We present next-to-leading order perturbative QCD predictions for inclusive dijet photoproduction in ultraperipheral nucleus-nucleus collisions (UPCs) within the impact-parameter dependent equivalent photon approximation. Taking into account the finite size of both the photon-emitting nucleus and the target nucleus, we show that this process is sensitive to the transverse-plane geometry of the UPC events. We show that this leads to a sizable, 20–40% effect for large values of the $z_{\gamma }$ variable in the dijet photoproduction cross section in lead-lead UPCs at 5.02 TeV compared to the widely used pointlike approximation where the nuclear radius is accounted for only as a sharp cutoff in the photon flux calculation. This resolution of the spatial degrees of freedom is a result of having high-transverse-momentum jets in the final state, which at the large-$z_{\gamma }$ kinematics requires a highly energetic photon in the initial state, thus biasing the collisions to small impact-parameter “near-encounter” configurations. We further discuss the role of the forward-neutron event-class selection in isolating the photonuclear cross section in the nucleus-nucleus collisions, and employ the needed electromagnetic breakup survival factor in our predictions.

I investigate the effect of Coulomb core polarization in ${}^{208}\mathrm{Pb}$, highlighting its impact on uncertainties in neutron distribution measurements due to the discrepancy between neutron excess and neutron skin regions at the surface. This effect is validated using the ${(}^3\text{He},t)$ isobaric analog state (IAS) reaction at 420 MeV. My findings reveal that the Coulomb boundary radius, where core polarization becomes negligible, is critical for accurately probing the neutron skin region in the target nucleus. Consequently, I propose extending the ${}^{208}\mathrm{Pb}{(}^3\text{He},t)\mathrm{IAS}$ reaction experiment conducted by Zegers et al. [Phys. Rev. Lett. 99, 202501 (2007)] to measure cross sections up to $3^{\circ }$ angles to more precisely determine the neutron skin thickness in ${}^{208}\mathrm{Pb}$ from theoretical reaction analysis. Additionally, I observe that, under the assumption of a large neutron skin in ${}^{208}\mathrm{Pb}$, as suggested by the PREX-II result, the core-polarization effect introduces impurity into the neutron skin region.

Ideas of applying electronic bridge for manipulations with nuclear isomers are analyzed using an example of the 8.36-eV ${}^{229m}\mathrm{Th}$ isomer. The principle of radical broadening the isomer line within the two-photon method is expressed. It can be used for reduction of the scan time. That is not burdened with the cross-section reduction, in contrast with internal-conversion-based resonance broadening or intended extrabroadening of the spectral line of a pumping laser. Following the principle allows one to increase the cross section of the isomer excitation by two orders of magnitude. It is applicable to both ionized and neutral thorium atoms. Realization of the method supposes excitation of the both nucleus and electron shell in the final state.

We propose a theoretical method to calculate the bound-state $\beta$-decay half-lives of highly ionized atoms, which is based on the combination of the Takahashi-Yokoi model and our recently developed projected shell model that can take into account both allowed and first-forbidden transitions of nuclear $\beta$ decay. Three examples that are of much experimental interests, ${}^{163}\mathrm{Dy}^{66+}, {}^{187}\mathrm{Re}^{75+}$, and ${}^{205}\mathrm{Tl}^{81+}$ are taken for calculations. The ground and low-lying states of related nuclei are described reasonably. The bound-state $\beta$-decay half-lives of ${}^{163}\mathrm{Dy}^{66+}$ and ${}^{187}\mathrm{Re}^{75+}$ are described within factors of 2 and 4 by our calculations without and with the quenching factors in allowed and first-forbidden transitions. The bound-state $\beta$-decay half-life of the last $s$-process branching point ${}^{205}\mathrm{Tl}^{81+}$ is predicted to be 58 and 305 days for cases without and with the quenching factors in calculations. The presented method provides a theoretical way to calculate systematically the bound-state $\beta$-decay half-lives of nuclei from light to heavy ones including odd-mass and even-mass cases for the first time.

High-spin states of ${}^{94}\mathrm{Nb}$ have been studied by in-beam $\gamma$-ray spectroscopic methods using the ${}^{82}\mathrm{Se}({}^{18}\mathrm{O},p5n){}^{94}\mathrm{Nb}$ reaction at beam energies of 82 and 88 MeV. Particle-$\gamma \text{−}\gamma$ coincidence measurements using CsI and high-purity germanium arrays are employed to gain selectivity to Nb isotopic products. The level scheme of ${}^{94}\mathrm{Nb}$ has been extended up to excitation energy $\approx 11\mathrm{MeV}$ and spin $24\hslash$ with the addition of 20 new $\gamma$ transitions, and the placement of some of the previously known transitions has been revised. The energy spectrum bears signature of core breaking, viz., presence of high energy ($E_{\gamma }\approx 2\mathrm{MeV}$) $\gamma$ rays originating due to excitation of nucleons across the shell gaps. The proposed level scheme is compared with large basis spherical shell model calculations using the GWBXG and SNET interactions.

For both reactions I use an approach similar to that of compound-nucleus reaction theory. For neutron-induced fission, the compound system generated by absorption of the neutron and the nuclear system near the scission point are described as two statistically independent systems governed by random-matrix theory. The systems are connected either by a barrier penetration factor or by a set of transition states above the barrier. Each system is coupled to a different set of channels. An analogous model is used for heavy-ion fusion. Under the assumption that (seen from the entrance channel) the system on the other side of the barrier is in the regime of strongly overlapping resonances, closed-form analytical expressions for the total probability for fission and for fusion are obtained for each value of spin and parity. Parts of these expressions can be calculated reliably within existing compound-nucleus reaction theory. The remaining parts are the probabilities for passage through or over the barrier. These may be determined theoretically from the liquid-drop model or experimentally from total fission or fusion cross sections.

At the earliest stage of ultrarelativistic heavy-ion collisions the produced matter is a highly populated system of gluons called glasma which can be approximately described in terms of classical chromodynamic fields. Although the system's dynamics is governed by Yang-Mills equations, glasma evolution is shown to strongly resemble hydrodynamic behavior.

A systematic study of intermediate invariant mass dilepton production in $\mathrm{Pb}+\mathrm{Pb}$ collisions at $\sqrt{s_{NN}}=5.02\mathrm{TeV}$ is performed, using next-to-leading order (NLO) thermal QCD dilepton emission rates with a multistage dynamical approach which includes event-by-event ip-glasma initial conditions, relativistic viscous fluid dynamics, and a hadronic afterburner. Considering dilepton yield and anisotropic flow, special attention is paid to the out-of-equilibrium aspects, both thermal and chemical, and to the contribution of the Drell-Yan process. The relative contribution of each of those different channels to dilepton observables is calculated and discussed.

We study the theoretical structure of compositeness with explicit energy dependency and find a possible explanation for the difficulty in the interpretation of compositeness of deuteron. Many approaches, including the weak-binding limit, calculate the deuteron compositeness as greater than unity, regardless of its interpretation as a proportion. The widely adopted surjective interpretation, which assumes the energy dependency in the interaction always comes from other states, is challenged by our study on deuteron. Based on numerical and perturbative calculations, we conclude that if the energy-dependent part of the interaction contributes to attraction, compositeness is likely to be enhanced from unity. Since the scattering length of the deuteron is insufficient to explain its binding energy, we are forced to use attractive energy-dependent interactions, resulting in unreasonable value of deuteron compositeness. We discuss the implications of this outcome and the model dependency of compositeness. To address this problem, we propose a straightforward extension, though it comes at the expense of model-independent calculations promised by the surjective interpretation.

Flavor-changing charged current (“Urca”) processes are of central importance in the astrophysics of neutron stars. The standard approach is to approximate the Urca rate as the sum of two contributions, direct Urca and modified Urca. Attempts to make Urca calculations more accurate have been blocked by an unphysical divergence in the mUrca rate at the dUrca threshold density. We argue that to make progress the traditional separation into “direct” and “modified” contributions should be replaced by a single calculation of the Urca rate that consistently includes collisional broadening of the nucleons in the medium. In this Letter we describe how to perform such a calculation in a systematically improvable way. In the simplest approximation this means including an imaginary part of the nucleon mass (nucleon width). The total Urca rate is then obtained via a straightforward generalization of the dUrca calculation, yielding results that agree with both direct and modified Urca at the densities where those approximations are valid. At low densities, we observe an enhancement of the rate by more than an order of magnitude, with important ramifications for neutron star cooling and other transport properties.

The cranked shell model with pairing correlations taken into account by a particle-number-conserving treatment is applied to investigate the two positive-parity yrast bands in ${}^{60,62}\mathrm{Fe}$. The experimental angular momentum alignments and kinematic moments of inertia are reproduced quite well and the contributions of protons and neutrons to both of them are analyzed in detail. The occupation probability of each cranked Nilsson level of neutrons near the Fermi surface is calculated, which reveals the influence of the intruder orbital $\nu g_{9/2}$ on the backbending. The calculated $B(E2$) and $J^{\left(2\right)}/B(E2$) ratios after backbending display the decreasing and increasing tendencies with the increasing of rotational frequency, respectively. The two-shears-like mechanism is exhibited by the closing of a pair of valence proton hole angular momentum vectors toward the resultant angular momentum vector of valence neutrons. Therefore, the parts after backbending of the two yrast bands are suggested as new possible candidates for an antimagnetic rotational band in the $A\approx 60$ mass region.

Quantum chromodynamics (QCD) is expected to have a first order phase transition between the confined hadron gas and the deconfined quark gluon plasma at high baryon densities. This will result in phase boundary effects in the metastable and unstable regions. It is important to include these effects in phenomenological models of heavy ion collisions to identify experimental signatures of a phase transition. This requires building intuition on phase separation in rapidly expanding fluids. In this work we present the covariant equations of relativistic hydrodynamics with a phase boundary, provide prescriptions to extend the equation of state to metastable and unstable regions, and show the effects of spinodal separation in a Bjorken flow.

An interesting connection is found between the coupled-reaction-channel (CRC) approach and the triad of Lippmann-Schwinger (LS) equations for the three-particle scattering state. It turns out that the CRC decomposition ansatz can be used as a vehicle to couple the three uncoupled LS equations. The possibility of using CRC decomposition as a means of coupling the three LS equations does not seem to have been noticed before. This finding allows one to introduce a set of coupled equations for CRC rearrangement operators in which two-particle resolvents appear naturally as the propagator term. The formal operator equations are then reduced to effective two-body form by employing two different separable expansions of the two-particle resolvent. The two versions of the ensuing CRC effective two-body equations are applied to a benchmark model of $\text{n}+\text{d}$ scattering. Although the two CRC versions differ considerably in the way breakup channel manifests itself in the effective two-body equations, both sets of results for elastic and breakup amplitudes of the benchmark model are almost the same and are in good agreement with the results available in the literature. This study further corroborates that the CRC approach is an alternative versatile tool for three-particle dynamics and is on par with approaches based on Faddeev theory.

The isoscalar and isovector components and their contributions to $M1$ transitions are discussed in the odd-$A, T=1/2$ mirror nuclei with mass number ranging from $A=23$ to 37. The orbital contributions in various $M1$ transitions and ground state magnetic moments are calculated by comparing analogous $M1$ and Gamow-Teller transitions between mirror pairs. The orbital contributions in different $M1$ transitions are explained on the basis of configurations of the initial and final states involved. In magnetic moments, the orbital contributions are found to be dependent on the deformation and single-particle nature of the states. All the $T=1/2$ mirror pairs are studied using isospin non-conserving interaction. The results are also compared with predictions from ab initio effective interaction derived from realistic nuclear forces.

Mass distribution of production cross sections in multinucleon transfer reactions are systematically investigated in the framework of the dinuclear system model combined with statistical $\text{GEMINI}++$ model. The calculated mass distribution for many reaction systems at collision energy above the Coulomb barrier are roughly in agreement with experimental data for a wide range of transfers, especially in the distribution trend. By analyzing the dependence of the mass distribution of production cross sections on the various projectile-target combinations and incident energy in the multinucleon transfer reaction, we hope to be able to find the optimum projectile-target combinations and incident energy for the given multinucleon transfer reaction products.

Heavy-ion experiments provide a new opportunity to gain a deeper understanding of the structure of nuclei. To achieve this, it is crucial to identify observables under circumstances that are minimally affected by the process that leads to the initial state of heavy-ion collisions from nuclear wave function. In this study, we demonstrate that when assuming scale invariance, the effect of this stage on the initial energy or entropy density moments in ultracentral symmetric collisions is negligible for nucleon sizes of approximately 0.7 fm or larger for large nuclei. By borrowing cluster expansion method from statistical physics and using scale-invariance assumption, we calculate the average ellipticity of initial density at the presence of short-range correlation. We compare our calculations to Monte Carlo studies and assess the accuracy of various methods of short-range correlation sampling. Additionally, we find that the isobar ratio can constrain the initial-state parameters, in addition to deformation. Our study indicates that the isobar ratios in ultracentral collisions are especially sensitive to the fluctuation in the weight of the nuclei constituents and the two-body correlation among nucleons. This insight is crucial for drawing conclusions about nuclear deformations based on isobar ratios.

We point out that the pseudospin symmetry (PSS) of nuclei significantly depends on the proton ($Z$) and neutron numbers ($N$), sometimes giving rise to characteristic structures. By using the nonrelativistic spherical Hartree-Fock calculation with a realistic tensor force, we show that the tensor force may be deeply relevant to the $Z$ and $N$ dependence of the PSS. While the PSS has often been discussed in the context of relativistic symmetry, the tensor-force effects on the PSS sometimes look analogous to the $Z$ and $N$ dependence of the PSS in relativistic mean-field (RMF) calculations without explicit tensor force. The observed variation of the $p0d_{3/2}-p1s_{1/2}$ levels from ${}^{40}\mathrm{Ca}$ to ${}^{34}\mathrm{Si}$ is consistent with the tensor-force-driven $Z$ dependence of the PSS, but not necessarily with the RMF result. The present analysis elucidates the significance of the tensor force when discussing the PSS.

Electric quadrupole ground-state excitation strengths $B\left(E2\right)\uparrow$ of the first $2^{+}$ states of midshell Sn isotopes were measured with the nuclear resonance fluorescence method to investigate the systematic disagreement between available experimental data from different techniques. Also, model calculations show conflicting trends of $B(E2;0_1^{+}\to 2_1^{+})$ values around ${}^{116}\mathrm{Sn}$. Three experiments on ${}^{112,116,120}\mathrm{Sn}$ were carried out at the superconducting Darmstadt linear accelerator with beams of bremsstrahlung. A consistent analysis including systematic effects for all experiments yields a decrease in excitation strength from $B\left(E2\right)\uparrow =0.234\left(13\right)e^2{\mathrm{b}}^2$ for ${}^{112}\mathrm{Sn}$ to $B\left(E2\right)\uparrow =0.195\left(13\right)e^2{\mathrm{b}}^2$ for ${}^{116}\mathrm{Sn}$, followed by a slight decline to $B\left(E2\right)\uparrow =0.188\left(14\right)e^2{\mathrm{b}}^2$ in ${}^{120}\mathrm{Sn}$. Reduced collectivity around ${}^{116}\mathrm{Sn}$, as measured with the Doppler-shift attenuation method and predicted by latest Monte Carlo shell model calculations, can thus not be confirmed by our results; whereas satisfactory agreement is found with available Coulomb excitation data.

We discuss renormalization of chiral nuclear forces in the ${}^{3}P_0$ channel of $NN$ scattering at next-to-next-to leading order (${\mathrm{N}}^2\mathrm{LO}$) if the one-pion exchange is treated nonperturbatively at leading order. The matrix elements of the subleading contact potentials become nearly dependent for the so-called exceptional ultraviolet momentum cutoff, making it difficult to determine the strengths of those contact potentials from the empirical phase shifts, as reported by A. M. Gasparyan and E. Epelbaum [Phys. Rev. C 107, 034001 (2023)]. We argue that this issue can be resolved by adjusting the strategy by which the low-energy constants are deduced from the data, thus making those exceptional cutoffs amenable to chiral effective field theory.