Nuclear Theory·nucl-th

Tuesday·March 21, 2023

14 papers—9 primary·5 cross-listed

01
Bayesian inference of in-medium baryon-baryon scattering cross sections from HADES proton flow data
Bao-An Li🇺🇸 · Wen-Jie Xie🇨🇳
Within a Bayesian statistical framework using a Gaussian Process emulator for an isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model simulator of heavy-ion reactions at intermediate energies, we infer from the HADES proton flow data the posterior probability distribution functions of in-medium baryon-baryon scattering cross section modification factor X with respect to free-space and the corresponding incompressibility K of nuclear matter as well as their correlation function. The mean value of X is found to be $X = 1.3 2_{- 0.40}^{+ 0.28}$ at 68\% confidence level assuming the nuclear incompressibility K will not exceed 400 MeV, providing circumstantial evidence for enhanced baryon-baryon scattering cross sections in hot and dense nuclear matter.
nucl-thnucl-exNPA(2023)·15 citations
02
Pair production as a probe for the dynamics of nuclear fission and $α$ decay
Thomas Settlemyre · Hua Zheng · Aldo Bonasera
Electron-positron pairs can be produced via the Schwinger mechanism in the presence of strong electric fields. In particular, the fields involved in $α$ decay and nuclear fission are strong enough to produce them. The energy of the $e^{+} e^{-}$ pair is related to the relative distance and velocity of the daughter nuclei. Thus, the energy distribution of the produced pairs can give information about the dynamics of the fission and $α$ decay processes. A neck model of nuclear fission is used to illustrate how the pairs can be used as a probe of the dynamics.
nucl-thPRC(2023)·2 citations
03
Diproton correlation and two-proton emission from proton-rich nuclei
Tomohiro Oishi
Open-print version of dissertation thesis. This thesis focuses on the relation between the diproton correlation and the two-proton emission with quantum entanglement. For this purpose, I developed a time-dependent three-body (proton-proton-core) model, where one Cooper pair of protons move inside the mean-field potential. The time-dependent calculation based on the three-body model provides an intuitive way to describe the quantum dynamics of the entangled fermionic pair. It has been shown that, by considering the Cooper-pairing correlation in the initial state of the two protons, (i) the experimental 2p-decay width of Be-6 is well reproduced, and (ii) the two protons are emitted mainly as a diproton-like cluster with the spin-singlet configuration in the early stage of the emission. Hence, the two-proton emission can provide an access to the diproton correlation. This thesis presented the first step to theoretically investigate the diproton correlation as well as quantum entanglement in the time-dependent radioactive emission. [NOTE] In this open-print version, several Figures were inevitably eliminated, because of the copyright and/or file-size problems. Several minor corrections have been done, but without changing the scientific discussions, results, and conclusions from the original version in 2014.
nucl-thcond-mat.supr-conquant-ph1 citation
04
Systematic analysis of $t$ and $^{3}$ He breakup reactions
Shoya Ogawa · Shin Watanabe · Takuma Matsumoto · Kazuyuki Ogata
Systematic measurement of $t$ and $^{3}$ He knockout processes is planned. The weakly-bound nature of these nuclei may affect the interpretation of forthcoming knockout reaction data. Purpose: We aim at clarifying breakup properties of $t$ and $^{3}$ He by investigating their elastic and breakup cross sections. We employ the four-body continuum-discretized coupled-channels method with the eikonal approximation to describe the $t$ and $^{3}$ He reactions. The breakup cross section of $t$ is found to be almost the same as that of $^{3}$ He and is about one-third of that of $d$ . Coulomb breakup plays negligible role in the breakup of $t$ and $^{3}$ He, in contrast to in the deuteron breakup reaction. It is found that $t$ and $^{3}$ He tend to breakup into three nucleons rather than $d$ and a nucleon. It is shown that the breakup cross sections of $t$ and $^{3}$ He are not as large as those of d but non-negligible. Because about 80% of them corresponds to the three-nucleon breakup process, a four-body breakup reaction model is necessary to quantitatively describe the breakup of $t$ and $^{3}$ He.
nucl-thPRC(2023)·3 citations
05
Origin of octupole deformation softness in atomic nuclei
Minh-Loc Bui · Le-Anh Nguyen · Panagiota Papakonstantinou · Naftali Auerbach
Recent high-energy heavy ion collision experiments have revealed that some atomic nuclei exhibit unusual softness and significant shape fluctuations. In this work, we use the fully self-consistent mean-field theory to identify all even-even nuclei that are unstable or soft against octupole deformation. All exceptional cases of enhanced octupole transition strengths in stable even-even nuclei throughout the nuclide chart are resolved and the origin is found in basic shell structure. The presence of atomic nuclei exhibiting significant softness to quadrupole-octupole deformation is suggested. These results represent a significant advance in our understanding of the underlying mechanisms of nuclear octupole deformation and have implications for further experimental and theoretical studies.
nucl-thPRC(2023)·11 citations
06
Radial Oscillations in Neutron Stars with Delta Baryons
Ishfaq A. Rather🇵🇹 · Kauan D. Marquez🇧🇷 · Grigoris Panotopoulos🇨🇱 · Ilidio Lopes🇵🇹
We investigate the effect of $Δ$ baryons on the radial oscillations of neutron and hyperon stars, employing a density-dependent relativistic mean-field model. The spin- $3/2$ baryons are described by the Rarita-Schwinger Lagrangian density. The baryon-meson coupling constants for the spin-3/2 decuplet and the spin-1/2 baryonic octet are calculated using a unified approach relying on the fact that the Yukawa couplings present in the Lagrangian density of the mean-field models must be invariant under the SU(3) and SU(6) group transformations. We calculate the 20 lowest eigenfrequencies and corresponding oscillation functions of $Δ$ -inclusive nuclear (N+ $Δ$ ) and hyperonic matter (N+H+ $Δ$ ) by solving the Sturm-Liouville boundary value problem and also verifying its validity. We see that the lowest mode frequencies for N+ $Δ$ and N+H EoSs are higher as compared to the pure nucleonic matter because of the deltas and hyperons present. Furthermore, the separation between consecutive modes increases with the addition of hyperons and $Δ$ s.
nucl-thastro-ph.HEPRD(2023)·24 citations
07
Investigation of isospin-symmetry-breaking in mirror energy difference and nuclear mass with ab initio calculations
H.H. Li · Q. Yuan · J.G. Li · M.R. Xie · S. Zhang · Y. H. Zhang · X.X. Xu · N. Michel · F.R. Xu · W. Zuo
Isospin-symmetry breaking is responsible for the energy difference of excited states in mirror nuclei. It also influences the coefficient of the isobaric multiplet mass equation. In the present work, we extensively investigate isospin-symmetry breaking in medium mass nuclei within ab initio frameworks. For this, we employ the ab initio valence-space in-medium similarity renormalization group approach, in which charge-symmetry and charge-independence breakings are included in the adopted nuclear force. The mirror energies of sd- and pf- shell nuclei are computed for that matter. The effects of single-particle states on weakly bound and unbound nuclear states, especially those of the s-wave, are discussed. Predictions are also made concerning proton drip-line nuclei bearing large mirror energy difference. Finally, the coefficient of the isobaric multiplet mass equation in T = 1/2 and T = 1 isospin multiplets for A = 18 to A = 76 is calculated.
nucl-thPRC(2023)·35 citations
08
Investigation of spectroscopic factors of deeply-bound nucleons in drip-line nuclei with the Gamow shell model
M.R. Xie · J.G. Li · N. Michel · H.H. Li · S.T. Wang · H.J. Ong · W. Zuo
Spectroscopic factors involving well bound nucleons in light nuclei are calculated with standard shell model, no-core shell model and Gamow shell model. Continuum coupling is included exactly in the Gamow shell model, due to the use of the Berggren basis, which contains bound, resonance and scattering states. Conversely, it is absent from standard and no-core shell models, where a basis of harmonic oscillator states is used. As the A - 1 nuclei for which spectroscopic factors are calculated are either weakly bound or unbound, coupling to continuum is prominent, even though the A nuclei are well bound. It is then showed that Gamow shell model can properly reproduce experimental data and is a predictive tool for detailed nuclear structure at drip-line, contrary to standard and no-core shell model.
nucl-thPLB(2023)·14 citations
09
Prevailing Triaxial Shapes in Atomic Nuclei and a Quantum Theory of Rotation of Composite Objects
T. Otsuka · Y. Tsunoda · N. Shimizu · Y. Utsuno · T. Abe · H. Ueno
In the traditional view, heavy deformed nuclei are like axially-symmetric prolate ellipsoids, rotating about one of the short axes. In the present picture, their shapes may be triaxial. The triaxial shape yields complex rotations, which actually well reproduce experimental data, as confirmed by state-of-the-art Configuration Interaction calculations. Two origins are suggested for the triaxiality: (i) binding-energy gain by the symmetry restoration for triaxial shapes, and (ii) another gain by specific components of the nuclear force, like tensor force and high-multipole (e.g. hexadecupole) central force. While the origin (i) produces basic smaller triaxiality for virtually all deformed nuclei, the origin (ii) produces medium triaxiality for a certain class of nuclei. An example of the former is 154Sm, a typical showcase of axial symmetry but is now suggested to depict a modest yet finite triaxiality. The latter, medium triaxiality, is discussed from various viewpoints for some exemplified nuclei including 166Er, and experimental findings. Many-body structures of the gamma band and the double-gamma band are clarified. Regarding the general features of rotational states of deformed many-body systems including triaxial ones, the well-known J(J+1) rule of rotational excitation energies is discussed, within the quantum mechanical many-body theory, without resorting to the quantization of a rotating classical rigid body. The picture of prevailing triaxial shapes thus emerges, where the empirically known rotational-band pattern appears with good K quantum number, but the internal structure is dfferent from conventional picture a la A. Bohr. The possible relations to Davydov's rigid-triaxial-rotor model are mentioned.
nucl-thnucl-exEPJA(2025)·51 citations
10
QCD Phase Diagrams via QHD and MIT-Based Models
Carline Biesdorf🇧🇷 · Debora P. Menezes🇧🇷 · Luiz L. Lopes🇧🇷
In this paper the QCD phase diagram is obtained by the crossing of two effective models: the MIT bag based models are used to describe quark matter and QHD type models to describe hadronic matter, being the use of the former something new to this kind of approach and the latter used with improved parameterizations as compared with previous calculations. We use the Gibbs' conditions to establish the crossing points of the pressure in function of the chemical potential obtained in both phases. We first analyze two-flavour symmetric matter constrained to both the freeze-out and the liquid-gas phase transition at the hadronic phase. Later we analyse the results for $β$ -stable and charge neutral stellar matter and compare two different prescriptions: one that assumes flavour conservation, so that the quark phase is completely determined from the hadronic phase, a prescription never applied to finite temperatures before, and the other based on the Maxwell construction, where the quark phase is also $β$ -stable. At the end, we compute the latent heat to find a signature of the critical end point.
↳ hep-phnucl-thBraz.J.Phys.(2023)·7 citations
11
Reconstruction of baryon number distributions
Chuang Huang🇨🇳 · Yang-yang Tan🇨🇳 · Rui Wen🇨🇳 · Shi Yin🇨🇳 · Wei-jie Fu🇨🇳
The maximum entropy method (MEM) and the Gaussian process (GP) regression, which are both well-suited for the treatment of inverse problems, are used to reconstruct net-baryon number distributions based on a finite number of cumulants of the distribution. Baryon number distributions across the chiral phase transition are reconstructed. It is found that with the increase of the order of cumulants, distribution in the long tails, i.e., far away from the central number, would become more and more important. We also reconstruct the distribution function based on the experimentally measured cumulants at the collision energy $s_{N N} = 7.7$ GeV. Given the sizable error of the fourth-order cumulant measured in experiments, the calculation of MEM shows that with the increasing fourth-order cumulant, there is another peak in the distribution function developed in the region of large baryon number. This unnaturalness observed in the reconstructed distribution function might in turn be used to constrain the cumulants measured in experiments.
↳ hep-phnucl-thCPC(2023)·4 citations
12
Taming Dyson-Schwinger equations with null states
Wenliang Li🇨🇳
In quantum field theory, the Dyson-Schwinger equations are an infinite set of coupled equations relating $n$ -point Green's functions in a self-consistent manner. They have found important applications in non-perturbative studies, ranging from quantum chromodynamics and hadron physics to strongly correlated electron systems. However, they are notoriously formidable to solve. One of the main problems is that a finite truncation of the infinite system is underdetermined. Recently, Bender et al. [Phys. Rev. Lett. 130, 101602 (2023)] proposed to make use of the large- $n$ asymptotic behaviors and successfully obtained accurate results in $D = 0$ spacetime. At higher $D$ , it seems more difficult to deduce the large- $n$ behaviors. In this paper, we propose another avenue in light of the null bootstrap. The underdetermined system is solved by imposing the null state condition. This approach can be extended to $D > 0$ more readily. As concrete examples, we show that the cases of $D = 0$ and $D = 1$ indeed converge to the exact results for several Hermitian and non-Hermitian theories of the $g ϕ^{n}$ type, including the complex solutions.
↳ hep-thhep-phmath-phmath.MP+2PRL(2023)·16 citations
13
Revealing the strength of three-nucleon interactions with the Einstein Telescope
Henrik Rose🇩🇪 · Nina Kunert🇩🇪 · Tim Dietrich🇩🇪 · Peter T. H. Pang🇳🇱 · Rory Smith🇺🇸 · Chris Van Den Broeck🇳🇱 · Stefano Gandolfi🇺🇸 · Ingo Tews🇺🇸
Three-nucleon forces are crucial for the accurate description of nuclear systems, including dense matter probed in neutron stars. We explore nuclear Hamiltonians that reproduce two-nucleon scattering data and properties of light nuclei, but differ in the three-nucleon interactions among neutrons. While no significantly improved constraints can be obtained from current astrophysical data, we show that observations of neutron star mergers by next-generation detectors like the proposed Einstein Telescope could provide strong evidence to distinguish between these Hamiltonians.
↳ astro-ph.HEgr-qcnucl-thPRC(2023)·22 citations
14
On excess entropy and latent heat in crystallizing white dwarfs
D. A. Baiko
Based on the linear mixing approach, we calculate the latent heat for crystallizing fully-ionized $^{12}$ C/ $^{16}$ O and $^{16}$ O/ $^{20}$ Ne mixtures in white dwarf (WD) cores for two different parametrizations of the corrections to the linear-mixing energies and with account of ion quantum effects. We report noticeable composition-dependent deviations of the excess entropy in both directions from the standard value of 0.77 per ion. Within the same framework, we evaluate the excess entropy and released or absorbed heat accompanying the exsolution process in solidified WD layers. The inclusion of this effect is shown to be important for reliable interpretation of WD cooling data. We also analyze the latent heat of crystallizing eutectic $^{12}$ C/ $^{22}$ Ne mixture, where we find a qualitative dependence of both the phase diagram and the latent heat behaviour on ion quantum effects. This may be important for the model with $^{22}$ Ne distillation in cooling C/O/ $^{22}$ Ne WD proposed as a solution for the ultramassive WD multi-Gyr cooling anomaly. Astrophysical implications of our findings for crystallizing WD are discussed.
↳ astro-ph.SRastro-ph.HEnucl-thMNRAS(2023)·0 citations

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first authorsco-authorsvia INSPIRE