The multipole modes of excitation for tetrahedrally deformed neutron-rich Zr isotopes are investigated using the quasiparticle finite amplitude method based on covariant density functional theories. By employing the density-dependent point-coupling covariant density functional theory with the parameter set DD-PC1 in the particle-hole channel and a separable pairing interaction of finite range, it is observed that a distinct peak emerges at $\omega =9.0–10.0$ MeV in the isoscalar quadrupole $K=0$ strength when ${\beta }_{32}$ distortion is considered for ${}^{110,112}\mathrm{Zr}$. This peak is absent when the deformation is limited to axially symmetric octuple or spherical cases. It also does not appear in neighboring axially quadrupole or octupole deformed nuclei, thus can be viewed as an indicator for the tetrahedral shape.

Following on our recent analysis of the energy momentum tensor (EMT) of light nuclei in the impulse approximation, we evaluate the leading exchange corrections also up to momenta of the order of the nucleon mass. The exchange contributions to the EMT are composed of the pair interaction, plus the seagull and the pion exchange interactions, modulo the recoil correction. The exchange contributions are shown to satisfy the current conservation requirement. These contributions are small compared to those from the impulse approximation for most of the deuteron gravitational form factors (GFFs), for momenta smaller than half of the nucleon mass. For larger momenta, the exchange contributions are significant for the deuteron A- and D-GFFs. We suggest that the pion GFFs can be extracted from the exchange contributions of select deuteron GFFs.

An interacting-boson-model-1 (IBM-1) Hamiltonian, derived from self-consistent mean-field calculations using a Skyrme energy density functional is employed for the study of energy spectra and $B\left(E2\right)$ transition strengths in the even-even ${}^{162–184}\mathrm{Hf}$ and ${}^{168–186}\mathrm{W}$. An intrinsic triaxial deformation, derived from fermionic proxy-SU(3) irreps, is incorporated into the IBM-1 potential energy curve, which is subsequently mapped to the fermionic one, in order to derive the parameters of the IBM-1 Hamiltonian. It is shown that the inclusion of the intrinsic triaxial deformation derived from the proxy-SU(3) irreps leads to a significantly improved agreement between the theoretical predictions and experimental data for the low-lying quadrupole bands in the examined isotopes, without the need of higher-order terms in the IBM-1 Hamiltonian. The calculated $B\left(E2\right)$ transition strengths are also improved, compared to the axially symmetric case. The recently suggested preponderance of triaxial deformation over extended regions of the nuclear chart is obtained as a byproduct. Future potential improvements and extensions to this mapping approach are also discussed.

We investigate the symmetry energy in relation with the two-proton and two-neutron separation energies using different nuclear mass data. For this aim, we exploit the deformed relativistic Hartree-Bogoliubov theory in the continuum (DRHBc), FRDM2012, and AME2020 data. First, we study the two-proton and two-neutron separation energies in Pb and Ca isotopes by subtracting the contribution of Coulomb energy. They show a strong correlation with neutron number as well as with the neutron skin thickness. By taking the relative difference of both separation energies, we derive the symmetry energy from Ca and Pb isotopes. Since the nuclear surface contributes to the symmetry energy, we deduce the volume symmetry energy by subtracting the surface contribution using several mass models. The obtained symmetry energy coefficient, $a_{\mathrm{sym}}$, is 20.0–22.7 MeV for Pb isotopes and 18.7–19.3 MeV for Ca isotopes from the DRHBc mass table data, while the results from other mass tables are 19.6–22.1 (20.7–22.3) MeV for Pb isotopes and 18.9–19.0 (19.6–19.7) MeV for Ca isotopes from AME2020 (FRDM2012) data. The volume contribution to the asymmetry coefficient, $a_{\mathrm{sym}}^v$, which depends on the ratio of the surface to the volume energy coefficients, $a_s/a_v$, is also provided for each mass model. Since the ratio $a_s/a_v$ is determined neither by nuclear theory nor by experimental data, we have investigated $a_{\mathrm{sym}}^v$ by using the ratio $a_s/a_v$ as a free parameter, and have obtained $a_{\mathrm{sym}}^v=$ 27.0 MeV, almost irrespective of nuclear model and isotopic chain, with the ratio $a_s/a_v$ constrained as $a_s/a_v=1.10–1.13$.

In this work, we present an updated model for nuclear ${\pi }^0$ photoproduction, which incorporates pion second-order rescattering on intermediate excited nuclear states. Our approach is based on the distorted wave impulse approximation in momentum space. The many-body medium effects are incorporated in the complex effective $\mathrm{\Delta }$ self-energy, employing the results of the recently developed second-order pion-nucleus scattering potential. The experimental data for ${}^{12}\mathrm{C}$ and ${}^{40}\mathrm{Ca}$ are successfully described without the need to fit the model parameters of the photoproduction amplitude as a result of incorporating the second-order part of the nuclear photoproduction potential, which involves intermediate nucleon spin-flip and charge exchange.

Spontaneous fission and $\alpha$ decay from $K$-isomeric states are studied within the dinuclear system model. All these processes are considered as evolution of a nucleus in the charge (mass) asymmetry coordinate. For even-even and even-odd actinides and superheavy nuclei, the spontaneous fission and $\alpha$-decay half-lives of $K$-isomeric states are calculated and compared with the available experimental data. The origin of the hindrance of spontaneous fission from the high-$K$ isomeric states is explained.

We measured the total reaction cross section $\left({\sigma }_R\right)$ for the proton-dripline nucleus ${}^{17}\mathrm{F}$ using a solid hydrogen target. Comparing the experimental results of ${}^{17}\mathrm{F}$ and ${}^{17}\mathrm{Ne}$, ${\sigma }_R$ on a proton target shows that the contribution of the isospin asymmetry of the nucleon-nucleon total cross section is more prominent than the changes in the nuclear radii of the two nuclei, while for a carbon target, the cross section simply reflects the nuclear matter radii of these isotopes, which are consistent with the results of previous theoretical works. The experimental values of ${\sigma }_R$ for ${}^{17}\mathrm{F}$ on a proton target at energies of several tens MeV/nucleon (several hundreds MeV/nucleon) are smaller (larger) than the theoretical values of ${\sigma }_R$; similar trend is observed for ${}^{17}\mathrm{Ne}$. This discrepancy is not resolved at this time; therefore, further studies of the experimental and theoretical sides are required to precisely understand nucleus-proton collisions.

Inclusive energy distributions of isotopically resolved intermediate-mass fragments with $Z=3$–6 have been measured for the reactions ${}^{20}\mathrm{Ne}+{}^{116}\mathrm{Sn}$ and ${}^{20}\mathrm{Ne}+{}^{124}\mathrm{Sn}$ at two excitation energies, 0.86 and 1.06 MeV/nucleon. The peak of energy spectra of each fragment is much higher than the peaks expected from asymmetric fission. The angular distributions of all fragments fall much faster than $\frac{1}{sin{\theta }_{\mathrm{c}.\mathrm{m}.}}$ which shows that fragments are emitted from a nonequilibrated source, produced in a highly energy-damped deep-inelastic collision. The lifetimes of the dinuclear composites extracted from the angular distribution of different fragments were found in the range of $\approx (0.5-3)\times {10}^{-22}$ s. Angular momentum dissipation factors have been extracted for each of the emitted isotopes. The mean angular momentum dissipation factor nearly matches with sticking limit predictions for the lighter fragments but gradually increases with the increase of fragment mass relative to the sticking limit predictions in both the reactions. In this study it is found that the neutron-rich system ${}^{20}\mathrm{Ne}+{}^{124}\mathrm{Sn}$ tends to emit neutron-rich isotopes, whereas the neutron-deficient system ${}^{20}\mathrm{Ne}+{}^{116}\mathrm{Sn}$ favors the emission of neutron-deficient isotopes at both energies, suggesting isospin relaxation. However, the variation in isotopic yield ratios with kinetic energy for certain isotopes indicates that isospin relaxation is incomplete at the higher excitation energy of 1.06 MeV/nucleon.

In this paper, the results of the measurements of the total cross sections for the reactions ${}^{10,11,12}\mathrm{Be}+{}^{28}\mathrm{Si}$ and ${}^{14}\mathrm{B}+{}^{28}\mathrm{Si}$ in the beam energy range $13A\text{–}47A\mathrm{MeV}$ are presented. The experimental cross sections were obtained by the detection of $\gamma$ quanta and neutrons accompanying the interaction of the isotopes of Be and B with ${}^{28}\mathrm{Si}$. It was found that the cross sections for ${}^{11,12}\mathrm{Be}$ are similar but significantly exceed those for ${}^{10}\mathrm{Be}$. A significant increase in the cross sections for ${}^{12}\mathrm{Be}$ with decreasing energy is observed in the entire measured energy range. The measured total reaction cross sections are discussed in terms of the reduced strong absorption radius with the empirical Kox parametrization formula and compared with other experimental data and with optical model calculations.

Relativistic beams of heavy ions interacting with various nuclear targets allow us to study a broad range of problems starting from nuclear equation of state to the traditional nuclear structure. Some questions which were impossible to answer heretofore—can be addressed nowadays by using inverse kinematics. These includes the structure of short-lived nuclei and the precision study of exclusive channels with production of residual nuclei in certain quantum states. Theoretical understanding such processes is so far based on factorization models which combine the single-step amplitude of the reaction on a bound nucleon or nuclear cluster with a certain wave function of its relative motion with respect to the residual nucleus. The nuclear structure information is encoded in the spectroscopic amplitude, calculable within nuclear many-body theories. In this work, we use for this purpose the translationally invariant shell model with configuration mixing and demonstrate that it successfully reproduces the single-differential and integrated cross sections of the quasielastic proton knockout, ${}^{12}\mathrm{C}(p,2p){}^{11}\mathrm{B}$, with outgoing ${}^{11}\mathrm{B}$ in the ground state and low-lying excited states measured at GSI at 400 MeV/nucleon.

We report the investigation of the kinetic freeze-out properties of identified hadrons $[{\pi }^{\pm }$, $K^{\pm }$. and $p\left(\overline{p}\right)]$ along with light (anti-)nuclei $d\left(\overline{d}\right)$, $t\left(\overline{t}\right)$, and ${}^3\mathrm{He}$ in relativistic heavy-ion collisions at BNL Relativistic Heavy Ion (RHIC) and CERN Large Hadron Collider (LHC) energies. A simultaneous fit is performed with the blast-wave model to the transverse momentum $\left(p_{\mathrm{T}}\right)$ spectra of identified hadrons together with light (anti-)nuclei produced in Au+Au collisions at $\sqrt{s_{NN}}=7.7$–200 GeV at the RHIC and in Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV at the LHC. The energy and centrality dependence of freeze-out parameters, i.e., kinetic freeze-out temperature $\left(T_{\mathrm{kin}}\right)$ and collective flow velocity $\langle \beta \rangle$ has been studied. It is observed that light (anti-)nuclei also participate in the collective expansion of the medium created in the collision when included in a common fit with the light hadrons. We observe a marginal rise in $T_{\mathrm{kin}}$ and a slight decrease in $\langle \beta \rangle$ when compared to the values obtained from the fit to light hadrons. A similar $\langle \beta \rangle$ and significantly larger $T_{\mathrm{kin}}$ is observed when a fit is performed to only protons and light (anti-)nuclei. Both $T_{\mathrm{kin}}$ and $\langle \beta \rangle$ show a weak energy dependence at most collision energies.

I introduce a method to reconstruct full rapidity distributions of charged particle multiplicity and net proton yields, crucial for constraining the longitudinal dynamics of nuclear matter created in the beam energy scan program. Employing rapidity distributions within a multistage hydrodynamic model calibrated for $\text{Au}+\text{Au}$ collisions at $\sqrt{s_{\mathrm{NN}}}=7.7–200\mathrm{GeV}$, I estimate the total energy and baryon number deposited into the collision fireball, offering insights into initial dynamics and the identification of nuclear remnants. I explore the potential of rapidity-dependent measurements in probing equations of state at finite chemical potentials. Furthermore, I compare the freeze-out parameters derived from both hydrodynamics and thermal models, highlighting that the parameters extracted via thermal models represent averaged properties across rapidities.

I analyze the trajectory of the Lee-Yang edge singularities of the QCD equation of state in the complex baryon chemical potential (${\mu }_B$) plane for different values of the temperature by using the recent lattice results for the Taylor expansion coefficients up to eighth order in ${\mu }_B$ and various resummation techniques that blend in Padé expansions and conformal maps. By extrapolating from this information, I estimate for the location of the QCD critical point: $T_c\approx 100$ MeV, ${\mu }_c\approx 580$ MeV. I also estimate the crossover slope at the critical point to be ${\alpha }_1\approx 9^{\circ }$ and further constrain the nonuniversal mapping parameters between the three-dimensional Ising model and QCD equations of state.

Stimulated by the recent suggestion of using a europium compound for the Cosmic Axion Spin Precession Experiment search for axionlike dark matter, I develop a new method for accurate calculation of Schiff moments of even-odd deformed nuclei. The method is based on experimental data on magnetic moments and $E1$ and $E3$ transition amplitudes in the given even-odd nucleus and in adjacent even-even nuclei. Despite the fact that such data sets are not yet available for a lot of the interesting nuclei, the full set of data is available for ${}^{153}\mathrm{Eu}$. Hence, I perform the calculation for ${}^{153}\mathrm{Eu}$ and find the value of the Schiff moment. The value is about 30 times larger than a typical Schiff moment of a spherical heavy nucleus. The enhancement of the Schiff moment in ${}^{153}\mathrm{Eu}$ is related to the low-energy octupole mode. On the other hand the value of the Schiff moment I find is 30 times smaller than that obtained under the assumption of a static octupole deformation.

The aCORN experiment measures the electron-antineutrino correlation $a$ coefficient in free neutron decay. We update the previous aCORN results [G. Darius et al., Phys. Rev. Lett. 119, 042502 (2017) and M. T. Hassan et al., Phys. Rev. C 103, 045502 (2021)] to include radiative and recoil corrections to first order, and discuss a key issue in the comparison of results from different $a$-coefficient experimental methods when these effects are considered. The corrected combined result is $\overline{a}=-0.10779\pm 0.00125\left(\mathrm{stat}\right)\pm 0.00134\left(\mathrm{sys}\right)$, averaged over the full Fermi neutron beta spectrum. The corresponding corrected result for the ratio of weak coupling constants $\lambda =G_A/G_V$ is $\lambda =-1.2712\pm 0.0061$, and the corresponding value of $a_0$, useful for comparing to proton recoil measurements, is $a_0=-0.1053\pm 0.0018$. This improves agreement with previous $a$-coefficient experiments, in particular the 2020 aSPECT result [M. Beck et al., Phys. Rev. C 101, 055506 (2020)].

The most probable outcome of ternary fission is the emission of two heavy fragments and one light charged particle. In about 90% of cases, these are $\alpha$ particles, which often referred to aslong-range alpha (LRA). Such decay has been extensively studied over decades in various heavy fissioning systems. The probability of such a process has been found to be about $(2–4)\times {10}^{-3}$ relative to binary fission. The experimental data showed an increasing trend in the probability of such a process with an increase in fissility parameter within the range of 35–39. In recent decades, a region of the heaviest nuclei has been substantially expanded in both proton and neutron numbers. This includes neutron-deficient heavy and superheavy nuclei with fissility parameters, which are significantly exceeding the aforementioned range. In the present work, the currently available experimental data on the probability of the LRA emission, which is a representative of ternary fission, are discussed. The probabilities of LRA emission were calculated within the various empirical approaches, including the presently suggested semiempirical expression. The latter one was derived on the basis of the $\alpha$-decay property of the fissioning nucleus. The results of all approaches discussed show that the probabilities of LRA emission are substantial (up to a percentage) in the fission of neutron-deficient heavy and superheavy nuclei.

In noncentral heavy-ion collisions, the quark-gluon plasma (QGP) encounters the most intense magnetic field ever produced in nature, with a strength of approximately $\sim {10}^{19-20}$ gauss. Recent lattice QCD calculations reveal that the QGP exhibits paramagnetic properties at high temperatures. When an external strong magnetic field is applied, it generates an anisotropic squeezing force density that competes with pressure gradients resulting from the purely QGP geometric expansion. In this study, we employ ($3+1$)-dimensional ideal hydrodynamics simulations to estimate the paramagnetic squeezing effect of this force density on the anisotropic expansion of QGP in noncentral $\mathrm{Pb}+\mathrm{Pb}$ collisions at the Large Hadron Collider. We consider both up-to-date magnetic susceptibility and various magnetic field profiles in this work. We find that the impact of rapidly decaying magnetic fields is insignificant, while enduring magnetic fields produce a strong force density that diminishes the momentum anisotropy of the QGP by up to 10% at the intial stage, leaving a visible imprint on the elliptic flow $v_2$ of final charged particles. Our results provide insights into the interplay between magnetic fields and the dynamics of QGP expansion in noncentral heavy-ion collisions.

Evidences are updated and strengthened for the two-scales picture of low-energy nucleon structure as a compact ‘hard’ valence quark core surrounded by a ‘soft’ cloud of quark-antiquark pairs (the meson cloud). These considerations are quantified by a spectral analysis of the mean-squared radii associated with the isoscalar and isovector electric form factors of the nucleon. Further supporting arguments come from corresponding studies of the axial and mass form factors and their inferred radii. Separating low-mass (mesonic) and high-mass (short-range) contributions in the spectral representations of each of these form factors, we conclude that a central core with a root mean square radius of about 1/2 fm results consistently as the common feature in all cases. Implications are discussed for baryonic matter at densities beyond that of equilibrium nuclear matter.