA(2023)·12 citations
08
Probing the QCD phase transition with chiral mixing in dilepton production
Azumi Sakai🇯🇵 · Masayasu Harada🇯🇵 · Chiho Nonaka🇯🇵 · Chihiro Sasaki🇯🇵 · Kenta Shigaki🇯🇵 · Satoshi Yano🇯🇵
We perform a systematic study of dilepton emission in a hot QCD medium based on three different scenarios of chiral mixing, each of which yields a characteristic structure in the vector spectral function. The in-medium spectral functions are accommodated into the state-of-the-art hydrodynamic simulations for a relativistic viscous fluid to calculate the dilepton production rate, fully accounting for the space-time evolution of a created fireball in relativistic heavy-ion collisions. We demonstrate that the low-temperature theorem of chiral mixing extrapolated toward a chiral crossover, often used in the literature, leads to critical shortcomings: the inadequacy of width broadening, and a substantial overestimate of the dilepton yield maximized around the invariant mass of $M = 1.2$ GeV. The proper prescription offers a milder yet sizable increase in the window of $1.1 < M < 1.4$ GeV as the direct signature of chiral symmetry restoration.
nucl-thhep-phnucl-ex3 citations
09
Relativistic model-free prediction for neutrinoless double beta decay at leading order
Y. L. Yang🇨🇳 · P. W. Zhao🇨🇳
Starting from a manifestly Lorentz-invariant chiral Lagrangian, we present a model-free prediction for the transition amplitude of the process $nn \to pp e^{-} e^{-}$ induced by light Majorana neutrinos, which is a key process of the neutrinoless double beta decay ( $0 ν β β$ ) in heavy nuclei employed in large-scale searches. Contrary to the nonrelativistic case, we show that the transition amplitude can be renormalized at leading order without any uncertain contact operators. The predicted amplitude defines a stringent benchmark for the previous estimation with model-dependent inputs, and greatly reduces the uncertainty of $0 ν β β$ transition operator in the calculations of nuclear matrix elements. Generalizations of the present framework could also help to address the uncertainties in $0 ν β β$ decay induced by other mechanisms. In addition, the present work motivates a relativistic {\it ab initio} calculation of $0 ν β β$ decay in light and medium-mass nuclei.
nucl-thhep-lathep-phPLB(2024)·15 citations
10
Sensitivity study of mirror energy differences in positive parity bands of T=3/2 A=45 nuclei
W. Satula · M. A. Bentley · A. Jalili · S. Uthayakumaar
Symmetry conserving density functional theory (DFT) based no-core-configuration-interaction framework (DFT-NCCI) is an excellent tool for precision calculation of diverse (pseudo-)observables related to isospin symmetry breaking from elusive isospin impurities trough isospin corrections to superallowed beta decays to mirror- and triplet-displacement energies and mirror energy differences (MED) along rotational bands. In our recent work [Phys. Rev. C {\bf 106}, 024327 (2022)] we performed axial DFT-NCCI calculations and failed to reproduce a sign of MED in positive-parity bands of 45Sc/45Cr T=3/2 mirror pair what casts a shadow on credibility of the model. In this work we aim to perform a thorough analysis of this case with the focus on sensitivity of our predictions with respect to: (i) low-energy constants (LECs) of our effective contact charge symmetry breaking (CSB) force and (ii) nuclear shape. We demonstrate, among the other, that inclusion of triaxial positive-parity ground-state - which is actually the global positive-parity minimum in our unconstrained mean-field calculation - in the DFT-NCCI calculations instead of the axial one used before leads to MED which are consistent with experimental data concerning both their sign as well as magnitude without any need for fine-tuning of the model's LECs.
nucl-thPRC(2023)·5 citations
11
Hexadecapole axial collectivity in the rare earth region, a beyond mean field study
C.V. Nithish Kumar · L. M. Robledo
Hexadecapole collectivity and its interplay with quadrupole degrees of freedom is studied in an axial symmetry preserving framework based on the Hartree Fock Bogoliubov (HFB) plus generator coordinate method (GCM). Results are obtained for several even-even isotopes of Sm and Gd with various parametrizations of the Gogny force. The analysis of the results indicates the strong coupling between the quadrupole and hexadecapole degrees of freedom. The first two excited states are vibrational in character in most of the cases. The impact of prolate-oblate shape mixing in the properties of hexadecapole states is analyzed.
nucl-thPRC(2023)·16 citations
12
A multistage framework for studying the evolution of jets and high- $p_{T}$ probes in small collision systems
Abhijit Majumder · Aaron Angerami · Ritu Arora · Steffen Bass · Shanshan Cao · Yi Chen · Raymond Ehlers · Hannah Elfner · Wenkai Fan · Rainer J. Fries · Charles Gale · Yayun He and 39 other authors
Understanding the modification of jets and high- $p_{T}$ probes in small systems requires the integration of soft and hard physics. We present recent developments in extending the JETSCAPE framework to build an event generator, which includes correlations between soft and hard partons, to study jet observables in small systems. The multi-scale physics of the collision is separated into different stages. Hard scatterings are first sampled at binary collision positions provided by the Glauber geometry. They are then propagated backward in space-time following an initial-state shower to obtain the initiating partons' energies and momenta before the collision. These energies and momenta are then subtracted from the incoming colliding nucleons for soft-particle production, modeled by the 3D-Glauber + hydrodynamics + hadronic transport framework. This new hybrid approach (X-SCAPE) includes non-trivial correlations between jet and soft particle productions in small systems. We calibrate this framework with the final state hadrons' $p_{T}$ -spectra from low to high $p_{T}$ in $p$ - $p$ , and and then compare with the spectra in $p$ - $P b$ collisions from the LHC. We also present results for additional observables such as the distributions of event activity as a function of the hardest jet $p_{T}$ in forward and mid-rapidity for both $p$ - $p$ and $p$ - $P b$ collisions.
↳ hep-phnucl-exnucl-thPoS(2024)·2 citations
13
Early time dynamics and constraints on medium evolution
Kirill Boguslavski🇦🇹
In relativistic heavy-ion collisions, a quark-gluon plasma (QGP) is created whose pre-equilibrium evolution includes a rich variety of exciting phenomena of Quantum Chromodynamics. In these Proceedings, we provide a short overview of our current understanding of the pre-equilibrium dynamics of the QGP from a weak-coupling perspective and highlight recent developments. Focusing on new studies, we then discuss how initial stages of the QGP medium may impact hard probes including direct photons, dileptons, jets, and heavy quarks. This introduces promising opportunities to obtain experimental signatures of the pre-equilibrium QGP.
↳ hep-phhep-exnucl-thPoS(2024)·0 citations
14
Causal and stable first-order chiral hydrodynamics
Nick Abboud🇺🇸 · Enrico Speranza🇺🇸 · Jorge Noronha🇺🇸
We derive the set of inequalities that is necessary and sufficient for nonlinear causality and linear stability of first-order relativistic hydrodynamics with either a $U (1)_{V}$ conserved current or a $U (1)_{A}$ current with a chiral anomaly or both. Our results apply to generic hydrodynamic frames in which no relations among the transport parameters are imposed. Furthermore, our analysis yields, to the best of our knowledge, the first theory of viscous chiral hydrodynamics proven to be causal and stable. We find that causality demands the absence of vorticity-induced heat flux, forcing a departure from the thermodynamic frame in the chiral case. The inequalities for causality and stability define a hypervolume in the space of transport parameters, wherein each point corresponds to a consistent formulation. Notably, causality is determined by just three combinations of transport parameters. We present our results in a form amenable to numerical hydrodynamic simulations.
↳ hep-thgr-qchep-phnucl-thPRD(2024)·32 citations
15
Efficient production of nuclear isomer $^{93 m}$ Mo with laser-accelerated proton beam and an astrophysical implication on $^{92 m}$ Mo production
Wenru Fan · Wei Qi · Jingli Zhang · Zongwei Cao · Haoyang Lan · Xinxiang Li · Yi Xu · Yuqiu Gu · Zhigang Deng · Zhimeng Zhang · Changxiang Tan · Wen Luo · Yun Yuan · Weimin Zhou
Nuclear isomers play a key role in the creation of the elements in the universe and have a number of fascinating potential applications related to the controlled release of nuclear energy on demand. Particularly, $^{93 m}$ Mo isomer is a good candidate for studying the depletion of nuclear isomer via nuclear excitation by electron capture. For such purposes, efficient approach for $^{93 m}$ Mo production needs to be explored. In the present work, we demonstrate experimentally an efficient production of $^{93 m}$ Mo through $^{93}$ Nb(p, n) reaction induced by intense laser pulse. When a ps-duration, 100-J laser pulse is employed, the $^{93 m}$ Mo isomer at 2425 keV (21/2 $^{+}$ , $T_{1/2}$ = 6.85 h) are generated with a high yield of $1.8 \times 1 0^{6}$ particles/shot. The resulting peak efficiency is expected to be $1 0^{17}$ particles/s, which is at least five orders of magnitudes higher than using classical proton accelerator. The effects of production and destruction of $^{93 m}$ Mo on the controversial astrophysical p-isotope $^{92}$ Mo are studied. It is found that the $^{93}$ Nb(p, n)- $^{93 m}$ Mo reaction is an important production path for ^{93m}Mo seed nucleus, and the influence of ^{93m}Mo-^{92}Mo reaction flow on ^{92}Mo production cannot be ignored. In addition, we propose to directly measure the astrophysical rate of (p, n) reaction using laser-induced proton beam since the latter one fits the Maxwell-Boltzmann distribution well. We conclude that laser-induced proton beam opens a new path to produce nuclear isomers with high peak efficiency towards the understanding of p-nuclei nucleosythesis.
↳ nucl-exastro-ph.SRnucl-thphysics.plasm-phPRResearch(2023)·5 citations
16
The effect of initial nuclear deformation on dielectron photoproduction in hadronic heavy-ion collisions
Jiaxuan. Luo🇨🇳 · Xinbai. Li🇨🇳 · Zebo. Tang🇨🇳 · Xin. Wu🇨🇳 · Wangmei. Zha🇨🇳
Significant excesses of $e^{+} e^{-}$ pair production at very low transverse momentum ( $p_{T} <$ 0.15 GeV/c) were observed by the STAR collaboration in hadronic heavy-ion collisions. Such enhancement is assumed to be a sign of photon-photon production in heavy-ion collisions with hadronic overlap, based on comparisons with model calculations for spherical Au + Au collisions. However, there is a lack of calculations for $e^{+} e^{-}$ pair production from coherent photon-photon interactions in hadronic U + U collisions, due to the deformity of Uranium nuclei. In this article, we present calculations for $e^{+} e^{-}$ pair photoproduction at $s_{N N}$ = 193 GeV in both spherical and deformed U + U collisions within STAR detector acceptance using the equivalent photon approximation (EPA). We conduct event-by-event analysis to investigate the effects of initial nuclear deformation on pair production. Our numerical results show good agreement with experimental data for the 40%--60% and 60%--80% centrality classes in U + U collisions, and the differences between spherical and deformed configurations are approximately 3\%. We also calculate the yields of the photoproduced $e^{+} e^{-}$ pair in hadronic deformed Ru + Ru and Zr + Zr collisions at $s_{N N}$ = 200 GeV. The results reveal that the ratios of the yields of Ru to Zr exhibit very small differences ( $<$ 1%) between spherical and deformed cases.
↳ hep-phnucl-thPRC(2023)·12 citations
17
Inelastic and elastic parton scatterings in the strongly interacting quark-gluon plasma
Ilia Grishmanovskii🇩🇪 · Olga Soloveva🇩🇪 · Taesoo Song🇩🇪 · Carsten Greiner🇩🇪 · Elena Bratkovskaya🇩🇪
We investigate the role of inelastic processes in the strongly interacting quark-gluon plasma (sQGP) based on the effective dynamical quasi-particle model (DQPM). In the DQPM the non-perturbative properties of the sQGP at finite temperature $T$ and baryon chemical potential $μ_{B}$ are described in terms of strongly interacting off-shell partons (quarks and gluons) with dynamically generated spectral functions whose properties are adjusted to reproduce the lQCD EoS for the QGP in thermodynamic equilibrium. For the first time the massive gluon radiation processes from the off-shell quark-quark ( $q + q$ ) and quark-gluon ( $q + g$ ) scatterings are calculated explicitly within leading order Feynman diagrams with effective propagators and vertices from the DQPM without any further approximations. We present the results for the energy and temperature dependencies of the total and differential radiative cross sections and compare them to the corresponding elastic cross sections. We show that our results reproduce the pQCD calculations in the limit of zero masses and widths of quasiparticles. Also we study the $μ_{B}$ dependence of the inelastic cross sections. Moreover, we present estimates for the transition rate and relaxation time of radiative versus elastic scatterings in the sQGP.
↳ hep-phnucl-thPRC(2024)·13 citations
18
Bottom-charmed baryons in a nonrelativistic quark model
Qing-Fu Song🇨🇳 · Qi-Fang Lü🇨🇳 · Atsushi Hosaka🇯🇵
In this work, we study the low-lying mass spectra for bottom-charmed baryons in a nonrelativistic quark model by solving the three-body Schrödinger equation. The lowest $Ξ_{b c}$ , $Ξ_{b c}^{'}$ , $Ω_{b c}$ , and $Ω_{b c}^{'}$ states are predicted to be about 6979, 6953, 7109, and 7092 MeV, respectively. Also, the strong decays for the low-lying excited states are investigated. Our results indicate that some of $λ -$ mode $P -$ wave bottom-charmed baryons are relatively narrow, which can be searched for in future experiments. For the low-lying $ρ -$ mode and $ρ - λ$ hybrid states, their strong decays are highly suppressed and they can survive as extremely narrow states. Moreover, the mass spectra and strong decays for bottom-charmed baryons preserve the heavy quark symmetry well. We hope our calculations can provide helpful information for further experimental and theoretical researches.
↳ hep-phhep-exnucl-thEPJC(2024)·7 citations
19
Interpretation of near-threshold peaks using the method of independent S-matrix poles
Leonarc Michelle Santos🇵🇭 · Denny Lane B. Sombillo🇵🇭
We propose a model-independent analysis of near-threshold enhancements using independent S-matrix poles. In this formulation, we constructed a Jost function with controllable zeros to ensure that no poles are generated on the physical Riemann sheet. We show that there is a possibility of misinterpreting the observed near-threshold signals if one utilized a limited parametrization and restrict the analysis to only one element of the S-matrix. Specifically, there is a possibility of the emergence of ambiguous pair of poles which are singularities of the full S-matrix but may not manifest in one of its elements. For a more concrete discussion, we focused on an effective two-channel scattering where the full S-matrix is a $2 \times 2$ matrix. We apply our method to the coupled two-channel analysis of the $P_{ψ}^{N} (4312)^{+}$ and found that the compact pentaquark interpretation cannot be ruled out yet.
↳ hep-phnucl-thPRC(2023)·11 citations
20
Quasiparticle Cosmology
Amaresh Jaiswal🇮🇳
We consider thermodynamics of the Universe within a quasiparticle approach where the collective dynamics of a system is governed by the thermal mass of the constituents. The spacetime dependence of this thermal mass leads to a negative contribution to the pressure and a positive contribution to the energy density, similar to the effect due to dark energy. We propose a mechanism based on thermodynamic arguments to quantify this contribution from the thermal vacuum of the system. For a sufficiently large spacetime variation of the thermal mass, the effective pressure can become negative and could mimic a dark energy equation of state. We validate our framework using results from renormalizable interacting scalar field theory and demonstrate an application on QCD axion.
↳ hep-thgr-qcnucl-thPRD(2024)·1 citation

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