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Nuclear Theory·nucl-th

Wednesday·August 14, 2024

13 papers—7 primary·6 cross-listed

All13Primary7Cross-lists6
  1. 01

    Renormalized critical dynamics and fluctuations in model A

    Nadine Attieh🇫🇷 · Nathan Touroux🇫🇷 · Marcus Bluhm🇫🇷 · Masakiyo Kitazawa🇯🇵 · Taklit Sami🇫🇷 · Marlene Nahrgang🇫🇷

    In the context of relativistic heavy-ion collisions, we explore the stochastic and dissipative relaxational dynamics of a non-conserved order parameter in a interaction. The cutoff of the theory is provided by the lattice spacing chosen for our numerical simulations. As a consequence, observables become dependent on that scale. We consider a possible first-order phase transition and an evolution close to a critical point. We demonstrate that using a lattice counterterm restores the expected behavior of the mean, variance and kurtosis: the mean and the variance become lattice spacing independent, and we recover the correct expectation value of the mean, the growth of the variance with the correlation length and the expected minimum in the kurtosis. Our findings hold true in equilibrium and during the dynamical relaxation, and therefore mark an important step towards a fully fluctuating fluid dynamical setup.

    nucl-thPRC(2025)·2 citations
  2. 02

    Chemical freeze-out curve in heavy-ion collisions and the QCD critical point

    Artemiy Lysenko🇺🇦 · Mark I. Gorenstein🇺🇦 · Roman Poberezhniuk🇺🇦 · Volodymyr Vovchenko🇺🇸

    The chemical freeze-out curve in heavy-ion collisions is investigated in the context of a quantum chromodynamics (QCD) critical point (CP) search at finite baryon densities. Taking the hadron resonance gas picture at face value, chemical freeze-out points at a given baryochemical potential provide a lower bound on the possible temperature of the QCD CP. We first verify that the freeze-out data in heavy-ion collisions are well described by a constant energy per particle curve, , under strangeness neutrality conditions (, ). We then evaluate the hypothetical lower bound on the freeze-out curve based on this criterion in the absence of strangeness neutrality (, ) and confront it with recent predictions on the CP location. We find that recent estimates based on Yang-Lee edge singularities from lattice QCD data on coarse lattices () place the CP significantly below the freeze-out curve, hinting at the importance of performing continuum extrapolation within this method. Predictions based on functional methods and holography place the CP slightly above the freeze-out curve, indicating that the QCD CP may be located very close to the chemical freeze-out in + collisions at - GeV.

    nucl-thPRC(2025)·29 citations
  3. 03

    Application of the shift-invert Lanczos algorithm to a non-equilibrium Green function for transport problems

    K. Uzawa · K. Hagino

    Non-equilibrium Green's function theory and related methods are widely used to describe transport phenomena in many-body systems, but they often require a costly inversion of a large matrix. We show here that the shift-invert Lanczos method can dramatically reduce the computational effort. We apply the method to two test problems, namely a simple model Hamiltonian and to a more realistic Hamiltonian for nuclear fission. For a Hamiltonian of dimension 66103 we find that the computation time is reduced by a factor of 33 compared to the direct calculation of the Green's function.

    nucl-thcond-mat.mes-hallcond-mat.stat-mechphysics.chem-phPRE(2024)·2 citations
  4. 04

    Radial oscillations of proto-neutron stars

    T. T. Sun🇨🇳 · H. Chen🇨🇳 · J. B. Wei🇨🇳 · Z. Y. Zheng🇨🇳 · G. F. Burgio🇮🇹 · H. -J. Schulze🇮🇹

    We investigate radial oscillations of proto-neutron stars, employing equations of state described by the Brueckner-Hartree-Fock theory or the relativistic mean field model, and assuming isentropy and fixed lepton fractions for the internal structure. We calculate the eigenfrequencies and corresponding oscillation functions, which show different characteristics in different mass regions. In the low-mass region around 1.4 solar mass, the radial oscillation frequencies are lowered by large entropy and neutrino trapping, along with a reduction of the average adiabatic index. In the region close to the maximum mass, the fundamental oscillation frequency drops rapidly and vanishes at the maximum mass, in accordance with the critical stability criterion , as for cold neutron stars.

    nucl-thPRD(2025)·7 citations
  5. 05

    The triton lifetime from nuclear lattice effective field theory

    Serdar Elhatisari🇹🇷 · Fabian Hildenbrand🇩🇪 · Ulf-G. Meißner🇩🇪

    In this work, we present a calculation of the triton -decay lifetime using Nuclear Lattice Effective Field Theory (NLEFT) at next-to-next-to-next-to-leading order in the chiral expansion. By incorporating a non-perturbative treatment of the higher-order corrections, we achieve consistent predictions for the Fermi and Gamow-Teller matrix elements, which are crucial for determining the triton lifetime. Our results are consistent with earlier theoretical calculations, confirming the robustness of our approach. This study marks a significant advancement in the systematic application of NLEFT to nuclear -decay processes, paving the way for future high-precision calculations in more complex nuclear systems. Additionally, we discuss potential improvements to our approach, including the explicit inclusion of two-pion exchange mechanisms and the refinement of three-nucleon forces. These developments are essential for extending the applicability of NLEFT to a broader range of nuclear phenomena, including neutrinoless double- decay.

    nucl-thhep-lathep-phnucl-exPLB(2024)·10 citations
  6. 06

    Multiboson Hanbury Brown-Twiss correlations for partially coherent sources in relativistic heavy-ion collisions in a multiphase transport model

    Shi-Yao Wang🇨🇳 · Jun-Ting Ye🇨🇳 · Wei-Ning Zhang🇨🇳

    We use a multi-phase transport (AMPT) model to study multi-pion and multi-kaon Hanbury Brown-Twiss (HBT) correlations for the partially coherent particle-emitting sources in relativistic heavy-ion collisions. A density-dependent longitudinal coherent emission length and density-dependent transverse coherent emission length are introduced in calculating the multi-boson HBT correlation functions of the partially coherent sources. We compare the model results of three- and four-pion HBT correlation functions with experimental data in Pb-Pb collisions at center-of-mass energy 2.76 TeV, and investigate the influences of boson coherent emissions on the multi-pion and multi-kaon correlation functions, respectively. We find that all of the three- and four-pion correlation functions of the partially coherent sources are consistent with experimental data. Coherent emission leads to the intercept decreases of the multi-boson correlation functions. The intercepts of the multi-kaon correlation functions of the partially coherent source are higher than those of the multi-pion correlation functions, because low kaon densities lead to smaller kaon coherent emission lengths than pion emission lengths. The intercepts of multi-boson correlation functions of partially coherent sources in high transverse momentum intervals are higher than those in low transverse momentum intervals because particle de Broglie wavelengths are small at high momenta.

    nucl-thPRC(2024)·1 citation
  7. 07

    Uncertainty quantification of optical models in fission fragment de-excitation

    Kyle A. Beyer · Amy E. Lovell · Cole D. Pruitt · Nathan P. Giha · Brian C. Kiedrowski

    We take the first step towards incorporating compound nuclear observables at astrophysically relevant energies into the experimental evidence used to constrain optical models, by propagating the uncertainty in two global optical potentials, one phenomenological and one microscopic, to correlated fission observables using the Monte Carlo Hauser-Feshbach formalism. We compare to a wide range of historic and recent experimental fission measurements, and discuss in detail regions of disagreement. We find that the parametric optical model uncertainty in neutron-fragment correlated observables involving neutron energy is significant. On the other hand, we observe that other experimental features, particularly neutron-fragment correlations near the Sn shell-closure and the high energy component of neutron spectra, are unlikely to be explained by the optical potential, and will require further experimental and theoretical effort to explain.

    nucl-thPRC(2025)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE