The neutron-unbound nucleus ${}^{13}\mathrm{Be}$ was populated with a nucleon exchange reaction from a 71 MeV/u secondary ${}^{13}\mathrm{B}$ beam. The decay-energy spectrum was reconstructed using invariant mass spectroscopy based on ${}^{12}\mathrm{Be}$ fragments in coincidence with neutrons. The data could be described with an $s$-wave resonance at $E_r=0.73\left(9\right)\mathrm{MeV}$ with a width of ${\mathrm{\Gamma }}_r=1.98\left(34\right)\mathrm{MeV}$ and a $d$-wave resonance at $E_r=2.56\left(13\right)\mathrm{MeV}$ with a width of ${\mathrm{\Gamma }}_r=2.29\left(73\right)\mathrm{MeV}$. The observed spectral shape is consistent with previous one-proton removal reaction measurements from ${}^{14}\mathrm{B}$.

We present a new method for imposing a realistic equation of state in anisotropic hydrodynamics. The method relies on the introduction of a single finite-temperature quasiparticle mass which is fit to lattice data. By taking moments of the Boltzmann equation, we obtain a set of coupled partial differential equations which can be used to describe the 3+1-dimensional (3+1d) spacetime evolution of an anisotropic relativistic system. We then specialize to the case of a 0+1d system undergoing boost-invariant Bjorken expansion and subject to the relaxation-time approximation collisional kernel. Using this setup, we compare results obtained using the new quasiparticle equation of state method with those obtained using the standard method for imposing the equation of state in anisotropic hydrodynamics. We demonstrate that the temperature evolution obtained using the two methods is nearly identical and that there are only small differences in the pressure anisotropy. However, we find that there are significant differences in the evolution of the bulk pressure correction.

Recent measurements of the centrality and rapidity dependence of single inclusive jet production in $p+\text{Pb}$ collisions at the Large Hadron Collider (LHC) have revealed large and nontrivial nuclear modification of the production cross section for this process. In this paper, we explore to what extent such nuclear modification can be understood by the framework of standard cold nuclear matter effects, in particular initial-state cold nuclear matter energy loss. We demonstrate quantitatively that theoretical calculations which include medium-induced radiative corrections can describe rather reasonably the attenuation of the jet production yields in the large transverse momentum region in $d+\text{Au}$ collisions at the Relativistic Heavy Ion Collider and $p+\text{Pb}$ collisions at the LHC for central to semicentral collisions. We further show that the observed scaling behavior of the nuclear modification factor as a function of the total jet energy $p_{T}cosh\left(y\right)$ for various rapidity intervals has a natural explanation in the picture of cold nuclear matter energy loss. However, the observed enhancement in peripheral collisions is not described in this picture and could have a different origin.

Multiple scattering and induced parton splitting lead to a medium modification of the QCD evolution for jet fragmentation functions and final hadron spectra. Medium-induced parton splittings not only lead to energy loss of leading partons and suppression of leading hadron spectra, but also modify the flavor composition of a jet due to induced flavor conversion via gluon emission and quark pair production and annihilation. Through a numerical study of the medium-modified QCD evolution, leading $K^{-}$ strange meson spectra are found to be particularly sensitive to the medium-induced flavor conversion in semi-inclusive deeply inelastic scatterings (SIDIS) off a large nucleus. The induced flavor conversion can lead to an increased number of gluons and sea quarks in a jet shower and, as a consequence, enhance the leading $K^{-}$ spectrum to counter the effect of parton energy loss in SIDIS with large momentum fractions $x_B$, where the struck quarks are mostly valence quarks of the nucleus.

Full angular distributions for elastic and inelastic scattering of ${}^{11}\mathrm{B}$ on ${}^{58}\mathrm{Ni}$ have been measured at different bombarding energies around the Coulomb barrier. Measurement and analysis with coupled-channel calculations have been performed for the first time for a system with the tightly bound ${}^{11}\mathrm{B}$ as projectile on a medium mass target. In these calculations, the real part of the interaction potential between nuclei was represented by a parameter-free double-folding potential. To avoid the use of an imaginary potential at the surface, several inelastic transitions of the projectile and the target have been included in the coupling matrix. The result of these coupled-channel calculations are in very good agreement with all experimental angular distributions. The most important result was the striking influence on the reaction mechanism of the ground-state-spin reorientation of the ${}^{11}\mathrm{B}$ nuclei.

The $\alpha$ decay rate of ${}^{210}\text{Po}$ was measured in a film sample $\left({}^{210}\text{Po}@{\mathrm{Bi}}_2{\mathrm{O}}_3\right)$ and a slice sample $\left({}^{210}\text{Po}@\mathrm{Bi}\mathrm{metal}\right)$, respectively. The former was used as a reference sample. The half-lives of ${}^{210}\text{Po}@{\mathrm{Bi}}_2{\mathrm{O}}_3$ and ${}^{210}\text{Po}@\mathrm{Bi}$ metal environments were observed to be $(138.40\pm 0.21\text{d})$ and $(138.87\pm 0.87\text{d})$ at room temperature, respectively. It was found that the half-life of ${}^{210}\text{Po}$ is consistent with international recommendations within the uncertainty limits, and we did not find any deviation of the $\alpha$ decay rate of ${}^{210}\text{Po}$ between film sample $\left({}^{210}\text{Po}@{\mathrm{Bi}}_2{\mathrm{O}}_3\right)$ and slice sample $\left({}^{210}\text{Po}@\mathrm{Bi}\mathrm{metal}\right)$.

We study the nuclear modification of angular and momentum correlations between heavy quark pairs in ultrarelativistic heavy-ion collisions. The evolution of heavy quarks inside the thermalized medium is described via a modified Langevin approach that incorporates both elastic and inelastic interactions with the medium constituents. The spacetime evolution of the fireball is obtained from a $\left(2+1\right)$-dimensional viscous hydrodynamics simulation. The hadronization of heavy quarks is performed by utilizing a hybrid model of fragmentation and coalescence. Our results show that the nuclear modification of the transverse momentum imbalance of $D\overline{D}$ pairs reflects the total energy loss experienced by the heavy quarks and may help us probe specific regions of the medium. The angular correlation of heavy-flavor pairs, especially in the low- to intermediate-transverse-momentum regime, is sensitive to the detailed energy-loss mechanism of heavy quarks inside the quark-gluon plasma.

Based on recent lattice QCD (LQCD) results obtained at finite temperature, we discuss the modeling of the hadronic phase of QCD in the framework of hadron resonance gas (HRG) with discrete and continuous mass spectra. We focus on fluctuations of conserved charges and show how a common limiting temperature can be used to constrain the Hagedorn exponential mass spectrum in different sectors of quantum number, through a matching of HRG and LQCD. For strange baryons, the extracted spectra are found to be consistent with all known and expected states listed by the Particle Data Group (PDG). The strange-mesonic sector, however, requires additional states in the intermediate mass range beyond that embodied in the database.

Uncertainties in the thermonuclear rates of the ${}^{15}\text{O}(\alpha ,\gamma ){}^{19}\text{Ne}$ and ${}^{18}\text{F}(p,\alpha ){}^{15}\text{O}$ reactions affect model predictions of light curves from type I x-ray bursts and the amount of the observable radioisotope ${}^{18}\text{F}$ produced in classical novae, respectively. To address these uncertainties, we have studied the nuclear structure of ${}^{19}\text{Ne}$ over $E_x=4.0-5.1$ and 6.1–7.3 MeV using the ${}^{19}\text{F}({}^3\text{He},t){}^{19}\text{Ne}$ reaction. We find the $J^{\pi }$ values of the 4.14- and 4.20-MeV levels to be consistent with $9/2^{-}$ and $7/2^{-}$, respectively, in contrast to previous assumptions. We confirm the recently observed triplet of states around 6.4 MeV and find evidence that the state at 6.29 MeV, just below the proton threshold, is either broad or a doublet. Our data also suggest that predicted but yet unobserved levels may exist near the 6.86-MeV state. Higher resolution experiments are urgently needed to further clarify the structure of ${}^{19}\text{Ne}$ around the proton threshold before a reliable ${}^{18}\text{F}(p,\alpha ){}^{15}\text{O}$ rate for nova models can be determined.

We investigate the role of pressure in a class of generalized Skyrme models. We introduce pressure as the trace of the spatial part of the energy-momentum tensor and show that it obeys the usual thermodynamical relation. Then, we compute analytically the mean-field equation of state in the high- and medium-pressure regimes by applying topological bounds on compact domains. The equation of state is further investigated numerically for the charge-one Skyrmions. We identify which term in a generalized Skyrme model is responsible for which part in the equation of state. Further, we compare our findings with the corresponding results in the Walecka model.

The $\beta$-decay properties of very neutron rich nuclei ${}^{86}\mathrm{Ge}$ and ${}^{86}\mathrm{As}$ were measured at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. Spectroscopic information on new excited states in ${}^{86}\mathrm{As}$ and in ${}^{86}\mathrm{Se}$ was obtained and is interpreted within an advanced shell model approach. These calculations, previously explaining well the structure of ${}^{84}\mathrm{Ge}$ and ${}^{85}\mathrm{Ge}$, are not able to reproduce all the experimentally determined features of the measured level schemes of ${}^{86}\mathrm{As}$ and ${}^{86}\mathrm{Se}$. The Gamow-Teller decay of ${}^{86}\mathrm{Ge}$ and ${}^{86}\mathrm{As}$ is also investigated in a shell-model framework. The fission yield for ${}^{86}\mathrm{Ge}$ is discussed.

The size of the particle emission region in high-energy collisions can be deduced using the femtoscopic correlations of particle pairs at low relative momentum. Such correlations arise due to quantum statistics and Coulomb and strong final state interactions. In this paper, results are presented from femtoscopic analyses of ${\pi }^{\pm }{\pi }^{\pm },{\mathrm{K}}^{\pm }{\mathrm{K}}^{\pm },{\mathrm{K}}_{\mathrm{S}}^0{\mathrm{K}}_{\mathrm{S}}^0,\mathrm{p}\mathrm{p}$, and $\overline{\mathrm{p}}\overline{\mathrm{p}}$ correlations from Pb-Pb collisions at $\sqrt{s_{\mathit{NN}}}=2.76$ TeV by the ALICE experiment at the LHC. One-dimensional radii of the system are extracted from correlation functions in terms of the invariant momentum difference of the pair. The comparison of the measured radii with the predictions from a hydrokinetic model is discussed. The pion and kaon source radii display a monotonic decrease with increasing average pair transverse mass $m_{\mathrm{T}}$ which is consistent with hydrodynamic model predictions for central collisions. The kaon and proton source sizes can be reasonably described by approximate $m_{\mathrm{T}}$ scaling.

We have performed $r$-process calculations for matter ejected dynamically in neutron star mergers based on a complete set of trajectories from a three-dimensional relativistic smoothed particle hydrodynamic simulation with a total ejected mass of $\sim 1.7\times {10}^{-3}{M}_{\odot }$. Our calculations consider an extended nuclear network, including spontaneous, $\beta$- and neutron-induced fission and adopting fission yield distributions from the abla code. In particular we have studied the sensitivity of the $r$-process abundances to nuclear masses by using different models. Most of the trajectories, corresponding to 90% of the ejected mass, follow a relatively slow expansion allowing for all neutrons to be captured. The resulting abundances are very similar to each other and reproduce the general features of the observed $r$-process abundance (the second and third peaks, the rare-earth peak, and the lead peak) for all mass models as they are mainly determined by the fission yields. We find distinct differences in the predictions of the mass models at and just above the third peak, which can be traced back to different predictions of neutron separation energies for $r$-process nuclei around neutron number $N=130$. In all simulations, we find that the second peak around $A\sim 130$ is produced by the fission yields of the material that piles up in nuclei with $A\gtrsim 250$ due to the substantially longer $\beta$-decay half-lives found in this region. The third peak around $A\sim 195$ is generated in a competition between neutron captures and $\beta$ decays during $r$-process freeze-out. The remaining trajectories, which contribute 10% by mass to the total integrated abundances, follow such a fast expansion that the $r$ process does not use all the neutrons. This also leads to a larger variation of abundances among trajectories, as fission does not dominate the $r$-process dynamics. The resulting abundances are in between those associated to the $r$ and $s$ processes. The total integrated abundances are dominated by contributions from the slow abundances and hence reproduce the general features of the observed $r$-process abundances. We find that, at timescales of weeks relevant for kilonova light curve calculations, the abundance of actinides is larger than the one of lanthanides. This means that actinides can be even more important than lanthanides to determine the photon opacities under kilonova conditions. Moreover, we confirm that the amount of unused neutrons may be large enough to give rise to another observational signature powered by their decay.

Background: The electric dipole strength detected around the particle threshold and commonly associated with the pygmy dipole resonance offers unique information on neutron skin and symmetry energy, and is of astrophysical interest. The nature of such a resonance is still under debate.

Purpose: We intend to describe the giant and pygmy resonances in ${}^{208}\mathrm{Pb}$ by enhancing their fragmentation with respect to the random-phase approximation.

Method: We adopt the equation of motion phonon method to perform a fully self-consistent calculation in a space spanned by one-phonon and two-phonon basis states using an optimized chiral two-body potential. A phenomenological density-dependent term, derived from a contact three-body force, is added to get single-particle spectra more realistic than the ones obtained by using the chiral potential only. The calculation takes into full account the Pauli principle and is free of spurious center-of-mass admixtures.

Results: We obtain a fair description of the giant resonance and obtain a dense low-lying spectrum in qualitative agreement with the experimental data. The transition densities as well as the phonon and particle-hole composition of the most strongly excited states support the pygmy nature of the low-lying resonance. Finally, we obtain realistic values for the dipole polarizability and the neutron skin radius.

Conclusions: The results emphasize the role of the two-phonon states in enhancing the fragmentation of the strength in the giant resonance region and at low energy, consistently with experiments. For a more detailed agreement with the data, the calculation suggests the inclusion of the three-phonon states as well as a fine tuning of the single-particle spectrum to be obtained by a refinement of the nuclear potential.

Neutron $2p$ and $1f$ spin-orbit splittings were recently measured in the isotones ${}^{37}\mathrm{S}$ and ${}^{35}\mathrm{Si}$ by $(d,p)$ transfer reactions. Values were reported by using the major fragments of the states. An important reduction of the $p$ splitting was observed, from ${}^{37}\mathrm{S}$ to ${}^{35}\mathrm{Si}$, associated with a strong modification of the spin-orbit potential in the central region of the nucleus ${}^{35}\mathrm{Si}$. We analyze $2p$ and $1f$ neutron spin-orbit splittings in the $N=20$ isotones ${}^{40}\mathrm{Ca},{}^{36}\mathrm{S}$, and ${}^{34}\mathrm{Si}$. We employ several Skyrme and Gogny interactions to reliably isolate pure spin-orbit and tensor-induced contributions, within the mean-field approximation. We use interactions (i) without the tensor force, (ii) with the tensor force and with tensor parameters adjusted on top of existing parametrizations, nd (iii) with the tensor force and with tensor and spin-orbit parameters adjusted simultaneously on top of existing parametrizations. We predict in cases (ii) and (iii) a non-negligible reduction of both $p$ and $f$ splittings, associated with neutron-proton tensor effects, from ${}^{40}\mathrm{Ca}$ to ${}^{36}\mathrm{S}$. The two splittings are further decreased for the three types of interactions, going from ${}^{36}\mathrm{S}$ to ${}^{34}\mathrm{Si}$. This reduction is produced by the spin-orbit force and is not affected by tensor-induced contributions. For both reductions, from ${}^{40}\mathrm{Ca}$ to ${}^{36}\mathrm{S}$ and from ${}^{36}\mathrm{S}$ to ${}^{34}\mathrm{Si}$, we predict in all cases that the modification is more pronounced for $p$ than for $f$ splittings. The measurement of the centroids for neutron $2p$ and $1f$ states in the nuclei ${}^{36}\mathrm{S}$ and ${}^{34}\mathrm{Si}$ would be interesting to validate this prediction experimentally. We show the importance of using interactions of type (iii), because they provide $p$ and $f$ splittings in the nucleus ${}^{40}\mathrm{Ca}$ which are in agreement with the corresponding experimental values.

We show a relationship between elastic electron scattering observables and the elastic neutrino cross section that provides a straightforward determination of the latter from experimental data of the former and relates their uncertainties. An illustration of this procedure is presented using a Hartree-Fock mean field for the nuclear structure of a set of even-even nuclear targets, using the spectra of the neutrinos produced in pion decay at rest. We also analyze the prospects for measuring the incoherent axial contribution to the neutrino elastic scattering in odd targets.

An effective field theory is used to describe light nuclei, calculated from quantum chromodynamics on a lattice at unphysically large pion masses. The theory is calibrated at leading order to two available data sets on two- and three-body nuclei for two pion masses. At those pion masses we predict the quartet and doublet neutron-deuteron scattering lengths, and the $\alpha$-particle binding energy. For $m_{\pi }=510$ MeV we obtain, respectively, ${}^4{a}_{\mathrm{nD}}=2.3\pm 1.3$ fm, ${}^2{a}_{\mathrm{nD}}=2.2\pm 2.1$ fm, and $B_{\alpha }=35\pm 22$ MeV, while for $m_{\pi }=805$ MeV ${}^4{a}_{\mathrm{nD}}=1.6\pm 1.3$ fm, ${}^2{a}_{\mathrm{nD}}=0.62\pm 1.0$ fm, and $B_{\alpha }=94\pm 45$ MeV are found. Phillips- and Tjon-like correlations to the triton binding energy are established. We find the theoretical uncertainty in the respective correlation bands to be independent of the pion mass. As a benchmark, we present results for the physical pion mass, using experimental two-body scattering lengths and the triton binding energy as input. Hints of subtle changes in the structure of the triton and $\alpha$ particle are discussed.

A systematic investigation of even-even superheavy elements in the region of proton numbers $100\le Z\le 130$ and in the region of neutron numbers from the proton-drip line up to neutron number $N=196$ is presented. For this study we use the five most up-to-date covariant energy density functionals of different types, with a nonlinear meson coupling, with density-dependent meson couplings, and with density-dependent zero-range interactions. Pairing correlations are treated within relativistic Hartree-Bogoliubov theory based on an effective separable particle-particle interaction of finite range and deformation effects are taken into account. This allows us to assess the spread of theoretical predictions within the present covariant models for the binding energies, deformation parameters, shell structures, and $\alpha$-decay half-lives. Contrary to the previous studies in covariant density functional theory, it was found that the impact of $N=172$ spherical shell gap on the structure of superheavy elements is very limited. Similar to nonrelativistic functionals, some covariant functionals predict the important role played by the spherical $N=184$ gap. For these functionals (NL3*, DD-ME2, and PC-PK1) there is a band of spherical nuclei along and near the $Z=120$ and $N=184$ lines. However, for other functionals (DD-PC1 and DD-$\mathrm{ME}\delta$) oblate shapes dominate at and in the vicinity of these lines. Available experimental data are, in general, described with comparable accuracy and do not make it possible to discriminate between these predictions.

The general nuclear contact matrices are defined, taking into consideration all partial waves and finite-range interactions, extending Tan's work on the zero range model. The properties of these matrices are discussed and the relations between the contacts and the one-nucleon and two-nucleon momentum distributions are derived. Using these relations, a new asymptotic connection between the one-nucleon and two-nucleon momentum distributions, describing the two-body short-range correlations in nuclei, is obtained. Using available numerical data, we extract a few connections between the different contacts and verify their relations to the momentum distributions. The numerical data also allows us to identify the main nucleon momentum range affected by two-body short-range correlations. Utilizing these relations and the numerical data, we also verify a previous independent prediction-connecting between the Levinger constant and the contacts. This work provides an important indication for the relevance of the contact formalism to nuclear systems, and should open the path for revealing more useful relations between the contacts and interesting quantities of nuclei and nuclear matter.