Nuclear Theory·nucl-th

Tuesday·April 2, 2024

15 papers—8 primary·7 cross-listed

01
Multiscale physics of atomic nuclei from first principles
Z. H. Sun · A. Ekström · C. Forssén · G. Hagen · G. R. Jansen · T. Papenbrock
Atomic nuclei exhibit multiple energy scales ranging from hundreds of MeV in binding energies to fractions of an MeV for low-lying collective excitations. As the limits of nuclear binding is approached near the neutron- and proton driplines, traditional shell-structure starts to melt with an onset of deformation and an emergence of coexisting shapes. It is a long-standing challenge to describe this multiscale physics starting from nuclear forces with roots in quantum chromodynamics. Here we achieve this within a unified and non-perturbative framework that captures both short- and long-range correlations starting from modern nucleon-nucleon and three-nucleon forces from chiral effective field theory. The short-range correlations which accounts for the bulk of the binding energy is included within a symmetry-breaking framework, while long-range correlations (and fine details about the collective structure) are included via symmetry projection. Our calculations accurately reproduce available experimental data for low-lying collective states and the electromagnetic quadrupole transitions in $^{20 - 30}$ Ne. We also reveal coexisting spherical and deformed shapes in $^{30}$ Ne, which indicates the breakdown of the magic neutron number $N = 20$ as the key nucleus $^{28}$ O is approached, and we predict that the dripline nuclei $^{32, 34}$ Ne are strongly deformed. By developing reduced-order-models for symmetry-projected states, we perform a global sensitivity analysis and find that the subleading singlet S-wave contact and a pion-nucleon coupling strongly impact nuclear deformation in chiral effective-field-theory. The techniques developed in this work clarify how microscopic nuclear forces generate the multiscale physics of nuclei spanning collective phenomena as well as short-range correlations and allow to capture emergent and dynamical phenomena in finite fermion systems.
nucl-thnucl-exPRX(2025)·71 citations
02
Uncertainty Quantification of Collective Nuclear Observables From the Chiral Potential Parametrization
Kevin S. Becker · Kristina D. Launey · Andreas Ekström · Tomáš Dytrych · Daniel Langr · Grigor H. Sargsyan · Jerry P. Draayer
We perform an uncertainty estimate of quadrupole moments and B(E2) transition rates that inform nuclear collectivity. In particular, we study the low-lying states of 6Li and 12C using the ab initio symmetry-adapted no-core shell model. For a narrow standard deviation of approximately 1% on the low-energy constants which parametrize high-precision chiral potentials, we find output standard deviations in the collective observables ranging from approximately 3-6%. The results mark the first step towards a rigorous uncertainty quantification of collectivity in nuclei that aims to account for all sources of uncertainty in ab initio descriptions of challenging collective and clustering observables.
nucl-thPhys.Scripta(2024)·3 citations
03
Decoding rotating neutron stars: Role of the symmetry energy slope
Luiz L. Lopes🇧🇷
In December 2023, the Fermi LAT Catalog announced the discovery of 33 new millisecond pulsars. Motivated by that, in this work, I study how different values of the symmetry energy slope $(L)$ affect the properties of static and slowly rotating neutron stars. For fixed values of angular velocity, I study how the slope influences the increase of the maximum mass, the radii of the canonical 1.4 solar mass, its eccentricity, as well the same quantities for the 2.01 $M_{⊙}$ stars. I show that different slope values cause different variations not only the absolute quantities but also in relative ones. Indeed, different slope values predict different values for the eccentricity, which does not depend on the absolute value of the neutron stars' radii. Therefore, this quantity can be a powerful tool to constrain the symmetry energy slope.
nucl-thastro-ph.HEgr-qcApJ(2024)·11 citations
04
Theoretical investigation of heavy cluster decay from Z=118 and 120 isotopes: A search for an empirical formula in superheavy region
G. Saxena · Dashty T. Akrawy · Ali H. Ahmed · Mamta Aggarwal
Various decay modes in superheavy nuclei have been of significant interest among which cluster radioactivity has recently gained sizable attention. The {\alpha}-decay being a predominant decay mode in the superheavy region, the accurate determination of cluster decay half-lives is also crucial in this region as it has tremendous potential to be explored as one of the major decay channels. The usability of the Royer analytical formula [Nuclear Physics A 683 (2001) 182], which is based on the asymmetric fission model, has been investigated for the cluster and {\alpha} decay in superheavy region, by comparing it with several other (semi)empirical/analytical formulas. After fitting the formula on around 100 cluster-decay data and around 423 {\alpha}-decay data, the refitted Royer formula (RRF) is found to be very robust which is able to estimate the cluster decay and {\alpha}-decay half-lives with good accuracy. In fact, a comparison of the half-lives of both the decay modes using the same formula points towards a substantial chance of heavy cluster (Kr and Sr) decay from various isotopes of Z=118 and 120. Hence, the formula proposed in this study works fairly well for the estimation of cluster decay half-lives in superheavy regions where most empirical formulas fail to match with the half-lives from the various established theories.
nucl-thNPA(2024)·2 citations
05
Thermal production of charm quarks in relativistic heavy-ion collisions
Taesoo Song🇩🇪 · Ilia Grishmanovskii🇩🇪 · Olga Soloveva🇩🇪 · Elena Bratkovskaya🇩🇪
We investigate the thermal production of charm quarks in the strongly interacting quark-gluon plasma (sQGP) created in heavy-ion collisions at relativistic energies. Our study is based on the off-shell parton-hadron-string dynamics (PHSD) transport approach describing the full time evolution of heavy-ion collisions on a microscopic basis with hadronic and partonic degrees of freedom. The sQGP is realized within the effective dynamical quasi-particle model (DQPM) which is adjusted to reproduce the lattice QCD results for the thermodynamic observables of the sQGP. Relying on the fact that the DQPM successfully describes the spatial diffusion coefficients $D_{s}$ from the lQCD, which control the interaction of charm quarks with thermal partons (expressed in terms of strongly interacting off-shell quasiparticles), we evaluate the production of charm quark pairs through the rotation of Feynman diagrams such that the incoming charm quark and outgoing light parton in elastic scattering diagrams are exchanged. The charm quark annihilation is realized by detailed balance. We find that the number of produced thermal charm quark pairs strongly depends on the charm quark mass in the QGP. While for the heavy charm quarks of mass $m_{c} = 1.8$ GeV it is subdominant compared to the primary charm production by binary nucleon-nucleon collisions at RHIC and LHC energies, the numbers of primary and thermal charm quarks become comparable for a smaller (bare) $m_{c} = 1.2$ GeV. Compared with the experimental data on the $R_{AA}$ of $D$ -mesons in heavy-ion collisions at RHIC and LHC energies, it is more favorable for charm quarks in the QGP to gain additional mass due to thermal effects rather than to have a low bare mass.
nucl-thhep-phnucl-exPRC(2024)·14 citations
06
Revisiting the 3{\alpha} reaction rates in helium burning stars
Theodoros Depastas · Shuting Sun · Hongbin Heb · Hua Zheng · Aldo Bonasera
Helium burning is one of the most fundamental steps of stellar nucleosynthesis, as it describes the formation of life-determining element of carbon, while it plays a key role in the evolution of Red Giant, accreting White Dwarfs and Neutron Stars. In this work we develop a generalized statistical theory for the 3{\alpha} reaction, which is based on the use of the Imaginary Time Method, along with the semi-classical Hybrid {\alpha}-Clustering (H{\alpha}C) and Neck Model (NM) frameworks. The results compared to the methodology and data of the NACRE collaboration, following in several orders of magnitude discrepancies, especially at low temperatures. This may be crucial for the early dynamics of helium burning stars.
nucl-thPLB(2025)·7 citations
07
Coordinate versus momentum cuts and effects of collective flow on critical fluctuations
Volodymyr A. Kuznietsov🇺🇸 · Mark I. Gorenstein🇺🇦 · Volker Koch🇺🇸 · Volodymyr Vovchenko🇺🇸
We analyze particle number fluctuations in the crossover region near the critical endpoint of a first-order phase transition by utilizing molecular dynamics simulations of the classical Lennard-Jones fluid. We extend our previous study [V.A. Kuznietsov et al., Phys. Rev. C 105, 044903 (2022)] by incorporating longitudinal collective flow. The scaled variance of particle number distribution inside different coordinate and momentum space acceptances is computed through ensemble averaging and found to agree with earlier results obtained using time averaging, validating the ergodic hypothesis for fluctuation observables. Presence of a sizable collective flow is found to be essential for observing large fluctuations from the critical point in momentum space acceptances. We discuss our findings in the context of heavy-ion collisions.
nucl-thhep-phPRC(2024)·10 citations
08
Farside-dominant quasinuclear rainbow in refractive $α$ + $α$ scattering
S. Ohkubo
$α$ + $α$ scattering has a long history since the first experiment by Rutherford and Chadwick in 1927 and has been studied thoroughly experimentally and theoretically. However, $α$ + $α$ scattering has never been paid attention from the viewpoint of refractive scattering. I have successfully analyzed the experimental angular distributions in $α$ + $α$ scattering systematically over a wide range of incident energies $E_{L}$ =53.4 - 280 MeV using a phenomenological optical model with a deep real potential. The existence of a farside-dominant quasinuclear rainbow with no well-defined rainbow angle and no supernumerary bow in the lit side followed by the shadow, which is not a genuine rainbow but a refractive scattering from a marginally small droplet at high energies, is found for the first time in $α$ + $α$ scattering. The refraction due to the deep potentials with an attractive core at short distances are discussed from the viewpoint of the Luneburg. The deep vs shallow problem of the potential and the nuclear rainbow scattering in inelastic channels are also discussed.
nucl-thnucl-exPRC(2024)·1 citation
09
Quantum simulation of entanglement and hadronization in jet production: lessons from the massive Schwinger model
Adrien Florio🇺🇸 · David Frenklakh🇺🇸 · Kazuki Ikeda🇺🇸 · Dmitri E. Kharzeev🇺🇸 · Vladimir Korepin🇺🇸 · Shuzhe Shi🇺🇸 · Kwangmin Yu🇺🇸
The possible link between entanglement and thermalization, and the dynamics of hadronization are addressed by studying the real-time response of the massive Schwinger model coupled to external sources. This setup mimics the production and fragmentation of quark jets, as the Schwinger model and QCD share the properties of confinement and chiral symmetry breaking. By using quantum simulations on classical hardware, we study the entanglement between the produced jets, and observe the growth of the corresponding entanglement entropy in time. This growth arises from the increased number of contributing eigenstates of the reduced density matrix with sufficiently large and close eigenvalues. We also investigate the physical nature of these eigenstates, and find that at early times they correspond to fermionic Fock states. We then observe the transition from these fermionic Fock states to meson-like bound states as a function of time. In other words, we observe how hadronization develops in real time. At late times, the local observables at mid-rapidity (such as the fermion density and the electric field) approach approximately constant values, suggesting the onset of equilibrium and approach to thermalization.
↳ hep-phhep-thnucl-thquant-phPRD(2024)·52 citations
10
Solving reaction dynamics with quantum computing algorithms
Ronen Weiss🇺🇸 · Alessandro Baroni🇺🇸 · Joseph Carlson🇺🇸 · Ionel Stetcu🇺🇸
The description of quantum many-body dynamics is extremely challenging on classical computers, as it can involve many degrees of freedom. On the other hand, the time evolution of quantum states is a natural application for quantum computers that are designed to efficiently perform unitary transformations. In this paper, we study quantum algorithms for response functions, relevant for describing different reactions governed by linear response. We focus on nuclear-physics applications and consider a qubit-efficient mapping on the lattice, which can efficiently represent the large volumes required for realistic scattering simulations. For the case of a contact interaction, we develop an algorithm for time evolution based on the Trotter approximation that scales logarithmically with the lattice size, and is combined with quantum phase estimation. We eventually focus on the nuclear two-body system and a typical response function relevant for electron scattering as an example. We also investigate ground-state preparation and examine the total circuit depth required for a realistic calculation and the hardware noise level required to interpret the signal.
↳ quant-phnucl-thPRC(2025)·13 citations
11
New method for the solution of the two-body Dirac equation for the positronium bound states
E.M. Tursunov · Sh.G. Norbutaev · B.A. Fayzullaev
A new theoretical method is developed to solve the two-body bound-state Dirac equation for positronium. Only Coulomb potential was included in the Dirac Hamiltonian. It is shown that the two-body Dirac Hamiltonian can be written in the Hermitian matrix form of the 4 $\times$ 4 size and diagonalized in the momentum-state representation. Numerical results for the energy spectrum of the para- and ortho-positronium ground states performed within the variational method using the harmonic oscillator basis functions are in good agreement with a high-precision finite-element method of T.C. Scott et al. After the Fourier transformation into the coordinate-state representation the bound state wave functions of the para-Ps and ortho-Ps do not contain any singularity at the origin in contrast to the method mentioned above. The weights of the large-small and small-large components of the ground state wave functions are estimated to be of order 10 $^{- 6}$ , while the weight of the small-small component is of order 10 $^{- 12}$ .
↳ hep-phhep-exnucl-thquant-ph1 citation
12
Order of the SU(N_f) x SU(N_f) chiral transition via the functional renormalization group
G. Fejos🇯🇵 · T. Hatsuda🇯🇵
Renormalization group flows of the $S U (N_{f}) \times S U (N_{f})$ symmetric Ginzburg-Landau potential are calculated for a general number of flavors, $N_{f}$ . Our approach does not rely on the $ϵ$ expansion, but uses the functional renormalization group, formulated directly in $d = 3$ spatial dimensions, with the inclusion of all possible (perturbatively) relevant and marginal operators, whose number is considerably larger than those in $d = 4$ . We find new, potentially infrared stable fixed points spanned throughout the entire $N_{f}$ range. By conjecturing that the thermal chiral transition is governed by these ``flavor continuous" fixed points, stability analyses show that for $N_{f} \geq 5$ the chiral transition is of second-order, while for $N_{f} = 2, 3, 4$ , it is of first-order. We argue that the $U_{A} (1)$ anomaly controls the strength of the first-order chiral transition for $N_{f} = 2, 3, 4$ , and makes it almost indistinguishable from a second-order one, if it is sufficiently weak at the critical point. This could open up a new strategy to investigate the strength of the $U_{A} (1)$ symmetry breaking around the critical temperature.
↳ hep-phhep-lathep-thnucl-thPRD(2024)·38 citations
13
A new approach for deducing rms proton radii from charge-changing reactions of neutron-rich nuclei and the reaction-target dependence
J.-C. Zhang · B.-H. Sun · I. Tanihata · R. Kanungo · C. Scheidenberger · S. Terashima · Feng Wang · F. Ameil · J. Atkinson · Y. Ayyad · S. Bagchi · D. Cortina-Gil and 26 other authors
We report the charge-changing cross sections ( $σ_{cc}$ ) of 24 $p$ -shell nuclides on both hydrogen and carbon at about 900 $A$ MeV, of which $^{8, 9}$ Li, $^{10 \textendash 12}$ Be, $^{10, 14, 15}$ B, $^{14, 15, 17 \textendash 22}$ N and $^{16}$ O on hydrogen and $^{8, 9}$ Li on carbon are for the first time. Benefiting from the data set,we found a new and robust relationship between the scaling factor of the Glauber model calculations and the separation energies of the nuclei of interest on both targets.This allows us to deduce proton radii ( $R_{p}$ ) for the first time from the cross sections on hydrogen. Nearly identical $R_{p}$ values are deduced from both target data for the neutron-rich carbon isotopes, however, the $R_{p}$ from the hydrogen target is systematically smaller in the neutron-rich nitrogen isotopes.This calls for further experimental and theoretical investigations.
↳ nucl-exnucl-thSci.Bull.(2024)·20 citations
14
Total Gluon Helicity from Lattice without Effective Theory Matching
Zhuoyi Pang🇨🇳 · Fei Yao🇨🇳 · Jian-Hui Zhang🇨🇳
We propose two approaches for extracting the total gluon helicity contribution to proton spin from lattice QCD, one from local operator matrix elements in a fixed gauge accessible on lattice with feasible renormalization, and the other from gauge-invariant nonlocal gluon correlators. Neither of these approaches requires a matching procedure when converted to the MS scheme. Our proposal resolves a long-standing inconsistency in the literature regarding lattice calculations of the total gluon helicity, and has the potential to greatly facilitate these calculations.
↳ hep-phhep-latnucl-exnucl-thJHEP(2024)·6 citations
15
Efficient and precise quantum simulation of ultra-relativistic quark-nucleus scattering
Sihao Wu🇨🇳 · Weijie Du🇺🇸 · Xingbo Zhao🇨🇳 · James P. Vary🇺🇸
We present an efficient and precise framework to quantum simulate the dynamics of the ultra-relativistic quark-nucleus scattering. This framework employs the eigenbasis of the asymptotic scattering system and implements a compact scheme for encoding this basis upon lattice discretization. It exploits the operator structure of the light-front Hamiltonian of the scattering system, which enables the Hamiltonian input that utilizes the quantum Fourier transform for efficiency. Our framework simulates the scattering by the efficient and precise algorithm of the truncated Taylor series. The qubit cost of our framework scales logarithmically with the Hilbert space dimension of the scattering system. The gate cost has optimal scaling with the simulation error and near optimal scaling with the simulation time. These scalings make our framework advantageous for large-scale dynamics simulations on future fault-tolerant quantum computers. We demonstrate our framework with a simple scattering problem and benchmark the results with those from the Trotter algorithm and the classical calculations, where good agreement between the results is found. Our framework can be generalized to simulate the dynamics of various scattering problems in quantum chromodynamics.
↳ quant-phhep-thnucl-thPRD(2024)·19 citations

Affiliations

first authorsco-authorsvia INSPIRE