Nuclear Theory·nucl-th

Tuesday·November 21, 2023

19 papers—14 primary·5 cross-listed

01
Sensitivity of one-neutron knockout observables of loosely- to more deeply-bound nuclei
Chloë Hebborn · Pierre Capel
For the last few decades, one-nucleon knockout reactions on light composite targets -- $^{9}$ Be or $^{12}$ C -- have been extensively used to study the single-particle (s.p.) structure of nuclei far from stability. To determine which information can be accurately inferred from knockout cross sections, we conduct a sensitivity analysis of these observables considering various s.p. descriptions within the usual eikonal description of the reaction. This work shows that total one-neutron knockout cross sections are not sensitive to the short-range part of the s.p. wave function. Rather, they scale with the mean square radius of the overlap function. Using a perturbative expression of the cross section, we can easily explain our numerical predictions analytically. This analysis suggests that (i) spectroscopic factors extracted from knockout data suffer from sizeable model uncertainties associated with the choice of s.p. wave functions and (ii) knockout reactions constitute an excellent probe of the radius of the nucleus and therefore offer an alternative technique to infer the neutron-skin thickness of exotic nuclei.
nucl-thPLB(2024)·1 citation
02
The effect of $T$ -invariance violation in scattering of polarized $^{3}$ He nuclei on tensor-polarized deuterons
Yu. N. Uzikov🇷🇺 · M. N. Platonova🇷🇺
In the interaction of a transversely polarized nuclear beam with a tensor-polarized deuteron target, a nonzero value of the component of the total cross section of the process corresponding to this combination of polarizations is an unambiguous signal of $T$ -invariance violation while $P$ -parity is preserved. The method developed earlier for calculating this component of the total cross section for $p d$ scattering based on the Glauber theory has been generalized by us to the case of $^{3}$ He $d$ scattering, and its energy dependence in the range of beam energies 0.1--1 GeV/nucleon has been calculated. It is found that in $^{3}$ He $d$ collisions, in contrast to $p d$ scattering, the contribution of only one type of $T$ -violating nucleon-nucleon forces dominates, which is essential for extraction of the unknown constant of this interaction from the corresponding data.
nucl-thJETP Lett.(2023)·6 citations
03
Dense-matter equation of state at zero & finite temperature
Alexander Clevinger🇺🇸 · Veronica Dexheimer🇺🇸 · Jeffrey Peterson🇺🇸
At high density, matter is expected to undergo a phase transition to deconfined quark matter. Although the density at which it happens and the strength of the transition are still largely unknown, we can model it to be in agreement with known experimental data and reliable theoretical results. We discuss how deconfinement in dense matter can be affected by both by temperature and by strong magnetic fields within the CMF model. To explore different dependencies in our approach, we also explore how deconfinement can be affected by the assumption of different degrees of freedom, different vector coupling terms, and different deconfining potentials, all at zero temperature. Both zero-net-strangeness and isospin-symmetric heavy-ion collision matter and beta-equilibrated charge-neutral matter in neutron stars are discussed.
nucl-thastro-ph.HEastro-ph.SRhep-phEPJ Web Conf.(2024)·0 citations
04
Towards consistent nuclear interactions from chiral Lagrangians I: The path-integral approach
Hermann Krebs🇩🇪 · Evgeny Epelbaum🇩🇪
Low-energy nuclear interactions have been extensively studied in the framework of chiral effective field theory. The corresponding potentials have been worked out using dimensional regularization to evaluate ultraviolet divergent loop integrals. An additional cutoff is then introduced in the nuclear Schrödinger equation to calculate observables. Recently, we have shown that such a mixture of two regularization schemes violates chiral symmetry when applied beyond the two-nucleon system and/or to processes involving external probes. To solve this issue, three- and four-nucleon forces as well as exchange current operators need to be re-derived using symmetry-preserving cutoff regularization. While it is possible to introduce a symmetry-preserving cutoff already in the effective chiral Lagrangian, the appearance of high-order time derivatives of the pion field, caused by the regulator, makes the standard Hamiltonian-based methods not well suited for the calculation of nuclear potentials. Here, we propose a new approach to derive nuclear interactions using the path integral method with no reliance on the canonical quantization. To this aim, the interaction part of the action is brought to an instantaneous form via suitably chosen nonlocal field redefinitions. Loop contributions to the nuclear potentials are then generated through the functional determinant, induced by the field redefinitions. We discuss in detail the application of these ideas to the case of a regularized Yukawa-type model of pion-nucleon interactions. Our new method allows to perform a systematic quantum mechanical reduction within the quantum field theory framework and opens the way for deriving consistently regularized nuclear forces and current operators from the effective chiral Lagrangian.
nucl-thhep-phhep-thPRC(2024)·26 citations
05
Thallium-208: a beacon of in situ neutron capture nucleosynthesis
Nicole Vassh · Xilu Wang · Maude Lariviere · Trevor Sprouse · Matthew R. Mumpower · Rebecca Surman · Zhenghai Liu · Gail C. McLaughlin · Pavel Denissenkov · Falk Herwig
We demonstrate that the well-known 2.6 MeV gamma-ray emission line from thallium-208 could serve as a real-time indicator of astrophysical heavy element production, with both rapid (r) and intermediate (i) neutron capture processes capable of its synthesis. We consider the r process in a Galactic neutron star merger and show Tl-208 to be detectable from ~12 hours to ~10 days, and again ~1-20 years post-event. Detection of Tl-208 represents the only identified prospect for a direct signal of lead production (implying gold synthesis), arguing for the importance of future MeV telescope missions which aim to detect Galactic events but may also be able to reach some nearby galaxies in the Local Group.
nucl-thastro-ph.HEPRL(2024)·14 citations
06
Mapping GENERIC hydrodynamics into Carter's multifluid theory
Lorenzo Gavassino
We show that the GENERIC model for relativistic heat conduction is a multifluid of Carter. This allows one to compute the multifluid constitutive relations directly from the GENERIC formalism. As a quick application, we prove that, in the limit of infinite heat conductivity, GENERIC heat conduction reduces to the relativistic two-fluid model for superfluidity. This surprising ``crossover'' is a consequence of relativistic causality: If diffusion happens too fast, all the diffusing charge cumulates on the surface of the lightcone, and it eventually travels at the speed of light like a wave. Our analysis is non-perturbative, and it is carried out in the fully non-linear regime.
nucl-thastro-ph.HEgr-qcSymmetry(2024)·2 citations
07
Thermodynamic Susceptibilities for a Unitary Fermi Gas
Max Weiner🇺🇸
The unitary Fermi gas provides a unique window into both cold atom experiments and neutron star properties. There are major challenges in determining the physical properties within a neutron star, both experimentally and theoretically. However, there is a region within the crust of a neutron star that resembles a gas of fermions that is recreated in a cold atom laboratory. This is the so-called unitary Fermi gas characterized by a large negative scattering length and small effective range. We set out to calculate from first principles certain transport coefficients that appear at second order in the hydrodynamic expansion. These particular transport coefficients are obtained from two point correlation functions in flat space that do not require analytic continuation from Euclidean to Minkowski space. We are motivated by the potential to learn about neutron star properties from cold atom experiments.
nucl-th1 citation
08
Contributions of $2 π$ -exchange, $1 π$ -exchange, and contact three-body forces in NNLO ChEFT to $_{Λ}^{3}$ H
M. Kohno🇯🇵 · H. Kamada🇯🇵 · K. Miyagawa🇯🇵
Faddeev calculations of hypertriton ( $_{Λ}^{3}$ H) separation energy are performed, incorporating all next-to-next-to-leading-order $Λ$ NN three-body forces (3BFs) in chiral effective field theory: $2 π$ -exchange, $1 π$ -exchange, and contact interactions. The $1 π$ -exchange and contact interactions are rewritten in a form suitable for evaluating partial-wave matrix elements. The $Λ$ -deuteron folding potentials constructed from these 3BFs are evaluated to demonstrate their contributions to \h3t. The $1 π$ -exchange interaction provides an attractive effect in which the d-state component of the deuteron wave function plays an important role. The attractive contribution tends to cancel the repulsive ones from the $2 π$ -exchange and contact 3BFs. Faddeev calculations show that the net effect of the 3BFs to the \h3t separation energy is small in a range between $- 5$ to $+ 20$ keV, depending on the NN interaction used. Although these results are based on speculative low-energy constants, they can serve as a reference for further investigations.
nucl-thPRC(2024)·6 citations
09
Rapidity scan approach for net-baryon cumulants with a statistical thermal model
Jianing Li🇨🇳 · Lipei Du🇨🇦 · Shuzhe Shi🇨🇳
Utilizing rapidity-dependent measurements to map the QCD phase diagram provides a complementary approach to traditional beam-energy-dependent measurements around midrapidity. The changing nature of thermodynamic properties of QCD matter along the beam axis in heavy-ion collisions at low collision energies both motivates and poses challenges for this method. In this study, we derive the analytical cumulant-generating function for subsystems within distinct rapidity windows, while accounting for global net-baryon charge conservation of the full system. Rapidity-dependent net-baryon cumulants are then calculated for a system exhibiting inhomogeneity along the beam axis, and their sensitivity to finite acceptances through changing rapidity bin widths is explored. We highlight the nontrivial behaviors exhibited by these cumulants, underscoring their importance in establishing a noncritical baseline for interpreting net-proton cumulants in the search for the QCD critical point. Finally, we discuss the implications of the rapidity scan for mapping the QCD phase diagram within the current context.
nucl-thhep-phnucl-exPRC(2024)·7 citations
10
Magnetic dipole transition in $^{48}$ Ca
B. Acharya🇺🇸 · B. S. Hu🇺🇸 · S. Bacca🇩🇪 · G. Hagen🇺🇸 · P. Navrátil🇨🇦 · T. Papenbrock🇺🇸
The magnetic dipole transition strength $B (M 1)$ of $^{48}$ Ca is dominated by a single resonant state at an excitation energy of 10.23 MeV. Experiments disagree about $B (M 1)$ and this impacts our understanding of spin flips in nuclei. We performed ab initio computations based on chiral effective field theory and found that $B (M 1 : 0^{+} \to 1^{+})$ lies in the range from $7.0$ to $10.2 μ_{N}^{2}$ . This is consistent with a $(γ, n)$ experiment but larger than results from $(e, e^{'})$ and $(p, p^{'})$ scattering. Two-body currents yield no quenching of the $B (M 1)$ strength and continuum effects reduce it by about 10%. For a validation of our approach, we computed magnetic moments in $^{47, 49}$ Ca and performed benchmark calculations in light nuclei.
nucl-thnucl-exPRL(2024)·16 citations
11
Shakhov-type extension of the relaxation time approximation in relativistic kinetic theory and second-order fluid dynamics
Victor E. Ambruş · Etele Molnár
We present a relativistic Shakhov-type generalization of the Anderson-Witting relaxation time model for the Boltzmann collision integral to modify the ratio of momentum diffusivity to thermal diffusivity. This is achieved by modifying the path on which the single particle distribution function $f_{k}$ approaches local equilibrium $f_{0 k}$ by constructing an intermediate Shakhov-type distribution $f_{S k}$ similar to the 14-moment approximation of Israel and Stewart. We illustrate the effectiveness of this model in case of the Bjorken expansion of an ideal gas of massive particles and the damping of longitudinal waves through an ultrarelativistic ideal gas.
nucl-thhep-phphysics.flu-dynPLB(2024)·4 citations
12
Extracting neutron skin from elastic proton-nucleus scattering with deep neural network
G. H. Yang · Y. Kuang · Z. X. Yang · Z. P. Li
Based on the relativistic impulse approximation of proton-nucleus elastic scattering theory, the nucleon density distribution and neutron skin thickness of $^{48}$ Ca are estimated via the deep learning method. The neural-network-generated densities are mainly compressed to be lower inside the nucleus compared with the results from the relativistic PC-PK1 density functional, resulting in a significant improvement on the large-angle scattering observables, both for the differential cross section and analyzing power. The neutron skin thickness of $^{48}$ Ca is captured to be 0.211(11) fm. The relatively thicker neutron skin is deemed reasonable from the perspective of density functional analysis.
nucl-thPLB(2025)·1 citation
13
Stellar $β$ -decay rate of $s$ -process branching-point $^{204}$ Tl: forbidden transitions
Yang Xiao · Bin-Lei Wang · Long-Jun Wang
We propose a theoretical method to calculate the stellar $β$ -decay rates of nuclei in stellar environments with high temperature and density, based on the projected shell model, where contributions from both allowed and first-forbidden transitions are taken into account. As the first example, the stellar $β$ -decay rate of one of the last $s$ -process branching-point nuclei, $^{204}$ Tl, is calculated and studied, where all related transitions are first-forbidden transitions. For the terrestrial case, the ground-state to ground-state transition is unique first-forbidden transition, which is described reasonably by our calculations. At the typical $s$ -process temperature ( $T \approx 0.3$ GK), non-unique first-forbidden transitions from thermally populated excited states of the parent nucleus are involved, the effective rate from our calculations is much lower than the one from the widely used data tables by Takahashi and Yokoi. Effect of the quenching factors for nuclear matrix elements in first-forbidden transitions on the stellar $β$ -decay rates is discussed as well.
nucl-thastro-ph.SRPRC(2024)·6 citations
14
Multimodal fission from self-consistent calculations
Daniel Lay · Eric Flynn · Sylvester Agbemava · Kyle Godbey · Witold Nazarewicz · Samuel A. Giuliani · Jhilam Sadhukhan
When multiple fission modes coexist in a given nucleus, distinct fragment yield distributions appear. Multimodal fission has been observed in a number of fissioning nuclei spanning the nuclear chart, and this phenomenon is expected to affect the nuclear abundances synthesized during the rapid neutron-capture process (r-process). In this study, we generalize the previously proposed hybrid model for fission-fragment yield distributions to predict competing fission modes and estimate the resulting yield distributions. Our framework allows for a comprehensive large-scale calculation of fission fragment yields suited for r-process nuclear network studies. Nuclear density functional theory is employed to obtain the potential energy and collective inertia tensor on a multidimensional collective space defined by mass multipole moments. Fission pathways and their relative probabilities are determined using the nudged elastic band method. Based on this information, mass and charge fission yields are predicted using the recently developed hybrid model. Fission properties of fermium isotopes are calculated in the axial quadrupole-octupole collective space for three energy density functionals (EDFs). Disagreement between the EDFs appears when multiple fission modes are present. Within our framework, the UNEDF1 $_{HFB}$ EDF agrees best with experimental data. Calculations in the axial quadrupole-octupole-hexadecapole collective space improve the agreement with the experiment for SkM $^{*}$ . We also discuss the sensitivity of fission predictions on the choice of EDF for several superheavy nuclei. Fission fragment yield predictions for nuclei with multiple fission modes are sensitive to the underlying EDF. For large-scale calculations in which a minimal number of collective coordinates is considered, UNEDF1 $_{HFB}$ provides the best description of experimental data.
nucl-thPRC(2024)·4 citations
15
Exploration of hadronization through heavy flavor production at the future Electron-Ion Collider
Xuan Li🇺🇸
The future Electron-Ion Collider will utilize high-luminosity high-energy electron+proton ( $e + p$ ) and electron+nucleus ( $e + A$ ) collisions to solve several fundamental questions in the high energy nuclear physics field. Heavy flavor products play an important role in constraining the initial-state nucleon/nucleus parton distribution functions especially in the high and low Bjorken-x ( $x_{B J}$ ) region and exploring the final-state parton propagation and hadronization processes under different nuclear medium conditions. Latest simulation studies of heavy flavor hadron and jet measurements with the EIC project detector conceptual design will be discussed. The projected statistical accuracy of heavy flavor jet and heavy flavor hadron inside jet measurements in comparison with latest theoretical calculations will be presented.
↳ nucl-exhep-exnucl-thEPJ Web Conf.(2024)·4 citations
16
Production of Protons and Light Nuclei in Au+Au Collisions at $s_{NN}$ = 3 GeV with the STAR Detector
STAR Collaboration: M. I. Abdulhamid · B. E. Aboona · J. Adam · L. Adamczyk · J. R. Adams · I. Aggarwal · M. M. Aggarwal · Z. Ahammed · E. C. Aschenauer · S. Aslam · J. Atchison · V. Bairathi and 354 other authors
We report the systematic measurement of protons and light nuclei production in Au+Au collisions at $s_{NN}$ = 3 GeV by the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The transverse momentum ( $p_{T}$ ) spectra of protons ( $p$ ), deuterons ( $d$ ), tritons ( $t$ ), $^{3} He$ , and $^{4} He$ are measured from mid-rapidity to target rapidity for different collision centralities. We present the rapidity and centrality dependence of particle yields ( $d N / d y$ ), average transverse momentum ( $⟨ p_{T} ⟩$ ), yield ratios ( $d / p$ , $t / p$ , $^{3} He / p$ , $^{4} He / p$ ), as well as the coalescence parameters ( $B_{2}$ , $B_{3}$ ). The 4 $π$ yields for various particles are determined by utilizing the measured rapidity distributions, $d N / d y$ . Furthermore, we present the energy, centrality, and rapidity dependence of the compound yield ratios ( $N_{p} \times N_{t} / N_{d}^{2}$ ) and compare them with various model calculations. The physics implications of those results on the production mechanism of light nuclei and on QCD phase structure are discussed.
↳ nucl-exnucl-thPRC(2024)·45 citations
17
Rapidity and Energy Dependences of Temperatures and Volume Extracted from Identified Charged Hadron Spectra in Proton-Proton Collisions at a Super Proton Synchrotron (SPS)
Pei-Pin Yang🇨🇳 · Fu-Hu Liu🇨🇳 · Khusniddin K. Olimov🇺🇿
The standard (Bose-Einstein/Fermi-Dirac or Maxwell-Boltzmann) distribution from the relativistic ideal gas model is used to study the transverse momentum ( $p_{T}$ ) spectra of identified charged hadrons ( $π^{-}$ , $π^{+}$ , $K^{-}$ , $K^{+}$ , $p ˉ$ , and $p$ ) with different rapidities produced in inelastic proton-proton ( $pp$ ) collisions at the Super Proton Synchrotron (SPS). The experimental data measured by the NA61/SHINE Collaboration at the center-of-mass (c.m.) energies $s = 6.3$ , 7.7, 8.8, 12.3, and 17.3 GeV are fitted well by the distribution. It is shown that the effective temperature ( $T_{e f f}$ or $T$ ), kinetic freeze-out temperature ( $T_{0}$ ), and initial temperature ( $T_{i}$ ) decrease with the increase in rapidity and increase with the increase in c.m. energy. The kinetic freeze-out volume ( $V$ ) extracted from the $π^{-}$ , $π^{+}$ , $K^{-}$ , $K^{+}$ , and $p ˉ$ spectra decreases with the rapidity and increase with the c.m. energy. The opposite tendency of $V$ , extracted from the $p$ spectra, is observed to be increasing with the rapidity and decreasing with the c.m. energy due to the effect of leading protons.
↳ hep-phhep-exnucl-exnucl-thEntropy(2023)·7 citations
18
Dense $QCD_{2}$ with matrix product states
Tomoya Hayata🇯🇵 · Yoshimasa Hidaka🇯🇵 · Kentaro Nishimura🇯🇵
We study one-flavor $SU (2)$ and $SU (3)$ lattice QCD in ( $1 + 1$ ) dimensions at zero temperature and finite density using matrix product states and the density matrix renormalization group. We compute physical observables such as the equation of state, chiral condensate, and quark distribution function as functions of the baryon number density. As a physical implication, we discuss the inhomogeneous phase at nonzero baryon density, where the chiral condensate is inhomogeneous, and baryons form a crystal. We also discuss how the dynamical degrees of freedom change from hadrons to quarks through the formation of quark Fermi seas.
↳ hep-lathep-thnucl-thquant-phJHEP(2024)·21 citations
19
Far-from-equilibrium attractors with Full Relativistic Boltzmann approach in boost-invariant and non-boost-invariant systems
Vincenzo Nugara (1 and 2)🇮🇹 · Salvatore Plumari (1 and 2)🇮🇹 · Lucia Oliva (1 and 3)🇮🇹 · Vincenzo Greco (1 and 2) ((1) Department of Physics and Astronomy, University of Catania, Via S. Sofia 64, I-95125 Catania, (2) INFN-Laboratori Nazionali del Sud, Via S. Sofia 62, I-95123 Catania, Italy, (3) INFN Sezione di Catania, Via S. Sofia 64, I-95123 Catania, Italy)🇮🇹
We study the universal behavior associated with a Relativistic Boltzmann Transport (RBT) approach with the full collision integral in 0+1D conformal systems. We show that all momentum moments of the distribution function exhibit universal behavior. Furthermore, the RBT approach allows to calculate the full distribution function, showing that an attractor behavior is present in both the longitudinal and transverse momentum dependence. We compare our results to the far-from-equilibrium attractors determined with other approaches, such as kinetic theory in Relaxation Time Approximation (RTA) and relativistic hydrodynamic theories, both in their viscous (DNMR) an anisotropic (aHydro) formulations, finding a very similar evolution, but an even faster thermalization in RBT for higher order moments. For the first time, we extended this analysis also to study the attractor behavior under a temperature-dependent viscosity $η / s (T)$ , accounting also for the rapid increase toward the hadronic phase. We find that a partial breaking of the scaling behavior with respect to $τ / τ_{e q}$ emerges only at $T \approx T_{c}$ generating a transient deviation from attractors; interestingly this in realistic finite systems may occur around the freeze-out dynamics. Finally, we investigate for the first time results beyond the boost-invariant picture, finding that also in such a case the system evolves toward the universal attractor. In particular, we present the forward and pull-back attractors at different space-time rapidities including rapidity regions where initially the distribution function is even vanishing.
↳ hep-phnucl-thEPJC(2024)·17 citations

Affiliations

first authorsco-authorsvia INSPIRE