We employ an equal-velocity quark combination model to study anisotropic flows $v_2, v_3$, and $v_4$ of identified hadrons at midrapidity in heavy-ion collisions at Relativistic Heavy Ion Collider energies. Under the equal-velocity combination mechanism of constituent quarks at hadronization, we build analytical formulas of anisotropic flows of hadrons in terms of those of quarks just before hadronization. We systematically analyze the contribution of higher-order flows of quarks, and show how simple formulas of $v_2, v_3$, and $v_4$ of identified hadrons with the desired precision can be obtained by neglecting the small contribution of higher-order flows of quarks. We systematically test these simple formulas of hadronic flows by the experimental data of $v_2, v_3$, and $v_4$ of identified hadrons $\varphi , \mathrm{\Lambda }, {\mathrm{\Xi }}^{-}, {\mathrm{\Omega }}^{-}, \overline{\mathrm{\Lambda }}, {\overline{\mathrm{\Xi }}}^{+}, {\overline{\mathrm{\Omega }}}^{+}, p$, and $\overline{p}$ in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=19.6$, 54.4, and 200 GeV, and we find that the equal-velocity quark combination model can well describe the measured $v_2, v_3$, and $v_4$ of identified hadrons in $\mathrm{Au}+\mathrm{Au}$ collisions at those collision energies. We further study the obtained anisotropic flows of quarks and find two scaling properties which can be qualitatively understood by the hydrodynamic evolution of the thermal quark medium produced in relativistic heavy-ion collisions.

Conditions are found under which, in nuclear matter, there may appear a spatially nonuniform $p$ wave ${\pi }^0$ condensate supplemented by a spatially varying spontaneous magnetization. The pion-nucleon interaction and the anomaly contributions to magnetization are taken into account. The response of the system to an external magnetic field is also considered, then the model of nonoverlapped nucleon Fermi spheres is employed. Arguments are given in favor of the possibility of the occurrence of ${\pi }^0$ condensation and a spatially varying magnetization, as well as effects of pronounced anisotropic pion fluctuations at finite pion momentum in peripheral heavy-ion collisions. Relevant effects such as the response to the rotation, charged pion condensation, and others are discussed.

$\beta$-decay properties play an important role in most astrophysical processes. In the absence of experimental data, astrophysical models rely on global theoretical calculations to provide the relevant properties. It is therefore important to provide strong experimental constraints when possible. In the case of $\beta$-decay, the most sensitive probe is the $\beta$-decay strength distribution. We report here on the first measurement of the latter quantity for the ${\beta }^{+}$ decay of ${}^{60}\mathrm{Ga}$ using the total absorption spectroscopy technique. The experimental results are compared to theoretical calculations often used in astrophysical models, namely the shell model and the quasiparticle random phase approximation (QRPA), as well as an extension of QRPA that includes higher-order nucleonic calculations. Both models are in reasonable agreement with the experimental results.

We probe the superfluid-superconductor dynamics of the rotating outer core of neutron stars through half-vortex states. By means of a generalized hydrodynamic model, where proton and neutron fluids are coupled by both dynamic entrainment and Skyrme SLy4 nucleon-nucleon interactions, we analyze single flux tubes in the proton-superconductor component of the system that thread proton vortices located faraway from neutron vortices. It is shown how they give rise to hydrodynamic perturbations in the coexisting neutron superfluid, and its structure remains unaltered for varying rotation rates and magnetic fields within ranges of observational values.

The process of $\beta$-delayed fission ($\beta \mathrm{DF}$) of ${}^{230,232}\mathrm{Fr}$ and ${}^{230,232,234}\mathrm{Ac}$ was studied in an experiment performed at the ISOLDE facility at CERN. As no fission fragments were observed for any of the nuclei investigated, upper limits for their $\beta \mathrm{DF}$ probability ($P_{\beta \text{DF}}$) were determined. The experimental results were compared with theoretical calculations that were first benchmarked on ${}^{178,180}\mathrm{Tl}{P}_{\beta \text{DF}}$ experimental values. The $P_{\beta \text{DF}}$ values were calculated using the code TALYS to which $\beta$-strength functions obtained from the D1M Gogny parametrization and from the Skyrme functional SKO' were given as input together with fission paths obtained with BSkG3 and BSk14 models. Sensitivity studies of different $\beta$-strength functions, and fission paths scaling on the $P_{\beta \text{DF}}$ values were conducted, suggesting a stronger dependence of the $P_{\beta \text{DF}}$ on the fission paths rather than on the $\beta$-strength function used.

Positive parity band structures in ${}^{82}\mathrm{Kr}$ were investigated using the reaction ${}^{76}\mathrm{Ge}$(${}^9\mathrm{Be},3n$) at $E_{\text{Lab}} \approx$ 31 MeV with the help of the Indian National Gamma Array. The predominant $E2$ component of the $\mathrm{\Delta }I=1$ band interlinking transitions and the decreasing nature of wobbling energy with spin were observed for the bands TW1 and TW2, reflecting their transverse wobbling character. The absolute $B$($E2$) transition strengths of the zeroth and first phonon wobbling bands as well as the signature partner band were extracted from the lifetime measurements. The extracted $B$($E2$) values in comparison with the triaxial projected shell model calculations confirm similar deformation for the three bands, which is an important characteristic of wobbling modes. This is conclusive evidence of transverse wobbling motion in an even-even nucleus based on a two-neutron configuration and also an observation of wobbling motion in the $A\approx$ 80 mass region.

This study investigates resonance states in ${}^{16}\mathrm{O}$, specifically the $E1$ giant resonance and isoscalar/isovector quadrupole resonances, using the Jost-RPA method. By applying the Mittag-Leffler theorem, we decompose the random phase approximation (RPA) response function to analyze the individual contributions from poles corresponding to collective excitation modes. This decomposition clarifies the role of each pole in shaping the strength function, providing insights into the nature and classification of resonance states essential for understanding collective nuclear excitations. Our analysis identifies the dominant pole contributions to the observed resonance structures, offering a novel approach for exploring collective excitation phenomena in nuclei with complex many-body correlations.

We present a data-driven analysis of dipole strength functions across the nuclear chart, employing an artificial neural network to model nuclear dipole responses. We train the network on a dataset of experimentally measured dipole strength functions for 216 different nuclei. To assess its predictive capability, we test the trained model on an additional set of 10 new nuclei, where experimental data exist. We demonstrate that the artificial neural network not only accurately reproduces known data but also identifies potential inconsistencies in experimental datasets, indicating which results may warrant further review or possible rejection. For nuclei where experimental data are sparse or unavailable, the network confirms theoretical calculations, reinforcing its utility as a predictive tool in nuclear physics. Finally, utilizing the predicted electric dipole polarizability, we extract the value of the symmetry energy at saturation density and find it consistent with results from the literature.

Nuclear mass can offer profound insights into many physical branches, e.g., nuclear physics and astrophysics, while the predicted accuracy by nuclear mass models is usually far from satisfactory until now, especially within the fully microscopic self-consistent mean-field theory. In this project, we present the predictive power for the binding energy within the Hartree-Fock-Bogoliubov (HFB) methods with six widely used Skyrme forces (SkM*, SkP, SLy4, SV-min, UNEDF0, and UNEDF1) and evaluate the refined performance of the machine learning based on a novel categorical boosting (CatBoost) algorithm to the Skyrme HFB mass models. The root-mean-square (rms) deviations between the bare HFB calculations with different Skyrme forces and the available experimental data range from the minimum, about 1.43 MeV, for the UNEDF0 parameter set to the maximum, about 7.03 MeV, for the SkM* paraterer set. For the CatBoost-refined HFB predictions, the predictive power can be significantly improved. All the prediction accurancies on the testing set can reach the level around 0.2 MeV and, meanwhile, the large model bias can be reduced. The model-repair coefficients for the adopted Skyrme parameter sets are uniformly more than 80%. Moreover, for 21 newly measured nuclei outside AME2020, the predicted masses by the CatBoost-refined HFB models are also in good agreement with the experimental data, illustrating their good generalization abilities. Intrestingly, it is found that the optimal Skyrme parameter set that possesses the highest predictive power for the bare HFB mass calculations may be not the best candidate for the CatBoost-refined HFB model, indicating the different abilities of picking up the missing physics for several Skyrme forces by the CatBoost algorithm.

We consider a problem borrowed from heavy-ion collisions, namely, the formation of bound states, as for example the deuteron, in the nonrelativistic regime by using the techniques of Lindblad dynamics considering an open quantum system. We show that the position-space Lindblad equation can be reformulated in terms of a diffusion-advection equation with sources and therefore provides a hydrodynamical formulation of a dissipative quantum master equation. Making use of this advanced machinery and these insights, we describe the possible formation of a bound state, which is realized by a Pöschl-Teller-like potential, of a particle in interaction with a heat bath in a one-dimensional setting and discuss general aspects of open quantum systems, such as decoherence, entropy production, purity, thermalization time, and thermalization. Finally, we also show an example of a much deeper potential, where we allow for three bound states, just in the spirit of quarkonia.

Removal or addition of just a few particles for closed-shell nuclei may lead to dramatic shape changes. Recent experiments have reported several notable observations beyond $Z=82$. Remarkably, the fascinating phenomena, such as prompt onset in deformation in Po isotopes and large odd-even shape staggering in Bi isotopes, all happen in the neutron midshell. A theoretical understanding of all these data in a unified fashion is still missing. Here, we apply the PMMU shell model based on the Hartree-Fock-Bogoliubov plus generator coordinate method in a large model space of $(1h_{11/2},1h_{9/2},2f_{7/2},1i_{13/2},3p_{3/2},2f_{5/2},3p_{1/2},2g_{9/2})$. On the basis of good reproduction of the data, we suggest that the physical origin to drive these phenomena is the cooperative effect of the isoscalar monopole interaction between $1h_{9/2}$ and $1i_{13/2}$ and two quasi-SU(3) quadrupole interactions in the proton $(1h_{11/2},$ $2f_{7/2})$ and in the neutron $(1i_{13/2},$ $2g_{9/2})$ orbits.

High-resolution collinear laser spectroscopy of neutron-rich actinium has been performed at TRIUMF's isotope separator and accelerator facility ISAC. By probing the $7s^2{}^{1}S_0\to 6d7p{}^{1}P_1$ ionic transition, the hyperfine structures and optical isotope shifts in ${}^{225,226,228,229}\mathrm{Ac}^{+}$ have been measured. This allows precise determinations of the changes in mean-square charge radii, magnetic dipole moments, and electric quadrupole moments of these actinium isotopes. The improved precision of charge radii and magnetic moments clears the ambiguity in the odd-even staggering from previous studies. The electric quadrupole moments of ${}^{225,226,228,229}\mathrm{Ac}$ are determined for the first time.

The chirality in Xe isotopes is investigated by using the constrained triaxial covariant density functional theory (CDFT) and quantum particle rotor model (PRM) calculations. The CDFT results show that the $\pi g_{9/2}^{-1}\otimes \pi h_{11/2}^1$ configurations with high-$j$ particle-hole character exhibit significant triaxial deformations in ${}^{116,118,120,122,124,126}\mathrm{Xe}$, making them suitable for establishing chirality. In ${}^{118}\mathrm{Xe}$ and ${}^{120}\mathrm{Xe}$, the available experimental energy spectra and the electromagnetic transition probabilities with the $\pi g_{9/2}^{-1}\otimes \pi h_{11/2}^1$ configuration are described well by PRM calculations. A systematic comparison with the chiral doublet bands based on the $\pi g_{9/2}^{-1}\otimes \nu h_{11/2}^1$ configuration is also discussed. The present work proposes a new chiral system formed by the coupling of two high-$j$ valence protons, contributing to the exploration of the key scientific question regarding the universality of nuclear chirality.

The study aims to explore the mechanism of heavy-ion fusion using various effective nucleon-nucleon (NN) interactions and nuclear density distributions. The nuclear potentials are obtained by folding the relativistic effective NN interaction (R3Y) potential with the densities derived from the relativistic mean-field (RMF) approach. Here, we have considered the RMF formalism with a nonlinear ${\mathrm{NL}3}^{*}$ parameter set and the relativistic-Hartree-Bogoliubov (RHB) approach with the DDME2 parameter set to obtain the medium-independent R3Y and density-dependent R3Y (DDR3Y) NN potentials, respectively. The results of these relativistic effective NN interactions are compared with the well-known Reid and Paris M3Y NN interactions and their density-dependent versions. Nuclear potentials are also used to calculate the fusion barrier characteristics and cross-section within the $\ell$-summed Wong model for ${}^{16}\mathrm{O}+{}^{144}\mathrm{Sm}$, ${}^{48}\mathrm{Ca}+{}^{208}\mathrm{Pb}$, ${}^{16}\mathrm{O}+{}^{154}\mathrm{Sm}$, and ${}^{48}\mathrm{Ca}+{}^{238}\mathrm{U}$ reactions. The relativistic R3Y and DDR3Y NN potentials are noted to provide a higher cross section than both the Reid and Paris versions of the nonrelativistic M3Y (Michigan 3 Yukawa) NN potentials. Moreover, the inclusion of in-medium effects in both relativistic and nonrelativistic effective NN interactions is noted to provide relatively repulsive nuclear potentials, which lead to higher fusion barriers and hindered cross sections. The impact of nuclear shape degrees of freedom in terms of nuclear deformation is also included in the description of nuclear fusion for ${}^{16}\mathrm{O}+{}^{154}\mathrm{Sm}$ and ${}^{48}\mathrm{Ca}+{}^{238}\mathrm{U}$ reactions involving deformed target nuclei. Furthermore, the results of RMF-${\mathrm{NL}3}^{*}$ densities are also compared with those obtained using the two-parameter Fermi (2pF) formula for the representative case of the ${}^{16}\mathrm{O}+{}^{154}\mathrm{Sm}$ reaction, and the RMF-${\mathrm{NL}3}^{*}$ densities are noted to provide a higher cross section for the considered reaction. The quantitative analysis of cross sections calculated using different nuclear potentials with the available experimental data shows that the R3Y NN potential and nuclear densities calculated within the RMF formalism for the nonlinear ${\mathrm{NL}3}^{*}$ parameter set provide a reasonable agreement with the experimental data for all the considered reactions containing spherical and deformed target nuclei.

Deformed nuclei exhibit enhanced moments that violate time-reversal invariance ($T$) and parity ($P$). This paper focuses on the enhanced nuclear electric dipole moment (EDM) and Schiff moment present in nuclei with octupole deformation (pear-shaped nuclei). These moments, which are proportional to the octupole deformation, have a collective nature and are large in the intrinsic frame that rotates with the nucleus. However, in a state with definite angular momentum and parity, $T$ and $P$ conservation forbid their expectation values in the laboratory frame, as nuclear rotation causes them to vanish. In nuclei with octupole deformation, close opposite-parity rotational states with identical spin are mixed by $T,P$-violating nuclear forces. This mixing polarizes the nuclear axis along the nuclear spin, allowing moments from the intrinsic frame to manifest in the laboratory frame, provided the nuclear spin $I$ is sufficiently large. Using half-life data for $E1$ transitions from the NuDat database, we calculate the intrinsic nuclear EDM $d_{\text{int}}$ for a range of nuclei theorised to exhibit octupole deformation. From these values, we independently estimate the intrinsic nuclear Schiff moment $S_{\text{int}}$ and the octupole deformation parameter ${\beta }_3$. Finally, we compare the magnitude of these collective moments in the laboratory frame with the contributions from valence nucleons, providing an estimate of the nuclear EDM and Schiff moment components unrelated to octupole deformation. The uncertainty of our estimates may exceed a factor of 10.

The spectroscopic quadrupole moment of the first excited state, $Q_{{}_S}\left(2_1^{+}\right)$, at 1.634 MeV in ${}^{20}\mathrm{Ne}$ was determined from sensitive reorientation-effect Coulomb-excitation measurements using a heavy target and safe energies well below the Coulomb barrier. Particle-$\gamma$ coincidence measurements were collected at iThemba LABS with a digital data-acquisition system using the AFRODITE array coupled to an annular, doubled-sided silicon detector. A precise value of $Q_{{}_S}\left(2_1^{+}\right)=-0.22\left(2\right)e\mathrm{b}$ was determined at backward angles in agreement with the only safe-energy measurement prior to this work, $Q_{{}_S}\left(2_1^{+}\right)=-0.23\left(8\right)e\mathrm{b}$. This result adopts $1\hslash \omega$ shell-model calculations of the nuclear dipole polarizability of the $2_1^{+}$ state that contributes to the effective quadrupole interaction and determination of $Q_{{}_S}\left(2_1^{+}\right)$. It disagrees, however, with the ideal rotor model for axially symmetric nuclei by almost $3\sigma$. Larger discrepancies are computed by modern state-of-the-art calculations performed in this and prior work, including ab initio shell model with chiral effective interactions and the multireference relativistic energy density functional (MR-EDF) model. The intrinsic nucleon density of the $2_1^{+}$ state in ${}^{20}\mathrm{Ne}$ calculated with the MR-EDF model illustrates the presence of $\alpha$ clustering, which explains the largest discrepancy with the rotor model found in the nuclear chart and motivates the explicit inclusion of $\alpha$ clustering for full convergence of $E2$ collective properties.

The yields of hadrons and light nuclei in relativistic collisions of heavy-nuclei at a center of mass energy of $\sqrt{s_{NN}}=2.6\text{TeV}$ can be described remarkably well by a thermal distribution of an ideal gas of hadrons and light nuclei interacting only via the decay of resonances. Given the particularly small binding energy of hypertritons relative to the temperature describing the yields (about $156\text{MeV}$), one might naturally expect hypertritons to dissociate in medium, making the agreement of hypertriton yields with thermal predictions highly puzzling. The puzzle is compounded by the fact that small binding energy is associated with the large size of the hypertriton. This size is on a similar scale to the overall size of the fireball and much larger than the length scale over which temperatures in the fireball vary over phenomenologically relevant amounts. This paper quantifies the tension this effect causes and shows that it is sufficiently large to render the thermal model inconsistent: its natural assumptions are in conflict with its outputs. The possibility that hypertritons are formed at freeze-out as compact objects, quark droplets, that subsequently evolve into hypertritons is considered as a way to resolve the puzzle. It is noted that beyond making the assumption that compact quark droplets form, additional detailed dynamical assumptions which have not been justified are needed to make the thermal model work. The issue of why, despite these issues, the hypertriton is well described by a simple statistical description at freeze-out is unresolved. Resolving the hypertriton puzzle is important as it may clarify whether the phenomenological success of the simple thermal model for yields accurately reflects the simple picture of the underlying physics on which it is based.

Neutron stars are usually assumed to be cold; however, in certain dynamical astrophysical scenarios such as newly born neutron stars or binary star mergers, the temperature effects play a non-negligible role. We systematically derive the equation of state at finite temperature within a relativistic mean field hadronic model applicable to such proto-neutron stars. The equation of state so derived considerably affects the mass-radius curve, thereby affecting the nonradial quadruple $f$-mode oscillation frequencies. Temperature effectively makes the equation of state stiffer at relatively low and intermediate densities, thereby making the star less compact and flattening the mass-radius curve. The $f$-mode frequency for low- and intermediate-mass neutron stars decreases with temperature and thus should be easier to detect. The universal relation (connecting $f$-mode frequency, mass, and radius) changes nonlinearly with temperature. The parameters defining the universal relation $[\omega M=a\left(T\right)\left(\frac{M}{R}\right)+b\left(T\right)]$ becomes temperature dependent with the coefficients following a parabolic relation with temperature.

The particle x-ray coincidence technique (PXCT) was originally developed to measure average lifetimes in the ${10}^{-17}–{10}^{-15}\mathrm{s}$ range for proton-unbound states populated by electron capture (EC). We have designed and built the Lifetimes and Branching Ratios Apparatus (LIBRA) to be used in the stopped-beam area at the Facility for Rare Isotope Beams that extends PXCT to measure lifetimes and decay branching ratios of resonances populated by $\mathrm{EC}/{\beta }^{+}$ decay. The first application of LIBRA aims to obtain essential nuclear data from ${}^{60}\mathrm{Ga}\mathrm{EC}/{\beta }^{+}$ decay to constrain the thermonuclear rates of the ${}^{59}\mathrm{Cu}(p,\gamma ){}^{60}\mathrm{Zn}$ and ${}^{59}\mathrm{Cu}(p,\alpha ){}^{56}\mathrm{Ni}$ reactions, and in turn, the strength of the NiCu nucleosynthesis cycle, which is predicted to significantly impact the modeling of type I x-ray burst light curves and the composition of the burst ashes. Detailed theoretical calculations, Monte Carlo simulations, and performance tests with radioactive sources have been conducted to validate the feasibility of employing LIBRA for the ${}^{60}\mathrm{Ga}$ experiment. LIBRA can be utilized to measure most essential ingredients needed for charged-particle reaction rate calculations in a single experiment, in the absence of direct measurements, which are often impractical for radioactive reactants.

The differential cross sections for the ${}^2\mathrm{H}$(p,pp)$n$ reaction have been measured for 84 angular configurations of the outgoing protons in the range of polar angles from ${13}^{\circ }$ to ${33}^{\circ }$ with a proton beam of 108 MeV. Data have been collected in the Cyclotron Center Bronowice at the Institute of Nuclear Physics PAS in Kracow using the BINA detector setup. Analysis leading to determination of the breakup cross-section values is described. Absolute normalization is obtained by normalization to the simultaneously measured ${}^2\mathrm{H}$(p,d)$p$ scattering events. Experimental results are compared to the state-of-the-art theoretical calculations. Global analysis shows significant influence of the Coulomb interaction and small effects of three-nucleon force in the studied phase-space region.