Timescales associated with many-body fast neutrino flavor conversions in core-collapse supernova are explored in the context of an effective two-flavor model with axial symmetry. We present a preliminary study of timescales obtained from a linear stability analysis and from the distributions of Loschmidt echo crossing times (intimately connected to dynamical phase transitions in nonequilibrium systems) determined by time evolution with the exact many-body Hamiltonian. Starting from a tensor-product initial state describing systems of $N$ neutrinos, with $N/2$ electron type and $N/2$ heavy type, with uniform angular distributions, the Loschmidt echo crossing times, $t_{{\mathcal{L}}_{\times }}$, are found to exhibit two distinct timescales that are exponentially separated. The second peak structure at longer times, effectively absent for $N=4$, develops with increasing $N$. When rescaled in terms of $ln{t}_{{\mathcal{L}}_{\times }}$, the distributions are found to become increasingly well described by the sum of two stable distributions. The distribution of Loschmidt echo crossing times differs somewhat from the results of the (numerical) linear stability analysis, which exhibits a peak at finite frequency and a second peak consistent with zero frequency. The exact analysis suggests that the zero-frequency instability manifests itself as a modest flavor-conversion timescale.

In the present work, based on the framework of the two-potential approach, we systematically investigate the incompressibility of nuclear matter $K$ from cluster radioactivity by considering the sum of an attractive double-folding potential and a repulsive Gaussian potential as the total nuclear potential of nucleon-nucleon interactions. The strength of the repulsive Gaussian core caused by the Pauli exclusion principle can be obtained by reproducing the cluster radioactivity experimental half-lives of 28 trans-lead nuclei ranging from ${}^{221}\mathrm{Fr}$ to ${}^{242}\mathrm{Cm}$. The incompressibility of nuclear matter can be calculated in the case of completely overlapped densities inside the potential barrier, which is related to the curvature of the nuclear matter equation of state. The obtained values for the incompressibility of nuclear matter range from 202.13–247.54 MeV. In addition, the influences of isospin asymmetry $\delta$ and the effective number of the valence particles $N_p{N}_n$ on the incompressibility of nuclear matter from cluster radioactivity are also discussed. The results show that the incompressibility of nuclear matter $K$ is linear to product of isospin asymmetry and the effective number of the valence particles $N_p{N}_n\delta$. At the same time, the estimated incompressibility of symmetric nuclear matter deduced from the results obtained for different asymmetric nuclei is $K(\delta =0)=251.14$ MeV.

Background: Understanding nuclear shape is a crucial problem in nuclear physics. In particular, determining the sign of quadrupole deformation, i.e., whether prolate or oblate, remains a challenging problem.

Purpose: Our aim is to propose a method for determining the sign of quadrupole deformation using $\alpha$ inelastic scattering data and to demonstrate its effectiveness.

Method: Our approach is the standard coupled-channel method based on the macroscopic model. We utilize the nuclear reorientation effect, a phenomenon associated with the self-coupling of excited states, as a probe sensitive to the sign of deformation.

Results: We first provide an overview of how the reorientation effect influences inelastic scattering cross sections, and numerically confirm its validity in realistic cases. We then demonstrate that the sign of deformation can be uniquely determined from inelastic scattering cross section data.

Conclusion: Our technique offers a systematic approach for determining the sign of deformation in both stable and unstable nuclei. The broad applicability of $\alpha$ inelastic scattering will make it a valuable tool to study shape of nuclei, especially unstable nuclei.

We investigate the Gamow-Teller (GT) transition strength distributions of strongly deformed nuclei, ${}^{24,26}\mathrm{Mg}$, as well as of ${}^{18}\mathrm{O}$. The calculations are performed within a deformed quasiparticle random-phase approximation which explicitly includes the deformation degree of freedom in the Skyrme-Hartree-Fock and random-phase approximation calculations. The residual particle-particle (p-p) interaction as well as the particle-hole (p-h) interaction are extracted from Brückner $G$-matrix calculations. The residual interaction dependence of the low-lying GT strength of these strongly deformed nuclei is examined by changing the strength of the residual p-p and p-h interactions. We have found that the low-lying GT peaks are quite similar in energy to those found in spherical $N=Z$ and $N=Z+2$ nuclei near magic shells, but the configurations of ${}^{24,26}\mathrm{Mg}$ are largely mixed by the pairing correlations and the deformation. Our results are compared with the experimental GT $(\pm )$ transition data by ($t, {}^3\mathrm{He}$) and (${}^3\mathrm{He}, t$) reactions and are found to reproduce the main features of GT strength distributions.

This work studies the influence of an external magnetic field on hadron yields and fluctuations in a hadron resonance gas by performing calculations within an updated version of the open-source thermal-fist package. The presence of the magnetic field has a sizable influence on certain hadron yield ratios. Most notably, it leads to enhanced $p/\pi$ and suppressed $n/p$ ratios, which may serve as a magnetometer in heavy-ion collisions. By attributing the centrality dependence of the $p/\pi$ ratio in Pb-Pb collisions at 5.02 TeV measured by the ALICE Collaboration entirely to the magnetic field, its maximal strength at freezeout is estimated to be $eB\simeq 0.12{\mathrm{GeV}}^2\simeq 6.3m_{\pi }^2$ in peripheral collisions. The magnetic field also enhances various conserved charge susceptibilities, which is qualitatively consistent with recent lattice QCD data and is driven in the HRG model by the increase of hadron densities. However, the variances of hadrons do not show any enhancement when normalized by the means, therefore, measurements of second-order fluctuations in heavy-ion collisions appear to offer limited additional information about the magnetic field relative to mean multiplicities.

We report on new precision mass measurements of neutron-rich ${}^{137}\mathrm{Sb}$ and ${}^{136–142}\mathrm{I}$ isotopes from the JYFLTRAP double Penning trap mass spectrometer. We confirm the value from the previous Penning-trap measurement of ${}^{137}\mathrm{Sb}$ at the Canadian Penning Trap and therefore rule out the conflicting result from the Experimental Storage Ring. The ground state and isomer in ${}^{136}\mathrm{I}$ were resolved and measured directly for the first time. The isomer excitation energy, $E_x=215.1\left(43\right)$ keV, agrees with the literature but is three times more precise. The measurements have improved the precision of the mass values and confirmed previous results in the majority of cases. However, for ${}^{138,140}\mathrm{I}$ the results differ by 17(6) keV and 23(12) keV, respectively. This could be explained by an unresolved contamination or different ratio of unresolved isomeric states in the case of ${}^{140}\mathrm{I}$.

The masses of ${}^{84}\mathrm{Br}, {}^{105}\mathrm{Mo}, {}^{115,119,121}\mathrm{Pd}, {}^{122}\mathrm{Ag}, {}^{127,129}\mathrm{In}, {}^{132}\mathrm{Sb}$, and their respective isomeric states have been measured with the JYFLTRAP Penning trap mass spectrometer using the phase-imaging ion-cyclotron-resonance technique. The excitation energies of the isomeric states in ${}^{132}\mathrm{Sb}$ and ${}^{119}\mathrm{Pd}$ were experimentally determined for the first time, while for ${}^{84}\mathrm{Br}, {}^{115}\mathrm{Pd}$, and ${}^{127,129}\mathrm{In}$, the precision of the mass values was substantially improved. In ${}^{105}\mathrm{Mo}$ and ${}^{121}\mathrm{Pd}$ there were no signs of a long-lived isomeric state. The ground-state measurements of ${}^{119}\mathrm{Pd}$ and ${}^{122}\mathrm{Ag}$ indicated that both are significantly more bound than the literature values. For ${}^{122}\mathrm{Ag}$, there was no indication of a proposed third long-lived state. The results for the $N=49$ nucleus ${}^{84}\mathrm{Br}$ and isomers close to doubly magic ${}^{132}\mathrm{Sn}$ have been compared to the shell-model and the microscopic quasiparticle-phonon model calculations.

The microscopic origin of the ${}^{229m}\mathrm{Th}$ isomer and its possible manifestation also in neighboring nuclei is explored within a self-consistent Skyrme Hartree-Fock plus Bardeen-Cooper-Schrieffer approach. By using the well-established SIII Skyrme parametrization, without any special adjustments related to low-energy isomer, the single-particle spectrum provided by the model reproduces the correct isomer $K^{\pi }=3/2^{+}$ spin and parity, and the relative proximity of the isomeric state to the $K^{\pi }=5/2^{+}$ ground state, yet on the keV scale. We show that this approach may provide microscopic estimates for some related observables, such as the quadrupole and octupole moments, deformation parameters, as well as magnetic dipole moments. Its ability to provide a prediction for the $M1$ isomer transition probability is discussed. The obtained ${}^{229}\mathrm{Th}$ single-particle structure is compared with that provided by calculations in neighboring actinide isotopes and isotones, allowing us to assess the more general role of the considered mechanism for the formation of low-energy isomers.

The $\beta$ decay of one-neutron halo nucleus ${}^{11}\mathrm{Be}$ was investigated using the Warsaw Optical Time Projection Chamber (OTPC) detector to measure $\beta$-delayed charged particles. The results of two experiments are reported. In the first one, carried out in LNS Catania, the absolute branching ratio for $\beta$-delayed $\alpha$ emission was measured by counting incoming ${}^{11}\mathrm{Be}$ ions stopped in the detector and the observed decays with the emission of $\alpha$ particle. The result of 3.27(46)% is in good agreement with the literature value. In the second experiment, performed at the HIE-ISOLDE facility at CERN, bunches containing several hundreds of ${}^{11}\mathrm{Be}$ ions were implanted into the OTPC detector followed by the detection of decays with the emission of charged particles. The energy spectrum of $\beta$-delayed $\alpha$ particles was determined in the full energy range. It was analyzed in the R-matrix framework and was found to be consistent with the literature. The best description of the spectrum was obtained assuming that the two $3/2^{+}$ and one $1/2^{+}$ states in ${}^{11}\mathrm{B}$ are involved in the transition. The search for $\beta$-delayed emission of protons was undertaken. Only the upper limit for the branching ratio for this process of $(2.2\pm 0.6_{\mathrm{stat}}\pm 0.6_{\mathrm{sys}})\times {10}^{-6}$ could be determined. This value is in conflict with the result published by Ayyad et al. [Phys. Rev. Lett. 123, 082501 (2019)] but does agree with the limit reported by Riisager et al. [Eur. Phys. J. A 56, 100 (2020)].

Artificial intelligence (AI) generative models, such as generative adversarial networks (GANs), variational autoencoders, and normalizing flows, have been widely used and studied as efficient alternatives for traditional scientific simulations. However, they have several drawbacks, including training instability and inability to cover the entire data distribution, especially for regions where data are rare. This is particularly challenging for whole-event, full-detector simulations in high-energy heavy-ion experiments, such as sPHENIX at the Relativistic Heavy Ion Collider and Large Hadron Collider experiments, where thousands of particles are produced per event and interact with the detector. This work investigates the effectiveness of denoising diffusion probabilistic models (DDPMs) as an AI-based generative surrogate model for the sPHENIX experiment that includes the heavy-ion event generation and response of the entire calorimeter stack. DDPM performance in sPHENIX simulation data is compared with a popular rival, GANs. Results show that both DDPMs and GANs can reproduce the data distribution where the examples are abundant (low-to-medium calorimeter energies). Nonetheless, DDPMs significantly outperform GANs, especially in high-energy regions where data are rare. Additionally, DDPMs exhibit superior stability compared to GANs. The results are consistent between both central and peripheral centrality heavy-ion collision events. Moreover, DDPMs offer a substantial speedup of approximately a factor of 100 compared to the traditional Geant4 simulation method.

We introduce a minimal model of ultracentral heavy-ion collisions to study the relation between the speed of sound of the produced plasma and the final particles' energy and multiplicity. We discuss how the particles' multiplicity $N_{\text{tot}}$ and average energy $E_{\text{tot}}/N_{\text{tot}}$ is related to the speed of sound $c_s$ by $c_s^2=dln(E_{\text{tot}}/N_{\text{tot}})/dln{N}_{\text{tot}}$ if the fluid is inviscid, its speed of sound is constant and all final particles can be measured. We show that finite rapidity cuts on the particles' multiplicity $N$ and energy $E$ introduce corrections between $c_s^2$ and $dln(E/N)/dlnN$ that depend on the system's lifetime. We study analytically these deviations with the Gubser hydrodynamic solution, finding that, for ultrarelativistic bosons, they scale as the ratio of the freeze-out temperature $T_{\mathrm{FO}}$ over the maximum initial temperature of the fluid $T_0$; the nonthermodynamic aspect of these corrections is highlighted through their dependence on the system's initial conditions.

The $\beta$ decay of ${}^{24}\mathrm{O}$ was investigated at NSCL/MSU using a combination of neutron and $\gamma$-ray spectroscopy. For the first time, the $\beta$-delayed neutron energy spectrum of ${}^{24}\mathrm{O}$ was measured, revealing three intensely populated, isolated neutron-unbound states in ${}^{24}\mathrm{F}$. This allowed for the extraction of the decay strength in ${}^{24}\mathrm{F}$ up to 6.2 MeV. A comprehensive comparison of the experimental results with various nuclear theories, ranging from the empirical shell model to the most advanced ab initio calculations, was conducted. While most theoretical predictions align with the experimental data for low-lying states, discrepancies arise at higher excitation energies. In the transition from ${}^{24}\mathrm{O}$ to ${}^{24}\mathrm{F}$, shell model calculations using the empirical USDB interaction predicted the structure of both nuclei without invoking the need for a stronger proton-neutron tensor force, which was postulated for the neighboring isotone ${}^{25}\mathrm{F}$.

The lifetimes of the $2_1^{+}$, $4_1^{+}$, $3_1^{-}$, $2_2^{+}$, and $0_2^{+}$ states in ${}^{214}\mathrm{Po}$ and the $1^{-}$ state at 295.2 keV in ${}^{214}\mathrm{Bi}$ were determined using the fast-timing method in combination with the Cologne HORUS and Cologne CATHEDRAL spectrometers. Both spectrometers were equipped with high-purity germanium (HPGe) and lanthanum-bromide $[{\mathrm{LaBr}}_3\left(\mathrm{Ce}\right)$] detectors. Furthermore, upper limits for the lifetimes of the $2_3^{+}$, $2_5^{+}$, and $1_1^{+}$ states in ${}^{214}\mathrm{Po}$ and for the lifetimes of the ($0_1^{-}$, $1_1^{-}$) state at 352 keV in ${}^{214}\mathrm{Bi}$ were obtained. The excited states in ${}^{214}\mathrm{Po}$ and ${}^{214}\mathrm{Bi}$ were populated after the $\beta$ decay of ${}^{214}\mathrm{Bi}$ and ${}^{214}\mathrm{Pb}$, respectively. The lifetimes and upper limits were used to calculate transition strengths which are important observables to explain structural phenomena in these nuclei. The results are compared to other nuclei in the region around the doubly magic nucleus of ${}^{208}\mathrm{Pb}$ and to shell model calculations using the KHPE interaction, and a general discussion is given.

Although neutron stars have been studied for decades, their internal structure remains enigmatic, mainly due to large uncertainties in the equation of state. In neutron stars, the nucleons are strongly interacting by exchanging mesons, which can lead to significant quantum many-body correlation effects. Mean-field calculations failed to capture these effects. Here, we develop a nonperturbative quantum field-theoretic approach to handle strongly correlated dense nuclear matter within the framework of quantum hadrodynamics. We show that the many-body effects can be incorporated in the Dyson-Schwinger equation of the nucleon propagator. Based on a linear $\sigma \text{−}\omega \text{−}\rho$ model, we successfully reproduce six empirical observable quantities of saturation nuclear matter by tuning six parameters. After including the many-body effects into the equation of state of realistic neutron star matter, we obtain a mass-radius relation that is comparable with recent astrophysical observations of neutron stars.

${}^3\mathrm{He}$ spin-dependent structure functions, $g_1^3\left(x\right)$ and $g_2^3\left(x\right)$, which parametrize the hadronic tensor in polarized deep-inelastic scattering, were evaluated within the Poincaré-covariant light-front framework. The Bakamjian-Thomas construction of the Poincaré generators allows us to make use of a realistic ${}^3\mathrm{He}$ wave function, obtained from refined nuclear phenomenological potentials. The same approach was already successfully applied to the ${}^3\mathrm{He}$ and ${}^4\mathrm{He}$ unpolarized deep-inelastic scattering. To investigate the neutron polarized structure functions, $g_1^n$ and $g_2^n$, a readily implementable procedure aimed at extracting the neutron spin structure functions from those of ${}^3\mathrm{He}$ is shown to hold. Moreover, the first moment of $g_1^3\left(x\right)$ was evaluated, aiming at providing a valuable check of the Bjorken sum rule. The present analysis is relevant for experiments involving polarized beams planned at future facilities such as electron ion colliders.

The anisotropic kernel ridge regression (AKRR) approach in nuclear mass predictions is developed by introducing the anisotropic kernel function into the kernel ridge regression (KRR) approach, without introducing new weight parameter or input in the training. A combination of double two-dimensional Gaussian kernel function is adopted, and the corresponding hyperparameters are tuned carefully through cross-validations to optimize the predictions. The anisotropic kernel shows cross-shape pattern, which highlights the correlations among the isotopes with the same proton number, and those among the isotones with the same neutron number. Significant improvements are achieved by the AKRR approach in both the interpolation and the extrapolation predictions of nuclear masses comparing with the original isotropic KRR approach.

We exploit a new update of the double folding potential for nuclear reactions by using the central part of the Argonne v18 (Av18) model for the direct term in the nucleon-nucleon ($NN$) interaction and matter densities of the projectile and target nuclei obtained from microscopic energy density functional (EDF) models. The elastic scattering cross sections for the ${}^{16}\mathrm{O}+{}^{208}\mathrm{Pb}$ system are calculated using an optical model with the double-folding potentials of the KKS (KAU-Kangwon-Soongsil)–Av18 (Argonne v18) and M3Y $NN$ interactions and four EDF models. We focus on the dependencies of the models. First, matter and charge densities are examined by comparing the results of the four EDF models. The results show model dependence in the core and surface regions. Next, the double folding potential is calculated using the KKS-Av18 and M3Y $NN$ potentials accompanied by the matter densities obtained from the four EDF models. The dependence on the $NN$ interaction is suppressed by fitting the exchange term, but the dependence on the EDF models appears in the strong absorption region. Finally, we obtain that the elastic scattering cross sections agree well with the experimental data in the forward direction, but the dependence on the models becomes apparent at backward angles.

Relativistic heavy-ion collisions give rise to the formation of both deconfined quantum chromodynamics (QCD) matter and a strong magnetic field. The spin of heavy quarks is influenced by interactions with the external magnetic field as well as by random scatterings with thermal light partons. The presence of QCD matter comprising charged quarks can extend the lifetime and strength of the magnetic field, thereby enhancing the degree of heavy quark polarization. However, the random scatterings with QCD matter tend to diminish heavy quark polarization. In this study, we utilize the Landau-Lifshitz-Gilbert equation to investigate both these contributions. Taking into account the realistic evolutions of medium temperatures and the in-medium magnetic fields at the BNL Relativistic Heavy-Ion Collider and the CERN Large Hadron Collider, we observe that heavy quark polarization is limited by the short lifetime of the magnetic field and the high temperatures of the medium. Furthermore, we explore the mass dependence of quark polarization, revealing that the polarization degree of strange quarks is much larger than that of charm quarks.

We investigate the effects of saturation dynamics on midrapidity flow observables by adding fluctuating hotspots into the novel Monte Carlo EKRT (MC-EKRT) event generator for high-energy nuclear collisions. We demonstrate that the intensity of the saturation effects significantly affects the ratio between the flow coefficients $v_3$ and $v_2$ at the LHC. Adding a hotspot substructure to the nucleons enhances the saturation effects and improves the agreement with the measured data. We show that the collision-energy dependence of the flow coefficients obtained using the MC-EKRT initial states with hotspots is improved in comparison with the earlier event-by-event EKRT model. In addition, we present the results for the charged hadron multiplicity distribution in $\text{Pb}+\text{Pb}$ collisions at the LHC, and show that the minijet multiplicity originating fluctuations of the saturation scale included in MC-EKRT, as well as the presence of hotspots, are necessary for describing the measured large-multiplicity tail in the distribution.

Deuterium-tritium (D-T) fusion is a key to generating safe, clean, and limitless energy on Earth in future fusion power plants. Its understanding at low collision energies is incomplete, as D-T fusion is a quantum tunneling process affected by resonances whose origin is linked to properties of not fully understood nuclear forces. Simplified quantum dynamical calculations of laser-assisted D-T fusion are presented, suggesting that laser-nucleus interaction can enhance the average D-T fusion probability by 7–$70\%$ at deep subbarrier energies using laser fields of intensity ${10}^{27}$–${10}^{29} {\mathrm{W}\mathrm{cm}}^{-2}$ and a photon energy of 1 eV.