Nuclear Theory·nucl-th

Friday·May 24, 2024

19 papers—8 primary·11 cross-listed

01
Prompt Fission Neutron Spectra of 233U(n,F)
V.M. Maslov
Prompt fission neutron spectra produced up to 20 MeV. Simultaneous analysis of measured and calculated data for 233U(n, F), 235U(n, F) and 239Pu(n, F) maintains stronger justification for the predicted PFNS of 233U(n, F). For the latter the reliable measured PFNS data are available at Eth only. Pre-fission neutron spectra influence the partitioning of fission energy between excitation energy and total kinetic energy of fission fragments. For the reactions 233U (n, F) and 235U (n, F) we have shown that the shape of PFNS depends on the fissility of composite and residual nuclei. The correlation of these peculiarities with contributions of (n, xnf) to the (n, F) and competition of (n, ng) and (n, xn) is established. Exclusive neutron spectra (n, xnf) are consistent with cross sections of 235U(n, F), 234U(n, F), 233U(n, F) and 232U(n,F) reactions, as well as neutron emissive spectra of 235U(n,xn) at 14 MeV. Initial model parameters for 233U (n,F) PFNS are fixed by description of prompt fission neutron spectra of 233U (nth, F). We predict the 233U(n,xnf) exclusive pre-fission neutron spectra of 233U(n,xn) reactions, total kinetic energy TKE of fission fragments and products, partials of average PFNS and observed PFNS of 233U(n,F). PFNS of 233U (n, F) are harder than those of 235U(n, F) PFNS, but softer than those of 239Pu(n, F). Difference of average energies of PFNS of 233U (n, F) and 235U(n, F) amounts to 1-3 %. At incident energies higher than (n, 2nf) reaction threshold the observed PFNS may seem similar, though the partial contributions of 233U(n,xnf) and 235U(n,xnf) are quite different. PFNS of 233U(n,xnf) are obtained in the energy range up to 20 MeV.
nucl-thnucl-ex2 citations
02
Universal separable structure of the optical potential
H. F. Arellano · G. Blanchon
Based on a momentum-space in-medium folding model, we disclose the universal separability of the optical potential, revealing its radial and nonlocality features at beam energies in the range 40 - 400 MeV and target mass numbers in the range $40 \leq A \leq 208$ . From this microscopic study we find that the nonlocality form factor is inherently complex and of hydrogenic nature, affecting both central and spin-orbit components of the potential. A striking outcome from this study is the consistent appearance of a nodal point in the imaginary radial form factor, notably suppressing surface absorption peaks, in evident contrast with Woods-Saxon's assumption of an absorptive peak at the nuclear surface. Our analysis reveals that the complex radial form factor can effectively be represented as convolutions of uniform spherical distribution with a Gaussian form factor and a Yukawa term. These robust microscopically-driven findings offer new ways for investigating nuclear reactions beyond the restricting Woods-Saxon and Perey-Buck assumptions.
nucl-thPRC(2024)·5 citations
03
Induced Isotensor Interactions in Heavy-Ion Double-Charge-Exchange Reactions and the Role of Initial and Final State Interactions
Horst Lenske · Jessica Bellone · Danilo Gambacurta · José-Antonio Lay
The role of initial state (ISI) and final state (FSI) ion-ion interactions in heavy-ion double-charge-exchange (DCE) reactions $A (Z, N) \to A (Z \pm 2, N \mp 2)$ are studied for double single-charge-exchange (DSCE) reactions given by sequential actions of the isovector nucleon-nucleon (NN) T-matrix. In momentum representation, the second-order DSCE reaction amplitude is shown to be given in factorized form by projectile and target nuclear matrix elements and a reaction kernel containing ISI and FSI. Expanding the intermediate propagator in a Taylor series with respect to auxiliary energy allows us to perform the summation in the leading-order term over intermediate nuclear states in closure approximation. %Please ensure meaning has been retained - corrected HL. The nuclear matrix element attains a form given by the products of two-body interactions directly exciting the $n^{2} p^{- 2}$ and $p^{2} n^{- 2}$ DCE transitions in the projectile and the target nucleus, respectively. %Please ensure meaning has been retained - corrected HL. A surprising result is that the intermediate propagation induces correlations between the transition vertices, showing that DSCE reactions are a two-nucleon process that resembles a system of interacting spin-isospin dipoles. Transformation of the DSCE NN T-matrix interactions from the reaction theoretical t-channel form to the s-channel operator structure required for spectroscopic purposes is elaborated in detail, showing that, in general, a rich spectrum of spin scalar, spin vector and higher-rank spin tensor multipole transitions will contribute to a DSCE reaction. Similarities (and differences) to two-neutrino double-beta decay (DBD) are discussed. ISI/FSI distortion and absorption effects are illustrated in black sphere approximation and in an illustrative application to data.
nucl-thhep-phnucl-exUniverse(2024)·8 citations
04
Initial energy-momentum to final flow: a general framework for heavy-ion collisions
Jefferson Sousa🇧🇷 · Jorge Noronha🇺🇸 · Matthew Luzum🇧🇷
The evolution of a relativistic heavy-ion collision is typically understood as a process that transmutes the initial geometry of the system into the final momentum distribution of observed hadrons, which can be described via a cumulant expansion of the initial distribution of energy density and is represented at leading order as the well-known eccentricity scaling of anisotropic flow. We extend this framework to include the contribution from initial momentum-space properties, as encoded in other components of the energy-momentum tensor. We confirm the validity of the framework in state-of-the-art hydrodynamic simulations of large and small systems. With this new framework, it is possible to separate the effects of early-time dynamics from those of final-state evolution, even in the case when the distribution of energy does not fully determine subsequent evolution, as for example, in small systems. Specifically, we answer the question of when and how azimuthal correlations from the initial state survive to the final state. In very small systems such as $p$ - $p$ , for example, initial momentum degrees of freedom dominate over energy. Thus, even if the system forms a quark-gluon plasma that is well described by hydrodynamics, the usual hydrodynamic picture of the transmutation of initial geometry to final momentum anisotropy is broken. Nevertheless, we show that the hydrodynamic response to the full energy-momentum tensor can be well understood in a similar manner as larger systems. Additionally, this framework elucidates the generic features of the system's evolution that are responsible for the impressive success of hydrodynamic simulations, but which may still hold even in cases where hydrodynamics is not applicable.
nucl-thPRC(2024)·10 citations
05
"Soft" interaction parameters setting in the extended quantum molecular dynamics model
Chen-Zhong Shi · Xiang-Zhou Cai · Bo-Song Huang · Yu-Gang Ma
The extended quantum molecular dynamics (EQMD) model is one of the few quantum molecular dynamics (QMD)-like transport approaches that can be used to study the effective clustering structure as well as heavily deformed nuclei in both ground state nuclei and nuclear reactions. However, there are only two parameter sets that lead to hard incompressibility for long times. The aim of the present work is to obtain a soft equation of state (EoS) in the EQMD model. In this context, we take the isoscalar giant monopole resonance (ISGMR), which is sensitive to the EoS, as an example to check our work. By introducing a kind of standard Skyrme energy density functional with different parameter sets, such as SkP, SkT1, and SKXce, whose incompressibility value ranges from 200 to 268 MeV, the ISGMR of $^{208}$ Pb and other nuclei are studied. When the SkP parameter sets are adopted, our new soft interaction in the EQMD model gives reasonable agreement with the experimental data in the heavy ion regime.
nucl-thnucl-exPRC(2024)·4 citations
06
Isovector giant dipole resonance mode with an improved propagation approach in the framework of EQMD model
Chen-Zhong Shi · Xiang-Zhou Cai · De-Qing Fang · Yu-Gang Ma
The Extended Quantum Molecular Dynamics (EQMD) model is one of the few QMD-like transport approaches that can describe the $α$ -clustering structure with efficient computational power. However, compared to most QMD-like models, the choice of equation of state (EOS) for nuclear matter is very limited. In this work, a Monte Carlo integral method is employed to calculate the density integration with non-integer exponent. We demonstrate the superiority of our approach by studying the isovector giant dipole resonance (IVGDR). This improvement will be beneficial for the EQMD model to study more valuable effects for heavy ion collisions in the near future.
nucl-thEPJA(2024)·2 citations
07
Theory of Majorana-Type Heavy Ion Double Charge Exchange Reactions by Pion--Nucleon Isotensor Interactions
Horst Lenske🇩🇪 · Jessica Bellone🇮🇹 · Maria Colonna🇮🇹 · Danilo Gambacurta🇮🇹
The theory of heavy ion double charge exchange (DCE) reactions proceeding by effective rank-2 isotensor interactions is presented. Virtual pion--nucleon charge exchange interactions are investigated as the source for induced isotensor interactions, giving rise to the Majorana DCE (MDCE) reaction mechanism. MDCE is of a generic character, proceeding through pairs of complementary ( $π^{\pm}, π^{\mp}$ ) reactions in the projectile and target nucleus. The dynamics of the elementary processes is discussed, where the excitation of pion--nucleon resonances are of central importance. Investigations of initial and final state ion--ion interactions show that these effects are acting as vertex renormalizations. In closure approximation, well justified by the finite pion mass, the second-order transition matrix elements reduce to pion potentials and effective two-body isotensor DCE interactions, giving rise also to two-body correlations in either of the participating nuclei. Connections to neutrinoless Majorana double beta decay (MDBD) are elucidated at various levels of the dynamics, from the underlying fundamental electro-weak and QCD scales to the physical scales of nuclear MDBD and MDCE physics. It is pointed out that heavy ion MDCE reactions may also proceed by competing electro-weak charge exchange processes, leading to lepton MDCE by electrons, positrons, and neutrinos.
nucl-thhep-phnucl-exUniverse(2024)·9 citations
08
Multiplicity fluctuations and rapidity correlations in ultracentral proton-nucleus collisions
Rupam Samanta🇵🇱 · Jean-Yves Ollitrault🇫🇷
A collision between a proton and a heavy nucleus at ultrarelativistic energy creates particles whose rapidity distribution is asymmetric, with more particles emitted in the direction of the nucleus than in the direction of the proton. This asymmetry becomes more pronounced as the centrality estimator, defined from the energy deposited in a calorimeter, increases. We argue that for high-multiplicity collisions, the variation of the impact parameter plays a negligible role, and that the fluctuations of the multiplicity and of the centrality estimator are dominated by quantum fluctuations, whose probability distribution can be well approximated by a correlated gamma distribution. We show that this simple model reproduces existing data, and we make quantitative predictions for collisions in the $0 - 0.1%$ and $0 - 0.01%$ centrality windows. We argue that by repeating the same analysis with a different centrality estimator, one can obtain direct information about the rapidity decorrelation in particle production.
nucl-thnucl-exPLB(2024)·1 citation
09
Qualitative explanation of the data on the decays $D^{0} \to a_{0} (980)^{\pm} π^{\mp}$ and $D^{+} \to a_{0} (980)^{+ (0)} π^{0 (+)}$ in the four-quark model of the $a_{0} (980)$ resonance
N. N. Achasov🇷🇺 · G. N. Shestakov🇷🇺
It is shown that the values of the ratios $B (D^{0} \to a_{0} (980)^{+} π^{-}) / B (D^{0} \to a_{0} (980)^{-} π^{+})$ and $B (D^{+} \to a_{0} (980)^{+} π^{0}) / B (D^{+} \to a_{0} (980)^{0} π^{+})$ , recently measured by the BESIII Collaboration, are naturally explained in the four-quark model of the $a_{0} (980)$ resonance.
↳ hep-phhep-exnucl-exnucl-thPRD(2024)·5 citations
10
Electromagnetic moments of the odd-mass nickel isotopes $^{59 - 67}$ Ni
P. Müller🇩🇪 · S. Kaufmann🇩🇪 · T. Miyagi🇩🇪 · J. Billowes🇬🇧 · M.L. Bissell🇬🇧 · K. Blaum🇩🇪 · B. Cheal🇬🇧 · R.F. Garcia Ruiz🇨🇭 · W. Gins🇧🇪 · C. Gorges🇩🇪 · H. Heylen🇩🇪 · A. Kanellakopoulos🇧🇪 and 15 other authors
The magnetic dipole and the spectroscopic quadrupole moments of the nuclear ground states in the odd-mass nickel isotopes $^{59 - 67}$ Ni have been determined using collinear laser spectroscopy at the CERN-ISOLDE facility. They are compared to ab initio valence-space in-medium similarity renormalization group (VS-IMSRG) calculations including contributions of two-body currents as well as to shell-model calculations. The two-body-current contributions significantly improve the agreement with experimental data, reducing the mean-square deviation from the experimental moments by a factor of 3 to 5, depending on the employed interaction. For all interactions, the largest contributions are obtained for the $5/ 2^{-}$ ( $7/ 2^{-}$ ) isotopes $^{65}$ Ni ( $^{55}$ Ni), which is ascribed to the high angular momentum of the $f$ orbitals. Our results demonstrate that the inclusion of two-body-current contributions to the magnetic moment in an isotopic chain of complex nuclei can be handled by the VS-IMSRG and can outperform phenomenological shell-model calculations using effective $g$ -factors in the nickel region.
↳ nucl-exnucl-thPLB(2024)·10 citations
11
History of N(1680)
Igor Strakovsky (GWU)🇺🇸
This paper describes my personal appreciation for some of the great research achievements of Mitya Diakonov, Vitya Petrov, and Maxim Polyakov and how my own research career has followed the paths they opened. Among the topics where they have been the most influential have been the pursuit and study of the exotic pentaquark. The search for exotics may require a complementary approach, such as experimental and theoretical activity. Here, I would like to focus on a story of $N (1680)$ in which I was involved.
↳ hep-phhep-exnucl-thActa Phys.Polon.B(2025)·2 citations
12
Flavor dependence of unpolarized quark Transverse Momentum Distributions from a global fit
Alessandro Bacchetta🇮🇹 · Valerio Bertone🇫🇷 · Chiara Bissolotti🇺🇸 · Giuseppe Bozzi🇮🇹 · Matteo Cerutti🇺🇸 · Filippo Delcarro🇮🇹 · Marco Radici🇮🇹 · Lorenzo Rossi🇮🇹 · Andrea Signori (the MAP Collaboration)🇮🇹
We present an extraction of the unpolarized transverse-momentum-dependent parton distribution and fragmentation functions that takes into account possible differences between quark flavors and final-state hadrons. The extraction is based on experimental measurements from Drell-Yan processes and semi-inclusive deep-inelastic scattering, whose combination is essential to distinguish flavor differences. The analysis is carried out at N $^{3}$ LL accuracy. The extracted flavor-dependent distributions give a very good description of the data ( $χ^{2} / N_{dat} = 1.08$ ). The resulting uncertainties take fully into account also the uncertainties in the determination of the corresponding collinear distributions.
↳ hep-phnucl-exnucl-thJHEP(2024)·99 citations
13
In-beam $γ -$ spectroscopy of the transitional nucleus $^{217}$ Ac
Dhananjaya Sahoo · A. Y. Deo · Madhu · Khamosh Yadav · S. S. Tiwary · P. C. Srivastava · R. Palit · S. K. Tandel · Anil Kumar · P. Dey · Biswajit Das · Vishal Malik and 5 other authors
High-spin states in the transitional $^{217}$ Ac nucleus are established up to 3.8 MeV excitation energy and $I^{π} =$ 41/2 $^{+}$ with the addition of around 20 new transitions. The structure of the yrast and near-yrast states below the 29/2 $^{+}$ isomer is revisited. The inconsistencies in the level schemes reported earlier are resolved. The level structure above the 29/2 $^{+}$ isomer is established for the first time. Large-basis shell-model calculations with the KHPE interaction are performed to compare the experimentally observed level energies with the theoretical predictions. A comparison with the systematics of the N = 128 isotones suggests that the yrast structures result from a weak coupling of the odd proton to the even-even 216Ra core, which is consistent with the shell-model configurations. Furthermore, alpha decay of the 29/2 $^{+}$ isomer is revisited and the decay scheme established from this work is discussed in the framework of the shell model.
↳ nucl-exnucl-th0 citations
14
On the properties of qudits
A. B. Balantekin🇺🇸 · Anna M. Suliga🇺🇸
Motivated by the growing interest in the applications of quantum information science in astrophysical settings, especially for the neutrino transport in compact objects where three-flavors of neutrinos need to be mapped on qutrits, we review properties of one- and two-qudit systems. We contrast two-qubit and two-qudits systems by pointing out how some of the properties of two-qubit systems generalize to higher dimensions and explore emerging new properties for dimensions three or higher. One example is provided by the Werner states: when the density operator is written in the fundamental representation, we show that only two-qubit Werner states can be pure states, but not two-qudit Werner states when the qudit dimension is larger than two.
↳ quant-phhep-phnucl-thEPJA(2024)·8 citations
15
The Intrabinary Shock and Companion Star of Redback Pulsar J2215+5135
Andrew G. Sullivan · Roger W. Romani
PSR J2215+5135 (J2215) is a `redback' spider pulsar, where the intrabinary shock (IBS) wraps around the pulsar rather than the stellar-mass companion. Spider orbital light curves are modulated, dominated by their binary companion thermal emission in the optical bands and by IBS synchrotron emission in the X-rays. We report on new XMM-Newton X-ray and U-band observations of J2215. We produce orbital light curves and use them to model the system properties. Our best-fit optical light model gives a neutron star mass $M_{N S} = 1.98 \pm 0.08$ M $_{⊙}$ , lower than previously reported. However, uncertainty in the stellar atmosphere metallicity, a parameter to which J2215 is unusually sensitive, requires us to consider an acceptable systematic plus statistical range of $M_{N S} \sim 1.85 - 2.3$ M $_{⊙}$ . From the X-ray analysis, we find that the IBS wraps around the pulsar, but with a pulsar wind to companion wind momentum ratio unusually close to unity, implying a flatter IBS geometry than seen in other spiders. Estimating the companion wind momentum and speed from the X-ray light curve, we find a companion mass-loss rate of $M ˙_{c} ≳ 1 0^{- 10}$ M $_{⊙}$ yr $^{- 1}$ , so that J2215 may become an isolated millisecond pulsar in $\sim 1$ Gyr. Our X-ray analyses place constraints on the magnetization and particle density of the pulsar wind and support models of magnetic reconnection and particle acceleration in the highly magnetized relativistic IBS.
↳ astro-ph.HEastro-ph.SRnucl-thApJ(2024)·22 citations
16
Pion gravitational form factors in the QCD instanton vacuum I
Wei-Yang Liu🇺🇸 · Edward Shuryak🇺🇸 · Christian Weiss🇺🇸 · Ismail Zahed🇺🇸
The pion form factors of the QCD energy-momentum tensor (EMT) are studied in the instanton liquid model (ILM) of the QCD vacuum. In this approach the breaking of conformal symmetry is encoded in the form of stronger-than-Poisson fluctuations in the number of instantons. For the trace of the EMT, it is shown that the gluonic trace anomaly term contributes half the pion mass, with the other half coming from the quark-mass-dependent sigma term. The $Q^{2}$ dependence of the form factors is governed by glueball and scalar meson exchanges. For the traceless EMT, the spin-0 and 2 form factors are computed at next-to-leading order in the instanton density using effective quark operators. Relations between the gluon and quark contributions to the EMT form factors are derived. The form factors are also expressed in terms of the pion light-front wave functions in the ILM. The results at the low resolution scale of the inverse instanton size are evolved to higher scales using the renormalization group equation. The ILM results compare well with those of recent lattice QCD calculations.
↳ hep-phhep-thnucl-thPRD(2024)·25 citations
17
Strangelets at finite temperature
Hao-Song You🇨🇳 · Huai-Min Chen🇨🇳 · Jian-Feng Xu🇨🇳 · Cheng-Jun Xia🇨🇳 · Ren-Xin Xu🇨🇳 · Guang-Xiong Peng🇨🇳
We study the properties of strangelets at finite temperature $T$ , employing an equivparticle model that incorporates both linear confinement and leading-order perturbative interactions with density-dependent quark masses. The shell effects are analyzed by solving the Dirac equations for quarks within the mean-field approximation. As temperature increases, these effects weaken due to the occupation probability of single-particle levels being governed by the Fermi-Dirac statistics, a phenomenon known as shell dampening. Surprisingly, the surface tension, derived from a liquid-drop formula, does not decrease with temperature but instead rises until it peaks at $T \approx 20 - 40$ MeV. At this temperature, shell corrections become negligible, and the formula provides a reasonable approximation for the free energy per baryon of strangelets. However, the curvature term decreases with $T$ despite the presence of shell effects. The neutron and proton emission rates are determined microscopically by the external nucleon gas densities that are in equilibrium with strangelets. These emission rate generally increases with $T$ for stable strangelets, but decrease for those that are unstable to nucleon emission at $T$ = 0. The other properties of $β$ -stable strangelets obtained with various parameter sets are presented as well. The results indicated in this work are useful for understanding the products of binary compact star mergers and heavy-ion collisions.
↳ hep-phnucl-th0 citations
18
High-precision spectroscopy of $^{20}$ O benchmarking ab-initio calculations in light nuclei
I. Zanon🇮🇹 · E. Clément🇫🇷 · A. Goasduff🇮🇹 · J. Menéndez🇪🇸 · T. Miyagi🇩🇪 · M. Assié🇫🇷 · M. Ciemała🇵🇱 · F. Flavigny🇫🇷 · A. Lemasson🇫🇷 · A. Matta🇫🇷 · D. Ramos🇫🇷 · M. Rejmund🇫🇷 and 69 other authors
The excited states of unstable $^{20}$ O were investigated via $γ$ -ray spectroscopy following the $^{19}$ O $(d, p)^{20}$ O reaction at 8 $A$ MeV. By exploiting the Doppler Shift Attenuation Method, the lifetime of the 2 $_{2}^{+}$ and 3 $_{1}^{+}$ states were firmly established. From the $γ$ -ray branching and E2/M1 mixing ratios for transitions deexciting the 2 $_{2}^{+}$ and 3 $_{1}^{+}$ states, the B(E2) and B(M1) were determined. Various chiral effective field theory Hamiltonians, describing the nuclear properties beyond ground states, along with a standard USDB interaction, were compared with the experimentally obtained data. Such a comparison for a large set of $γ$ -ray transition probabilities with the valence space in medium similarity renormalization group ab-initio calculations was performed for the first time in a nucleus far from stability. It was shown that the ab-initio approaches using chiral EFT forces are challenged by detailed high-precision spectroscopic properties of nuclei. The reduced transition probabilities were found to be a very constraining test of the performance of the ab-initio models.
↳ nucl-exnucl-thPRL(2023)·7 citations
19
Fully charmed tetraquarks from LHC to FCC: Natural stability from fragmentation
Francesco Giovanni Celiberto🇪🇸 · Gabriele Gatto🇮🇹 · Alessandro papa🇮🇹
We investigate the inclusive production of fully charmed tetraquarks, $T_{4 c} (0^{++})$ or $T_{4 c} (2^{++})$ radial excitations, in high-energy proton collisions. We build our study upon the collinear fragmentation of a single parton in a variable-flavor number scheme, suited to describe the tetraquark formation mechanism from moderate to large transverse-momentum regimes. To this extent, we derive a novel set of DGLAP-evolving collinear fragmentation functions, named TQ4Q1.0 determinations. They encode initial-scale inputs corresponding to both gluon and heavy-quark fragmentation channels, defined within the context of quark-potential and spin-physics inspired models, respectively. We work within the NLL/NLO $^{+}$ hybrid factorization and make use of the JETHAD numeric interface along with the symJETHAD symbolic calculation plugin. With these tools, we provide predictions for high-energy observables sensitive to $T_{4 c}$ plus jet emissions at center-of-mass energies ranging from 14 TeV at the LHC to the 100 TeV nominal energy of the FCC.
↳ hep-phhep-exnucl-exnucl-thEPJC(2024)·35 citations

Affiliations

first authorsco-authorsvia INSPIRE