We calculate the total and the differential cross section for $np$ scattering at low energies in the isospin $I=1$ channel within the so-called extended linear sigma model. This model contains conventional (pseudo)scalar and (axial-)vector mesons, as well as the nucleon and its chiral partner within the mirror assignment. In order to obtain good agreement with experimental data analysis results we need to consider two additional resonances: the lightest scalar state $f_0\left(500\right)$ and a dibaryon state with quantum numbers $I=1,J^P=0^{+}$ (also known as ${}^{1}S_0$ resonance). The resonance $f_0\left(500\right)$ is coupled to nucleons in a chirally invariant way through the mirror assignment and is crucial for a qualitatively correct description of the shape of the differential cross section. On the other hand, the dibaryon is exchanged in the $s$ channel and is responsible of the large cross section close to threshold. We compare our results to data analysis results performed by the said program of the CNS Data Analysis Center (in the following “said results”).

The mass ordering of $v_2^{\mathrm{hadron}}$ is regarded as one of the key signatures of collective behavior in ultrarelativistic heavy ion collisions. This observation has been found to be in compliance with the hydrodynamical response of a strongly interacting system to the initial spatial anisotropy. Flow coefficients measured with identified particles in $p$-Pb/$d$-Au collisions have shown similar mass-splitting of $v_2^{\mathrm{hadron}}$ indicating towards the presence of collective dynamics in small collision systems. Arguably, the small size in the overlap geometry of such colliding systems may not be suitable for hydrodynamical treatment that demands an early thermalization. Studies based on a multiphase transport model (AMPT) suggest that elliptic or triangular anisotropy is primarily due to the escape mechanism of partons rather than hydro-like collectivity and mass ordering of $v_2^{\mathrm{hadron}}$ can be generated from coalescence dynamics as implemented in string melting version of AMPT even when parton azimuthal directions are randomized. In this work, studies have been performed on $p$-Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV using AMPT model which has been found to explain the elliptic and triangular flow in such a system where the escape mechanism is the dominant source of flow generation. We report that the mass splitting of $v_2^{\mathrm{hadron}}$ can originate independently both at the partonic and hadronic level in the string melting version of the AMPT model.

The quark-gluon matter produced in relativistic heavy-ion collisions may contain local domains in which parity ($\mathcal{P}$) and combined charge conjugation and parity ($\mathcal{C}\mathcal{P}$) symmetries are not preserved. When coupled with an external magnetic field, such $\mathcal{P}$- and $\mathcal{C}\mathcal{P}$-odd domains will generate electric currents along the magnetic field—a phenomenon called the chiral magnetic effect (CME). Recently, the STAR Collaboration at the BNL Relativistic Heavy Ion Collider (RHIC) and the ALICE Collaboration at the CERN Large Hadron Collider (LHC) released data of charge-dependent azimuthal-angle correlators with features consistent with the CME expectation. However, the experimental observable is contaminated with significant background contributions from elliptic-flow-driven effects, which makes the interpretation of the data ambiguous. We show that the collisions of isobaric nuclei, ${}_{44}{}^{96}\mathrm{Ru}+{}_{44}{}^{96}\mathrm{Ru}$ and ${}_{40}{}^{96}\mathrm{Zr}+{}_{40}{}^{96}\mathrm{Zr}$, provide an ideal tool to disentangle the CME signal from the background effects. Our simulation demonstrates that the two collision types at $\sqrt{s_{NN}}=200$ GeV have more than $10\%$ difference in the CME signal and less than $2\%$ difference in the elliptic-flow-driven backgrounds for the centrality range of 20–60%.

Background: Recently, the cluster radioactivity of heavy nuclei decaying to ${}^{208}\mathrm{Pb}$ was successfully used to constrain the density slope of the symmetry energy $L\left({\rho }_0\right)$ at saturation density ${\rho }_0$.

Purpose: By using well-measured experimental decay energy and half-life, proton radioactivity is proposed to further constrain $L\left({\rho }_0\right)$ in this work.

Method: From the Hugenholtz–Van Hove theorem, $L\left({\rho }_0\right)$ is found to be directly related to the magnitude of the symmetry potential, which can be extracted from the proton radioactivity within the density-dependent cluster model.

Results: By investigating the radioactivity of proton emitters with large isospin asymmetry, the value of the density slope is found to be $L\left({\rho }_0\right)=51.8\pm 7.2$ MeV.

The difference between the one-neutron and one-proton separation energies is strongly correlated to the difference of Coulomb energies of two mirror nuclei. In this paper we generalize and refine this correlation and then apply it to predict unknown masses of proton-rich nuclei for mass number $A\le 110$ within competitive accuracy.

Photoactivation yield measurements on ${}^{115}\mathrm{In}$ have been performed at the ELSA facility with Bremsstrahlung photon beams over a range of endpoint energies between 4.5 and 18 MeV. The measured photoexcitation yields of the ${}^{115m}\mathrm{In}$ metastable state are compared with calculated yields using cross sections obtained with different models of the photon strength function. It is shown that additional photon strength with respect to the general Lorentzian model is needed at 8.1 MeV for the calculated yields to reproduce the data. The origin of this extra strength is unclear, because it is compatible with additional strength predicted in both $E1$ and $M1$ photon strength distributions by quasiparticle random-phase approximation calculations using the Gogny D1S force.

The level scheme of the neutron-deficient nuclide ${}^{168}\mathrm{Os}$ has been extended and mean lifetimes of excited states have been measured by the recoil distance Doppler-shift method using the JUROGAM $\gamma$-ray spectrometer in conjunction with the IKP Köln plunger device. The ${}^{168}\mathrm{Os}\gamma$ rays were measured in delayed coincidence with recoiling fusion-evaporation residues detected at the focal plane of the RITU gas-filled separator. The ratio of reduced transition probabilities $B(E2;4_1^{+}\to 2_1^{+})/B(E2;2_1^{+}\to 0_1^{+})$ is measured to be 0.34(18), which is very unusual for collective band structures and cannot be reproduced by interacting boson model (IBM-2) calculations based on the SkM* energy-density functional.

Low-spin excited levels in ${}_{35}{}^{86}\mathrm{Br}_{51}$ and ${}_{36}{}^{86}\mathrm{Kr}_{50}$, populated following ${\beta }^{-}$ decay and the neutron-induced fission of ${}^{235}\mathrm{U}$, were measured using the Lohengrin fission-fragment separator and the EXILL array of Ge detectors at the PF1B cold-neutron facility of the Institute Laue-Langevin Grenoble. Improved populations of excited levels in ${}^{86}\mathrm{Br}$ remove inconsistencies existing in the literature on this nucleus. Directional-linear-polarization correlations, analyzed using newly developed formulas, as well as precise angular correlations allowed the unique $1^{-}$ and $2^{-}$ spin and parity assignments to the ground state of ${}^{86}\mathrm{Br}$ and the 4016.3-keV level in ${}^{86}\mathrm{Kr}$, respectively. Based on these results we propose that the Gamow-Teller ${\beta }^{-}$ decays of ${}^{86}\mathrm{Se}$ and ${}^{86}\mathrm{Br}$ involve the $\nu g_{7/2}\to \pi g_{9/2}$ transition in addition to the $\nu p_{3/2}\to \pi p_{3/2}$ transition proposed earlier. In ${}^{86}\mathrm{Kr}$ we have identified $1_1^{+}, 2_3^{+}$, and $3_1^{+}$ levels, analogous to the mixed-symmetry states in ${}^{94}\mathrm{Mo}$, which in ${}^{86}\mathrm{Kr}$ are from proton excitations, only. Large-scale, shell-model calculations with refined interactions reproduce well excitations in ${}^{86}\mathrm{Br}$ and ${}^{86}\mathrm{Kr}$ and support our interpretations.

We investigate the property of the high-density nuclear matter probed by the nucleus-nucleus elastic scattering in the framework of the double-folding model with the complex $G$-matrix interaction. The medium effect including the three-body-force (TBF) effect is investigated with present two methods based on the frozen density approximation. The medium effect is clearly seen on the potential and the elastic cross section for the ${}^{16}\mathrm{O}+{}^{16}\mathrm{O}$ system at $E/A=70\mathrm{MeV}$. The crucial role of the medium effect is also confirmed with other effective nucleon-nucleon ($\mathit{NN}$) interactions. In addition, the present methods are applied to other heavy-ion elastic scattering systems. Again, the medium effect is clearly seen in the heavy-ion elastic cross section. The medium effect on the elastic cross section becomes invisible with the increase of the target mass and the incident energy (up to $E/A=200\mathrm{MeV}$). However, the medium effect is again important to fix the heavy-ion scattering over $E/A=200\mathrm{MeV}$. Finally, we make clear the crucial role of the TBF effect up to $k_F=1.6{\mathrm{fm}}^{-1}$ in the nucleus-nucleus elastic scattering.

The proton-proton momentum correlation functions $\left[C_{pp}\left(q\right)\right]$ for the kinematically complete decay channels ${}^{23}\mathrm{Al}\to p+p+{}^{21}\mathrm{Na}$ and ${}^{22}\mathrm{Mg}\to p+p+{}^{20}\mathrm{Ne}$ have been measured at the RIKEN RI Beam Factory. From the very different correlation strength of $C_{pp}\left(q\right)$ for ${}^{23}\mathrm{Al}$ and ${}^{22}\mathrm{Mg}$, the source size and emission time information were extracted from the $C_{pp}\left(q\right)$ data by assuming a Gaussian source profile in the correlation function calculation code (crab). The results indicated that the mechanism of two-proton emission from ${}^{23}\mathrm{Al}$ was mainly sequential emission, while that of ${}^{22}\mathrm{Mg}$ was mainly three-body simultaneous emission. By combining our earlier results of the two-proton relative momentum and the opening angle, it is pointed out that the mechanism of two-proton emission could be distinguished clearly.

The thermalization process of nuclear matter in the central fireball region of heavy-ion collisions is investigated by employing an extended Boltzmann-Uehling-Uhlenbeck model, namely, the van der Waals Boltzmann-Uehling-Uhlenbeck (VdWBUU) model. The temperature ($T$) is extracted by the quantum fermion fluctuation approach and other thermodynamic quantities, such as the density ($\rho$), entropy density ($s$), shear viscosity ($\eta$), isospin diffusivity ($D_I$), and heat conductivity ($\kappa$), are also deduced. The liquidlike and gaslike phase signs are discussed through the behavior of the shear viscosity during the heavy-ion collision process in the VdWBUU model.

The production of $\alpha$ and ${}^3\mathrm{He}$ particles, the cluster constituents of ${}^7\mathrm{Be}$, in the ${}^7\mathrm{Be}+{}^{28}\mathrm{Si}$ reaction was studied at three near-barrier energies, namely 13, 20, and 22 MeV. Angular distribution measurements were performed at each energy, and the data were analyzed in both statistical model and Distorted-Wave Born Approximation (DWBA) frameworks in order to disentangle the degree of competition between direct and compound channels. The energy evolution of the ratio of direct to total reaction cross section was mapped in comparison with similar data for ${}^6\mathrm{Li}$ and ${}^7\mathrm{Li}$ projectiles on a ${}^{28}\mathrm{Si}$ target. The results indicate larger transfer contributions for collisions involving the mirror nuclei ${}^7\mathrm{Be}$ and ${}^7\mathrm{Li}$ than in the ${}^6\mathrm{Li}$ case. Fusion cross sections were deduced, taking into account the $\alpha$-particle cross sections due to compound-nucleus formation and particle multiplicities deduced from our statistical model framework. It was found that fusion is compatible with systematics and single-barrier penetration cross sections to within an uncertainty band of 10% to 20%. Indications of fusion hindrance for ${}^7\mathrm{Li}$ and ${}^7\mathrm{Be}$ compared to ${}^6\mathrm{Li}$, starting from the barrier and below it, are given. This hindrance is attributed to the existence of large transfer channels. Furthermore, the experimental results, analyzed in the DWBA framework, suggest ${}^3\mathrm{He}$ and ${}^4\mathrm{He}$ transfer as the dominant direct reaction mechanism.

The quantal diffusion mechanism of nucleon exchange is studied in the central collisions of several symmetric heavy ions in the framework of the stochastic mean-field (SMF) approach. Since, at bombarding energies below the fusion barrier, dinuclear structure is maintained, it is possible to describe nucleon exchange as a diffusion process familiar from deep-inelastic collisions. Quantal diffusion coefficients, including memory effects, for proton and neutron exchanges are extracted microscopically employing the SMF approach. The quantal calculations of neutron and proton variances are compared with the semiclassical results.

We present an event generator based on the three-fluid hydrodynamics approach for the early stage of the collision, followed by a particlization at the hydrodynamic decoupling surface to join to a microscopic transport model, ultrarelativistic quantum molecular dynamics, to account for hadronic final-state interactions. We present first results for nuclear collisions of the Facility for Antiproton and Ion Research–Nuclotron-based Ion Collider Facility energy scan program (Au+Au collisions, $\sqrt{s_{NN}}=4-11\mathrm{GeV}$). We address the directed flow of protons and pions as well as the proton rapidity distribution for two model equations of state, one with a first-order phase transition and the other with a crossover-type softening at high densities. The new simulation program has the unique feature that it can describe a hadron-to-quark matter transition which proceeds in the baryon stopping regime that is not accessible to previous simulation programs designed for higher energies.

We study the effect of intrinsic fluctuations of the proton saturation momentum scale on event-by-event rapidity distributions. Saturation scale fluctuations generate an asymmetry in the single-particle rapidity distribution in each event resulting in genuine $n$-particle correlations having a component linear in the rapidities of the produced particles, $y_1\cdots y_n$. We introduce a color domain model that naturally explains the centrality dependence of the two-particle rapidity correlations recently measured by ATLAS [M. Aaboud et al. (ATLAS Collaboration), arXiv:1606.08170] while constraining the probability distribution of saturation scale fluctuations in the proton. Predictions for $n=4$, 6, and 8 particle correlations find that the four- and eight-particle cumulants change sign at an intermediate multiplicity, a signature which could be tested experimentally.

The correlations between mass distributions of the binary fragments, total kinetic energy (TKE), and neutron multiplicity have been investigated for the reaction ${}^{50}\text{Ti}+{}^{208}\text{Pb}$ at 294 MeV bombarding energy. Although this reaction has been used to synthesize the Rf ($Z=104$) superheavy element, a complete study of its fragmentation dynamics is still not available in the literature. In this work, average neutron multiplicities were extracted as a function of different fragment mass splits and TKE windows. A weak increase of the prescission neutron multiplicity is observed going from asymmetric to symmetric mass splits. A fission delay time of $4.5\times {10}^{-20}$ s has been extracted for the symmetric fission. The neutron multiplicity extracted for the symmetric mass split was used to derive the average number of neutrons emitted in the spontaneous fission of ${}^{258}\text{Rf}$. The extrapolated value of $4.7\pm 1.4$ is found to be consistent with systematics of spontaneous and neutron-induced fission in heavy nuclei and with the results of previous works for superheavy nuclei with $Z=116$ and $Z=124$.

The microscopic effective reaction theory is applied to deuteron-induced reactions. A reaction model space characterized by a $p+n+A$ three-body model is adopted, where $A$ is the target nucleus, and the nucleon-target potential is described by a microscopic folding model based on an effective nucleon-nucleon interaction in nuclear medium and a one-body nuclear density of $A$. The three-body scattering wave function in the model space is obtained with the continuum-discretized coupled-channels (CDCC) method, and the eikonal reaction theory (ERT), an extension of CDCC, is applied to the calculation of neutron removal cross sections. Elastic scattering cross sections of deuteron on ${}^{58}\mathrm{Ni}$ and ${}^{208}\mathrm{Pb}$ target nuclei at several energies are compared with experimental data. The total reaction cross sections and the neutron removal cross sections at 56 MeV on 14 target nuclei are calculated and compared with experimental values.

Initial partonic eccentricities in $\text{Au}+\text{Au}$ collisions at center-of-mass energy $\sqrt{s_{NN}}=200$ GeV are investigated by using a multiphase transport model with a string-melting scenario. The initial eccentricities in different order of harmonics are studied by using participant and cumulant definitions. Eccentricity in terms of second-, fourth- and sixth-order cumulants as a function of number of participant nucleons are compared systematically with the traditional participant definition. The ratio of the cumulant eccentricities $\varepsilon \left\{4\right\}/\varepsilon \left\{2\right\}$ and $\varepsilon \left\{6\right\}/\varepsilon \left\{4\right\}$ are studied in comparison with the ratio of the corresponding flow harmonics. The conversion coefficients ($v_n/{\varepsilon }_n$) are explored up to fourth-order harmonics based on the cumulant method. Furthermore, studies on transverse momentum ($p_T$) and pseudorapidity ($\eta$) dependencies of eccentricities and their fluctuations are presented. As in ideal hydrodynamics, initial eccentricities are expected to be closely related to the final flow harmonics in relativistic heavy-ion collisions, studies of the fluctuating initial condition in the AMPT model will shed light on the tomography properties of the initial source geometry.

Because quarks carry electric charge, they can radiate light when they change energy levels, which is exactly what happens when they hadronize. This is true not only in jets but also in heavy-ion collisions, where a thermalized plasma of quarks and gluons cools into a gas of hadrons. First, direct emission of photons from two quarks coalescing from the continuum into pions is calculated using the quark-meson model. The yield of final-state photons to pions is found to be about $e^2/g_{\pi qq}^2$, which is on the order of a percent. Second, the yield of photons from the decay of highly excited color singlets, which may exist ephemerally during hadronizaton, is estimated. Because these contributions occur late in the reaction, they should carry significant elliptic flow, which may help explain the large observed flow of direct photons by the PHENIX Collaboration at the BNL Relativistic Heavy Ion Collider. The enhanced emission also helps explain the PHENIX Collaboration's surprisingly large observed $\gamma /\pi$ ratio.