The thermal QCD dilepton production rate is calculated at next-to-leading order in the strong coupling and at finite baryon chemical potential. The two-loop virtual photon self-energy is evaluated using finite temperature field theory and combined consistently with the self-energy in the Landau-Pomeranchuk-Migdal regime. We present new results for a dense baryonic plasma. The rates are then integrated using ($3+1$)-dimensional fluid-dynamical simulations calibrated to reproduce hadronic experimental results obtained at the BNL Relativistic Heavy Ion Collider (RHIC) at energies ranging from those of the Beam Energy Scan to $\sqrt{s_{NN}}=200$ GeV. We elaborate on the ability of dileptons to relay information about the plasma baryonic content and temperature.

The gravitational form factors of light nuclei are evaluated up to momenta of the order of the nucleon mass, using the impulse approximation. The nucleon gravitational form factors are reduced nonrelativistically, and used to derive the gravitational form factors of light nuclei. The deuteron gravitational form factors are analysed using the Reid soft core potential. The helium-4 gravitational form factors are assessed using the $K$-harmonics method, and compared to those following from a mean-field approximation with a Woods-Saxon potential. The importance of removing the center of mass motion for the ensuing form factors is emphasized. The mass radii of these light nuclei are extracted and compared to their charge radii counterparts. The details of their pressure and shear distributions are discussed.

We measure triangular flow relative to the reaction plane at 3 GeV center-of-mass energy in $\text{Au}+\text{Au}$ collisions at the BNL Relativistic Heavy Ion Collider. A significant $v_3$ signal for protons is observed, which increases for higher rapidity, higher transverse momentum, and more peripheral collisions. The triangular flow is essentially rapidity-odd with a slope at midrapidity, $d{v}_3{/dy|}_{(y=0)}$, opposite in sign compared to the slope for directed flow. No significant $v_3$ signal is observed for charged pions and kaons. Comparisons with models suggest that a mean field potential is required to describe these results, and that the triangular shape of the participant nucleons is the result of stopping and nuclear geometry.

An extension of the Barcelona Catania Paris Madrid (BCPM) energy density functional is proposed to deal with odd-mass systems as well as multiquasiparticle excitations. The extension is based on the assumption that the equal filling approximation (EFA) is a valid alternative to the traditional full blocking procedure of the Hartree-Fock-Bogoliubov method. The assumption is supported by the excellent agreement between full blocking and EFA calculations obtained with different parametrizations of the Gogny interaction. The EFA augmented BCPM functional is used to compute low energy excitation spectra of selected nuclei in different regions of the nuclear chart, and high-$K$ isomers in ${}^{178}\mathrm{Hf}$. We show that BCPM predictions are in good agreement with Gogny D1M results and experimental data.

The quantum imaginary time evolution (QITE) algorithm is a direct implementation of the classical imaginary time evolution algorithm on quantum computer. We implement the QITE algorithm for the case of nuclear Hartree-Fock equations in a formalism equivalent to nuclear density functional theory. We demonstrate the algorithm in the case of the helium-4 nucleus with a simplified effective interaction of the Skyrme kind and demonstrate that the QITE, as implemented on simulated quantum computer, gives identical results to the classical algorithm.

The measurement of the direct-photon spectrum from $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV is presented by the PHENIX Collaboration using the external-photon-conversion technique for 0%–93% central collisions in a transverse-momentum ($p_T$) range of 0.8–10 $\text{GeV}/c$. An excess of direct photons, above prompt-photon production from hard-scattering processes, is observed for $p_T<6\text{GeV}/c$. Nonprompt direct photons are measured by subtracting the prompt component, which is estimated as $N_{\mathrm{coll}}$-scaled direct photons from $p+p$ collisions at 200 GeV, from the direct-photon spectrum. Results are obtained for $0.8<p_T<6.0\text{GeV}/c$ and suggest that the spectrum has an increasing inverse slope from $\approx 0.2$ to 0.4 $\text{GeV}/c$ with increasing $p_T$, which indicates a possible sensitivity of the measurement to photons from earlier stages of the evolution of the collision. In addition, like the direct-photon production, the $p_T$-integrated nonprompt direct-photon yields also follow a power-law scaling behavior as a function of collision-system size. The exponent, $\alpha$, for the nonprompt component is found to be consistent with 1.1 with no apparent $p_T$ dependence.

The ultrarelativistic quantum molecular dynamics model is employed to simulate ${\pi }^{-}+\mathrm{C}$ and ${\pi }^{-}+\mathrm{W}$ collisions at $p_{\mathrm{lab}}=1.7$ GeV motivated by the recent HADES results. By comparing the proton and $\mathrm{\Lambda }$ transverse momentum spectra, it was observed that the data and transport model calculation show a good agreement, if cluster formation is included to obtain the free proton spectra. Predictions of light cluster ($d, t, {}^3\mathrm{He}, {}^4\mathrm{He}$, as well as ${}_{\mathrm{\Lambda }}{}^3\mathrm{H}$ and $\mathrm{\Xi }\mathrm{N}$) multiplicities and spectra are made using a coalescence mechanism. The resulting multiplicities suggest that the pion beam experiment can produce a substantial amount of ${}_{\mathrm{\Lambda }}{}^3\mathrm{H}$, especially in ${\pi }^{-}+\mathrm{W}$ collisions due to the stopping of the $\mathrm{\Lambda }$ inside the large tungsten nucleus. The findings are supplemented by a statistical multifragmentation analysis suggesting that even larger hyperfragments are produced copiously. It is suggested that even double strange hypernuclei are in reach and might be studied in more detail using a slightly higher pion beam momentum.

We study the heavy-dense limit of QCD on the lattice with heavy quarks at high density. The effective three-dimensional theory has a sign problem which is alleviated by sign optimization where the path integration domain is deformed in complex space in a way that minimizes the phase oscillations. We simulate the theory via a hybrid Monte Carlo approach, for different volumes, both to leading order and next-to-next-to leading order in the hopping expansion, and show that sign optimization successfully mitigates the sign problem at large enough volumes where usual reweighting methods fail. Finally we show that there is a significant overlap between the complex manifold generated by sign optimization and the Lefschetz thimbles associated with the theory.

In this article, ${\beta }^{-}$ decay studies of neutron-rich isotopes ${}^{43,45}\mathrm{S}$ performed at the National Superconducting Cyclotron Laboratory are reported. $\beta$-delayed $\gamma$ transitions were detected by an array of 16 clover detectors surrounding the Beta Counting Station, which consists of a $40\times 40$ double-sided silicon strip detector followed by a single-sided silicon strip detector. $\beta$-decay half-lives were extracted for ${}^{43,45}\mathrm{S}$ by correlating implants and decays in the pixelated implant detector and by considering further coincidences with $\gamma$ transitions in the daughter nuclei. The level structures of ${}^{43,45}\mathrm{Cl}$ are expanded by the addition of 20 and 8 new $\gamma$ transitions in ${}^{43}\mathrm{Cl}$ and ${}^{45}\mathrm{Cl}$ respectively, and core-excited negative-parity states were observed in both nuclei for the first time. For ${}^{45}\mathrm{S}$, a large fraction of the $\beta$-decay strength was observed feeding neutron-unbound states in ${}^{45}\mathrm{Cl}$, which, decaying by delayed neutrons, populated excited states in the $\beta 1n$ daughter, ${}^{44}\mathrm{Cl}$. Experimental observations were compared to detailed shell-model calculations using the SDPFSDG-MU interaction to highlight the role of the diminished $N=28$ neutron shell gap and the near degeneracy of the proton $s_{1/2}$ and $d_{3/2}$ orbitals in the structure of the neutron-rich Cl isotopes. The current work also provides further support to a ground-state spin-parity assignment of $3/2^{+}$ in ${}^{45}\mathrm{Cl}$.

Based on the variational principle, we discuss self-consistent single-particle (s.p.) potentials at positive energies, which correspond to the real part of the optical potential as the single folding potential (SFP). The nuclear-matter s.p. potential produced by the semi-realistic nucleonic interaction M3Y-P6, which has links to the bare nucleonic interaction, resembles those extracted from the empirical optical potential. Applying M3Y-P6 both to the self-consistent mean-field calculations for the target nucleus and to the SFP for the scattered nucleon, we find that the differential cross sections of the nucleon-nucleus elastic scattering are reproduced almost comparably to the empirical potentials up to $80\mathrm{MeV}$ incident energy. The results demonstrate that the s.p. potential compatible with available experimental data can be derived from a single energy-independent effective interaction in this wide energy range.

The neutronic properties of ${}^{233}\mathrm{Pa}$ play a crucial role in the thorium fuel cycle since it directly impacts the inventory of the fissile isotope ${}^{233}\mathrm{U}$. Currently, the experimental data of the ${}^{233}\mathrm{Pa}(n,\gamma )$ cross section are rather scanty with poor accuracy and significant discrepancy exists in the experimental and evaluated data. In this work, the ${}^{233}\mathrm{Pa}(n,\gamma )$ cross section is studied through the surrogate reaction ${}^{232}\mathrm{Th}({}^3\mathrm{He},p){}^{234}\mathrm{Pa}^{*}$. The spin-parity (SP) distribution of the ${}^{232}\mathrm{Th}({}^3\mathrm{He},p){}^{234}\mathrm{Pa}^{*}$ is calculated with the distorted wave Born approximation and then the ${}^{233}\mathrm{Pa}(n,\gamma )$ cross section is extracted using the statistical Hauser-Feshbach model. It is found that the extracted ${}^{233}\mathrm{Pa}(n,\gamma )$ data considering the SP distribution have a tendency to agree with the evaluated nuclear data files, ENDF/B-VIII.0 and JENDL-5, whereas the experimental ones without considering the SP distribution are visibly higher than the evaluated data. This suggests that the SP distribution should be considered reasonably when employing the surrogate-reaction method to extract the ${}^{233}\mathrm{Pa}(n,\gamma )$ cross section.

We extend the recent study of $K_1/K^{*}$ enhancement as a signature of chiral symmetry restoration in heavy ion collisions at the CERN Large Hadron Collider via the kinetic approach to include the effects due to nonunity hadron fugacities during the evolution of produced hadronic matter and the temperature-dependent $K_1$ mass. Although including nonunity pion and kaon fugacities reduces slightly the $K_1/K^{*}$ enhancement found in previous study due to chiral symmetry restoration, adding temperature-dependent $K_1$ mass leads to a substantial further reduction of the $K_1/K^{*}$ enhancement. However, the final $K_1/K^{*}$ ratio still shows a factor of 2.4 and 1.3 enhancement, respectively, in peripheral and midcentral collisions compared to the case without chiral symmetry restoration, confirming its use as a good signature for chiral symmetry restoration in the hot dense matter produced in relativistic heavy ion collisions.

The region of neutron-rich nuclei surrounding $N=28$ has garnered attention due to experimental and theoretical evidence indicating a diversity of shape and configuration coexistence. In the present Letter, we have performed a comprehensive study for these nuclei utilizing ab initio valence-space in-medium similarity renormalization group calculations with chiral nucleon-nucleon and three-nucleon interactions. First, the band structures of ${}^{41,43}\mathrm{S}$ and ${}^{45}\mathrm{Ar}$ are established via calculated spectra and $E2$ maps. The results well reproduce the $K=1/2$ ground state band and the $K=7/2$ band built upon the $7/2_1^{-}$ isomer in ${}^{43}\mathrm{S}$, which coexists with its $3/2_1^{-}$ ground state. Subsequently, the band structures of neutron-rich $N=27$ and $N=29$ isotones are discussed, with a focus on the potential emergence of configuration coexistence and isomers. We predict the presence of a similar configuration-coexisting $7/2_1^{-}$ isomeric state in ${}^{45}\mathrm{S}$, as an extension from ${}^{43}\mathrm{S}$. Furthermore, our calculations predict that the configuration-coexisting states also occur in the unbound ${}^{39}\mathrm{Mg}$ nucleus. Our ab initio calculations provide crucial insights into the collective structures of neutron-rich nuclei around $N=28$, specifically elucidating the phenomenon of configuration coexistence and isomers.

The triaxial quadrupole collective Hamiltonian, based on relativistic energy density functionals, is extended to include a pairing collective coordinate. In addition to triaxial shape vibrations and rotations, the model describes pairing vibrations and the coupling between triaxial shape and pairing degrees of freedom. The parameters of the collective Hamiltonian are determined by a covariant energy density functional with constraints on the intrinsic triaxial shape and pairing deformations. The effect of coupling between triaxial shape and pairing degrees of freedom is analyzed in a study of low-lying spectra and transition rates of ${}^{128}\mathrm{Xe}$. When compared to results obtained with the standard triaxial quadrupole collective Hamiltonian, the inclusion of dynamical pairing compresses the low-lying spectra and improves interband transitions, in better agreement with data. The effect of zero-point energy correction on low-lying excited spectra is also discussed.

In our current study, we delve into the peak-like structure observed during the reaction process of $K^{+}n\to K^{0}p$ at approximately $\sqrt{s}\approx 2.5$ GeV. Our focus centers on exploring the potential $S=+1$ resonance $P_0^{+*}\equiv P_0^{*}$ as an excited state within the extended vector-meson and baryon ($VB$) antidecuplet. To achieve this aim, we employ the effective Lagrangian method in conjunction with the $(u,t)$-channel Regge approach, operating within the tree-level Born approximation. We thoroughly examine various spin-parity quantum numbers for the resonance, resulting in a compelling description of the data, where $M_{P_0^{*}}\approx 2.5$ GeV and ${\mathrm{\Gamma }}_{P_0^{*}}\approx 100$ MeV. Furthermore, we propose an experimental technique to amplify the signal-to-noise ratio ($S/N$) for accurately measuring the resonance. Notably, our findings reveal that background interference diminishes significantly within the $K^{*}$ forward-scattering region in the center-of-mass frame when the $K^{*}$ is perpendicularly polarized to the reaction plane. Additionally, we explore the recoil-proton spin asymmetry to definitively determine the spin and parity of the resonance. This study stands to serve as a valuable reference for designing experimental setups aimed at investigating and comprehending exotic phenomena in quantum chromodynamics. Specifically, our insights will inform future J-PARC experiments, particularly those employing higher kaon beam energies.

The ${}^{22}\mathrm{Ne}(p,\gamma ){}^{23}\mathrm{Na}$ capture reaction is a key step in the Ne-Na cycle of hydrogen burning. The rate of this reaction is critical in classical novae nucleosynthesis and hot bottom burning (HBB) processes in asymptotic giant branch (AGB) stars. Despite its astrophysical importance, significant uncertainty remains in the reaction rate due to several narrow low-energy resonances lying within and near the Gamow window. The present work revisits this reaction by examining the contribution of the 8664 keV subthreshold state and the 8945 keV doublet resonance state of $7/2^{-}$ configuration in ${}^{23}\mathrm{Na}$. Finite range distorted-wave Born approximation (FRDWBA) analysis of existing ${}^{22}\mathrm{Ne}({}^3\mathrm{He},d){}^{23}\mathrm{Na}$ transfer reaction data was carried out to extract the peripheral asymptotic normalization coefficients (ANCs) of the 8664 keV state. The ANC value obtained in the present work is $\approx 25\%$ higher compared to the previous work by Santra et al. [Phys. Rev. C 101, 025802 (2020)]. Systematic $R$-matrix calculations were performed to obtain the nonresonant astrophysical $S$ factor utilizing the enhanced ANC value. The resonance strengths of the 8945 keV doublets were deduced from shell model calculations. The rate calculations are performed by omitting the resonances at $E_x=8862$, 8894, and 9000 keV, which are unlikely to exist as reported by Carrasco-Rojas et al. [Phys. Rev. C 108, 045802 (2023)]. The total reaction rate is found to be $\approx 15–20\%$ higher at temperatures relevant for the HBB processes, compared to the recent rate measured by Williams et al. [Phys. Rev. C 102, 035801 (2020)], and matches their rate at temperatures of interest for classical novae nucleosynthesis.

Heavy-ion collisions at near-barrier energies provide a crucial pathway for investigating nucleon correlations and clustering structures. Recent experimental results showed that the valence neutrons in light projectiles obviously enhance the $\alpha$ transfer. This finding is extremely puzzling and fascinating, because it violates the ground-state $Q$ value systematics unexpectedly. In this work, the time-dependent Hartree-Fock approach is utilized to investigate the cluster transfer. By comparing the reactions ${}^{12,14}\mathrm{C}+{}^{209}\mathrm{Bi}$, we discover that above puzzling behavior is because of the strong correlation between isospin diffusion and clustering. Our calculations clearly show that the equilibrium of neutron-to-proton ratio strongly inhibits the clustering. This work opens a prospect for investigating the clustering in an open quantum system.

Two complementary real-photon scattering experiments were conducted on the proton-magic ${}^{64}\mathrm{Ni}$ nucleus to study the dipole response up to its neutron-separation energy of $S_n=9.7\mathrm{MeV}$. By combining both measurements, 87 $E1$ and 23 $M1$ transitions were identified above 4.3 MeV. The results of the observed $M1$ transitions were compared to shell-model calculations using two different model spaces. It was found that the inclusion of excitations across the $Z=28$ shell gap in the calculations has a large impact. Furthermore, average cross sections for decays to the ground state (elastic transitions) as well as to lower-lying excited states (inelastic decays) were determined. The corresponding $E1$ channel was compared to calculations within the relativistic equation of motion (REOM) framework. Whereas the calculations of highest possible complexity reproduce the fragmentation and overall behavior of the $E1$ average elastic cross section well, the predicted absolute cross sections are approximately twice as high as the experimental upper limits even though the latter also include an estimate of the inelastic-decay channel.

The fusion mechanism of reactions involving even-even ${}^{112–124}\mathrm{Sn}$, doubly magic ${}^{132}\mathrm{Sn}, {}^{208}\mathrm{Pb}$ as targets, and ${}^{64}\mathrm{Ni}$ as the projectile is explored within the relativistic mean field (RMF) formalism. The main aim of choosing these nuclei is to explore the correlation between the nuclear incompressibility and the fusion cross section. The nucleus-nucleus interaction potential is calculated by folding the axially deformed nuclear densities and the relativistic R3Y nucleon-nucleon ($NN$) potential obtained for the nonlinear ${\mathrm{NL}3}^{*}$, hybrid, and NL1 parameter sets, which yield different values for various characteristics of nuclear matter at saturation. The fusion barrier characteristics obtained for different RMF parametrizations are further used to calculate the cross section within the $\ell$-summed Wong model. We found a decrease in the barrier height and, consequently, an increase in the cross section with a decrease in the incompressibility for all sets of parameters considered. Furthermore, comparing the barrier heights obtained for ${\mathrm{NL}3}^{*}$ and the hybrid parameters, it is observed that the barrier height decreases with decreasing symmetric energy and incompressibility value. Moreover, a lower barrier height and, consequently, a higher cross section at below-barrier energies is observed for the NL1 parameter set, which gives a soft equation of state (EoS) having a lower value of nuclear matter incompressibility. The calculated cross section is satisfactorily consistent with the available experimental data for ${}^{64}\mathrm{Ni}+{}^{208}\mathrm{Pb}$ system. In contrast, the nuclear potentials obtained for ${\mathrm{NL}3}^{*}$ and hybrid parameter sets underestimate the cross section at below-barrier energies for ${}^{64}\mathrm{Ni}+{}^{112–124,132}\mathrm{Sn}$ reactions. This discrepancy between the experimental data and the theoretical results for ${}^{64}\mathrm{Ni}+{}^{112–124,132}\mathrm{Sn}$ reactions can be correlated with the soft behavior of the Sn isotopes. The compressible nature of Sn isotopes is inferred to lower the barrier height, which further leads to enhancement of the experimental fusion and/or capture cross section at below-barrier energies. Thus, the NL1 parameter set with a comparatively soft EoS is observed to be a better choice to describe the sub-barrier nuclear fusion dynamics of reactions involving the Sn isotopes.