PaperPanorama

Nuclear Theory·nucl-th

Wednesday·September 7, 2022

21 papers12 primary·9 cross-listed

  1. 01

    Effects of a phase transition on two-pion interferometry in heavy-ion collisions at GeV

    Pengcheng Li🇩🇪 · Jan Steinheimer🇩🇪 · Tom Reichert🇩🇪 · Apiwit Kittiratpattana🇩🇪 · Marcus Bleicher🇩🇪 · Qingfeng Li🇨🇳

    Hanbury-Brown-Twiss (HBT) correlations for charged pions in central Au+Au collisions at (corresponding to beam kinetic energies in the fixed target frame from ) are calculated using the UrQMD model with different equations of state. The effects of a phase transition at high baryon densities are clearly observed in the HBT parameters that are explored. It is found that the available data on the HBT radii, and , in the investigated energy region favors a relatively stiff equation of state at low beam energies which then turns into a soft equation of state at high collision energies consistent with astrophysical constraints on the high density equation of state of QCD. The specific effects of two different phase transition scenarios on the and are investigated. It is found that a phase transition with a significant softening of the equation of state below 4 times nuclear saturation density can be excluded using HBT data. Our results highlight that the pion's and are sensitive to the stiffness of the equation of state, and can be used to constrain and understand the QCD equation of state in the high baryon density region.

    nucl-thSCPMA(2023)·45 citations
  2. 02

    Nuclear masses and the equation of state of nuclear matter

    Kazuhiro Oyamatsu

    The incompressible liquid-drop (ILD) model reproduces masses of stable nuclei rather well. Here we show how the ILD volume, surface, symmetry, and Coulomb energies are related to the equation of state of nuclear matter using the Oyamatsu-Iida (OI) macroscopic nuclear model, which has reasonable many-body energy and isoscalar inhomogeneity gradient energy. We use 304 update interactions, covering wide ranges of the incompressibility of symmetric matter and the density slope of symmetry energy , which fit almost equally empirical mass and radius data of stable nuclei. Thus, the and dependences are nearly frozen in stable nuclei as in the ILD model, leading to clear correlations among interaction and saturation parameters. Furthermore, we assume that the surface energy of the OI model is twice as large as the gradient energy using the size equilibrium conditions of the ILD and OI models. Then, the four energies of the ILD and OI models agree well for stable nuclei with . Meanwhile, the OI model with MeV predicts the latest mass data better than those of stable nuclei, and we suggest MeV, although the lower boundary is not constrained well.

    nucl-thnucl-exPTEP(2023)·4 citations
  3. 03

    Has J-PARC E07 observed a nuclear state?

    E. Friedman🇮🇱 · A. Gal🇮🇱

    The Strangeness J-PARC E07 emulsion experiment published recently two new --N capture events, IRRAWADDY and IBUKI, identified by observing weak-decay sequences of pairs of single- hypernuclei and interpreted as and nuclear bound states, respectively, with binding energies =6.270.27 MeV and =1.270.21 MeV. capture events in emulsion play a major role in determining the -nuclear and the potential strengths. Here we question the assignment of a nuclear bound state to IRRAWADDY and offer an alternative assignment as a near-threshold --C nuclear bound state, slightly admixed with a --N nuclear bound state component corresponding to IBUKI. We also question using IBUKI's value as is to determine the -nuclear potential depth. Altogether, capture events in C and O should prove less ambiguous than in N.

    nucl-thhep-phnucl-exPLB(2023)·16 citations
  4. 04

    Mass splitting and spin alignment for mesons in a magnetic field in NJL model

    Xin-Li Sheng🇨🇳 · Shu-Yun Yang🇨🇳 · Yao-Lin Zou🇨🇳 · Defu Hou🇨🇳

    Based on the Nambu-Jona-Lasinio (NJL) model, we develop a framework for calculating the spin alignment of vector mesons and applied it to study mesons in a magnetic field. We calculate mass spectra for mesons and observe mass splitting between the longitudinally polarized state and transversely polarized states. The meson in a thermal equilibrium system is preferred to occupy the state with spin than those with spin , because the former state has a smaller energy. As a consequence, we conclude that the spin alignment will be larger than 1/3 if one measures along the direction of the magnetic field, which is qualitatively consistent with the recent STAR data. Around the critical temperature MeV, the positive deviation from 1/3 is proportional to the square of the magnetic field strength, which agrees with the result from the non-relativistic coalescence model. Including the anomalous magnetic moments for quarks will modify the dynamical masses of quarks and thus affect the mass spectra and spin alignment of mesons. The discussion of spin alignment in the NJL model may help us better understand the formation of hadron's spin structure during the chiral phase transition.

    nucl-thhep-phEPJC(2024)·29 citations
  5. 05

    Recovering the conformal limit of color superconducting quark matter within a confining density functional approach

    Oleksii Ivanytskyi🇵🇱 · David Blaschke🇵🇱

    We generalize a recently proposed confining relativistic density-functional approach to the case of density dependent vector and diquark couplings. The particular behavior of these couplings is motivated by the non-perturbative gluon exchange in dense quark matter and provides the conformal limit at asymptotically high densities. We demonstrate that this feature of the quark matter EoS is consistent with a significant stiffness in the density range typical for the interiors of neutron stars. In order to model these astrophysical objects we construct a family of hybrid quark-hadron EoSs of cold stellar matter. We also confront our approach with the observational constraints on the mass-radius relation of neutron stars and their tidal deformabilities and argue in favor of a quark matter onset at masses below

    nucl-thastro-ph.HEhep-phParticles(2022)·35 citations
  6. 06

    Trimmed Sampling Algorithm for the Noisy Generalized Eigenvalue Problem

    Caleb Hicks🇺🇸 · Dean Lee🇺🇸

    Solving the generalized eigenvalue problem is a useful method for finding energy eigenstates of large quantum systems. It uses projection onto a set of basis states which are typically not orthogonal. One needs to invert a matrix whose entries are inner products of the basis states, and the process is unfortunately susceptible to even small errors. The problem is especially bad when matrix elements are evaluated using stochastic methods and have significant error bars. In this work, we introduce the trimmed sampling algorithm in order to solve this problem. Using the framework of Bayesian inference, we sample prior probability distributions determined by uncertainty estimates of the various matrix elements and likelihood functions composed of physics-informed constraints. The result is a probability distribution for the eigenvectors and observables which automatically comes with a reliable estimate of the error and performs far better than standard regularization methods. The method should have immediate use for a wide range of applications involving classical and quantum computing calculations of large quantum systems.

    nucl-thcond-mat.quant-gashep-latquant-phPRResearch(2023)·11 citations
  7. 07

    Simultaneous description of decay and low-lying structure of neutron-rich even- and odd-mass Rh and Pd nuclei

    K. Nomura · L. Lotina · R. Rodríguez-Guzmán · L. M. Robledo

    The low-energy structure and decay properties of neutron-rich even- and odd-mass Pd and Rh nuclei are studied using a mapping framework based on the nuclear density functional theory and the particle-boson coupling scheme. Constrained Hartree-Fock-Bogoliubov calculations using the Gogny-D1M energy density functional are performed to obtain microscopic inputs to determine the interacting-boson Hamiltonian employed to describe the even-even core Pd nuclei. The mean-field calculations also provide single-particle energies for the odd systems, which are used to determine essential ingredients of the particle-boson interactions for the odd-nucleon systems, and of the Gamow-Teller and Fermi transition operators. The potential energy surfaces obtained for even-even Pd isotopes as well as the spectroscopic properties for the even- and odd-mass systems suggest a transition from prolate deformed to -unstable and to nearly-spherical shapes. The predicted decay values are shown to be sensitive to the details of the wave functions for the parent and daughter nuclei, and therefore serve as a stringent test of the employed theoretical approach.

    nucl-thnucl-exPRC(2022)·9 citations
  8. 08

    Pion absorption from the lowest atomic orbital in 2H, 3H and 3He

    J. Golak🇵🇱 · V. Urbanevych🇵🇱 · R. Skibinski🇵🇱 · H. Witala🇵🇱 · K. Topolnicki🇵🇱 · V. Baru🇩🇪 · A. A. Filin🇩🇪 · E. Epelbaum🇩🇪 · H. Kamada🇯🇵 · A. Nogga🇩🇪

    The pi- + 2H -> n + n, pi- + 3H -> n + n + n, pi- + 3He -> n + d and pi- + 3He -> p + n + n capture reactions from the lowest atomic orbitals are studied under full inclusion of final state interactions. Our results are obtained with the single-nucleon and two-nucleon transition operators derived at leading order in chiral effective field theory. The initial and final three-nucleon states are calculated with the chiral nucleon-nucleon SMS potential up to N4LO+ augmented by the consistently regularized chiral N2LO three-nucleon potential. We found that absorption rates depend strongly on the nuclear pion absorption operator used, and its two-body parts change the rates by a few orders of magnitude. The final state interactions between nucleons generated by the two-nucleon forces are also important, while the three-nucleon interaction plays a visible role only in the pi- + 3He -> n + d reaction. Our absorption rate for the pi- + 2H -> n + n process is in good agreement with the experimental data from the hadronic ground-state broadening in pionic deuterium. The capture rates on 3He are also generally consistent with the spectroscopic data within error bars, though our central values are found to be systematically below the data. We show that for the three-body breakup processes the dominant contributions to the absorption rates arise from the quasi-free scattering and final-state interaction kinematical configurations.

    nucl-thnucl-exPRC(2022)·2 citations
  9. 09

    "Pseudo-Conformal" Sound Speed in the Core of Compact Stars

    Mannque Rho🇫🇷

    We present the argument that "pseudo-conformal" symmetry permeates from low density near nuclear matter to high density in the core of massive neutron stars. As a support of this argument, we describe how the quenched in nuclei and the sound speed in compact stars are controlled by emerging scale invariance in nuclear interactions. In our description, quasi-baryons could "masquerade" de-confined quarks in the interior of compact stars.

    nucl-thastro-ph.HEhep-phSymmetry(2022)·13 citations
  10. 10

    On the influence of Maxwell--Chern--Simons electrodynamics in nuclear fusion involving electronic and muonic molecules

    Francisco Caruso · Vitor Oguri · Felipe Silveira · Amos Troper

    New results recently obtained (\textit{Annals of Physics} (New York) a.n.~168943) established some non-relativistic ground state solutions for three-body molecules interacting through a Chern--Simons model. Within this model, it was argued that Chern--Simons potential should not help improve the fusion rates by replacing electrons with muons, in the case of particular muonic molecules. This achievement motivated us to investigate quantitatively whether or not the Maxwell--Chern--Simons electrodynamics could influence positively, for example, the probability of having a muon-catalyzed fusion; its contribution to electronic molecules is also considered in this letter. The principal factors related to the probability of elementary nuclear fusion are therefore numerically calculated and compared with their analogs admitting other forms of interaction like and . The analysis carried on here confirms that one should not expect a significant improvement in nuclear fusion rates in the case of muonic molecules, although, surprisingly, the same is not true for electronic molecules, compared with other theoretical predictions. Numerical predictions for the fusion rates for , , and molecules are given as well as the predicted value for the tunneling rate for these molecules.

    nucl-thphysics.atom-phEPL(2022)·0 citations
  11. 11

    Fission dynamics, dissipation and clustering at finite temperature

    B. Li · D. Vretenar · Z. X. Ren · T. Nikšić · J. Zhao · P. W. Zhao · J. Meng

    The saddle-to-scission dynamics of the induced fission process is explored using a microscopic finite-temperature model based on time-dependent nuclear density functional theory (TDDFT), that allows to follow the evolution of local temperature along fission trajectories. Starting from a temperature that corresponds to the experimental excitation energy of the compound system, the model propagates the nucleons along isentropic paths toward scission. For the four illustrative cases of induced fission of Pu, U, Cm, and Cf, characteristic fission trajectories are considered, and the partition of the total energy into various kinetic and potential energy contributions at scission is analyzed, with special emphasis on the energy dissipated along the fission path and the prescission kinetic energy. The model is also applied to the dynamics of neck formation and rupture, characterized by the formation of few-nucleon clusters in the low-density region between the nascent fragments.

    nucl-thPRC(2023)·20 citations
  12. 12

    Building Surrogate Models of Nuclear Density Functional Theory with Gaussian Processesand Autoencoders

    Marc Verriere · Nicolas Schunck · Irene Kim · Petar Marević · Kevin Quinlan · Michelle N. NGo · David Regnier · Raphael David Lasseri

    From the lightest Hydrogen isotopes up to the recently synthesized Oganesson (Z=118), it is estimated that as many as about 3000 atomic nuclei could exist in nature. Most of these nuclei are too short-lived to be occurring on Earth, but they play an essential role in astrophysical events such as supernova explosions or neutron star mergers that are presumed to be at the origin of most heavy elements in the Universe. Understanding the structure, reactions, and decays of nuclei across the entire chart of nuclides is an enormous challenge because of the experimental difficulties in measuring properties of interest in such fleeting objects and the theoretical and computational issues of simulating strongly-interacting quantum many-body systems. Nuclear density functional theory (DFT) is a fully microscopic theoretical framework which has the potential of providing such a quantitatively accurate description of nuclear properties for every nucleus in the chart of nuclides. Thanks to high-performance computing facilities, it has already been successfully applied to predict nuclear masses, global patterns of radioactive decay like or decay, and several aspects of the nuclear fission process such as, e.g., spontaneous fission half-lives. Yet, predictive simulations of nuclear spectroscopy or of nuclear fission, or the quantification of theoretical uncertainties and their propagation to applications, would require several orders of magnitude more calculations than currently possible. However, most of this computational effort would be spent into generating a suitable basis of DFT wavefunctions. Such a task could potentially be considerably accelerated by borrowing tools from the field of machine learning and artificial intelligence. In this paper, we review different approaches to applying supervised and unsupervised learning techniques to nuclear DFT.

    nucl-thFront.Phys.(2022)·8 citations
  13. 13

    Resumming Quark's Longitudinal Momentum Logarithms in LaMET Expansion of Lattice PDFs

    Yushan Su🇺🇸 · Jack Holligan🇺🇸 · Xiangdong Ji🇺🇸 · Fei Yao🇨🇳 · Jian-Hui Zhang🇨🇳 · Rui Zhang🇺🇸

    In the large-momentum expansion for parton distribution functions (PDFs), the natural physics scale is the longitudinal momentum () of the quarks (or gluons) in a large-momentum hadron. We show how to expose this scale dependence through resumming logarithms of the type in the matching coefficient, where is a fixed renormalization scale. The result enhances the accuracy of the expansion at moderate GeV, and at the same time, clearly shows that the partons cannot be approximated from quarks with which are not predominantly collinear with the parent hadron momentum, consistent with power counting of the large-momentum effective theory. The same physics mechanism constrains the coordinate space expansion at large distances , the conjugate of , as illustrated in the example of fitting the moments of the PDFs.

    hep-phhep-latnucl-thNPB(2023)·62 citations
  14. 14

    First Observation of Large Missing-Momentum (e,e'p) Cross-Section Scaling and the onset of Correlated-Pair Dominance in Nuclei

    I. Korover · A.W. Denniston · A. Kiral · A. Schmidt · A. Lovato · N. Rocco · A. Nikolakopoulos · L.B. Weinstein · E. Piasetzky · O. Hen · the CLAS Collaboration

    We report the first measurement of -scaling in cross-section ratios off nuclei relative to deuterium at large missing-momentum of MeV/c. The observed scaling extends over a kinematic range of , which is significantly wider than previously observed for inclusive cross-section ratios. The -integrated cross-section ratios become constant (i.e., scale) beginning at , the nuclear Fermi momentum. Comparing with theoretical calculations we find good agreement with Generalized Contact Formalism calculations for high missing-momentum ( MeV/c), suggesting the observed scaling results from interacting with nucleons in short-range correlated (SRC) pairs. For low missing-momenta, mean-field calculations show good agreement with the data for , and suggest that contributions to the measured cross-section ratios from scattering off single, un-correlated, nucleons are non-negligible up to MeV/c. Therefore, SRCs become dominant in nuclei at MeV/c, well above the nuclear Fermi Surface of MeV/c.

    nucl-exnucl-thPRC(2023)·16 citations
  15. 15

    Possible origin of HADES data on proton number fluctuations in Au+Au collisions

    O. Savchuk🇺🇦 · R. V. Poberezhnyuk🇺🇦 · M.I. Gorenstein🇺🇦

    Recent data of the HADES Collaboration in Au+Au central collisions at GeV indicate large proton number fluctuations inside one unit of rapidity around midrapidity. This can be a signature of critical phenomena due to the strong attractive interactions between baryons. We study an alternative hypothesis that these large fluctuations are caused by the event-by-event fluctuations of the number of bare protons, and no interactions between these protons are assumed. The proton number fluctuations in five symmetric rapidity intervals inside the region are calculated using the binomial acceptance procedure. This procedure assumes the independent (uncorrelated) emission of protons, and it appears to be in agreement with the HADES data. To check this simple picture we suggest to calculate the correlation between proton multiplicities in non-overlapping rapidity intervals and placed inside .

    hep-phnucl-thPLB(2022)·6 citations
  16. 16

    The Core of F studied by the F(-1p)O reaction

    H. L. Crawford · M. D. Jones · A. O. Macchiavelli · P. Fallon · D. Bazin · P. C. Bender · B. A. Brown · C. M. Campbell · R. M. Clark · M. Cromaz · B. Elman · A. Gade and 10 other authors

    The F(O reaction was studied at the NSCL using the S800 spectrometer. The experimental spectroscopic factor for the ground-state to ground-state transition indicates a substantial depletion of the proton strength compared to shell-model expectations. Our result supports the findings reported by Tang \textit{et al.}, from their study of the reaction at RIBF. The overlap between the F and O ground-states is considerably less than anticipated if O acted as a robust and rigid doubly-magic core in F. We interpret the results within the framework of the Particle-Vibration Coupling (PVC) of a proton coupled to a quadrupole phonon of an effective core. This approach provides a good description of the experimental data by requiring an effective O* core with a phonon energy of = 3.2 MeV, and a W.u., softer and more collective than a bare O. Both the Nilsson deformed mean field and the PVC models appear to capture the properties of the effective core of F, suggesting that the additional proton tends to polarize the free, doubly magic O in such a way that it becomes either slightly deformed or a quadrupole vibrator.

    nucl-exnucl-th0 citations
  17. 17

    Anisotropic pressure of magnetized quark matter with anomalous magnetic moment

    Nilanjan Chaudhuri🇮🇳 · Snigdha Ghosh🇮🇳 · Pradip Roy🇮🇳 · Sourav Sarkar🇮🇳

    We investigate magnetic field dependence of constituent quark mass, the longitudinal and transverse pressure as well as the magnetization and magnetic susceptibility of strongly interacting quark matter. We employ the two-flavour Polyakov Nambu--Jona-Lasinio model with the inclusion of the anomalous magnetic moment (AMM) of the quarks at finite temperature and finite quark chemical potential capturing different stages of chiral phase transition. We find that the transverse pressure, magnetization and magnetic susceptibility become highly oscillatory for large values of in the chiral symmetry broken phase. However the oscillations cease to occur at higher values of and when chiral symmetry is (partially) restored and the anisotropic nature of the pressure becomes significant even at smaller values of . As the inclusion of AMM of the quarks leads to inverse magnetic catalysis of the transition temperature we observe that the variations of transverse pressure, magnetization and magnetic susceptibility are significantly modified in the vicinity of the chiral transition temperature. Furthermore, above the chiral transition temperature the magnetic susceptibility is found to remain positive for a wide range of indicating a paramagnetic character of the strongly interacting quark matter. Finally, we have also examined the magnetism of strongly interacting matter in the quarkyonic phase. The obtained results could be useful for a magnetohydrodynamic evolution of hot and dense matter created in heavy-ion collisions.

    hep-phnucl-thPRD(2022)·22 citations
  18. 18

    Quark-model relations among TMDs in the parton model

    F. Aslan🇺🇸 · S. Bastami🇺🇸 · A. Mahabir🇺🇸 · A. Tandogan🇺🇸 · P. Schweitzer🇺🇸

    The covariant parton model (CPM) is a consequent application of the parton model concept to the nucleon structure. In this model, there is a choice to put quarks either in a pure-spin state or in a mixed-spin state. We show that the mixed-spin version of the CPM does not support the quark-model relations among transverse momentum dependent parton distributions (TMDs) which were shown to hold in a large class of quark models. One can enforce the quark-model relations to be valid in the CPM by imposing a condition which is equivalent to putting the quarks in a pure-spin state. This gives a complementary perspective on the connection of the pure- and mixed-spin state CPM versions, and provides a fresh view on the question whether the quark-model relations could be realized in QCD as "approximate relations" with some useful numerical accuracy.

    hep-phnucl-thPRD(2022)·4 citations
  19. 19

    Cross-channel constraints on resonant antikaon-nucleon scattering

    Jun-Xu Lu🇨🇳 · Li-Sheng Geng🇨🇳 · Michael Doering🇺🇸 · Maxim Mai🇺🇸

    Chiral perturbation theory and its unitarized versions have played an important role in our understanding of the low-energy strong interaction. Yet, so far, such studies typically deal exclusively with perturbative or nonperturbative channels. In this letter, we report on the first global study of meson-baryon scattering up to one-loop order. It is shown that covariant baryon chiral perturbation theory, including its unitarization for the negative strangeness sector, can describe meson-baryon scattering data remarkably well. This provides a highly non-trivial check on the validity of this important low-energy effective field theory of QCD. We show that the related quantities can be better described in comparison with those of lower-order studies, and with reduced uncertainties due to the stringent constraints from the and phase shifts. In particular, we find that the two-pole structure of persists up to one-loop order reinforcing the existence of two-pole structures in dynamically generated states.

    hep-phhep-exnucl-exnucl-thPRL(2023)·60 citations
  20. 20

    Effects of nuclear matter and composition in core-collapse supernovae and long-term proto-neutron star cooling

    Kohsuke Sumiyoshi · Shun Furusawa · Hiroki Nagakura · Akira Harada · Hajime Togashi · Ken'ichiro Nakazato · Hideyuki Suzuki

    We study the influence of hot and dense matter in core-collapse supernovae by adopting up-to-date nuclear equation of state (EOS) based on the microscopic nuclear many-body frameworks. We explore effects of EOS based on the Dirac Brueckner Hartree-Fock theory through comparisons with those based on the variational method. We also examine effects of the differences in the composition of nuclei and nucleons by using the same EOS by the variational method but employing two different treatments in computations of nuclear abundances. We perform numerical simulations of core-collapse supernovae adopting the three EOSs. We also perform numerical simulations of the long-term evolution over 70 s of the proto-neutron star cooling. We show that impacts by different modeling of composition are remarkable as in those by different treatments of uniform matter in the gravitational collapse, bounce, and shock propagation. The cooling of proto-neutron star and the resulting neutrino emission are also affected by the compositional difference even if the same treatment in computing uniform matter of EOS.

    astro-ph.HEnucl-thPTEP(2023)·10 citations
  21. 21

    Synthesis of cold and trappable fully stripped HCI's via antiproton-induced nuclear fragmentation in traps

    G. Kornakov (1) · G. Cerchiari (2) · J. Zieliński (1) · L. Lappo (1) · G. Sadowski (3) · M. Doser (3) ((1) Warsaw University of Technology · (2) Institut für Experimentalphysik Universität Innsbruck · (3) CERN)

    The study of radioisotopes as well as of highly charged ions is a very active and dynamic field. In both cases, the most sensitive probes involve species trapped in Penning or Paul traps after a lengthy series of production and separation steps that limit the types and lifetimes of species that can be investigated. We propose a novel production scheme that forms fully (or almost fully) stripped radionuclei in form of highly charged ions (HCI's) directly in the trapping environment. The method extends the range of species, among them radioisotopes such as F, Sn or Th, that can be readily produced and investigated and is complementary to existing techniques.

    physics.atom-phnucl-exnucl-thPRC(2023)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE