The origin of weakly bound nuclear clusters in hadronic collisions is a key question to be addressed by heavy-ion collision (HIC) experiments. The measured yields of clusters are approximately consistent with expectations from phenomenological statistical hadronization models (SHMs), but a theoretical understanding of the dynamics of cluster formation prior to kinetic freeze-out is lacking. The competing model is nuclear coalescence, which attributes cluster formation to the effect of final state interactions (FSI) during the propagation of the nuclei from kinetic freeze-out to the observer. This phenomenon is closely related to the effect of FSI in imprinting femtoscopic correlations between continuum pairs of particles at small relative momentum difference. We give a concise theoretical derivation of the coalescence-correlation relation, predicting nuclear cluster spectra from femtoscopic measurements. We review the fact that coalescence derives from a relativistic Bethe-Salpeter equation, and recall how effective quantum mechanics controls the dynamics of cluster particles that are nonrelativistic in the cluster center-of-mass frame. We demonstrate that the coalescence-correlation relation is roughly consistent with the observed cluster spectra in systems ranging from PbPb to $p\mathrm{Pb}$ and $pp$ collisions. Paying special attention to nuclear wave functions, we derive the coalescence prediction for the hypertriton and show that it, too, is roughly consistent with the data. Our work motivates a combined experimental programme addressing femtoscopy and cluster production under a unified framework. Upcoming $pp, p\mathrm{Pb}$, and peripheral PbPb data analyzed within such a program could stringently test coalescence as the origin of clusters.

Background: Classical novae result from thermonuclear explosions producing several $\gamma$-ray emitters which are prime targets for satellites observing in the MeV range. The early $\le 511\mathrm{keV}$ $\gamma$-ray emission depends critically on the ${}^{18}\mathrm{F}(p,\alpha ){}^{15}\mathrm{O}$ reaction rate which, despite many experimental and theoretical efforts, still remains uncertain.

Purpose: One of the main uncertainties in the ${}^{18}\mathrm{F}(p,\alpha ){}^{15}\mathrm{O}$ reaction rate is the contribution in the Gamow window of interference between sub-threshold ${}^{19}\mathrm{Ne}$ states and known broad states at higher energies. Therefore the goal of this work is to clarify the existence and the nature of these sub-threshold states.

Methods: States in the ${}^{19}\mathrm{Ne}$ compound nucleus were studied at the Tandem-ALTO facility using the ${}^{19}\mathrm{F}({}^3\mathrm{He},t){}^{19}\mathrm{Ne}$ charge-exchange reaction. Tritons were detected with an Enge Split-pole spectrometer while decaying protons or $\alpha$ particles from unbound ${}^{19}\mathrm{Ne}$ states were collected, in coincidence, with a double-sided silicon strip detector array. Angular correlations were extracted and constraints on the spin and parity of decaying states established.

Results: The coincidence yield at $E_x=6.29\mathrm{MeV}$ was observed to be high spin, supporting the conclusion that it is indeed a doublet consisting of high-spin and low-spin components. Evidence for a broad, low-spin state was observed around 6 MeV. Branching ratios were extracted for several states above the proton threshold and were found to be consistent with the literature. $\mathcal{R}$-matrix calculations show the relative contribution of sub-threshold states to the astrophysically important energy region above the proton threshold.

Conclusions: The levels schemes of ${}^{19}\mathrm{Ne}$ and ${}^{19}\mathrm{F}$ are still not sufficiently well known and further studies of the analog assignments are needed. The tentative broad state at 6 MeV may only play a role if the reduced proton width is large.

Electric dipole moments of nuclei, diamagnetic atoms, and certain molecules are induced by $CP$-violating nuclear forces. Naive dimensional analysis predicts these forces to be dominated by long-range one-pion-exchange processes with short-range forces entering only at next-to-next-to-leading order in the chiral expansion. Based on renormalization arguments we argue that a consistent picture of $CP$-violating nuclear forces requires a leading-order short-distance operator contributing to ${}^{1}S_0\text{−}{}^{3}P_0$ transitions due to the attractive and singular nature of the strong tensor force in the ${}^{3}P_0$ channel. The short-distance operator leads to $O\left(1\right)$ corrections to static and oscillating, relevant for axion searches, electric dipole moments. We discuss strategies how the finite part of the associated low-energy constant can be determined in the case of $CP$ violation from the QCD $\overline{\theta }$ term by the connection to charge-symmetry violation in nuclear systems.

We propose a hybrid approach between the sudden model and the adiabatic model to explain the fusion hindrance in heavy-ion fusion reactions at deep subbarrier energies. Due to the strong Pauli blocking effects at the density overlap region, the $\alpha$ particle approaching the target ${}^{208}\mathrm{Pb}$ becomes enlarged and its density distribution gets changed. By introducing energy dependence into this density variation effect, the potentials at different colliding energies are diverse. With the decrease of colliding energies, the significantly enhanced density variation effects make the nuclear potential more attractive and result in a deeper pocket in the inner part. A reasonable description of the experimental fusion cross sections is achieved for the $\alpha + {}^{208}\mathrm{Pb}$ reaction. On account of highlighting the influence of density variation effects on the fusion process at deep subbarrier energies, we further investigate the density variation effects in the ${}^{16}\mathrm{O} + {}^{208}\mathrm{Pb}$ fusion reaction based on the $\alpha$-cluster structures in ${}^{16}\mathrm{O}$ nuclei. The fusion hindrance at deep subbarrier energies is described well by considering the density variation effects. In addition, an astrophysical $S$ factor between the sudden model and adiabatic model is predicted at the energies below the experimental data.

Neutron-rich radioactive isotope (RI) beams in the vicinity of ${}^{110}\mathrm{Zr}$ were produced using the in-flight fission of a 345-MeV/nucleon ${}^{238}\mathrm{U}$ beam at the RIKEN Radioactive Isotope Beam Factory. The RI beams were separated in flight by the large-acceptance two-stage fragment separator BigRIPS. Isotopes were clearly identified in a low-background particle-identification plot, which was obtained from the measurements of time of flight, magnetic rigidity, and energy loss using beam-line detectors placed in the BigRIPS separator and the ZeroDegree spectrometer. Nine new isotopes, ${}^{101}\mathrm{Br}, {}^{102}\mathrm{Kr}, {}^{105,106}\mathrm{Rb}, {}^{108}\mathrm{Sr}, {}^{110,111}\mathrm{Y}, {}^{114}\mathrm{Zr}$, and ${}^{117}\mathrm{Nb}$, are reported for the first time, with their measured production cross sections compared with the extrapolations of lighter isotopes down to the femtobarn regime.

The Hauser-Feshbach fission fragment decay model, ${\mathrm{HF}}^3\mathrm{D}$, which calculates the statistical decay of fission fragments, has been expanded to include multichance fission, up to neutron incident energies of 20 MeV. The deterministic decay takes as input prescission quantities—fission probabilities and the average energy causing fission—and postscission quantities—yields in mass, charge, total kinetic energy, spin, and parity. From these fission fragment initial conditions, the full decay is followed through both prompt and delayed particle emissions, allowing for the calculation of prompt neutron and $\gamma$ properties, such as multiplicity and energy distributions, both independent and cumulative fission yields, and delayed neutron observables. In this work, we describe the implementation of multichance fission in the ${\mathrm{HF}}^3\mathrm{D}$ model, and show an example of prompt and delayed quantities beyond first-chance fission, using the example of neutron-induced fission on ${}^{235}\mathrm{U}$. This expansion represents significant progress in consistently modeling the emission of prompt and delayed particles from fissile systems.

The production of ${}_{\mathrm{\Lambda }}{}^3\mathrm{H}$ and ${}_{\overline{\mathrm{\Lambda }}}{}^3\overline{\mathrm{H}}$, as well as ${}^3\mathrm{H}, {}^3\overline{\mathrm{H}}, {}^3\mathrm{He}$, and ${}^3\overline{\mathrm{H}}\mathrm{e}$ are studied in central collisions of isobars ${}_{44}{}^{96}\mathrm{Ru}+{}_{44}{}^{96}\mathrm{Ru}$ and ${}_{40}{}^{96}\mathrm{Zr}+{}_{40}{}^{96}\mathrm{Zr}$ at $\sqrt{s_{\mathrm{NN}}}=200$ GeV, using the dynamically constrained phase-space coalescence model and the paciae model with chiral magnetic effect. The yield, yield ratio, coalescence parameters, and strangeness population factor of (anti-)hypertriton and (anti-)nuclei produced in isobaric ${}_{44}{}^{96}\mathrm{Ru}+{}_{44}{}^{96}\mathrm{Ru}$ and ${}_{40}{}^{96}\mathrm{Zr}+{}_{40}{}^{96}\mathrm{Zr}$ collisions are predicted. The (anti-)hypertriton and (anti-)nuclei production is found to be insensitive to the chiral magnetic effects. Experimental data of $\text{Cu}+\text{Cu}, \text{Au}+\text{Au,}$ and $\text{Pb}+\text{Pb}$ collisions from RHIC, LHC, and the results of the paciae $+$ dcpc model are presented in the results for comparison.

We investigate the pentaquark system $qqqs\overline{q}$ in a framework of chiral quark model. Two structures, $\left(qqq\right)\left(s\overline{q}\right)$ and $\left(qqs\right)\left(q\overline{q}\right)$, with all possible color, spin, flavor configurations are considered. The calculations show that there are several possible resonance states, $\mathrm{\Sigma }\pi$ and $N\overline{K}$ state with $I{J}^P=0{\frac{1}{2}}^{-}$, ${\mathrm{\Sigma }}^{*}\pi$ with $I{J}^P=0{\frac{3}{2}}^{-}$, ${\mathrm{\Sigma }}^{*}\rho$ with $I{J}^P=0{\frac{5}{2}}^{-}$, $\mathrm{\Delta }\overline{K}$ with $I{J}^P=1{\frac{3}{2}}^{-}$, and $\mathrm{\Delta }{\overline{K}}^{*}$ with $I{J}^P=1{\frac{5}{2}}^{-}$. Where the $N\overline{K}$ state with $I{J}^P=0{\frac{1}{2}}^{-}$ can be used to explain the $\mathrm{\Lambda }\left(1405\right)$, and together with another state $\mathrm{\Sigma }\pi$ is related to the two-pole structure of the scattering amplitude proposed before. The decay properties of $\mathrm{\Lambda }\left(1520\right)$ prevent the assignment of ${\mathrm{\Sigma }}^{*}\pi$ with $I{J}^P=0{\frac{3}{2}}^{-}$ to $\mathrm{\Lambda }\left(1520\right)$, although the energy $\approx 1518\mathrm{MeV}$ of ${\mathrm{\Sigma }}^{*}\pi$ is close to experimental value of $\mathrm{\Lambda }\left(1520\right)$. Other resonance states generally have a large width.

Hyperfine spectra of ${}^{27–32}\mathrm{Al}$ ($Z=13$) have been measured at the ISOLDE-CERN facility via collinear laser spectroscopy using the $3s^{2}3p{}^2{P}_{3/2}^{\text{o}}\to 3s^{2}4s{}^2{S}_{1/2}$ atomic transition. For the first time, mean-square charge radii of radioactive aluminum isotopes have been determined alongside the previously unknown magnetic dipole moment of ${}^{29}\mathrm{Al}$ and electric quadrupole moments of ${}^{29,30}\mathrm{Al}$. A potentially reduced charge radius at $N=19$ may suggest an effect of the $N=20$ shell closure, which is visible in the Al chain, contrary to other isotopic chains in the $sd$ shell. The experimental results are compared with theoretical calculations in the framework of the valence-space in-medium similarity renormalization group using multiple sets of two- and three-nucleon forces from chiral effective field theory. While the trend of experimental magnetic dipole and electric quadrupole moments is well reproduced, the absolute values are underestimated by theory, which is consistent with earlier studies. Moreover, both the scale and trend of the charge radii appear to be very sensitive to the chosen interaction.

Isomeric states and associated collective structures have been studied up to high spin in ${}^{198,200,202}\mathrm{Hg}$ using multinucleon transfer reactions and the Gammasphere array. A coupled rotational band, with possible four-quasiparticle character, is established in ${}^{198}\mathrm{Hg}$. Sequences built on two-quasiparticle, positive- and negative-parity levels are assigned to ${}^{202}\mathrm{Hg}$. New isomers in ${}^{202}\mathrm{Hg}$ with $I^{\pi }=\left(7^{-}\right)$ and $\left(9^{-}\right)$, and $T_{1/2}$ = 10.4(4) ns and 1.4(3) ns, respectively, have been identified. A half-life of 1.0(3) ns is established for the $I^{\pi }={12}^{+}$ state in ${}^{200}\mathrm{Hg}$. $B\left(E2\right)$ values deduced from isomeric transitions in Hg isotopes indicate that, while collectivity near the ground state gradually diminishes from $N$ = 112 to $N$ = 124, it is found to increase for the ${12}^{+}$ and $9^{-}$ states up to $N$ = 118, followed by a reduction for higher neutron numbers. Calculations using the ultimate cranker code provide insight into the variation of deformation with spin and allow for an understanding of observed band crossings. The evolution of collectivity with spin, and along the isotopic chain, is described.

The calculable $R$-matrix theory has been formulated successfully for regular boundary conditions with vanishing radial wave functions at the coordinate origins [P. Descouvemont and D. Baye, Rep. Prog. Phys. 73, 036301 (2010)]. We generalize the calculable $R$-matrix theory to the incoming-wave boundary condition (IWBC), which is widely used in theoretical studies of low-energy heavy-ion fusion reactions to simulate the strong absorption of incoming flux inside the Coulomb barriers. The generalized calculable $R$-matrix theory also provides a natural starting point to extend eigenvector continuation (EC) [D. Frame et al., Phys. Rev. Lett. 121, 032501 (2018)] to fusion observables. The ${}^{14}\mathrm{N}+{}^{12}\mathrm{C}$ fusion reaction is taken as an example to validate these new theoretical tools. Both local and nonlocal potentials are considered in numerical calculations. Our generalizations of the calculable $R$-matrix theory and EC are found to work well for IWBC.

A second order relativistic hydrodynamic theory has been derived using momentum dependent relaxation time in the relativistic transport equation. In order to do that an iterative technique of gradient expansion approach, namely the Chapman-Enskog (CE) expansion of the particle distribution function has been employed. The key findings of this work are (i) momentum dependent relaxation time in the collision term results in an extended Landau matching condition for the thermodynamic variables, (ii) the result from the numerical solution of the Boltzmann equation lies somewhere in between the two popular extreme limits: linear and quadratic ansatz, indicating a fractional power of momentum dependence in relaxation time to be appropriate, (ii) an equivalence has been established between the iterative gradient expansion method like CE and the well known moment approach like Grad's 14-moment method.

We propose a novel semiclassical approach to intranuclear cascades, which takes as input quantum Monte Carlo nuclear configurations and uses a semiclassical, impact-parameter-based algorithm to model the propagation of protons and neutrons in the nuclear medium. We successfully compare our simulations to available proton-carbon scattering data and nuclear-transparency measurements. By analyzing the dependence of the simulated observables upon the ingredients entering our intranuclear cascade algorithm, we provide a quantitative understanding of their impact. Particular emphasis is devoted to the role played by nuclear correlations, the Pauli exclusion principle, and interaction probability distributions.

In this paper we develop a model to describe $\nu$ and $\overline{\nu }$ scattering in the GeV region by nuclei within a nuclear matter quantum hadrodynamics approach that is fully relativistic. We simplify it as much as possible, keeping the most relevant effects and trying to describe the greatest number of observables. We introduce explicitly the effect of ground-state correlations through a momentum distribution calculated perturbatively, and also final-state interactions using a perturbed nucleon propagator dressed by a relativistic self-energy containing nucleon-nucleon and $\mathrm{\Delta }$-nucleon correlations. Also, primary $\mathrm{\Delta }$ excitations are considered within a consistent approach. All these mentioned effects are built on together, into the Lehmann representation of the propagator. Within our model we take into account the effect of 2p2h and 3p3h excitations in addition to the quasielastic 1p1h ones, needed to describe the experimental data. The obtained results are promising, showing that the model works quit well and thus putting to disposal a simple but powerful approach developed within the context of nuclear matter field theory.

The ${}^{26}\mathrm{Si}(p,\gamma ){}^{27}\mathrm{P}$ reaction might be relevant in understanding the ${}^{26}\mathrm{Si}$ depletion and ${}^{26}\mathrm{Al}$ production in stars. The asymptotic normalization coefficients (ANC) for the ${}^{26}\mathrm{Si}(p,\gamma ){}^{27}\mathrm{P}$ reaction were extracted earlier from the reanalysis of ${}^{26}\mathrm{Mg}(d,p){}^{27}\mathrm{Mg}$ and ${}^{26}\mathrm{Mg}(t,d){}^{27}\mathrm{Mg}$ reactions, in which the deduced ANC's show significant discrepancies. In this work, a dedicated ($d,p$) measurement is presented: the ANC for the ${}^{27}\mathrm{Mg}\to {}^{26}\mathrm{Mg}+n$ virtual decay is deduced from the ${}^{26}\mathrm{Mg}(d,p){}^{27}\mathrm{Mg}$ reaction populating the ground and the first excited state of ${}^{27}\mathrm{Mg}$ using the distorted wave Born approximation (DWBA). The charge symmetry properties for mirror nuclei have been used to calculate the ANC for the direct capture ${}^{26}\mathrm{Si}+p\to {}^{27}\mathrm{P}$ populating the ground state of ${}^{27}\mathrm{P}$. By means of the same formalism, the ${\mathrm{\Gamma }}_p$ width for the first excited state has also been deduced. The reaction rate is also updated using recent values for the ${\mathrm{\Gamma }}_{\gamma }/{\mathrm{\Gamma }}_p$ ratio measured by [Sun et al., Phys. Rev. C 99, 064312 (2019); Sun et al., Phys. Lett. B 802, 135213 (2020)].

Neutron-rich nuclei ${}^{162,164}\mathrm{Eu}$ were produced by bombarding a proton beam on a ${}^{238}\mathrm{U}$ target at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory and mass separating the ${}^{162,164}\mathrm{Eu}$ products. New level schemes and new $\gamma$-ray transitions of the daughters ${}^{162,164}\mathrm{Gd}$ were identified from $\beta$-decay spectroscopy studies. Half-lives of the ${}^{162,164}\mathrm{Eu}$ were remeasured to clarify the previous ambiguous results. Two quasiparticle band structures were built and compared with neighboring nuclei. The $\beta$ and $\gamma$ bands were extended in ${}^{162}\mathrm{Gd}$ and a $\gamma$ band was extended in ${}^{164}\mathrm{Gd}$. Half-lives of the isomeric states at ($6^{-}$) 1449 keV in ${}^{162}\mathrm{Gd}$ and ($4^{-}$) 1096 keV in ${}^{164}\mathrm{Gd}$ were measured to be 99(3) $\mu \mathrm{s}$ and 0.56(3) $\mu \mathrm{s}$, respectively. Projected shell model calculations were performed and found to be in good agreement with all of the experimental data.

Two methods used to subtract the effect of the decay of different nuclear reaction products on the cross-section measurement of the studied nuclear reaction were given. Taking the cross-section measurement of the ${}^{91}\mathrm{Zr}(n,p){}^{91\mathrm{m}}\mathrm{Y}$ reaction as an example, the accurate and reliable cross section of the ${}^{91}\mathrm{Zr}(n,p){}^{91\mathrm{m}}\mathrm{Y}$ reaction in the neutron energy range of 13.5–14.8 MeV was measured by using the activation technique and the above two methods. Moreover, the excitation function in the neutron energies from the threshold to 21 MeV was calculated by using the nuclear theoretical model program system talys–1.9 with the adjusted relevant parameters. The measured cross-section values were discussed and compared with previous experiments by other researchers and with the theoretical values based on talys–1.9. The experimental values obtained by the above two methods were highly consistent within experimental error, and at some neutron energies they were consistent, within experimental error, with those of the fitting line of previous experiments at the corresponding energies, and were also consistent with those of theoretical excitation curve at the corresponding energies. The obtained theoretical excitation curve can match most of the experimental data.

We report ab initio benchmark calculations of nuclear matrix elements (NMEs) for neutrinoless double-$\beta$ ($0\nu \beta \beta$) decays in light nuclei with mass numbers ranging from $A=6$ to $A=22$. We use the transition operator derived from light-Majorana neutrino exchange and evaluate the NME with three different methods: two variants of in-medium similarity renormalization group (IMSRG) and importance-truncated no-core shell model (IT-NCSM). The same two plus three nucleon interaction from chiral effective field theory is employed, and both isospin-conserving ($\mathrm{\Delta }T=0$) and isospin-changing ($\mathrm{\Delta }T=2$) transitions are studied. We compare our resulting ground-state energies and NMEs to those of recent ab initio no-core shell model and coupled-cluster calculations, also with the same inputs. We show that the NMEs of $\mathrm{\Delta }T=0$ transitions are in good agreement among all calculations, at the level of 10%. For $\mathrm{\Delta }T=2$, relative deviations are more significant in some nuclei. The comparison with the exact IT-NCSM result allows us to analyze these cases in detail, and indicates the next steps toward improving the IMSRG-based approaches. The present study clearly demonstrates the power of consistent cross checks that are made possible by ab initio methodology. This capability is crucial for providing meaningful many-body uncertainties in the NMEs for the $0\nu \beta \beta$ decays in heavier candidate nuclei, where quasiexact benchmarks are not available.

High-spin excited states of ${}^{135}\mathrm{Pm}$ have been investigated using the ${}^{107}\mathrm{Ag}({}^{32}\mathrm{S}$, $2p2n$) reaction at 145-MeV beam energy. Three negative-parity bands have been investigated up to $\sim 9.0-$, $7.6-$, and $6.9-\mathrm{MeV}$ excitation energies with spin parities $(55/2^{-})$, $(49/2^{-})$, and $(47/2^{-})\hslash$, respectively. The experimental results have been interpreted using the triaxial projected shell model. It is shown that the observation of the parallel band structures can be explained in terms of crossing of two $s$ bands with the yrast band, which is a rare phenomenon for an odd-$A$ nucleus. Further, the lifetimes of levels in yrast band have been extracted using Doppler shift attenuation method. The evaluated $B\left(E2\right)$ values of yrast states show the loss of collectivity at higher spin, attributed to the alignment process.