We explore the implications of the late-stage hadronic rescattering phase on the flow of $K^{*0}$. The model calculations are done using a $(3+1)$-dimensional hybrid framework, incorporating both hydrodynamic evolution and hadronic transport that is calibrated to agree with bulk observables including the elusive rapidity differential $v_1$ of light-flavor hadrons. We find that the late-stage hadronic rescattering phase causes significant qualitative modification of the $K^{*0}$ rapidity differential directed flow $v_1$ resulting in $\frac{d{v}_1}{dy}\left(K^{*0}\right)-\frac{d{v}_1}{dy}\left(K^{+}\right)$ and $\frac{d{v}_1}{dy}\left(\varphi \right)-\frac{d{v}_1}{dy}\left(K^{+}\right)$ having opposite signs with the effect being more pronounced in central collisions as compared to peripheral ones due to the larger multiplicity as well as longer duration of the hadronic phase. Further, this effect is enhanced in low-energy collisions owing to a stronger breaking of boost invariance. On the contrary, the influence of the hadronic phase on the $K^{*0}$ elliptic flow $v_2$ is found to be less significant and quantitative.

The formation of weakly bound clusters in the hot and dense environment at midrapidity is one of the surprising phenomena observed experimentally in heavy-ion collisions from a low center of mass energy of a few GeV up to an ultrarelativistic energy of several TeV. Three approaches have been advanced to describe the cluster formation: coalescence at kinetic freeze-out, cluster formation during the entire heavy-ion collision by potential interaction between nucleons, and deuteron production by hadronic kinetic reactions. Based on the parton-hadron-quantum molecular dynamics microscopic transport approach, which incorporates all three mechanisms for deuteron production, we identify experimental observables, which can discriminate these production mechanisms for deuterons.

The composition of the inner crust of neutron stars is usually studied using phenomenological interactions such as Skyrme energy-density functionals. But most of these functionals do not agree well with ab initio calculations of very dilute neutron matter. In this work, we study the inner crust of neutron stars in the model of phase coexistence of dense neutron-rich nuclear clusters and dilute neutron gas, and we investigate how employing a realistic microscopic equation of state for the neutron gas alters the composition. Our results indicate that, with a functional that reproduces the correct equation of state of neutron matter at moderate densities, one can obtain a good description of the crust even if the functional does not have the correct behavior at extremely low density.

The recent pioneering campaigns conducted by the Lead Radius Experiment (PREX) and the Calcium Radius Experiment (CREX) Collaborations have uncovered major deficiencies in the theoretical description of some fundamental properties of atomic nuclei. Following a recent refinement to the isovector sector of covariant energy density functionals by Reed et al. [Phys. Rev. C 109, 035803 (2024)], we present here additional improvements to the functional by including both tensor couplings and an isoscalar-isovector mixing term in the scalar sector. Motivated by the distinct surface properties of calcium and lead, we expect that the tensor terms that generate derivative couplings will help break the linear correlation between the neutron skin thickness of these two nuclei. Moreover, the addition of these new terms mitigates most of the problems identified by Reed et al. in describing the properties of both finite nuclei and neutron stars. While significant progress has been made in reconciling the PREX-CREX results without compromising other observables, the final resolution awaits the completion of a proper calibration for this new class of functionals. We expect that powerful reduced basis methods used recently to create efficient emulators will be essential to accomplish this task.

The ${}^{12}\mathrm{C}(\alpha ,\gamma ){}^{16}\mathrm{O}$ reaction substantially influences the abundance ratios of the main isotopes of carbon and oxygen and hence has been regarded as the holy grail in nuclear astrophysics. Its importance lies in the fact that it significantly affects the yield of key elements and that it plays a crucial role in the study of the mass gap of black holes. This reaction's cross section is greatly influenced by the subthreshold state 7.117-MeV $1^{-}$ of ${}^{16}\mathrm{O}$, which is challenging to determine. To study such states the $\alpha$-cluster transfer reaction can be helpful. In this work, the angular distribution of the ${}^{12}\mathrm{C}({}^{11}\mathrm{B},{}^7\mathrm{Li}){}^{16}\mathrm{O}$ reaction was measured, leading to the 7.117-MeV $1^{-}$ state at $E_{{}^{11}\mathrm{B}}\left(\mathrm{lab}\right)=50$ MeV. By using the finite-range distorted-wave Born approximation and coupled-reaction-channel analysis, we obtained the asymptotic normalization coefficient (ANC) to be $(2.54\pm 0.40)\times {10}^{28}$ ${\mathrm{fm}}^{-1}$ and the reduced $\alpha$ width to be $4.92\pm 0.77$ keV at a channel radius of 6.5 fm. Then, by using the $R$-matrix code azure, we calculated the astrophysical $S$ factor of the ${}^{12}\mathrm{C}(\alpha ,\gamma ){}^{16}\mathrm{O}$ reaction and found that the astrophysical $S_{E1}$ (300) factor of the ground-state transitions is $55.3\pm 9.0$ keV b. This value is lower than what was found in previous works, indicating that the $S$ factor is highly sensitive to the ANC.

The interacting boson model with configuration mixing due to two-particle–two-hole excitations is applied to describe even-even ${}^{148-154}\mathrm{Sm}$ to investigate the cross-shell excitation effects in these nuclei. It is shown from the fitting results to the experimentally known positive-parity level energies, $B\left(E2\right)$ values, and electric quadrupole moments that the IBM configuration mixing (CM) describes these nuclei better than the IBM consistent-$Q$ formalism without the configuration mixing. Especially, the IBM-CM fitting results to the known $B\left(E2\right)$ values are significantly improved. Furthermore, it is shown from the IBM-CM fitting results that the intruder configuration turns to be always dominant in the $0_2^{+}, 2_2^{+}$, and $4_2^{+}$ states of well-deformed ${}^{150,152,154}\mathrm{Sm}$. Most notably, there is a clear normal-intruder configuration crossover along the yrast line of these nuclei described by the IBM-CM.

The binding energy of an isotope is a sensitive indicator of the underlying shell structure as it reflects the net energy content of a nucleus. Since magic nuclei are significantly lighter, or more bound, compared to their neighbors, the presence of nucleonic shell structure makes an imprint on nuclear masses. In this work, using a carefully designed binding-energy indicator, we catalog the appearance of spherical and deformed shell and subshell closures throughout the nuclear landscape. After presenting experimental evidence for shell and subshell closures as seen through the lens of nuclear masses, we study the ability of global nuclear mass models to predict local binding-energy variations related to shell effects.

Nuclei around the $N=40$ “island of inversion” exhibit interesting structure features that have been the focus of several experimental and theoretical studies. The present work presents the first complete study of the $\beta$-decay feeding intensity distribution and Gamow-Teller distribution for the $\beta$ decay of ${}^{64}\mathrm{Mn}$ to ${}^{64}\mathrm{Fe}$ up to $\approx 10$ MeV. The $\beta$-decay intensity function was extracted from total absorption spectroscopy measurements made at the National Superconducting Cyclotron Laboratory with the Summing NaI(Tl) (SuN) detector. The experimental results are compared to shell model calculations with and without the inclusion of the $\nu g_{9/2}$ orbital. From this comparison it is clear that the $\nu g_{9/2}$ orbital is essential for the accurate description of the ${}^{64}\mathrm{Fe}\beta$-decay strength above $\approx 3$ MeV, emphasizing once again the transitional nature of this nucleus into the $N=40$ island of inversion.

Within the Transport Model Evaluation Project (TMEP), we present a detailed study of the performance of different transport models in $\text{Sn}+\text{Sn}$ collisions at $270A\mathrm{MeV}$, which are representative reactions used to study the equation of state at suprasaturation densities. We put particular emphasis on the production of pions and $\mathrm{\Delta }$ resonances, which have been used as probes of the nuclear symmetry energy. In this paper, we aim to understand the differences in the results of different codes for a given physics model to estimate the uncertainties of transport model studies in the intermediate energy range. Thus, we prescribe a common and rather simple physics model, and follow in detail the results of four Boltzmann-Uehling-Uhlenbeck (BUU) models and six quantum molecular dynamics (QMD) models. The nucleonic evolution of the collision and the nucleonic observables in these codes do not completely converge, but the differences among the codes can be understood as being due to several reasons: the basic differences between BUU and QMD models in the representation of the phase-space distributions, computational differences in the mean-field evaluation, and differences in the adopted strategies for the Pauli blocking in the collision integrals. For pionic observables, we find that a higher maximum density leads to an enhanced pion yield and a reduced ${\pi }^{-}/{\pi }^{+}$ yield ratio, while a more effective Pauli blocking generally leads to a slightly suppressed pion yield and an enhanced ${\pi }^{-}/{\pi }^{+}$ yield ratio. We specifically investigate the effect of the Coulomb force and find that it increases the total ${\pi }^{-}/{\pi }^{+}$ yield ratio but reduces the ratio at high pion energies, although differences in its implementations do not have a dominating role in the differences among the codes. Taking into account only the results of codes that strictly follow the homework specifications, we find a convergence of the codes in the final charged-pion yield ratio to a $1\sigma$ deviation of about $5\%$. However, the uncertainty is expected to be reduced to about $1.6\%$ if the same or similar strategies and ingredients, i.e., an improved Pauli blocking and calculation of the nonlinear term in the mean-field potential, are similarly used in all codes. As a result of this work, we identify the sensitive aspects of a simulation with respect to pion observables, and suggest optimal procedures in some cases. This work provides benchmark calculations of heavy-ion collisions to be complemented in the future by simulations with more realistic physics models, which include the momentum-dependence of isoscalar and isovector mean-field potentials and pion in-medium effects.

The lifetimes of the first excited ${\frac{7}{2}}^{-}$ states in the $T_z=\pm \frac{3}{2}$ mirror nuclei ${}^{47}\mathrm{Mn}$ and ${}^{47}\mathrm{Ti}$ have been extracted utilizing the $\gamma$-ray line shape method, giving $\tau =687\left(36\right)$ ps and $\tau =331\left(15\right)$ ps respectively. Since these transitions are essentially pure $M1$ transitions, these results allow for a high-precision comparison of analog $M1$ strengths in mirror nuclei. The two analog $B\left(M1\right)\mathrm{s}$ are observed to be identical to a precision of about $10\%$. The expected dependence of the transition matrix element with $T_z$ has been used to extract the separate isoscalar and isovector components of the transition strength, and the results are discussed in the context of predictions, based on the isospin formalism, regarding analog $B\left(M1\right)$ strengths.

Background: A recent inelastic $\alpha$-scattering experiment [P. Adsley et al., Phys. Rev. Lett. 129, 102701 (2022)] found $0^{+}$ resonances in ${}^{24}\mathrm{Mg}$ on and above the ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ break-up threshold. It has been conjectured that the states have a ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ cluster structure, and play a similar role in accelerating ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ fusion to the manner in which the Hoyle state accelerates production of ${}^{12}\mathrm{C}$ in massive stars.

Purpose: We aim to build up a quantitative theoretical basis for the considerations of the Hoyle-state paradigm, by calculating the distribution of the $0^{+}$ states in the shell model, as well as in the relevant cluster models.

Methods: We determine the spectrum of excited $0^{+}$ states in ${}^{24}\mathrm{Mg}$ nucleus using multiconfigurational dynamical symmetry calculations leading to a unified description of the quartet (or shell), ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ and ${}^{20}\mathrm{Ne}+{}^4\mathrm{He}$ cluster configurations.

Results: The density of $0^{+}$ states in the quartet spectrum is comparable to that found in experiment; however, the density of cluster states is considerably less.

Conclusions: The recently observed $\alpha$-scattering resonances do not seem to be simple ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ cluster states, but are more plausibly interpreted as fragmented cluster states due to coupling to quartet excitations, as background states.

Extending from previous research where formation and decay analysis was carried out for even mass nuclei, this investigation includes the fusion-fragmentation analysis of odd mass isotopic compound systems, ${}^{165,167}\mathrm{Tm}^{*}$, formed in reactions induced by ${}^{35,37}\mathrm{Cl}$ projectiles carrying energy spanning the Coulomb barrier region ($E_{\mathrm{c}.\mathrm{m}.}=90$ to 125 MeV), offering valuable insights into the reaction dynamics of these nuclear systems. To analyze the fusion dynamics of ${}^{35,37}\mathrm{Cl}+{}^{130}\mathrm{Te}$ reactions, the energy-dependent Woods-Saxon potential (EDWSP) model is utilized and it introduces alterations in the alterations in the potential barrier characteristics of the fusing nuclei. This results in the reduction of the effective fusion barrier, and accordingly influences the fusion outcomes. In contrast to the one-dimensional barrier penetration model (BPM), the EDWSP calculations yield enhanced fusion cross sections. This augmentation is especially evident in the energy-dependent behavior of cross sections for the selected fusion reactions, both in the near and sub-barrier energy domains. Furthermore, to address the decay of compound nuclei ${}^{165,167}\mathrm{Tm}^{*}$, the evaporation residue (ER) cross sections are meticulously addressed for quadrupole $\left({\beta }_2\right)$ deformed fragments with orientations optimized for hot configurations, using the DCM model. The sub-barrier fusion enhancement in the excitation functions of lighter isotope ${}^{165}\mathrm{Tm}^{*}$ are explored in terms of preformation and penetration profiles. Lastly, comparative studies of odd mass nuclear systems ${}^{165,167}\mathrm{Tm}^{*}$ are carried out with even mass systems generated in Ca and Ni induced reactions.

The ${}^{13}\mathrm{C}+{}^{27}\mathrm{Al}$ reaction ($E_{\text{lab}}=32$ MeV) has been measured, and the elastic scattering, target excitation, and one-neutron transfer channels have been investigated. A comparison of the data with the results of different theoretical frameworks indicates the necessity of including the effect of the spin-orbit interaction of the target to properly reproduce the data. The inclusion of the one-neutron transfer did not significantly affected the elastic angular distribution. The one-neutron transfer reaction could be well reproduced when the psdmod interaction was used to describe the ${}^{27,28}\mathrm{Al}$ nuclei and their associated features. The results reported here are consistent with those previously reported for the ${}^{13}\mathrm{C}+{}^{28}\mathrm{Si}$ reaction measured at similar bombarding energies, providing further evidence of the similarities between these nuclei.

We propose an algorithm to detect minijet clusters in high-energy nuclear collisions, by selecting a high-transverse-momentum ($p_T$) particle as a seed and assigning a clustering radius ($R$) in the pseudorapidity and azimuthal-angle space. Our pythia simulations for $p+p$ collisions show that a scheme with a seeding $p_T$ of around 0.5 GeV/$c$ and $R$ of approximately 0.6 satisfactorily identifies minijet clusters. The correlation between clusters obtained in pythia calculations using the algorithm exhibits the proper behavior of hard-scattering-like processes, suggesting its usefulness in isolating minijet-like clusters from nonhard-scattering soft processes when applied to actual nuclear-collision data, thereby allowing a closer examination of both the minijet and the soft mechanisms.

The production of $K^{*}{\left(892\right)}^{\pm }$ meson resonance is measured at midrapidity ($\left|y\right|<0.5$) in $\mathrm{Pb}\text{−}\mathrm{Pb}$ collisions at $\sqrt{s_{NN}}=5.02$ TeV using the ALICE detector at the CERN Large Hadron Collider. The resonance is reconstructed via its hadronic decay channel $K^{*}{\left(892\right)}^{\pm }\to K_{\mathrm{S}}^0{\pi }^{\pm }$. The transverse momentum distributions are obtained for various centrality intervals in the $p_{\mathrm{T}}$ range of $0.4\text{−}16 \mathrm{GeV}/c$. Measurements of integrated yields, mean transverse momenta, and particle yield ratios are reported and found to be consistent with previous ALICE measurements for $K^{*}{\left(892\right)}^0$ within uncertainties. The $p_{\mathrm{T}}$-integrated yield ratio $2K^{*}{\left(892\right)}^{\pm }/(K^{+}+K^{-}$) in central $\mathrm{Pb}\text{−}\mathrm{Pb}$ collisions shows a significant suppression at a level of $9.3\sigma$ relative to $pp$ collisions. Thermal model calculations result in an overprediction of the particle yield ratio. Although both hadron resonance gas in partial chemical equilibrium (HRG-PCE) and music $+$ smash simulations consider the hadronic phase, only HRG-PCE accurately represents the measurements, whereas music $+$ smash simulations tend to overpredict the particle yield ratio. These observations, along with the kinetic freeze-out temperatures extracted from the yields measured for light-flavored hadrons using the HRG-PCE model, indicate a finite hadronic phase lifetime, which decreases with increasing collision centrality percentile. The $p_{\mathrm{T}}$-differential yield ratios $2K^{*}{\left(892\right)}^{\pm }/(K^{+}+K^{-}$) and $2K^{*}{\left(892\right)}^{\pm }/({\pi }^{+}+{\pi }^{-}$) are presented and compared with measurements in pp collisions at $\sqrt{s}=5.02$ TeV. Both particle ratios are found to be suppressed by up to a factor of five at $p_{\mathrm{T}}<2.0 \mathrm{GeV}/c$ in central $\mathrm{Pb}\text{−}\mathrm{Pb}$ collisions and are qualitatively consistent with expectations for rescattering effects in the hadronic phase. The nuclear modification factor ($R_{\mathrm{AA}}$) shows a smooth evolution with centrality and is found to be below unity at $p_{\mathrm{T}}>8 \mathrm{GeV}/c$, consistent with measurements for other light-flavored hadrons. The smallest values are observed in most central collisions, indicating larger energy loss of partons traversing the dense medium.

An extension to our previous study on nuclear parton distribution functions (nPDFs) [Kim and Miller, Phys. Rev. C 106, 055202 (2022)] using light-front holographic quantum chromodynamics (LFHQCD) [Brodsky, de Teramond, Dosch, and Erlich, Phys. Rep. 584, 1 (2015)] is presented. We apply the effects of nucleon motion inside the nucleus (Fermi motion/smearing) to deuterium, extending our deuterium nPDFs to the superfast, $x>1$, region [Frankfurt and Strikman, Phys. Rep. 160, 235 (1988)] where we estimate our results to be reasonable up to $x\approx 1.7$. We utilize four different deuteron wave functions (AV18, NijmI, NijmII, Nijm93). We find that our model, with no additional new parameters, shows very good agreement with deuterium EMC ratio data obtained from the BONuS experiment [Fenker et al., Nucl. Instrum. Methods Phys. Res. A 592, 273 (2008); Baillie et al. (CLAS Collaboration), Phys. Rev. Lett. 108, 142001 (2012); Phys. Rev. Lett. 108, 199902(E) (2012); Tkachenko et al. (CLAS Collaboration), Phys. Rev. C 89, 045206 (2014); Phys. Rev. C 90, 059901(E) (2014); Griffioen et al., Phys. Rev. C 92, 015211 (2015)]. Looking beyond conventional nuclear physics, and in anticipation of 12 GeV experiments at Jefferson Lab, we use a LFHQCD ansatz to predict the contributions of an exotic six-quark state to the deuteron $F_2$ structure function, $F_2^D$, in the superfast region. We find that the effects of using other potentials are about the same magnitude as six-quark effects—both have small effects in $x<1$, but have significant contributions at $x>1$.

We develop a density-dependent quark mean-field (DDQMF) model to study the properties of nuclear matter and neutron stars, where the coupling strength between $\sigma$ meson and nucleon is generated by the degree of freedom of quarks, while other meson coupling constants are regarded as density-dependent ones. Two values for the nucleon effective mass, $M_{N0}^{*}/M_N=0.556,0.70$ at the saturation density are chosen based on the consideration of the core-collapse supernova simulation and finite nuclei when the meson-nucleon coupling constants are fixed. We find that the equation of state (EOS) of nuclear matter, the symmetry energy, the mass-radius relations, and the tidal deformabilities of neutron stars with larger nucleon effective mass are more sensitive to the skewness coefficient $J_0$. The EOSs with $M_{N0}^{*}/M_N=0.70$ are softer when the skewness coefficient $J_0=-800$ MeV. However, the maximum masses of the neutron star can be around $2.32M_{\odot }$ with $J_0=400$ MeV regardless of the value of the nucleon effective mass. By manipulating the coupling strength of the isovector meson to generate different slopes of symmetry energy, we construct the neutron star EOSs that can satisfy the different variables from the simultaneous mass-radius measurements of PSR $\mathrm{J}0030+0451$, PSR $\mathrm{J}0740+6620$ by the NICER collaboration, the mass-radius relations of HESS J1731-347, and the radius constraints from the gravitational-wave signal GW170817 in the framework of a DDQMF model. At the same time, most of these constructed EOSs can also satisfy the constraints of the tidal deformability from GW170817 event.

An analysis of the slab phase as it is expected in the innermost layer of neutron-star crusts is performed within the Hartree-Fock-Bogoliubov framework. We take the periodicity of the slabs into account using Bloch boundary conditions, in order to well describe the interplay between the band structure and superfluidity. We introduce a relative flow between the slabs and the surrounding neutron gas in a time-independent way. This induces a nontrivial phase of the complex order parameter, leading to a counterflow between neutrons inside and outside the slabs. With the resulting current, we compute the actual neutron superfluid fraction. For the latter our results are slightly larger than previous ones obtained in normal band theory, suggesting that normal band theory overestimates the entrainment effect.