We use the extended relaxation time approximation for the collision kernel, which incorporates a particle-energy dependent relaxation time, to derive second-order viscous hydrodynamics from the Boltzmann equation for a system of massless particles. The resulting transport coefficients are found to be sensitive to the energy dependence of the relaxation time and have significant influence on the fluid's evolution. Using the derived hydrodynamic equations, we study the evolution of a fluid undergoing ($0+1$)-dimensional expansion with Bjorken symmetry and investigate the fixed point structure inherent in the equations. Further, by employing a power law parametrization to describe the energy dependence of the relaxation time, we successfully reproduce the stable free-streaming fixed point for a specific power of the energy dependence. The impact of the energy-dependent relaxation time on the processes of isotropization and thermalization of an expanding plasma is discussed.

We report on precision mass measurements of ${}^{113,115,117}\mathrm{Ru}$ performed with the JYFLTRAP double Penning trap mass spectrometer at the Accelerator Laboratory of University of Jyväskylä. The phase-imaging ion-cyclotron-resonance technique was used to resolve the ground and isomeric states in ${}^{113,115}\mathrm{Ru}$ and enabled for the first time a measurement of the isomer excitation energies, $E_x\left({}^{113}\mathrm{Ru}^{\mathrm{m}}\right)=100.5\left(8\right)$ keV and $E_x\left({}^{115}\mathrm{Ru}^{\mathrm{m}}\right)=129\left(5\right)$ keV. The ground state of ${}^{117}\mathrm{Ru}$ was measured using the time-of-flight ion-cyclotron-resonance technique. The new mass-excess value for ${}^{117}\mathrm{Ru}$ is around 36 keV lower and seven times more precise than the previous literature value. With the more precise ground-state mass values, the evolution of the two-neutron separation energies is further constrained and a similar trend as predicted by the BSkG1 model is obtained up to the neutron number $N=71$.

The nuclear collision ${}^{18}\mathrm{O}+{}^{40}\mathrm{Ca}$ at 275 MeV is theoretically studied in the elastic, inelastic, one-nucleon transfer, and charge-exchange channels. The elastic scattering channel is treated within the optical model framework with the help of semimicroscopic double folding potentials, which are constructed by using the realistic nuclear matter densities obtained within the Hartree-Fock-Bogoliubov method, while the distorted wave Born approximation method is adopted to calculate differential cross sections for the other channels. The charge exchange nuclear reaction ${}^{40}\mathrm{Ca}({}^{18}\mathrm{O},$ ${}^{18}\mathrm{F}){}^{40}\mathrm{K}$ is analyzed by assuming the two-step transfer mechanisms, namely by considering a succession of proton-neutron pickup-stripping processes. Large-scale shell-model calculations are employed to compute the spectroscopic amplitudes, needed in our approach. When compared to the available experimental angular distributions, the obtained results show that the two-step transfer mechanisms play a relevant role in the description of the ${}^{40}\mathrm{Ca}({}^{18}\mathrm{O},$ ${}^{18}\mathrm{F}){}^{40}\mathrm{K}$ reaction and need to be accounted for in any accurate analysis of the measured cross section.

The Gubser solution to inviscid relativistic fluid dynamics is used to examine the role of transverse expansion on the energy spectrum of photons radiated by quark-gluon plasma. Transverse flow is shown to be a modest effect on the energy spectrum of photons as a whole, despite its large effect on rare high-energy photons produced at low temperatures. An exact expression is derived for the volume of the plasma as a function of its temperature. A simple formula is obtained for the energy spectrum of high-energy thermal photons, which is used to relate the inverse slope $T_{\text{eff}}$ of the photon spectrum at energy $E$ to the maximum temperature of the plasma $T_0$, finding $T_{\text{eff}}\approx T_0/(1+\frac{5}{2}\frac{T_0}{E})$.

New experimental and theoretical results obtained in 2021 made it acutely clear that more than 80 years after the discovery of nuclear fission we do not understand the generation and dynamics of fission fragment (FF) intrinsic spins well, in particular their magnitudes, their spatial orientation, and their correlations. The magnitude and orientation of the primary FFs have a crucial role in defining the angular distribution and correlation between the emitted prompt neutrons, and subsequent emission of statistical (predominantly $E1$) and stretched $E2 \gamma$ rays, and their correlations with the final fission fragments. Here, we present detailed microscopic evaluations of the FF intrinsic spins, for both even- and odd-mass FFs, and of their spatial correlations. These point to a well-defined three-dimensional FF intrinsic spin dynamics, characteristics absent in semiphenomenological studies, due to the presence of the twisting spin modes, which artificially were suppressed in semiphenomenological studies.

Excited states in the yrast and negative parity bands in ${}^{92}\mathrm{Mo}$ were populated in two different experiments using the ${}^{90}\mathrm{Zr}(\alpha ,2n){}^{92}\mathrm{Mo}$ and ${}^{93}\mathrm{Nb}(p,2n){}^{92}\mathrm{Mo}$ fusion-evaporation reactions at the Cologne FN Tandem accelerator and measured using a hybrid setup of high purity germanium and lanthanum bromide detectors. Lifetimes of the excited $2_1^{+}, 4_1^{+}, 6_1^{+}, 8_1^{+}, 5_1^{-}, 7_1^{-}$, and $9_1^{-}$ states were measured using the $\gamma \text{−}\gamma$ fast-timing technique. The newly measured lifetime of the $4_1^{+}$ state differs from the recently published value measured using the recoil distance Doppler shift method. Experimental $B\left(E2\right)$ strengths of excited states in ${}^{92}\mathrm{Mo}$ are used to predict theoretical $B\left(E2\right)$ values in the $N=50$ isotones from ${}^{93}\mathrm{Tc}$ up to ${}^{95}\mathrm{Rh}$ using semiempirical calculations in the single-$j$ orbital $0g_{9/2}$ for the protons.

We propose a method to optimize the multi-Slater determinants of the antisymmetrized molecular dynamics (AMD) in the linear combination form and apply it to the neutron-rich ${}^{10}\mathrm{Be}$ nucleus. The individual Slater determinants and their weights in the superposition are determined simultaneously according to the variational principle of the energy of the total wave function. The multi-AMD basis states of ${}^{10}\mathrm{Be}$ show various cluster structures as well as the shell-model type. In the cluster configurations, different intercluster distances are superposed automatically, indicating the role of the generator coordinates. We further introduce a procedure to obtain the configurations for the excited states imposing the orthogonal condition to the ground-state configurations. In the excited states of ${}^{10}\mathrm{Be}$, the linear-chain-like structure is confirmed to consist of various clusters. The energy spectrum using the obtained basis states reproduces the experiments. The present framework can be used to find the optimal multiconfiguration for nuclear ground and excited states.

We provide a generalized formulation of fluctuating hydrodynamics for the far-from-equilibrium noisy medium. As an example, we consider a noisy plasma experiencing Bjorken expansion, for which the leading order evolution is captured by the hydrodynamic attractor of classical hydrodynamics, while the quadratic couplings of fluctuations are solved effectively via a generalized version of the hydrodynamic kinetic equation. In the far-from-equilibrium plasma, backreaction of hydrodynamic fluctuations results in renormalization of transport properties, as well as long-time tails, of high orders. In particular, corresponding to a renormalized hydrodynamic attractor, evolution in a noisy plasma towards equilibrium becomes nonmonotonic.

We investigate the response of a Ramsey-type experiment on an additional oscillating magnetic field. This superimposed field is oriented in the same direction as the static main magnetic field and causes a modulation of the original Larmor spin precession frequency. The observable magnitude of this modulation decreases at higher frequencies of the oscillating field. It disappears completely if the interaction time of the particles matches the oscillation period, which we call resonant cancellation. We present an analytical approach that describes the effect and compare it to a measurement using a monochromatic cold neutron beam.

The speed of sound is a novel probe of equation of state and phase transitions in dense cores of neutron stars. Recently nuclear experiments extracted a surprising thick neutron skin of ${}^{208}\mathrm{Pb}$, causing tensions to reproduce the tidal deformability in gravitational-wave observations. This work finds that exotic structures in the speed of sound with a small softening slope followed by a steep-rising peak are required to reconcile the thick neutron skin of ${}^{208}\mathrm{Pb}$ with astronomical observations of neutron stars. Furthermore, the peak of the speed of sound is narrowly constrained around two times the nuclear saturation density with the thick neutron skin. Consequently early and strong first-order phase transitions are comparatively more favorable.

In reference to the complete fusion (CF) and incomplete fusion (ICF) processes, the analysis of ${}^6\mathrm{Li}+{}^{120}\mathrm{Sn}$ and ${}^7\mathrm{Li}+{}^{119}\mathrm{Sn}$ reactions forming the ${}^{126}\mathrm{I}$ compound nucleus (CN) is carried out at incident energies spreading across the Coulomb barrier. The theoretical calculations of the formation of the compound nucleus ${}^{126}\mathrm{I}$ via two different entrance channels are done by opting for the energy-dependent Woods-Saxon potential (EDWSP) model and the $\ell$-summed Wong model. The available CF cross-section data of these systems at above-barrier energies is suppressed with respect to the EDWSP outcomes, and a reducing factor is needed to explain above-barrier CF data of given reactions. Such suppression effects at above-barrier energies can be correlated with the breakup of weakly bound systems (${}^{6,7}\mathrm{Li}$) before reaching the Coulomb barrier. The total fusion (TF) cross-section data, which are the sum of CF and ICF cross-section data, are fairly addressed by using the EDWSP predictions. The difference between CF and TF data represents ICF yields and hence qualified in terms of range parameter $r_0$. Besides this, the $\ell$-summed Wong approach has been used to address CF, ICF, and TF cross-section data, which limits the contribution of partial waves to the maximum $\ell$ value. Within the $\ell$-summed Wong model, the CF and ICF contributions are separated out on the basis of the angular-momentum window. In the angular-momentum distribution case, CF and ICF contributions are estimated in view of $\ell$-windows assigned for CF ($\ell =0$ to ${\ell }_{\mathrm{crit}.}$) and ICF (${\ell }_{\mathrm{crit}.}$ to ${\ell }_{\max }$) components. Furthermore, the decay analysis of ${}^{126}\mathrm{I}$ compound nucleus is made using the dynamical cluster decay model (DCM). Calculations are made to analyze the decay cross sections ${\sigma }_{xn}$ of neutron channels for given entrance channels at a wide spread of energies ($E_{\mathrm{lab}}=14$–28 MeV). The neck-length parameter $\mathrm{\Delta }R$, which decides the first turning point, is optimized to address the decay cross sections of different neutron evaporation channels and DCM-based calculations fairly explained the decay patterns of the CN.

We develop a parton and hadron cascade model paciae 3.0 based on pythia 6.428 and the paciae 2.2 program series for nuclear collisions. The original simulation framework composed of the initial partonic state, the partonic rescattering stage, hadronization stage, and the hadronic rescattering stage, is renamed a C-simulation framework for high-energy ($\sqrt{s_{NN}}\ge 3$ GeV) nuclear collisions. A B-simulation framework without partonic rescattering is designed for the high-energy nuclear collisions, too. In addition, an A-simulation framework is introduced for the low-energy ($\sqrt{s_{NN}}<3$ GeV) nuclear collisions, which is developed in the hadronic degree of freedom only. In the C-simulation framework, the parton-parton inelastic-scattering processes are implemented, the single-string structure and multiple-string interaction mechanisms are proposed to investigate the strangeness enhancement, and the phenomenological coalescence hadronization model is modified. With the model, the particle yield, transverse momentum distribution, and rapidity distribution resulted from A-simulation framework well reproduce the data measured at the FOPI and E895 experiments, and the results from B- and C-simulation frameworks are well consistent with the data measured at the energies of the BNL Relativistic Heavy Ion Collider and the Large Hadron Collider.

The ip-glasma initial condition has been highly successful in the phenomenology of ultrarelativistic heavy ion collisions. The assumption of boost invariance, however, while good for collision energies probed at the Large Hadron Collider, limits the use of ip-glasma to the transverse dynamics of heavy ion collision to near midrapidity. There is a wealth of physics to be explored and understood in the longitudinal dynamics of heavy ion collisions, and a full understanding of heavy ion collisions can only come from three-dimensional studies. In particular, long range rapidity correlations are seeded in the initial collision and provide additional information on the high energy nuclear wave functions that have thus far been inaccessible to the ip-glasma model. In this paper, we introduce a way to extend the ip-glasma model to $3+1$ dimensions while preserving its key features.

The intrinsic sea content in the ground state decuplet baryons is investigated employing an extended chiral constituent quark model, in which the wave functions of the baryons are taken to be superposition of the traditional $qqq$ and the $qqqq\overline{q}$ higher Fock components. The probability amplitudes of corresponding pentaquark components are calculated using the widely employed ${}^{3}P_0$ model, which could lead to transition couplings between the $qqq$ and the $qqqq\overline{q}$ components in the studied baryons. All the involved model parameters are taken to be the empirical values, and our numerical results show the total probabilities ${\mathcal{P}}_5^B$ of the pentaquark components in the decuplet baryons are close to each others, while ${\mathcal{P}}_5^B$ decreases with the increasing strangeness number of the baryon.

A unified Chew-Mandelstam description of single-pion photoproduction data, together with pion- and $\eta$-hadroproduction data, has been extended to include measurements carried out over the last decade. We consider photodecay amplitudes evaluated at the pole with particular emphasis on $n\gamma$ couplings and the influence of weighting on our fits. Both energy-dependent and single-energy analysis (energy-binned data) are considered.

Charmed ${\mathrm{\Lambda }}_c^{+}$ hypernuclei are investigated in the framework of the deformed Skyrme-Hartree-Fock approach. Their ground-state bulk properties, single-particle energy levels, potential energy curves, as well as the existence limit of charmed hypernuclei are studied with particular regard to the effects of deformation. ${\mathrm{\Lambda }}_c^{+}1p$ states are found to be strongly bound, in particular in deformed nuclei.

A phenomenological analysis of the experimental measurements of transverse momentum spectra of identified charged hadrons and strange hyperons in Pb-Pb and Xe-Xe collisions at the CERN Large Hadron Collider (LHC) is presented. The analysis is based on the relativistic fluid dynamics description implemented in the numerically efficient Fluid$\mathit{u}$M approach. Building on our previous work, we separate in our treatment the chemical and kinetic freeze-outs, and incorporate the partial chemical equilibrium to describe the late stages of the collision evolution. This analysis makes use of Bayesian inference to determine key parameters of the quark-gluon plasma (QGP) evolution and its properties including the shear and bulk viscosity to entropy ratios, the initialization time, the initial entropy density, and the freeze-out temperatures. The physics parameters and their posterior probabilities are extracted using a global search in multidimensional space with modern machine learning tools, such as ensembles of neural networks. We employ our newly developed fast framework to assess systematic uncertainties in the extracted model parameters by systematically varying key components of our analysis.

We present results from direct measurements of the total ${}^{13}\mathrm{C}(\alpha ,n){}^{16}\mathrm{O}$ cross section over laboratory energies $E_{\alpha }=2.9$–8.0 MeV, performed with the ${}^3{\mathrm{HeBF}}_3$ giant barrel neutron detector at the Edwards Accelerator Laboratory. The cross sections reported in this work are considerably lower than prior direct measurements for $E_{\alpha }>5$ MeV, in agreement with prior corrections based on Hauser-Feshbach estimates. However, applying branching ratios based on Hauser-Feshbach estimates to our data would not reproduce existing direct measurements for partial decay channels. This indicates both the promise and limitations of Hauser-Feshbach for branching ratio estimates of $(\alpha ,n)$ reactions on light nuclides. The ${}^{13}\mathrm{C}(\alpha ,n)$ thick-target yields inferred from this work for $E_{\alpha }>6$ MeV are significantly larger than those currently employed in estimates of dark matter and neutrino detector backgrounds.

The neutron-rich strontium, zirconium, and molybdenum nuclei have been observed to undergo a dramatic evolution, becoming strongly deformed around $N=60$, sometimes interpreted as a quantum phase transition between “normal” and intruder configurations. Key to understanding this evolution is to understand the configurations in isolation, in regions where interference can be neglected. A deformed coexisting configuration is inferred from the presence of a $0_2^{+}$ state which decreases in excitation energy with increasing neutron number, becoming the first-excited state at ${}^{98}\mathrm{Mo}$. We present here the results of a low-energy Coulomb-excitation measurement of the nucleus ${}^{96}\mathrm{Mo}$, extracting $B\left(E2\right)$ values and quadrupole moments. It is found that, while the $B\left(E2\right)$ values agree with those found in the literature, there is a significant disagreement with literature spectroscopic quadrupole moments. The results are compared with shell-model calculations using a ${}^{88}\mathrm{Sr}$ core with good agreement found, likely indicating that intruder structures do not significantly impact the ground-state structure, in contrast with the heavier molybdenum isotopes.