We investigate correlations in the fragment momentum distribution owing to the propagation of fragments under the influence of their mutual Coulomb field after the breakup of an excited nuclear source. The magnitude of the effects on the nuclear temperatures obtained from such distributions is estimated with the help of a simple approach in which a charged fragment interacts with a homogeneous charged sphere. The results are used to correct the temperatures obtained from the asymptotic momentum distributions of fragments produced by a Monte Carlo simulation in which the system's configuration at breakup is provided by the canonical version of the statistical multifragmentation model. In a separate calculation, the dynamics of this many-particle charged system is followed in a molecular dynamics calculation until the fragments are far away from the breakup volume. The results suggest that, although the magnitude of the corrections is similar in both models, many-particle correlations present in the second approach are non-negligible and should be taken into account to minimize ambiguities in such studies.

$K^{-}$ optical potentials relevant to calculations of $K^{-}$ nuclear quasibound states were developed within several chiral meson-baryon coupled-channels interaction models. The applied models yield quite different $K^{-}$ binding energies and widths. Then the $K^{-}$ multinucleon interactions were incorporated by a phenomenological optical potential fitted recently to kaonic atom data. Though the applied $K^{-}$ interaction models differ significantly in the $K^{-}N$ subthreshold region, our self-consistent calculations of kaonic nuclei across the periodic table lead to conclusions valid quite generally. Due to $K^{-}$ multinucleon absorption in the nuclear medium, the calculated widths of $K^{-}$ nuclear states are sizable, ${\mathrm{\Gamma }}_{K^{-}}\ge 90$ MeV, and exceed substantially their binding energies in all considered nuclei.

The formalism to augment the classical models of the equation of state for real gases with quantum statistical effects is presented. It allows an arbitrary excluded volume procedure to model repulsive interactions, and an arbitrary density-dependent mean field to model attractive interactions. Variations on the excluded volume mechanism include van der Waals (VDW) and Carnahan-Starling models, while the mean fields are based on VDW, Redlich-Kwong-Soave, Peng-Robinson, and Clausius equations of state. The VDW parameters of the nucleon-nucleon interaction are fitted in each model to the properties of the ground state of nuclear matter, and the following range of values is obtained: $a=330–430\mathrm{MeV}{\mathrm{fm}}^3$ and $b=2.5–4.4{\mathrm{fm}}^3$. In the context of the excluded volume approach, the fits to the nuclear ground state disfavor the values of the effective hard-core radius of a nucleon significantly smaller than $0.5\mathrm{fm}$, at least for the nuclear matter region of the phase diagram. Modifications to the standard VDW repulsion and attraction terms allow one to improve significantly the value of the nuclear incompressibility factor $K_0$, bringing it closer to empirical estimates. The generalization to include the baryon-baryon interactions into the hadron resonance gas model is performed. The behavior of the baryon-related lattice QCD observables at zero chemical potential is shown to be strongly correlated to the nuclear matter properties: an improved description of the nuclear incompressibility also yields an improved description of the lattice data at $\mu =0$.

We have studied the scaling properties of the electromagnetic response functions of ${}^4\mathrm{He}$ and ${}^{12}\mathrm{C}$ nuclei computed by the Green's function Monte Carlo approach, retaining only the one-body current contribution. Longitudinal and transverse scaling functions have been obtained in the relativistic and nonrelativistic cases and compared to experiment for various kinematics. The characteristic asymmetric shape of the scaling function exhibited by data emerges in the calculations in spite of the nonrelativistic nature of the model. The results are mostly consistent with scaling of zeroth, first, and second kinds. Our analysis reveals a direct correspondence between the scaling and the nucleon-density response functions. The scaling function obtained from the proton-density response displays scaling of the first kind, even more evidently than the longitudinal and transverse scaling functions.

Spectroscopic properties of odd-mass nuclei are studied within the framework of the interacting boson-fermion model (IBFM) with parameters based on the Hartree-Fock-Bogoliubov (HFB) approximation. The parametrization D1M of the Gogny energy density functional (EDF) was used at the mean-field level to obtain the deformation energy surfaces for the considered nuclei in terms of the quadrupole deformations $\left(\beta ,\gamma \right)$. In addition to the energy surfaces, both single-particle energies and occupation probabilities were used as a microscopic input for building the IBFM Hamiltonian. Only three strength parameters for the particle-boson-core coupling are fitted to experimental spectra. The IBFM Hamiltonian is then used to compute the energy spectra and electromagnetic transition rates for selected odd-mass Eu and Sm nuclei as well as for ${}^{195}\mathrm{Pt}$ and ${}^{195}\mathrm{Au}$. A reasonable agreement with the available experimental data is obtained for the considered odd-mass nuclei.

Background: It is a well established fact that nuclear deformation and vibration influence fusion dynamics around the Coulomb barrier. This effect was observed for several systems with the inclusion of inelastic excitations in coupled-channels calculations. Sub-barrier fusion cross sections were also observed to be affected by neutron transfer in systems carrying positive $Q$ value for transfer channels. However, recent experimental analysis with a few systems showed that inelastic excitations are enough to explain the sub-barrier fusion behavior, and no effect was noticed due to positive $Q$-value transfer channels.

Purpose: The motivation behind present investigation is to explore the effects of colliding nuclei structure and the transfer channel on enhancement of sub-barrier fusion cross sections.

Method: An experiment was performed with Heavy Ion Reaction Analyzer (HIRA) at New Delhi to measure the fusion cross sections for ${}^{28}\mathrm{Si}+{}^{92,96}\mathrm{Zr}$ systems. These cross sections were later compared with quantum mechanical coupled-channels calculations. In order to explore the effects of nuclear deformation on fusion cross sections, the present data were compared with those of other researchers on fusion who have used various projectiles of different structural properties on a ${}^{96}\mathrm{Zr}$ target.

Results: Experimental fusion cross sections have been extracted around the Coulomb barrier. In the coupled-channels framework, inclusion of inelastic excitations of both projectile $\left({}^{28}\mathrm{Si}\right)$ and targets $\left({}^{92,96}\mathrm{Zr}\right)$ could reproduce the experimental cross sections around the Coulomb barrier, but they deviated substantially in the sub-barrier region. This indicates that positive $Q$-value neutron transfer channels may need to be included in the calculations to reproduce the experimental cross sections at sub-barrier energies.

Conclusions: The nuclear structure of interacting nuclei has a strong influence on sub-barrier fusion enhancement. The effect of multineutron transfer channels was observed to be significant for fusion, especially for those systems where interacting nuclei are less deformed or spherical.

We calculate elliptic and triangular flow parameters of thermal photons using an event-by-event hydrodynamic model with fluctuating initial conditions at $200A$ GeV Au+Au collisions at the BNL Relativistic Heavy Ion Collider (RHIC) and at $2.76A$ TeV Pb+Pb collisions at the Cern Large Hadron Collider (LHC) for three different centrality bins. The photon elliptic flow shows strong centrality dependence where $v_2\left(p_T\right)$ increases towards peripheral collisions both at RHIC and at the LHC energies. However, the triangular flow parameter does not show significant dependence on the collision centrality. The elliptic as well as the triangular flow parameters found to underestimate the PHENIX data at RHIC by a large margin for all three centrality bins. We calculate $p_T$ spectrum and anisotropic flow of thermal photons from $200A$ GeV Cu+Cu collisions at RHIC for a 0–20% centrality bin and compare with the results with those from Au+Au collisions. The production of thermal photons is found to decrease significantly for Cu+Cu collisions compared to Au+Au collisions. However, the effect of initial state fluctuation is found to be more pronounced for anisotropic flow, resulting in larger $v_2$ and $v_3$ for Cu+Cu collisions. We study the correlation between the anisotropic flow parameters and the corresponding initial spatial anisotropies from their event-by-event distributions at RHIC and at the LHC energies. The linear correlation between $v_2$ and ${\epsilon }_2$ is found be stronger compared to the correlation between $v_3$ and ${\epsilon }_3$. In addition, the correlation coefficient is found to be larger at LHC than at RHIC.

Cross sections for inclusive neutrino scattering off the deuteron induced by neutral and charge-changing weak currents are calculated from threshold up to 150 MeV energies in a chiral effective field theory including high orders in the power counting. Contributions beyond leading order (LO) in the weak current are found to be small, and increase the cross sections obtained with the LO transition operators by a couple of percent over the whole energy range 0–150 MeV. The cutoff dependence is negligible, and the predicted cross sections are within $\sim 2\%$ of, albeit consistently larger than, corresponding predictions obtained in conventional meson-exchange frameworks.

The level structure of ${}^{134}\mathrm{Xe}$ was studied with the inelastic neutron scattering reaction followed by $\gamma$-ray detection. A number of level lifetimes were determined for the first time with the Doppler-shift attenuation method and the low-lying excited states were characterized. From this new spectroscopic information, the third excited state, a $0^{+}$ level which had only been observed in a previous inelastic neutron scattering study, was verified. Reduced transition probabilities were calculated; comparisons were drawn with a vibrational description of the nucleus and found lacking. The $3^{-}$ octupole phonon has been confirmed, and the complete negative-parity multiplet resulting from the $\nu \left(1h_{11/2}2d_{3/2}\right)$ configuration has also been tentatively identified for the first time in the $N=80$ isotones.

The $\gamma$ decay of ${}^{65}\mathrm{Ni}$ has been studied from particle-$\gamma$ coincidence data on the ${}^{64}\mathrm{Ni}(d,p\gamma ){}^{65}\mathrm{Ni}$ reaction. $\gamma$-ray spectra at excitation energies below $E_x\approx 2\mathrm{MeV}$ have been studied and compared with previous measurements. Coincidences corresponding to $E_x\approx 4.4–6.1\mathrm{MeV}$ have been used to constrain the shape of the nuclear level density and $\gamma$-strength function of ${}^{65}\mathrm{Ni}$ by means of the Oslo method. The experimental $\gamma$-strength function presents an enhancement at $\gamma$ energies below $E_{\gamma }\approx 3\mathrm{MeV}$. In addition, a resonance-like structure centered at $E_{\gamma }\approx 4.6\mathrm{MeV}$ is seen together with accumulated strength at $E_{\gamma }\approx 2.6–3.6\mathrm{MeV}$. The obtained results contribute to the systematic study of $\gamma$ decay in the Ni isotopes, which is of great interest for the understanding of both single-particle and collective nuclear structure phenomena.

The half-life of ${}^{51}\mathrm{Mn}$ was measured by serial gamma spectrometry of the 511-keV annihilation photon following decay by ${\beta }^{+}$ emission. Data were collected every 100 seconds for 100,000–230,000 seconds within each measurement ($n=4$). The 511-keV incidence rate was calculated from the 511-keV spectral peak area and count duration, corrected for detector dead time and radioactive decay. Least-squares regression analysis was used to determine the half-life of ${}^{51}\mathrm{Mn}$ while accounting for the presence of background contaminants, notably ${}^{55}\mathrm{Co}$. The result was $45.59\pm 0.07$ min, which is the highest precision measurement to date and disagrees with the current Nuclear Data Sheets value by over $6\sigma$.

The cross section for coherent $J/\psi$ photoproduction in Pb-Pb collisions is the sum of two contributions: one from low-energy and the other from high-energy photon-nucleus interactions. A novel method to disentangle the two contributions, allowing one to extract the coherent photo-nuclear cross section for coherent $J/\psi$ production, ${\sigma }_{\gamma \mathrm{Pb}}$, is presented. The utility of the method is demonstrated using measurements from peripheral and ultraperipheral Pb-Pb collisions at the CERN Large Hadron Collider. Applying the proposed method to the available data, it is possible to obtain ${\sigma }_{\gamma \mathrm{Pb}}$ up to a photon-lead center-of-mass energy of 470 GeV, which corresponds to $x$ of $4.4\times {10}^{-5}$. To illustrate a possible use of the extracted photonuclear cross sections, the corresponding nuclear suppression factors are computed and they are compared to predictions of gluon shadowing calculated in the leading-twist approximation approach.

We investigate the in-medium masses of a $\overline{D}\left(0^{-}\right)$ meson and a ${\overline{D}}_0^{*}\left(0^{+}\right)$ meson, and spectral functions for $\overline{D}$ and ${\overline{D}}_0^{*}$ meson channels in nuclear matter. These mesons are introduced as chiral partners in the chiral-symmetry-broken vacuum, hence they are useful to explore the partial restoration of the broken chiral symmetry in nuclear matter. We consider the linear sigma model to describe the chiral symmetry breaking and to investigate a qualitative tendency of changes of $\overline{D}$ mesons at low density. Our study shows that the loop corrections to $\overline{D}$ and ${\overline{D}}_0^{*}$ meson masses provide a smaller mass splitting at finite density than that in vacuum, a result that indicates a tendency of the restoration of the chiral symmetry. We investigate also the spectral function for ${\overline{D}}_0^{*}$ meson channel, and find three peaks. The first peak, which corresponds to the resonance of the ${\overline{D}}_0^{*}$ meson, is broadened by collisions with nucleons in medium, and the peak position shifts to lower mass due to the partial restoration of chiral symmetry as the density increases. The second peak is identified as a threshold enhancement which shows a remarkable enhancement as the density increases. The third peak is Landau damping. The obtained properties of $\overline{D}$ and ${\overline{D}}_0^{*}$ mesons in nuclear matter will provide useful information for experiments.

Background: Long-baseline experiments such as T2K, NOvA, or the planned Deep Underground Neutrino Experiment require theoretical descriptions of the complete event in a neutrino-nucleus reaction. Since nuclear targets are used this requires a good understanding of neutrino-nucleus interactions.

Purpose: One of the dominant reaction channels in neutrino-nucleus interactions is pion production. This paper aims for a theoretically consistent treatment of all charged current charged pion production data that are available from the experiments MiniBooNE, the near detector experiment at T2K, and MINERvA.

Method: Pion production is treated through excitations of nucleon resonances, including background terms, and deep inelastic scattering. The final state interactions of the produced pions are described within the Giessen-Boltzmann-Uehling-Uhlenbeck implementation of quantum-kinetic transport theory.

Results: Results are given for MiniBooNE, the near detector experiment at T2K and for MINERvA. While the theoretical results for MiniBooNE differ from the data both in shape and magnitude, their agreement both with the T2K and the MINERvA data is good for all pion and lepton observables. Predictions for pion spectra are shown for MicroBooNE and NOvA.

Conclusions: Based on the GiBUU model of lepton-nucleus interactions a consistent, good theoretical description of CC charged pion production data from the T2K ND and the MINERvA experiments is possible, without any parameter tunes.

In this paper, we study the charge-exchange reaction to the isobaric analog state using two types of transition densities. One transition density is equal to the difference of the total neutron density minus the total proton density and the other one is the density of the excess neutrons only. We show that for projectiles that do not probe the interior of the nucleus but mostly the surface of this nucleus, distinct differences in the cross section arise when two types of transition densities are employed. We demonstrate this by considering the (${}^3\mathrm{He},t$) reaction.

Collective reaction paths for fusion reactions ${}^{16}\mathrm{O}+\alpha \to {}^{20}\mathrm{Ne}$ and ${}^{16}\mathrm{O}+{}^{16}\mathrm{O}\to {}^{32}\mathrm{S}$ are microscopically determined on the basis of the adiabatic self-consistent collective coordinate (ASCC) method. The collective path is maximally decoupled from other intrinsic degrees of freedom. The reaction paths turn out to deviate from those obtained with standard mean-field calculations with constraints on quadrupole and octupole moments. The potentials and inertial masses defined in the ASCC method are calculated along the reaction paths, which leads to the collective Hamiltonian used for calculation of the subbarrier fusion cross sections. The inertial mass inside the Coulomb barrier may have a significant influence on the fusion cross section at the deep subbarrier energy.

To extend the applications of the so-called “three-dimensional” formalism to the description of three-nucleon scattering within the Faddeev formalism, we develop a general form of the three-nucleon scattering amplitude. This form significantly decreases the numerical complexity of the “three-dimensional” calculations by reducing the scattering amplitude to a linear combination of momentum-dependent spin operators and scalar functions of momenta. The number and structure of the spin operators is fixed and the scalar functions can be represented numerically using standard methods such as multidimensional arrays. In this paper, we show that all orders of the iterated Faddeev equation can be written in this general form. We argue that calculations utilizing the three-nucleon force will also conform to the same general form. Additionally, we show how the general form of the scattering amplitude can be used to transform the Faddeev equation to make it suitable for numerical calculations using iterative methods.

Background: The distribution of protons and neutrons in the matter created in heavy-ion collisions is one of the main points of interest for the collision physics, especially at supranormal densities. These distributions are the basis for predictions of the density dependence of the symmetry energy and the density range that can be achieved in a given colliding system. We report results of the first systematic simulation of proton and neutron density distributions in central heavy-ion collisions within the beam energy range of $E_{\mathrm{beam}}\le 800\mathrm{MeV}/\mathrm{nucl}$. The symmetric ${}^{40}\mathrm{Ca}+{}^{40}\mathrm{Ca}, {}^{48}\mathrm{Ca}+{}^{48}\mathrm{Ca}, {}^{100}\mathrm{Sn}+{}^{100}\mathrm{Sn}$, and ${}^{120}\mathrm{Sn}+{}^{120}\mathrm{Sn}$ and asymmetric ${}^{40}\mathrm{Ca}+{}^{48}\mathrm{Ca}$ and ${}^{100}\mathrm{Sn}+{}^{120}\mathrm{Sn}$ systems were chosen for the simulations.

Purpose: We simulate development of proton and neutron densities and asymmetries as a function of initial state, beam energy, and system size in the selected collisions in order to guide further experiments pursuing the density dependence of the symmetry energy.

Methods: The Boltzmann-Uhlenbeck-Uehling (pBUU) transport model with four empirical models for the density dependence of the symmetry energy was employed. Results of simulations using pure Vlasov dynamics were added for completeness. In addition, the time-dependent Hartree-Fock (TDHF) model, with the SV-bas Skyrme interaction, was used to model the heavy-ion collisions at $E_{\mathrm{beam}}\le 40\mathrm{MeV}/\mathrm{nucl}$. Maximum proton and neutron densities ${\rho }_{\mathrm{p}}^{\max }$ and ${\rho }_{\mathrm{n}}^{\max }$, reached in the course of a collision, were determined from the time evolution of ${\rho }_{\mathrm{p}}$ and ${\rho }_{\mathrm{n}}$.

Results: The highest total densities predicted at $E_{\mathrm{beam}}=800\mathrm{MeV}/\mathrm{nucl}.$ were of the order of $\sim 2.5{\rho }_0$ (${\rho }_0=0.16{\text{fm}}^{-3}$) for both Sn and Ca systems. They were found to be only weakly dependent on the initial conditions, beam energy, system size, and a model of the symmetry energy. The proton-neutron asymmetry $\delta =({\rho }_{\mathrm{n}}^{\max }-{\rho }_{\mathrm{p}}^{\max })/({\rho }_{\mathrm{n}}^{\max }+{\rho }_{\mathrm{p}}^{\max })$ at maximum density does depend, though, on these parameters. The highest value of $\delta$ found in all systems and at all investigated beam energies was $\sim 0.17$.

Conclusions: We find that the initial state, beam energy, system size, and a symmetry energy model affect very little the maximum proton and neutron densities, but have a subtle impact on the proton-neutron asymmetry. Most importantly, the variations in the proton-neutron asymmetry at maximum densities are related at most at 50% level to the details in the symmetry energy at supranormal density. The reminder is due to the details in the symmetry energy at subnormal densities and proton and neutron distributions in the initial state. This result brings to the forefront the need for a proper initialization of the nuclei in the simulation, but also brings up the question of microscopy, such as shell effects, that affect initial proton and neutron densities, but cannot be consistently incorporated into semiclassical transport models.

The string melting version of a multi-phase transport model is often applied to high-energy heavy-ion collisions since the dense matter thus formed is expected to be in parton degrees of freedom. In this work we improve its quark coalescence component, which describes the hadronization of the partonic matter to a hadronic matter. We removed the previous constraint that forced the numbers of mesons, baryons, and antibaryons in an event to be separately conserved through the quark coalescence process. A quark now could form either a meson or a baryon depending on the distance to its coalescence partner(s). We then compare results from the improved model with the experimental data on hadron $dN/dy,p_{{}_{\mathrm{T}}}$ spectra, and $v_2$ in heavy-ion collisions from $\sqrt{s_{{}_{\mathrm{NN}}}}=62.4$ GeV to 5.02 TeV. We show that, besides being able to describe these observables for low-$p_{{}_{\mathrm{T}}}$ pions and kaons, the improved model also better describes the low-$p_{{}_{\mathrm{T}}}$ baryon observables in general, especially the baryon $p_{{}_{\mathrm{T}}}$ spectra and antibaryon-to-baryon ratios for multistrange baryons.

We use an event-by-event hydrodynamical description of the heavy-ion collision process with Glauber initial conditions to calculate the thermal emission of photons. The photon rates in the hadronic phase follow from a spectral function approach and a density expansion, while in the partonic phase they follow from the Arnold-Moore-Yaffe (AMY) perturbative rates. The calculated photon elliptic flows are lower than those reported recently by both the ALICE and PHENIX collaborations.