Nuclear Theory·nucl-th

Tuesday·January 2, 2024

11 papers—5 primary·6 cross-listed

01
Radius extrapolations for two-body bound states in finite volume
Anderson Taurence · Sebastian König
Simulations of quantum systems in finite volume have proven to be a useful tool for calculating physical observables. Such studies to date have focused primarily on understanding the volume dependence of binding energies, from which it is possible to extract asymptotic properties of the corresponding bound state, as well as on extracting scattering information. For bound states, all properties depend on the size of the finite volume, and for precision studies it is important to understand such effects. In this work, we therefore derive the volume dependence of the mean squared radius of a two-body bound state, using a technique that can be generalized to other static properties in the future. We test our results with explicit numerical examples and demonstrate that we can robustly extract infinite-volume radii from finite-volume simulations in cubic boxes with periodic boundary conditions.
nucl-thhep-latPRC(2024)·0 citations
02
3D Multi-system Bayesian Calibration with Energy Conservation to Study Rapidity-dependent Dynamics of Nuclear Collisions
Andi Mankolli🇺🇸 · Aaron Angerami · Ritu Arora · Steffen Bass · Shanshan Cao · Yi Chen · Lipei Du · Raymond Ehlers · Hannah Elfner · Wenkai Fan · Rainer J. Fries · Charles Gale and 39 other authors
Considerable information about the early-stage dynamics of heavy-ion collisions is encoded in the rapidity dependence of measurements. To leverage the large amount of experimental data, we perform a systematic analysis using three-dimensional hydrodynamic simulations of multiple collision systems -- large and small, symmetric and asymmetric. Specifically, we perform fully 3D multi-stage hydrodynamic simulations initialized by a parameterized model for rapidity-dependent energy deposition, which we calibrate on the hadron multiplicity and anisotropic flow coefficients. We utilize Bayesian inference to constrain properties of the early- and late- time dynamics of the system, and highlight the impact of enforcing global energy conservation in our 3D model.
nucl-thhep-phnucl-exEPJ Web Conf.(2024)·7 citations
03
Magnetic dipole $γ$ -ray strength functions of heavy nuclei in the configuration-interaction shell model
Y. Alhassid · P. Fanto · A. Mercenne
A low-energy enhancement (LEE) has been observed in the deexcitation $γ$ -ray strength function ( $γ$ SF) of compound nuclei. The LEE has been a subject of intense experimental and theoretical interest since its discovery, and, if the LEE persists in heavy neutron-rich nuclei, it would have significant effects on calculations of r-process nucleosynthesis. Standard configuration-interaction (CI) shell-model calculations in medium-mass nuclei have attributed the LEE to the magnetic dipole $γ$ SF but such calculations are computationally intractable in heavy nuclei. We review a combination of beyond-mean-field many-body methods within the framework of the CI shell model that enables the calculation of $γ$ SF in heavy nuclei, and discuss the recent theoretical identification of a LEE in the magnetic dipole $γ$ SF of lanthanide isotopes.
nucl-thEPJ Web Conf.(2024)·0 citations
04
Extracting spectra in the shell model Monte Carlo method using imaginary-time correlation matrices
Y. Alhassid · M. Bonett-Matiz · C.N. Gilbreth · S. Vartak
Conventional diagonalization methods to calculate nuclear energy levels in the framework of the configuration-interaction (CI) shell model approach are prohibited in very large model spaces. The shell model Monte Carlo (SMMC) is a powerful technique for calculating thermal and ground-state observables of nuclei in very large model spaces, but it is challenging to extract nuclear spectra in this approach. We present a novel method to extract low-lying energy levels for given values of a set of good quantum numbers such as spin and parity. The method is based on imaginary-time one-body density correlation matrices that satisfy asymptotically a generalized eigenvalue problem. We validate the method in a light nucleus that allows comparison with exact diagonalization results of the CI shell model Hamiltonian. The method is applicable to other finite-size quantum many-body systems that can be described within a CI shell model approach.
nucl-thPRL(2024)·1 citation
05
Bottom-hadron production in high-energy $pp$ and heavy-ion collisions
Min He🇨🇳
The hadro-chemistry of bottom quarks produced in hadronic collisions encodes valuable information on the mechanism of color-neutralization in these reactions. We first compute the chemistry of bottom-hadrons in high-energy $pp$ collisions employing statistical hadronization with a largely augmented set of states beyond the currently measured spectrum. This enables a comprehensive prediction of fragmentation fractions of weakly decaying bottom hadrons for the first time and a satisfactory explanation of the existing measurements in $pp$ collisions at the LHC. Utilizing the bottom hadro-chemistry thus obtained as the baseline, we then perform transport simulations of bottom quarks in the hot QCD matter created in PbPb collisions at the LHC energy and calculate the pertinent bottom-hadron observables. The transverse momentum ( $p_{T}$ ) dependent modifications of the bottom baryon-to-meson ratio ( $Λ_{b}^{0} / B^{-}$ ) relative to their $pp$ counterparts are highlighted as a result of bottom quark diffusion and hadronization in the Quark-Gluon Plasma (QGP). We finally summarize the heavy quark (charm vs bottom) diffusion coefficients as extracted from transport simulations and compare them to result from recent full lattice QCD computations.
nucl-thEPJ Web Conf.(2024)·0 citations
06
Doubly heavy tetraquark states in a mass splitting model
Shi-Yuan Li🇨🇳 · Yan-Rui Liu🇨🇳 · Zi-Long Man🇨🇳 · Zong-Guo Si🇨🇳 · Jing Wu🇨🇳
Treating the $X (4140)$ as a compact $J^{P C} = 1^{++}$ $cs c ˉ s ˉ$ state and using its mass as a reference scale, we systematically estimate the masses of doubly heavy tetraquark states $QQ q ˉ q ˉ$ where $Q = c, b$ and $q = u, d, s$ . Their decay properties are studied with a simple rearrangement scheme. Based on our results, the lowest $I (J^{P}) = 0 (1^{+})$ $bb n ˉ n ˉ$ state is a stable tetraquark about 20 MeV below the $B ˉ^{*} B ˉ$ threshold. The mass and width of the low-mass $0 (1^{+})$ $cc n ˉ n ˉ$ ( $n = u, d$ ) tetraquark are compatible with the $T_{cc} (3875)^{+}$ observed by the LHCb Collaboration. The location of the lowest $0 (0^{+})$ and $0 (1^{+})$ $b c n ˉ n ˉ$ states are found to be close to the $B ˉ D$ and $B ˉ^{*} D$ thresholds, respectively. We hope that the predicted ratios between partial widths of different channels may be helpful to identify compact tetraquark states from future measurements.
↳ hep-phhep-exhep-latnucl-thPRD(2024)·16 citations
07
Spin current generation due to differential rotation
Takumi Funato · Shunichiro Kinoshita · Norihiro Tanahashi · Shin Nakamura · Mamoru Matsuo
We study nonequilibrium spin dynamics in differentially rotating systems, deriving an effective Hamiltonian for conduction electrons in the comoving frame. In contrast to conventional spin current generation mechanisms that require vorticity, our theory describes spins and spin currents arising from differentially rotating systems regardless of vorticity. We demonstrate the generation of spin currents in differentially rotating systems, such as liquid metals with Taylor-Couette flow. Our alternative mechanism will be important in the development of nanomechanical spin devices.
↳ cond-mat.mes-hallhep-phhep-thnucl-thPRB(2025)·3 citations
08
In-medium mass shift of two-flavored heavy mesons, $B_{c}$ , $B_{c}^{*}$ , $B_{s}$ , $B_{s}^{*}$ , $D_{s}$ and $D_{s}^{*}$
G. N. Zeminiani🇧🇷 · S. L. P. G. Beres🇧🇷 · K. Tsushima🇧🇷
For the first time, we estimate the in-medium mass shift of the two-flavored heavy mesons $B_{c}, B_{c}^{*}, B_{s}, B_{s}^{*}, D_{s}$ and $D_{s}^{*}$ in symmetric nuclear matter. The estimates are made by evaluating the lowest order one-loop self-energies. The enhanced excitations of intermediate state heavy-light mesons in symmetric nuclear matter are the origin of their negative mass shift. This negative mass shift may be regarded as a signature of partial restoration of chiral symmetry in an empirical sense because the origin of the negative mass shift in the study is not directly related to the chiral symmetry mechanism. Our results show that the magnitude of the mass shift for the $B_{c}$ meson ( $b ˉ c$ or $b c ˉ$ ) is larger than those of the $η_{c} (c ˉ c)$ and $η_{b} (b ˉ b)$ , different from a naive expectation that it would be in between them. While, that of the $B_{c}^{*}$ shows the in between of the $J / ψ$ and $Υ$ . We observe that the lighter vector meson excitation in each meson self-energy gives a dominant contribution for the corresponding meson mass shift, $B_{c}, B_{s},$ and $D_{s}$ .
↳ hep-phhep-exhep-latnucl-ex+1PRD(2024)·8 citations
09
Measurements of $p - Λ$ and $d - Λ$ correlations in 3 GeV Au+Au collisions at STAR
Yu Hu (for the STAR Collaborations)🇺🇸
Heavy-ion collisions provide a unique opportunity to explore nucleon-hyperon (N-Y) interactions through two-particle correlations. The $p - Λ$ and $d - Λ$ correlations shed light on both N-Y two-body and N-N-Y three-body interactions, which is crucial for understanding neutron star properties. We present the high precision measurement of $p - Λ$ and the first measurement of $d - Λ$ correlation with $s_{_{NN}} =$ 3 GeV Au+Au collisions at STAR. Using the Lednicky-Lyuboshitz formalism, we characterized emission source size, the scattering length ( $f_{0}$ ), and the effective range ( $d_{0}$ ) of $p - Λ$ and $d - Λ$ interactions. Using the $f_{0}$ and $d_{0}$ extracted from two spin states in $d - Λ$ correlation, the parameters from the doublet state indicate the hypertriton binding energy is consistent with the current average of world measurements.
↳ nucl-exhep-exhep-phnucl-thEPJ Web Conf.(2024)·10 citations
10
Bulk medium properties of heavy-ion collisions from the beam energy scan with a multistage hydrodynamic model
Lipei Du🇨🇦
We introduce a method to reconstruct full rapidity distributions of charged particle multiplicity and net proton yields, crucial for constraining the longitudinal dynamics of nuclear matter created in the beam energy scan program. Employing rapidity distributions within a multistage hydrodynamic model calibrated for Au+Au collisions at $s_{NN} = 7.7 - 200$ GeV, we estimate the total energy and baryon number deposited into the collision fireball, offering insights into initial dynamics and the identification of nuclear remnants. We explore the potential of rapidity-dependent measurements in probing equations of state at finite chemical potentials. Furthermore, we compare the freeze-out parameters derived from both hydrodynamics and thermal models, highlighting that the parameters extracted via thermal models represent averaged properties across rapidities.
↳ hep-phhep-exnucl-exnucl-thPRC(2024)·17 citations
11
Collision energy dependence of source sizes for primary and secondary pions at NICA energies
Alejandro Ayala🇲🇽 · Santiago Bernal-Langarica🇲🇽 · Isabel Dominguez🇲🇽 · Ivonne Maldonado🇷🇺 · Maria Elena Tejeda-Yeomans🇲🇽
We study the evolution of the two-pion correlation function parameters with collision energy in the context of relativistic heavy-ion collisions within the NICA energy range. To this end, we perform UrQMD simulations in the cascade mode to produce samples of pions from $5 \times 1 0^{6}$ Bi+Bi collisions for each of the studied energies. The effects of the quantum-statistical correlations are introduced using the correlation afterburner code CRAB. We fit the correlation function using Gaussian, exponential and symmetric Lévy shapes and show that for all collision energies the latter provides the best fit. We separate the sample into pions coming from primary processes and pions originating from the decay of long-lived resonances, and show that the source size for the latter is significantly larger than for the former. The source size for the secondaries, is similar but in general larger than the size for the whole pion sample. To further characterize the pion source, we also simulate the effects of a non-ideal detector introducing a momentum smearing parameter, representing the minimum pair momentum and thus a maximum source size that can be resolved. The values of the correlation function intercept parameter are therefore modified from the values they attain for the perfect detector case. Using the core-halo picture of the source, we show that the values of the intercept parameter are influenced by the presence of a significant fraction of core pions coming from the decay of long-lived but slow-moving resonances. These findings serve as a benchmark to compare with future Monte Carlo studies that consider an Equation of State and thus allow for a phase transition within the studied energy domain.
↳ hep-phnucl-thEPJA(2024)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE