arXiv subjects

Asanosuke Jinno

Publications and source records attributed to Asanosuke Jinno.

13 recordsLinked to original sources

arXiv2026

Covariant formulation of relativistic quantum molecular dynamics for a system of interacting wave packets

We present a new formulation for the mean-field propagation part of relativistic quantum molecular dynamics, simulating an $N$-body system of interacting Gaussian wave packets via Lorentz scalar and vector potentials. Covariant equations of motion are derived based on the principle of least action with a weak form of mass-shell conditions and time-fixation constraints defined with respect to a chosen foliation. However, as is common with traditional relativistic quantum molecular dynamics, the dynamics exhibits a residual dependence on the chosen foliation, which is unavoidable because a finite number of interacting degrees of freedom is not strictly compatible with relativity. Nevertheless, we show that this dependence remains small for physically reasonable choices of the foliation in practical applications. By introducing a new approximation method to the spatial integral in the equations of motion, these covariant equations of motion can be solved with a computational cost comparable to that of conventional noncovariant quantum molecular dynamics. Furthermore, the new equations of motion accurately estimate the density-dependent potential, as demonstrated through comparison of the forces with the numerical integration. We apply them to $N$-body systems interacting via the Skyrme-type potentials or the relativistic mean field to simulate heavy-ion collisions. Our results show that the derived equations of motion provide a robust approximation to the dynamics of the full numerical integrations.

hep-ph↗

arXiv2026

Theoretical study of the $Ξα$ correlation function

We study $Ξ$-$^4{\mathrm{He}}$ ($α$) momentum correlation functions in the high-energy nuclear collisions to investigate the nature of the $ΞN$ interactions. We employ the folding $Ξα$ potential based on the lattice QCD $ΞN$ interactions to compute the correlation function. The $Ξα$ potential supports a Coulomb-assisted bound state ${}^5_Ξ\mathrm{H}$ in the $Ξ^-α$ channel, while the $Ξ^0α$ channel is unbound. To examine the sensitivity of the correlation function to the nature of the $Ξα$ interaction, we vary the potential strength simulating stronger and weaker interactions. The result of the correlation function is sensitive to the existence of the bound state in the $Ξ^0 α$ channel, and the characteristic behavior of the bound state remains also in the $Ξ^-α$ correlation with the Coulomb interaction. The effect of the repulsive core of the $Ξα$ potential can be found in the correlation from the small source as the distinctive dip in the intermediate momentum region.

nucl-th↗

arXiv2026

Hyperon single-particle potentials in nuclear matter based on baryon-baryon interactions derived within chiral effective field theory

An analysis of the Lambda and Sigma single-particle potentials is presented, based on YN interactions derived within chiral effective field theory up to next-to-next-to-leading order (N$^2$LO). The self-consistent Brueckner-Hartree-Fock framework is employed within the continuous choice for the single-particle potential. The result for the Lambda single-particle potential is comparable to the ones obtained with previous chiral YN interactions up to next-to-leading order (NLO). The Sigma single-particle potential is found weakly attractive, in contrast to earlier weakly repulsive results, reflecting new constraints from the recent J-PARC E40 data on $Σ^+p$ scattering. An estimate of the theoretical uncertainty of the single-particle potentials is provided.

nucl-th↗

arXiv2025

Properties of hyperons in nuclear matter from chiral hyperon-nucleon interactions at next-to-next-to-leading order

The $Λ$ and $Σ$ single-particle potentials in infinite nuclear matter are analyzed within a recently established chiral hyperon-nucleon ($YN$) interaction up to N$^2$LO in combination with an nucleon-nucleon interaction derived in the same scheme. The self-consistent Brueckner-Hartree-Fock method with the continuous choice of the single-particle potential is employed. It is found that the $Λ$ single-particle potential is comparable to the results achieved with the NLO $YN$ interaction from 2019. The resulting $Σ$ potential becomes more attractive compared to the previous NLO results due to the constraint from the recent $ΣN$ differential cross section data measured in the J-PARC E40 experiment. An estimate of the theoretical uncertainty of the single-particle potentials is provided in terms of the truncation error in the chiral expansion.

nucl-th↗

arXiv2025

$Λ$ and $Σ$ potentials in dense matter based on chiral EFT: Bridging heavy-ion collisions, hypernuclei, and neutron stars

The $Λ$ and $Σ$ directed flows at $\sqrt{s_{NN}}=4.5~\mathrm{GeV}$ are investigated to examine their sensitivity to the hyperon single-particle potentials. The single-particle potentials are obtained from $G$-matrix calculations with two- and three-body forces based on SU(3) chiral effective field theory. The $Λ+Σ^0$ directed flow shows sensitivity to the variation in the $Σ$ single-particle potential. Its effect is more pronounced for the $Σ^0$ directed flow.

nucl-th↗

arXiv2025

Optimal collision-energy range for realizing macroscopic high-baryon-density matter

We investigate the volume and lifetime of the high baryon-density matter created in heavy-ion collisions and estimate the optimal collision-energy range to realize the high baryon-density region over a large spacetime volume. We simulate central collisions of gold ions for the center-of-mass energy per nucleon pair $\sqrt{s_{NN}}=2.4 - 19.6\;{\rm GeV}$ with a microscopic transport model JAM. We discover that the optimal range is around $\sqrt{s_{NN}}=3 - 5\;{\rm GeV}$, where a baryon density exceeding three times the normal nuclear density is realized with a substantially large spacetime volume. Higher and lower energies are disfavored due to short lifetime and low density, respectively. We also point out that event-by-event fluctuations of the spacetime density profile are large, indicating the importance of the event selection in the experimental analysis.

hep-ph↗

arXiv2025

$Λ$ and $Σ$ potentials in neutron stars, hypernuclei, and heavy-ion collisions

With an appropriate $YNN$ force, the $Λ$ single-particle potential ($Λ$ potential) can be made strongly repulsive at high density, and one can solve the hyperon puzzle of neutron stars. We investigate the consistency of such a $Λ$ potential, evaluated recently from $YN$ and $YNN$ forces based on chiral effective field theory, with hypernuclear data and heavy-ion collision data. It is found that model calculations with such a $Λ$ potential can reproduce the data of the $Λ$ hypernuclear spectroscopy and the $Λ$ directed flow in heavy-ion collisions. Also, we evaluate the $Σ$ potential, which can be calculated by using the same hyperon forces as for the $Λ$ potential. Specifically, we show that the low-energy constants characterizing the strength of the $YNN$ force can be chosen to suppress the appearance of the $Λ$'s in neutron stars while at the same time the empirical value of the $Σ$ potential is reproduced.

nucl-th↗

arXiv2024

Theoretical study on $Λα$ and $Ξα$ correlation functions

We examine the $Λ$-${}^4\mathrm{He}$ ($α$) and $Ξα$ momentum correlation in high-energy collisions to further elucidate the properties of the hyperon-nucleon interactions. For the $Λα$ system, we compare $Λα$ potential models with different strengths at short range. We find that the difference among the models is visible in the momentum correlation from a small-size source. This indicates that the $Λα$ momentum correlation can constrain the property of the $ΛN$ interaction at short range, which plays an essential role in dense nuclear matter. For the $Ξα$ system, we employ the folding $Ξα$ potential based on the lattice QCD $ΞN$ interactions. The $Ξα$ potential supports a Coulomb assisted bound state of ${}^5_Ξ\mathrm{H}$ in the $Ξ^-α$ channel, while the $Ξ^0α$ channel is unbound. To examine the sensitivity of the correlation function to the nature of the $Ξα$ potential, we vary the potential strength simulating stronger and weaker interactions. The result of the correlation function clearly reflects the bound state nature in the $Ξ^-α$ correlation.

nucl-th↗

arXiv2024

Femtoscopic study of the $Λα$ interaction

We examine the $Λ$-${}^4\mathrm{He}$ ($α$) momentum correlation in high-energy collisions to elucidate the interaction between Lambdas ($Λ$) and nucleons ($N$). We compare phenomenological $Λα$ potentials with different strengths at short range. In addition to the conventional Gaussian-type potentials, we construct the $Λα$ potentials by substituting the nucleon density distribution in $α$ into the Skyrme-type $Λ$ potentials. We find that the dependence on the employed potential models is visible in the correlation functions from a small-size source. This indicates that the $Λα$ momentum correlation could constrain the property of the $ΛN$ interaction at high densities, which is expected to play an essential role in dense nuclear matter. Also, we verify that the Lednicky-Lyuboshits formula can yield erroneous results for a small-size source with a potential which has a large interaction range, like the $Λα$ system.

nucl-th↗

arXiv2023

Repulsive $Λ$ potentials in dense neutron star matter and binding energy of $Λ$ in hypernuclei

The repulsive three-body force between the lambda ($Λ$) hyperon and medium nucleons is a key element in solving the hyperon puzzle in neutron stars. We investigate the binding energies of $Λ$ hyperon in hypernuclei to verify the repulsive $Λ$ potentials from the chiral effective field theory ($χ$EFT) employing the Skyrme Hartree-Fock method. We find that the $χ$EFT $Λ$ potential with the $ΛNN$ three-body forces reproduces the existing hypernuclear binding energy data, whereas the $Λ$ binding energies are overestimated without the $ΛNN$ three-body force. Additionally, we search for the parameter space of the $Λ$ potentials by varying the Taylor coefficients of the $Λ$ potential and the effective mass of $Λ$ at the saturation density. Our analysis demonstrates that the parameter region consistent with the $Λ$ binding energy data spans a wide range of the parameter space, including even more repulsive potentials than the $χ$EFT prediction. We confirm that these strong repulsive $Λ$ potentials suppress the presence of $Λ$ in the neutron star matter. We found that the $Λ$ potentials repulsive at high densities are favored when the depth of the $Λ$ potential at the saturation density, $U_Λ(ρ_0)=J_Λ$, is $J_Λ\gtrsim-29~\text{MeV}$, while attractive ones are favored when $J_Λ\lesssim -31~\text{MeV}$. This suggests that the future high-resolution data of hypernuclei could rule out the scenario in which $Λ$s appear through the precise determination of $J_Λ$ within the accuracy of $1~\text{MeV}$.

nucl-th↗

arXiv2023

A Poincaré covariant cascade method for high-energy nuclear collisions

We present a Poincaré covariant cascade algorithm based on the constrained Hamiltonian dynamics in an $8N$-dimensional phase space to simulate the Boltzmann-type two-body collision term. We compare this covariant cascade algorithm with traditional $6N$-dimensional phase-space cascade algorithms. To validate the covariant cascade algorithm, we perform box calculations. We examine the frame dependence of the algorithm in a one-dimensionally expanding system as well as the compression stages of colliding two nuclei. We confirm that our covariant cascade method is reliable to simulate high-energy nuclear collisions. Furthermore, we present Lorentz-covariant equations of motion for the $N$-body system interacting via potentials, which can be efficiently solved numerically.

nucl-th↗

arXiv2022

Directed flow of $Λ$ from heavy-ion collisions and hyperon puzzle of neutron stars

We examine the $Λ$ potential from the chiral effective field theory ($χ$EFT) via the $Λ$ directed flow from heavy-ion collisions. We implement the $Λ$ potential obtained from the $χ$EFT in a vector potential version of relativistic quantum molecular dynamics. We find that the $Λ$ potentials obtained from the $χ$EFT assuming weak momentum dependence reproduce the $Λ$ directed flow measured by the STAR collaboration in the Beam Energy Scan program. While the $Λ$ directed flow is not very sensitive to the density dependence of the potential, the directed flow at large rapidities is susceptible to the momentum dependence. Thus understanding the directed flow of hyperons in a wide range of beam energy and rapidity is helpful in understanding hyperon potentials in dense matter.

nucl-th↗

arXiv2022

Directed flow of $Λ$ in high-energy heavy-ion collisions and $Λ$ potential in dense nuclear matter

We investigate the sensitivity of the $Λ$ directed flow to the $Λ$ potential in mid-central Au + Au collisions at $\sqrt{s_{NN}}\approx3.0$--$30$ GeV. The $Λ$ potential obtained from the chiral effective field theory ($χ$EFT) is used in a microscopic transport model, a vector version of relativistic quantum molecular dynamics (RQMDv). We find that the density-dependent $Λ$ potentials, obtained from the $χ$EFT assuming weak momentum dependence of the potential, reproduce the rapidity and the beam-energy dependence of the $Λ$ directed flow measured by the STAR collaboration in the Beam Energy Scan program. Although the $Λ$ directed flow is insensitive to the density dependence of the potential, it is susceptible to the momentum dependence. We also show that a hydrodynamics picture based on the blast-wave model predicts a similarity of the proton, $Λ$, and $Ξ$ directed flows, but the directed flow of $Ω$ baryons slightly deviates from other baryons. We also show that the quark coalescence predicts different rapidity dependence of the directed flows for hyperons. These investigations suggest that measurements of a wide range of the rapidity dependence of the directed flow of hyperons may provide important information about the properties of hot and dense matter created in high-energy heavy-ion collisions.

nucl-th↗