A comparative analysis of the breakup cross-sections, using continuum discretized coupled-channel approach, is presented for the weakly bound $p\text{−}$wave neutron-${}^7\mathrm{Li}$ and nucleon-${}^7\mathrm{Be}$ projectiles on the ${}^{208}\mathrm{Pb}$ target, by investigating the role of interaction effects between the core $({}^7\mathrm{Li},$ ${}^7\mathrm{Be})$ with the target. The extra charge in the ${}^8\mathrm{B}$ has the effect to increase the Coulomb contribution in the breakup reaction channel. By fixing both projectile ground-state binding energies at 0.137 MeV (${}^8\mathrm{B}$ experimental one), with incident energies at the Coulomb barrier and above, we found that the charge difference accounts for over 30% of the neutron$\text{−}{}^7\mathrm{Be}$ breakup cross sections, substantially larger than the corresponding one for proton$\text{−}{}^7\mathrm{Be}$. The large enhancement of the neutron-halo breakup cross-section with respect to the proton-halo case shown in this work is associated to dynamical effects coming from the excitation of the projectile internal continuum due to the nucleon-target and core-target interactions, together with the widely accepted static effects coming from the long wave-function tail of the weakly bound neutron. The interplay between these dynamical and static effects in the energy spectrum of the ${}^8\mathrm{B}$ fragments is visible, revealed by the peak of the energy distribution pushed to higher relative energies. This follows from the two-body final state interactions between the charged fragments distorted by the three-body reaction environment.

Neutron-proton equilibration is a process which has been used to study the density dependence of the symmetry energy term in the nuclear equation-of-state. This study utilizes constrained molecular dynamics (CoMD) simulations of ${}^{70}\mathrm{Zn}+{}^{70}\mathrm{Zn}$ with collision energies of 35 and 45 MeV/nucleon. An algorithm is used which searches through CoMD events and identifies the PLF* after it separates from the target and determines its lifetime, $\mathrm{\Delta }t$. It also determines the fragments that the PLF* breaks apart into and determines their angular alignment. This technique gives an opportunity to explore how the average alignment of dynamically produced fragments, ${〈\alpha 〉}_{\mathrm{dyn}}$, evolves with PLF* lifetime. An approximately linear relationship was determined with $d{〈\alpha 〉}_{\mathrm{dyn}}/d\mathrm{\Delta }t=0.98\pm 0.08\mathrm{rad}/\mathrm{zs}$ and $1.06\pm 0.09\mathrm{rad}/\mathrm{zs}$ for the 35 and $45\mathrm{MeV}/\mathrm{nucleon}$, respectively, indicating a correlation with magnitude consistent with classically determined values which were used for prior experimental studies.

Measurements of the net polarization of $\mathrm{\Lambda }$ and $\overline{\mathrm{\Lambda }}$ hyperons at the Relativistic Heavy Ion Collider have stimulated much interest in how strange quarks might align their spin with the vorticity of the matter created in heavy ion collisions. We calculate the Lagrangian in the rest frame of a fluid element undergoing rotation with angular velocity $\omega$ including photon and gluon fields. There is an additional coupling between the quarks and the gauge fields proportional to $\omega$, but this vertex does not change the spin of the quarks. We also show that the times to equilibrate quark helicity and spin parallel to the vorticity are the same so long as $\omega$ is small compared to the temperature.

In the limit of a large number of colors $\left(N\right)$, both Yang-Mills and quantum chromodynamics are expected to have a first-order phase transition separating a confined hadronic phase and a deconfined plasma phase. One aspect of this separation is that at large $N$, one can unambiguously identify a plasma regime that is strongly coupled. The existence of a first-order transition suggests that the hadronic phase can be superheated and the plasma phase supercooled. The supercooled deconfined plasma present at large $N$, if it exists, has the remarkable property that it has negative absolute pressure—i.e., a pressure below that of the vacuum. For energy densities of order unity in a $1/N$ expansion but beyond the endpoint of the hadronic superheated phase, a description of homogeneous matter composed of ordinary hadrons with masses of order unity in a $1/N$ expansion can exist, and acts as though it has a temperature of $T_H$ in order unity. However, the connection between the canonical and microcanonical descriptions breaks down and the system cannot fully equilibrate as $N\to \infty$. Rather, in a hadronic description, energy is pushed to hadrons with masses that are arbitrarily large. The thermodynamic limit of large volumes becomes subtle for such systems: the energy density is no longer intensive. These conclusions follow provided that standard large-$N$ scaling rules hold, the system at large $N$ undergoes a generic first-order phase transition between the hadronic and plasma phases and that the mesons and glueballs follow a Hagedorn-type spectrum.

Low-lying excited states in the $N=32$ isotope ${}^{50}\mathrm{Ar}$ were investigated by in-beam $\gamma$-ray spectroscopy following proton- and neutron-knockout, multinucleon removal, and proton inelastic scattering at the RIKEN Radioactive Isotope Beam Factory. The energies of the two previously reported transitions have been confirmed, and five additional states are presented for the first time, including a candidate for a $3^{-}$ state. The level scheme built using $\gamma \gamma$ coincidences was compared to shell-model calculations in the $sd\text{−}pf$ model space and to ab initio predictions based on chiral two- and three-nucleon interactions. Theoretical proton- and neutron-knockout cross sections suggest that two of the new transitions correspond to $2^{+}$ states, while the previously proposed $4_1^{+}$ state could also correspond to a $2^{+}$ state.

A new analysis of the data from measurements of $\gamma$ radiation following spontaneous fission of ${}^{248}\mathrm{Cm}$ and ${}^{252}\mathrm{Cf}$, performed using the Eurogam2 and Gammashpere arrays, respectively, has revealed, for the first time, excited states in the neutron-rich nucleus ${}^{154}\mathrm{Ce}_{96}$. Using these fission data we have also improved uncertainties on $\gamma$-ray energies in the ground-state bands of several neutron-rich nuclei of the $\mathrm{A}\approx 150$ mass region. The improved data provided precise systematics of the ${\mathrm{E}}_{\mathrm{exc}}\left(4^{+}\right)/{\mathrm{E}}_{\mathrm{exc}}\left(2^{+}\right)$ ratio in the region, which indicate that, in the Ce isotopic chain, the rigid-rotation limit is reached at the neutron number $N=96$, two neutrons “later” than in the chain of Nd isotopes. The new results suggest the involvement of the proton $9/2^{+}\left[404\right]$ extruder orbital in generating nuclear deformation in the $\mathrm{A}\approx 150$ region, in addition to and analogous to the known role played by the neutron $11/2^{-}\left[505\right]$ extruder in this region. The catalytic-type action of both extruders is discussed.

The effective isospin-density-dependent pairing interaction (P1) [S. S. Zhang, U. Lombardo, and E. G. Zhao, Sci. Chin. Phys. Mech. Astron. 54, 236 (2011)] extracted from neutron pairing gaps for ${}^{1}S_0$ in asymmetric nuclear matter calculations [S. S. Zhang, L. G. Cao, U. Lombardo, E. G. Zhao, and S. G. Zhou, Phys. Rev. C 81, 044313 (2010)] is employed to study the bulk properties of Ca, Ni, Zr, and Sn isotopes. The odd-even mass (OEM) staggering is calculated by the Skyrme Hartree-Fock plus BCS method ($\text{SHF}+\text{BCS}$) with the SkP force. For comparison, we study two other types of isovector effective pairing interactions. One is also extracted from pairing gaps of infinite nuclear matter by the Brueckner-Hartree-Fock (BHF) method but for free spectrum (P2). The other is obtained by fitting the empirical OEM (P3). An isoscalar effective pairing interaction (P4) is also adopted, which is determined by fitting the empirical OEM. We find that interaction P1 can better describe the OEM staggering of Ni, Zr, and Sn isotopes by $14.3\%, 41\%$, and $30.4\%$ compared with interaction P2, in terms of root-mean-square deviations to the empirical OEM, respectively. On the other hand, the performance of P1 and P2 is comparable for Ca isotopes. For Ca and Ni isotopes, P1 behaves similarly to P3, but for Zr isotopes P1 is better than P3 by $\approx 34\%$. One may conclude that the isovector pairings are preferred over the isoscalar one for neutron pairings in finite nuclei with the SkP force. It is quite interesting to note that the pairing interaction P1 extracted from nuclear matter calculations can describe pairing gaps of finite nuclei as well as or even better than the interaction P3 directly fitted to finite nuclei. To study the influence from the mean fields on the OEM, we perform the same analysis using the SLy4 and SkI4 forces as well. It turns out that pairing gaps described by these two forces with four pairing interactions are underestimated, so that P2 seems to be better than P1 and is comparable with P3.

Prompt and delayed $\gamma$-ray spectroscopy of the neutron-rich ${}^{94}\mathrm{Kr}$ was performed, as part of the fission campaign at the ALTO facility of the IPN Orsay, using the fast-neutron-induced fission reaction ${}^{238}\mathrm{U}(n,f)$ in combination with the $\nu$-Ball array, a novel hybrid $\gamma$ spectrometer for energy and lifetime measurements. Several new yrast and nonyrast transitions were observed for the first time, extending the previously known level scheme. Additionally, we report on the observation of a new short-lived isomer at 3444 keV with a half-life of 32(3) ns. The analysis of the Nilsson orbitals obtained from Gogny cranked Hartree-Fock-Bogoliubov calculations suggests a ($9^{-}$) spin and an oblate deformation for this isomer corresponding to a two-quasineutron state, indicating an isomeric structure very similar to that of the neighboring isotones ${}^{96}\mathrm{Sr}$ and ${}^{92}\mathrm{Se}$.

Background: In our recent experiment, ${}^9\mathrm{Be}+p$ at $5.67A$ MeV, the breakup decay rates to the three configurations, $\alpha +\alpha +n, {}^8\mathrm{Be}^{*}+n$ and ${}^5\mathrm{He}+{}^4\mathrm{He}$ of ${}^9\mathrm{Be}$, were observed and quantified in the proton recoil spectra, in a full kinematics approach. Unfolding step by step the accessibility to the above configurations, it will require similar experiments at lower or/and higher energies. It will also require the interpretation of the data in a theoretical framework. Three-body models for the structure of ${}^9\mathrm{Be}$ have been developed and applied to reactions with heavy targets. Further research on lighter targets is required for the best establishment of the model. Such models are relevant for the calculation of the corresponding radiative capture reaction rate, $\alpha (\alpha ,\gamma ){}^9\mathrm{Be}$ followed by ${}^9\mathrm{Be}(\alpha ,n){}^{12}\mathrm{C}$. The last is essential for the $r$-process abundance predictions.

Purpose: Investigate the breakup decay rate of ${}^9\mathrm{Be}+p$ at $2.72A$ MeV, where the direct configuration $\alpha +\alpha +n$ is mainly accessible. Compare and interpret data at this low energy and at the higher energy of $5.67A$ MeV into a four-body continuum discretized coupled-channel formalism. Point out and discuss couplings to continuum.

Methods: Our experimental method includes an exclusive breakup measurement in a full kinematic approach of ${}^9\mathrm{Be}$ incident on a proton target at 24.5 MeV ($2.72A$ MeV). Complementary the elastic scattering is measured and other reaction channels are evaluated from previous measurements under the same experimental conditions. The interpretation of present data at $2.72A$ MeV and previous data at $5.67A$ MeV, are considered in a four-body continuum discretized coupled channel (CDCC) approach, using the transformed harmonic oscillator method for the three-body projectile.

Results: An elastic scattering angular distribution at $2.72A$ MeV is measured, which compares very well with CDCC calculations, indicating a strong coupling to continuum. At the same energy, the breakup and total reaction cross sections are measured as ${\sigma }_{\mathrm{break}}=2.5\pm 1\mathrm{mb}$ and ${\sigma }_{\mathrm{tot}}=510\pm L90\mathrm{mb}$, in good agreement with the calculated values of 3.7 and 433 mb, respectively. Further on, into the same theoretical framework, the elastic scattering and breakup cross section data at $5.67A$ MeV are found in very good agreement with the CDCC calculations.

Conclusions: It was confirmed in a global experimental framework that four-body CDCC calculations can describe very well the data even at low energies. Coupling to continuum is very strong despite the small measured breakup cross section. Moreover, the present results support further our three-body model for the structure of ${}^9\mathrm{Be}$, validating relevant radiative reaction rates obtained previously.

Very recently, for the first time, the two channels of nuclear deeply virtual Compton scattering, the coherent and incoherent ones, have been separated by the CLAS collaboration at the Jefferson Laboratory, using a ${}^4\mathrm{He}$ target. The incoherent channel, which can provide a tomographic view of the bound proton and shed light on its elusive parton structure, is thoroughly analyzed here in the impulse approximation. A convolution formula for the relevant nuclear cross sections in terms of those for the bound proton is derived. Novel scattering amplitudes for a bound moving nucleon have been obtained and used. A state-of-the-art nuclear spectral function, based on the Argonne-18 potential, exact in the two-body part, with the recoiling system in its ground state, and modelled in the remaining contribution, with the recoiling system in an excited state, has been used. Different parametrizations of the generalized parton distributions of the struck proton have been tested. A good overall agreement with the data for the beam spin asymmetry is obtained. It is found that the conventional nuclear effects predicted by the present approach are relevant in deeply virtual Compton scattering and in the competing Bethe-Heitler mechanism, but they cancel each other to a large extent in their ratio, to which the measured asymmetry is proportional. Besides, the calculated ratio of the beam spin asymmetry of the bound proton to that of the free one does not describe that estimated by the experimental collaboration. This points to possible interesting effects beyond the impulse approximation analysis presented here. It is therefore clearly demonstrated that the comparison of the results of a conventional realistic approach, as the one presented here, with future precise data, has the potential to expose quark and gluon effects in nuclei. Interesting perspectives for the next measurements at high luminosity facilities, such as JLab at 12 GeV and the future Electron Ion Collider, are addressed.

The formal implications of a quartet coherent-state ansatz for proton-neutron pairing are analyzed. Its nonlinear annihilation operators, which generalize the BCS linear quasiparticle operators, are computed in the quartetting case. Their structure is found to generate nontrivial relationships between the many-body correlation functions. The intrinsic structure of the quartet coherent state is detailed as it hints to the precise correspondence between the quartetting picture and the symmetry restored pair condensate picture for the proton-neutron pairing correlations.

The ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ sub-barrier fusion cross section is calculated within the framework of a time-dependent Hartree-Fock-based classical model using the Feynman path-integral method. The modified astrophysical $S^{*}$ factor is compared to direct and indirect experimental results. A good agreement with the direct data is found. In the lower-energy region where recent analyses of experimental data obtained with the Trojan horse method (THM) lead to contrasting results, the model predicts a nonresonant $S^{*}$ factor half-way between those results. Low-energy resonances revealed in the THM data are added to the calculation, and the relative reaction rate in the Gamow region is calculated. In particular, including $0^{+}$ resonances result in some agreement with the THM data. The role of different resonances is discussed in detail, and their influence on the reaction rate at temperatures relevant to stellar evolution is investigated.

The main goal of the paper is to investigate the experimentally observed spectral fragmentation of the isovector $M1$ resonance in ${}^{208}\mathrm{Pb}$ within a self-consistent model based on an energy-density functional (EDF) of the Skyrme type. This fragmentation is not reproduced in a conventional one-particle–one-hole $\left(1\mathrm{p}1\mathrm{h}\right)$ random-phase approximation (RPA) and thus has to be investigated in the framework of models including complex configurations. However, previously applied models of this type were not self-consistent. In the present work, we use a recently developed renormalized version of the self-consistent time-blocking approximation (RenTBA) in which $1\mathrm{p}1\mathrm{h}\otimes \mathrm{phonon}$ configurations are included on top of the RPA $1\mathrm{p}1\mathrm{h}$ configurations. We have investigated several parameter sets of modified Skyrme EDFs which were fitted within the RenTBA and RPA to reproduce the basic experimental characteristics of the low-energy $M1$ excitations in ${}^{208}\mathrm{Pb}$. We have found as a necessary condition for producing the appropriate fragmentation of the $M1$ resonance in ${}^{208}\mathrm{Pb}$ that the minimum energy of the intermediate $1\mathrm{p}1\mathrm{h}\otimes \mathrm{phonon}$ configurations comes close to the mean energy of the $M1$ resonance. We present also results of the RenTBA and RPA calculations for the first excited states of the natural parity modes in ${}^{208}\mathrm{Pb}$ obtained with the modified parametrizations.

Yields of equatorially emitted light isotopes, $1\le Z\le 14$, observed in ternary fission in the reaction ${}^{241}\mathrm{Pu}(n_{\mathrm{th}},\mathrm{f})$ are employed to determine apparent chemical equilibrium constants for low-temperature and low-density nuclear matter. The degree of equilibration and the role of medium modifications are probed through a comparison of experimentally derived reaction quotients with equilibrium constants calculated using a relativistic mean-field model employing a universal medium modification correction for the attractive $\sigma$ meson coupling. The results of these comparisons indicate that equilibrium is achieved for the lighter ternary fission isotopes. For the heavier isotopes experimental reaction quotients are well below calculated equilibrium constants. This is attributed to a dynamical limitation reflecting insufficient time for full equilibrium to develop. The role of medium effects leading to yield reductions is discussed, as is the apparent enhancement of yields for ${}^8\mathrm{He}$ and other very neutron-rich exotic nuclei.

Background: Microscopic mean-field approaches have been successful in describing the most probable reaction outcomes in low-energy heavy-ion reactions. However, those approaches are known to severely underestimate dispersions of observables around the average values that has limited their applicability. Recently it has been shown that a quantal transport approach based on the stochastic mean-field (SMF) theory significantly improves the description, while its application has been limited so far to fragment mass and charge dispersions.

Purpose: In this work, we extend the quantal transport approach based on the SMF theory for relative kinetic energy dissipation and angular momentum transfer in low-energy heavy-ion reactions.

Methods: Based on the SMF concept, analytical expressions are derived for the radial and tangential friction and associated diffusion coefficients. Those quantal transport coefficients are calculated microscopically in terms of single-particle orbitals within the time-dependent Hartree-Fock (TDHF) approach.

Results: As the first application of the proposed formalism, we consider the radial linear momentum dispersion, neglecting the coupling between radial and angular momenta. We analyze the total kinetic energy (TKE) distribution of binary reaction products in the ${}^{136}\mathrm{Xe}+{}^{208}\mathrm{Pb}$ reaction at $E_{\mathrm{c}.\mathrm{m}.}=$ 526 MeV and compare with experimental data. From time evolution of single-particle orbitals in TDHF, the radial diffusion coefficient is computed on a microscopic basis, while a phenomenological treatment is introduced for the radial friction coefficient. By solving the quantal diffusion equation for the radial linear momentum, the dispersion of the radial linear momentum is obtained, from which one can construct the TKE distribution. We find that the calculations provide a good description of the TKE distribution for strongly damped events with large energy losses, $\text{TKEL}\gtrsim 150\mathrm{MeV}$. However, the calculations underestimate the TKE distribution for smaller energy losses. Further studies are needed to improve the technical details of calculations.

Conclusions: It has been shown that the quantal transport approach based on the SMF theory provides a promising basis for the microscopic description of the TKE distribution as well as the isotopic distributions in damped collisions of heavy ions at around the Coulomb barrier.

In this work, we have developed an extended statistical model to study nuclear multifragmentation reactions at intermediate energies, and we link the associated observables to the properties of supernova matter. The canonical thermodynamical model, used for this study, is modified by including inputs from the relativistic mean-field energy functionals. Even though the length scale of the supernova matter is very large compared to that of the multifragmentation reaction, we find an isospin observable, the average $\langle Z/N\rangle$ of the fragments, which is almost independent of the size of system, and can be directly compared to the estimation of fractionation in infinite nuclear matter. The isospin ratio $\langle Z/N\rangle$ of the heaviest cluster produced in nuclear fragmentation and of the corresponding pasta structure occurring in supernova matter are significantly lower than the spinodal estimation in uncharged nuclear matter, due to the presence of lighter isospin symmetric clusters that dominate the mass fraction in full equilibrium at finite temperature. The screening effect of electrons is also studied.

The connection between initial-state geometry and anisotropic flow can be quantified through a well-established mapping between $p_T$-integrated flow harmonics and cumulants of the initial transverse energy distribution. In this paper we successfully extend this mapping to also include $p_T$-differential flow. In doing so, we find that subleading principal components of anisotropic flow can reveal previously unobserved details of the hydrodynamic response, in both the linear and the nonlinear regimes. Most importantly, we show that they provide novel information on the small-scale structures present in the initial stage of relativistic heavy-ion collisions.

We extend the Boltzmann equation in the relaxation-time approximation to explicitly include transitions between particles forming an interacting mixture. Using the detailed balance condition as well as conditions of energy-momentum and current conservation, we show that only two independent relaxation time scales are allowed in such an interacting system. Dissipative hydrodynamic equations and the form of transport coefficients are subsequently derived for this case. We find that the shear and bulk viscosity coefficients, as well as the baryon charge conductivity, are independent of the transition time scale. However, the bulk viscosity and conductivity coefficients that can be attributed to the individual components of the mixture depend on the transition time.

Parfenova et al. state in [Phys. Rev. C 98, 034608 (2018)] that the results presented by Casal et al. [Phys. Rev. C 94, 054622 (2016)] concerning the radiative capture for ${}^{17}\mathrm{Ne}$ formation are incorrect and their conclusions erroneous mainly because of two reasons: (1) it is “expressed” that the resonant rate is not important for ${}^{15}\mathrm{O}(2p,\gamma ){}^{17}\mathrm{Ne}$ since it is negligibly small compared with the nonresonant contribution to the rate, and (2) the electromagnetic dipole cross section predicted is dramatically different from the available experimental data for ${}^{17}\mathrm{Ne}+{}^{208}\mathrm{Pb}$ at 500 MeV/u [Phys. Lett. B 759, 200 (2016)]. We demonstrate here that these conclusions are incorrectly extracted from our work.