The presence of pairing correlations within the time-dependent density-functional-theory (TDDFT) extension to superfluid systems is tantamount to the presence of a quantum collision integral in the evolution equations, which leads to an obviously non-Markovian behavior of the single-particle occupation probabilities, unexpected in a traditional quantum extension of kinetic equations. The quantum generalization of the Boltzmann equation, based on a collision integral in terms of phase-space occupation probabilities, is the most used approach to describe nuclear dynamics and which by construction has a Markovian character. By contrast, the extension of TDDFT to superfluid systems has similarities with the Baym and Kadanoff kinetic formalism, which, however, is formulated with much more complicated evolution equations with long-time memory terms and nonlocal interactions. The irreversibility of quantum dynamics is properly characterized using the canonical wave functions/natural orbitals and the associated canonical occupation probabilities, which provide the smallest possible representation of any fermionic many-body wave function. In this basis, one can evaluate the orbital entanglement entropy, which is an excellent measure of the nonequilibrium dynamics of an isolated system. To explore the phenomena of memory effects and irreversibility, we investigate the use of canonical wave functions/natural orbitals in nuclear many-body calculations, assessing their utility for static calculations, dynamics, and symmetry restoration. As the number of single-particle states is generally quite large, it is highly desirable to work in the canonical basis whenever possible, preferably with a cutoff. We show that truncating the number of canonical wave functions can be a valid approach in the case of static calculations, but that such a truncation is not valid for time-dependent calculations, as it leads to the violation of continuity equation, energy conservation, and other observables, as well as an inaccurate representation of the dynamics. Indeed, in order to describe the dynamics of a fissioning system within a TDDFT framework all the canonical states must be included in the calculation. Finally, we demonstrate that the canonical representation provides a very efficient basis for performing symmetry projections.

The charged particles produced in the ${}^{18}\mathrm{O}+{}^{12}\mathrm{C}$ reaction at 16.7 MeV/nucleon have been detected using the GARFIELD+RCo apparatus at Laboratori Nazionali di Legnaro and compared with the transport code antisymmetrized molecular dynamics (AMD) followed by gemini$++$ as afterburner. To our knowledge, it is the first time that this model is applied to a nuclear reaction between light nuclei at so relatively low bombarding energy. The general agreement between experimental data and model is very good for fragments with $Z\ge 10$, assuming a fusion process source, and for intermediate fragments ($Z=3,4$). A discrepancy in the relative cross section of the different reaction mechanisms has been pointed out for fragments with $4<Z<10$ as the model seems to produce less dissipative reactions.

We investigated the effect of the degree of freedom of neutron transfer on the cross section of heavy-ion fusion reactions, using the relativistic mean-field formalism within the coupled-channels approach (ccfull). We obtain the microscopic nuclear interaction potential in terms of the density distributions for the targets and projectiles with the ${\mathrm{NL}3}^{*}$ parameter set and corresponding R3Y nucleon-nucleon potential. The present analysis includes the ${}^{18}\mathrm{O}$-induced reactions, namely, ${}^{18}\mathrm{O}+{}^{58,60,64}\mathrm{Ni}$, ${}^{18}\mathrm{O}+{}^{74}\mathrm{Ge}$, ${}^{18}\mathrm{O}+{}^{148}\mathrm{Nd}$, ${}^{18}\mathrm{O}+{}^{150}\mathrm{Sm}$, and ${}^{18}\mathrm{O}+{}^{182,184,186}\mathrm{W}$ for which experimental fusion cross sections are available around the Coulomb barrier. It is evident from the results that including vibrational and/or rotational degrees of freedom enhances the fusion cross section at energies below the barrier. However, fusion hindrance persists in this energy region. To address this, we incorporated the two-neutron $\left(2n\right)$ transfer channels in the coupled-channels calculation. A comparison with the Woods-Saxon (WS) potential shows that the R3Y nucleon-nucleon ($NN$) potential, with intrinsic degrees of freedom, is superior to it, especially at energies below the barrier. This superiority can be attributed to the observed higher barrier heights and lower cross section of the WS potential compared to the relativistic R3Y $NN$ potential for the considered reaction systems. Consequently, we employed the relativistic mean-field formalism to estimate fusion characteristics for the unknown ${}^{18}\mathrm{O}$-induced reactions, namely ${}^{18}\mathrm{O}+{}^{62}\mathrm{Ni}$, ${}^{18}\mathrm{O}+{}^{70,72,76}\mathrm{Ge}$, ${}^{18}\mathrm{O}+{}^{144,150}\mathrm{Nd}$, and ${}^{18}\mathrm{O}+{}^{144,148,152,154}\mathrm{Sm}$. Our analysis highlights the significant role of positive $Q$-value neutron transfer in enhancing the sub-barrier fusion cross section for the ${}^{18}\mathrm{O}+{}^{148}\mathrm{Nd}$ reaction with the R3Y $NN$ potential. However, the effect of this transfer channel for the other considered reactions is comparatively less pronounced.

Kavita et al. [Phys. Rev. C 100, 024626 (2019)] analyze the width of the mass distributions of fission fragments from ${}^{28}\mathrm{Si}+{}^{160}\mathrm{Gd}$ and ${}^{12}\mathrm{C}+{}^{178}\mathrm{Hf}$ collisions. The authors report that the distributions “are reproducible with a single Gaussian at all studied energies”. However, the fits presented in the figures show functions that do not correspond to single-Gaussian distributions. A critical analysis, presented here, sheds doubts on the characterization of the mass distributions.

The Comment by Caamaño concerns the issue of single versus multiple Gaussian fits to the observed mass distributions in the fusion-fission reactions as studied in Kavita et al. [Phys. Rev. C 100, 024626 (2019)]. The Comment suggests an alternative approach to the analysis of fission mass distribution data, which appears to deviate from the observed trends of mass distributions at the measured energies and thus was not used in our study. However, we would like to emphasize that multi-Gaussian fit as suggested will not have any impact on the conclusion of our work.

An accurate way to incorporate long-range Coulomb interaction alongside short-range nuclear interaction has been a challenge for theoretical physicists. In this paper, we propose a methodology based on the reference potential approach for constructing inverse potentials for charged particle scattering. The central idea is to obtain the inverse potential directly from the expected scattering phase shifts by comparing them with those obtained by solving the phase equation for a chosen reference potential. The design of the reference potential is key to incorporating the Coulomb interaction successfully. Here, a combination of two smoothly joined Morse functions, one regular followed by an inverted one, is considered. While the former takes care of short-range nuclear and Coulomb interactions, the latter accounts for expected barrier height due to the long-range Coulomb part that dominates once nuclear interaction subsides. The final step is to incorporate the phase equation within an iterative loop of an optimization algorithm to obtain the model parameters for the reference potential by minimizing the mean absolute percentage error between the obtained and expected scattering phase shifts. We have applied the methodology to the $\alpha -\alpha$ system and constructed the inverse potentials for its $S, D$, and $G$ states with mean absolute percentage errors of 0.9, 0.5, and 0.4 respectively. Their respective resonances (experimental), in MeV, are found to be at 0.1240 (0.0918), 2.95 (3.03), and 11.89 (11.35). One can conclude that the reference potential approach using a combination of smoothly joined Morse functions is successful in accurately accounting simultaneously for the short-range nuclear and the long-range Coulomb interactions between charged particles in nuclear scattering studies.

Background: In several processes of stellar nucleosynthesis, like the astrophysical $\gamma$ process, nuclear reactions involving $\alpha$ particles play an important role. The description of these reactions necessitates the knowledge of the $\alpha$-nucleus optical model potential (AOMP) which is highly ambiguous at low, astrophysical energies. This ambiguity introduces a substantial uncertainty in the stellar models for predicting elemental and isotopic abundances.

Purpose: The experimental study of the AOMP is thus necessary, and can be implemented by measuring the cross section of $\alpha$-induced nuclear reactions. At low energies, $(\alpha ,n)$ reactions are suitable for such a purpose. Therefore, in the present work, the $(\alpha ,n)$ cross sections of four Te isotopes have been measured, mostly for the first time, and compared with theoretical predictions.

Method: The $(\alpha ,n)$ cross sections of ${}^{120,122,124,130}\mathrm{Te}$ have been measured in the energy range between about 10 and 17 MeV using the activation method. The detection of the $\gamma$ radiation following the decay of the radioactive reaction products were used to determine the cross sections.

Results: The measured cross sections are compared with statistical model calculations obtained from the widely used talys nuclear reaction simulation code. Predictions using various available AOMPs are investigated.

Conclusions: It is found that the recently developed Atomki-V2 AOMP provides the best description for all studied reactions, and this potential also reproduces well the total reaction cross sections from elastic scattering experiments, when they are available in literature. We recommend therefore to use the astrophysical reaction rates based on this potential for nucleosynthesis models of heavy elements.

We calculate two-body scattering phase shifts on a quantum computer using a leading order short-range effective field theory Hamiltonian. The algorithm combines the variational quantum eigensolver and the quantum subspace expansion. As an example, we consider scattering in the deuteron ${}^3{S}_1$ partial wave. We calculate scattering phase shifts with a quantum simulator and on real hardware. We also study how noise impacts these calculations and discuss noise mitigation required to extend our work to larger quantum processing units. With current hardware, up to five superconducting qubits can produce acceptable results, and larger calculations will require a significant noise reduction.

We investigate the fusion cross sections of light nuclei in the presence of linearly polarized intense laser fields. By combining the Coulomb-Volkov solutions with the complex spherical square-well nuclear potential, we derive an explicit formulation of the multiphoton cross section in a self-consistent manner. Our analysis is specifically focused on deuteron-triton (DT) and proton-boron ($p{}^{11}\mathrm{B}$) fusion reactions, both of which have garnered widespread attention. The theoretical results reveal that, under conditions of longer laser wavelengths and lower incident particle kinetic energies, a few thousands of photons can participate in the fusion reactions, resulting in a substantial enhancement of fusion cross sections by almost ten orders of magnitude. We elucidate the multiphoton mechanism underlying these findings and discuss their implications.

The correlation between the mean transverse momentum and the harmonic flow coefficients is an observable which is of great interest; it is sensitive to shape fluctuations in the initial state of a relativistic nuclear collision. The measurement of that correlation coefficient in central collisions allows one to infer about the intrinsic deformation of the colliding nuclei. We propose to study the momentum-dependent covariance and correlation coefficient between the mean transverse momentum and the harmonic flow in a given transverse momentum bin. Two possible constructions of such observables are provided and predictions are obtained from a viscous hydrodynamic model. We find that such momentum-dependent correlation coefficients between the mean transverse momentum and the harmonic flow show a strong and nontrivial momentum dependence. We also explore the effects of granularity (nucleon width) in the initial state, the nuclear deformation, and the shear viscosity on this momentum-dependent correlation coefficient. The shape of the momentum dependence of the correlation coefficient for the triangular flow is found to be sensitive to the size of small-scale fluctuations in the initial state. On the other hand, the shape of the momentum dependence of the covariance between the mean transverse momentum and the harmonic flow coefficients is found to be sensitive to the value of the shear viscosity and to the granularity of the initial state.

The production of light nuclei in isobaric ${}_{44}{}^{96}\mathrm{Ru}+{}_{44}{}^{96}\mathrm{Ru}$ and ${}_{40}{}^{96}\mathrm{Zr}+{}_{40}{}^{96}\mathrm{Zr}$ collisions, ranging from $\sqrt{s_{NN}}=7.7$ to 200 GeV, are studied using the string melting version of a multiphase transport model in combination with a coalescence approach to light nuclei production. From the calculated yields, transverse momentum ($p_T$) spectra, and rapidity dependences of light nuclei ($p, n, d, t, {}^3\mathrm{He}$), we find that the $\mathrm{Ru}+\mathrm{Ru}/\mathrm{Zr}+\mathrm{Zr}$ ratios for the yields of these particles exceed unity with the inclusion of a quadrupole deformation ${\beta }_2$ and octupole deformation ${\beta }_3$ as well as the neutron skins. We also find that heavier particles have a larger deviation from unity. Furthermore, we find that as the collision energy increases, the influence of isospin effects on the production of light nuclei in isobar collisions gradually decreases, while the influence of nuclear structure becomes more significant, particularly evident from the energy dependence of the deuteron ratio, which is unaffected by isospin effects.

Mixed species charge and baryon balance functions are computed based on proton-proton ($pp$) collisions simulated with the PYTHIA8 model. Simulations are performed with selected values of the collision energy $\sqrt{s}$ and the Monash tune and the ropes and shoving modes of PYTHIA8 to explore whether such measurements provide useful new information and constraints on mechanisms of particle production in $pp$ collisions. Charge balance functions are studied based on mixed pairs of pions, kaons, and protons, whereas baryon balance functions are computed for mixed low mass strange and nonstrange baryons. Both charge and baryon balance functions of mixed particle pairs feature shapes and amplitudes that sensitively depend on the particle considered owing largely to the particle production mechanisms implemented in PYTHIA. The evolution of balance functions integrals with the longitudinal width of the acceptance are presented and one finds that sums of such integrals for a given reference particle obey expected sum rules for both charge and baryon balance functions. Additionally, both types of balance functions are found to evolve in shape and amplitude with increasing collision energy $\sqrt{s}$ and the PYTHIA tunes considered.

The single-differential and fully integrated cross sections for quasifree ${\pi }^{+}{\pi }^{-}$ electroproduction off protons bound in deuterium have been extracted for the first time. The experimental data were collected at Jefferson Laboratory with the CLAS detector. The measurements were performed in the kinematic region of the invariant mass $W$ from 1.3 to 1.825 GeV and the photon virtuality $Q^2$ from 0.4 to 1.0 ${\mathrm{GeV}}^2$. Sufficient experimental statistics allowed for narrow binning in all kinematic variables, while maintaining a small statistical uncertainty. The extracted cross sections were compared with the corresponding cross sections off free protons, which allowed us to obtain an estimate of the contribution from events in which interactions between the final-state hadrons and the spectator neutron took place.

The electro- and photoproduction of the $J/\psi$ meson near the threshold from the proton are relevant to the search of hidden charm pentaquark candidates reported by the LHCb collaboration, and the study of the contribution of the quantum chromodynamics (QCD) trace anomaly to the proton mass. It is also expected to be sensitive to the QCD van der Waals interaction, that is mediated by multigluon exchanges and expected to dominate the interaction between two hadrons with no common valence quarks. Subthreshold production of $J/\psi$ from a nuclear target is expected to enhance such attractive interaction, and also allows for a direct probe of short range correlations inside a nucleus. With the high luminosity capability of the 12-GeV CEBAF facility at Jefferson Laboratory, high-precision data on $J/\psi$ meson production from the proton are becoming available, providing also a reference for subthreshold $J/\psi$ production from the deuteron. Data from the deuteron will establish the baseline for subthreshold $J/\psi$ production from other nuclear targets. In this paper, we present our findings from a feasibility study of subthreshold $J/\psi$ production from the deuteron using the proposed Solenoidal Large Intensity Device (SoLID), and discuss the potential physics impact of such data.

About half of the heavy elements beyond iron are known to be produced by the rapid neutron capture process, known as the $r$ process. However, the astrophysical site producing the $r$ process is still uncertain. Chemical abundances observed in several cosmic sites indicate that different mechanisms should be at play. For instance, the abundances around silver measured in a subset of metal-poor stars indicate the presence of a weak $r$ process. This process may be active in neutrino-driven winds of core collapse supernovae where $(\alpha ,n)$ reactions dominate the synthesis of $Z\approx 40$ elements in the expelled materials. Scarcely measured, the rates of $(\alpha ,n)$ reactions are determined from statistical Hauser-Feshbach calculations with $\alpha$-optical-model potentials, which are still poorly constrained. The uncertainties of the $(\alpha ,n)$ reaction rates therefore make a significant contribution to the uncertainties of the abundances determined from stellar modeling. In this work, the ${}^{88}\mathrm{Sr}(\alpha ,n){}^{91}\mathrm{Zr}$ reaction which impacts the weak $r$-process abundances has been probed at astrophysics energy for the first time; directly measuring the total cross sections at astrophysical energies of 8.37–13.09 MeV in the center of mass (3.8–7.5 GK). Two measurements were performed at ATLAS with the electrically segmented ionization chamber MUSIC, in inverse kinematics, while following the active target technique. The cross sections of this $\alpha$-induced reaction on ${}^{88}\mathrm{Sr}$, located at the shell closure $N=50$, have been found to be lower than expected, by a factor of 3, despite recent statistical calculations validated by measurements on neighboring nuclei. This result encourages more experimental investigations of ($\alpha ,n$) reactions, at $N=50$ and towards the neutron-rich side, to further test the predictive power and reliability of such calculations.

Ab initio calculations have achieved remarkable success in nuclear structure studies. Numerous works highlight the pivotal role of three-body forces in nuclear ab initio calculations. Concurrently, efforts have been made to replicate these calculations using only realistic nucleon-nucleon $\left(NN\right)$ interactions. A novel local chiral next-to-next-to-next-to-leading order $\left({\mathrm{N}}^3\mathrm{LO}\right)$ $NN$ interaction, distinct due to its weaker tensor force, has recently been established. This paper applies this local $NN$ interaction in ab initio frameworks to calculate the low-lying spectra of $p$-shell light nuclei, particularly ${}^{10}\mathrm{B}$, ground-state energies and shell evolution in oxygen isotopes. Results are compared with calculations utilizing nonlocal chiral ${\mathrm{N}}^3\mathrm{LO}NN$ and chiral $NN+3N$ interactions. The ab initio calculations with the local $NN$ potential accurately describe the spectra of $p$-shell nuclei, notably the ${}^{10}\mathrm{B}$. Additionally, the neutron drip line for oxygen isotopes, with ${}^{24}\mathrm{O}$ as the drip line nucleus, is accurately reproduced in ab initio calculations with the local $NN$ interaction. Calculations with the local $NN$ interaction also reproduce the subshell closure at $N=14$ and 16, albeit with a stronger shell gap compared to experimental data. However, the calculated charge radii based on the local $NN$ interaction are underestimated compared with experimental data, which is similar to results from the nonlocal $NN$ interaction. Consequently, the present ab initio calculations further indicate significant spin-orbit splitting effects with the new local $NN$ potential, suggesting that 3N forces remain an important consideration.