Excited states in the neutron-deficient nucleus ${}^{87}\mathrm{Tc}$ have been studied via the fusion-evaporation reaction ${}^{54}\mathrm{Fe}({}^{36}\mathrm{Ar},2n1p){}^{87}\mathrm{Tc}$ at 115 MeV beam energy. The AGATA $\gamma$-ray spectrometer coupled to the DIAMANT, NEDA, and Neutron Wall detector arrays for light-particle detection was used to measure the prompt coincidence of $\gamma$ rays and light particles. Six transitions from the deexcitation of excited states belonging to a new band in ${}^{87}\mathrm{Tc}$ were identified by comparing $\gamma$-ray intensities in the spectra gated under different reaction channel selection conditions. The constructed level structure was compared with the shell model and total Routhian surface calculations. The results indicate that the new band structure in ${}^{87}\mathrm{Tc}$ is built on a spherical configuration, which is different from that assigned to the previously identified oblate yrast rotational band.

We propose a semimicroscopic model for the simultaneous emission of two protons. This model has the advantage of avoiding certain technical aspects of a fully microscopic three-body framework, while also allowing the investigation of the influence of proton pairing on the total lifetime of the decaying nucleus. Thus, we use the standard singlet two-proton wave function on the nuclear surface, provided by the Bardeen-Cooper-Schrieffer (BCS) approach, as a boundary condition for the propagator operator. Our model allows for the estimation of all quantities related to the $2p$ emission process, since it provides the three-body wave function over most of the domain. We show that reasonable agreement with experimental values can be reached by varying the $pp$ pairing strength outside the nucleus in an interval close to the “bare” singlet value.

We explore the response to energetic partons of a baryon-charged medium produced in low energy heavy-ion collisions in which the partonic energy loss rate is expected to depend on both temperature and baryon chemical potential. The energy and momentum deposited by the partons are described by dynamical sources added to hydrodynamic equations of motion. We study the distortions of various hydrodynamic quantities, especially the energy and baryon densities, induced by energetic partons plowing through the medium. By studying the contribution from this medium response to the emission spectra of several identified hadron species we identify qualitative differences between the jet-induced modifications for mesons and net protons.

The ratios of bulk observables, such as harmonic flow $v_2$ and $v_3$, between high-energy ${}^{96}\mathrm{Ru}+{}^{96}\mathrm{Ru}$ and ${}^{96}\mathrm{Zr}+{}^{96}\mathrm{Zr}$ collisions were recently argued to be a clean probe of the nuclear structure differences between ${}^{96}\mathrm{Ru}$ and ${}^{96}\mathrm{Zr}$. Using a transport model simulation of isobar collisions, we quantify this claim from the dependence of the ratios $v_{2,\mathrm{Ru}}/v_{2,\mathrm{Zr}}$ and $v_{3,\mathrm{Ru}}/v_{3,\mathrm{Zr}}$ on various final-state effects, such as the shear viscosity, hadronization, and hadronic cascade. Although the $v_2$ and $v_3$ change by more than 50% when varying the final-state effects, the ratios are unchanged. In addition, these ratios are independent of the transverse momentum $p_{\mathrm{T}}$ and hadron species, despite of up to a factor of 2 change in $v_n$. The ratio of mean transverse momentum $\langle p_{\mathrm{T}}\rangle$ is found to be controlled by the nuclear skin and nuclear radius but is only slightly impacted by the final-state effects. Therefore, these isobar ratios serve as a clean probe of the initial condition of the quark-gluon plasma, which, in turn, is controlled by the collective structure of the colliding nuclei.

We study the nucleon-nucleon interaction up to next-to-next-to-leading order using time-ordered perturbation theory in the framework of manifestly Lorentz-invariant chiral effective field theory. We present the two-pion exchange contribution at one-loop level, which is consistent with the corresponding nonrelativistic expressions in the large-nucleon-mass limit. Using the Born series truncated at one-loop order, we calculate the phase shifts and mixing angles of the partial waves with the angular momentum $l\ge 2$. Comparing with the results of the nonrelativistic formulation, we find an improved description of the phase shifts for some $D$ waves such as the ${}^{3}D_3$ one. For the other partial waves, both approaches show globally similar results.

We employ two models of the nucleon-nucleon force: the OPE-Gaussian as well as the chiral $\mathrm{N}{}^4\mathrm{LO}$ and $\mathrm{N}{}^4\mathrm{LO}^{+}$ interactions with semilocal regularization in momentum space to study correlations among two-nucleon and three-nucleon elastic scattering observables. These models contain a number of free parameters whose values and covariance matrices are evaluated from a fit to the two-nucleon data. Such detailed knowledge of parameters allows us to create, using various sets of statistically generated parameters, numerous versions of these potentials and next apply them to two- and three-nucleon scattering to make predictions of various observables at the reaction energies up to 200 MeV. This permits a systematic analysis of correlations among two-nucleon and three-nucleon observables, based on a relatively big sample of predictions. We found that most observables in neutron-proton and neutron-deuteron systems are uncorrelated, but there are exceptions revealing strong correlations, which depend on the reaction energy and scattering angle. This information may be useful for precise fixing free parameters of two-nucleon and three-nucleon forces and for understanding dependencies and correlations between potential parameters and observables.

Reflection-asymmetric relativistic mean-field theory is used to explore the ground state properties for the even-even Dy isotopes. The results are compared with those from the finite-range droplet model (FRDM), the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc), and the available data. The calculated binding energies and quadrupole deformations agree with the experimental data as well as the FRDM and DRHBc calculations. The obtained matter density distributions and potential energy surfaces clearly exhibit the ground state shapes and the presence of deformation in these nuclei. The experimental fingerprints of octupolarity in ${}^{148,154,156,160}\mathrm{Dy}$ around $N=88$ are convincing in the present calculations. The predictions on the octupole deformation in ${}^{190\text{–}194,200,202}\mathrm{Dy}$ around $N=134$ agree with the results from the FRDM calculations. In addition, we obtain more knowledge about the shape evolution and phase transition from oblate to pear shape and then to prolate shapes in the Dy isotopes.

Background: Calculations of the structure of the low-lying states of nuclei with $Z\ge 100$ play an important role in understanding the properties of nuclei belonging to the new region of the nuclide chart, which is available now for experimental study.

Purpose: We calculate quasiparticle-phonon structure and the reduced $\gamma$-transition probabilities for the excited states with excitation energies up to 1 MeV for nuclei with $Z\ge 100$.

Methods: The quasiparticle-phonon model, which takes into account the quasiparticle-phonon interaction of different multipolarities, is used as a basis for the calculations.

Results: The quasiparticle-phonon structure and the $\gamma$-reduced transition probabilities of odd-neutron ${}^{265,267,269}\mathrm{Hs}$, ${}^{261,263,265}\mathrm{Sg}$, ${}^{257,259,261}\mathrm{Rf}$, ${}^{253,255,257}\mathrm{No}$, and ${}^{249,251,253}\mathrm{Fm}$ are calculated. The $\alpha$-decay chains starting from ${}^{265,267,269}\mathrm{Hs}$ are analyzed.

Conclusion: It is shown that below 500 keV the structure of the nuclear states is mainly exhausted by the single-quasiparticle component. The quasiparticle-phonon interaction starts to play an important role at excitation energies above 500 keV. The nuclei before Fm in the $\alpha$-decay chains starting from ${}^{265,267,269}\mathrm{Hs}$ have at least two $\alpha$-decay lines.

Multinucleon transfer reactions provide a possible access to the synthesis of new neutron-rich isotopes. Within the theoretical framework of a hybrid model combining the dinuclear system model and the GRAZING model together, the transfer reaction is investigated in ${}^{86}\mathrm{Kr}+{}^{248}\mathrm{Cm}$. In this work, it is found that the hybrid model can reproduce experimental transfer cross sections well. After the verification of the hybrid model, the transfer reactions ${}^{112,124,132}\mathrm{Sn}+{}^{249}\mathrm{Cf}$ are investigated by the influence of charge equilibration on the production cross sections of the exotic nuclei. The neutron-deficient projectile ${}^{112}\mathrm{Sn}$ shows advantages of producing neutron-deficient nuclei, while ${}^{124,132}\mathrm{Sn}$ are favorable to produce neutron-rich nuclei. In order to obtain available production cross sections of the unknown neutron-rich isotopes with $Z=99\text{−}102$, the dependence of cross sections on incident energy in the reaction ${}^{132}\mathrm{Sn}+{}^{249}\mathrm{Cf}$ is also investigated. It is found that the reaction ${}^{132}\mathrm{Sn}+{}^{249}\mathrm{Cf}$ at 510 MeV is a potential candidate to produce unknown neutron-rich isotopes of trans-target.

We report measurements of forward jets produced in $\mathrm{Cu}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=200$ GeV at the Relativistic Heavy Ion Collider. The jet-energy distributions extend to energies much larger than expected by Feynman scaling. This constitutes the first clear evidence for Feynman-scaling violations in heavy-ion collisions. Such high-energy particle production has been in models via QCD string interactions, but so far is untested by experiment. One such model calls this a hadronic accelerator. Studies with a particular heavy-ion event generator (hijing) show that photons and mesons exhibit such very high-energy production in a heavy-ion collision, so a QCD accelerator appropriately captures the physics associated with such QCD string interactions. All models other than hijing used for hadronic interactions in the study of extensive air showers from cosmic rays either do not include these QCD string interactions or have smaller effects from the QCD accelerator.

The Korea-IBS-Daegu-SKKU energy density functional (KIDS-EDF) models, constructed from the perturbative expansion of the energy density in nuclear matter, have been successfully and widely applied in describing the properties of finite nuclei and infinite nuclear matter. In the present work, we extend the applications of the KIDS-EDF models to investigate the implications of the nucleon effective mass and nuclear symmetry energy for the properties of neutron stars (NSs) and neutrino interaction with the NS constituent matter in the linear response approximation (LRA). At fixed neutrino energy and momentum transfer, we analyze the total differential cross section of neutrinos, the neutrino mean free path (NMFP), and the NS mass-radius (M-R) relations. Remarkable results are given by the KIDS0-m*87 and SLy4 models, in which $M_n^{*}/M\lesssim 1$, and their NMFPs are quite higher in comparison with those obtained from the KIDS0, KIDS-A, and KIDS-B models, which result in $M_n^{*}/M\gtrsim 1$. For the KIDS0, KIDS-A, and KIDS-B models, we obtain $\lambda \lesssim R_{\text{NS}}$, indicating that these models could predict the slow NS cooling and neutrino trapping in NSs. In contrast, the KIDS0-m*87 and SLy4 models yield $\lambda \gtrsim R_{\text{NS}}$ and thus we expect faster NS cooling and a small possibility of neutrino trapping within NSs. We also calculate the NMFP as a function of the neutrino energy and the nuclear matter density and find that the NMFP decreases as the density and neutrino energy increase, which is consistent with the result obtained in the Brussels-Montreal Skyrme (BSk17 and BSk18) models at saturation density.

In most $r$-process expansions, the dominant nuclear evolution occurs in an $(n,\gamma \left)\text{−}\right(\gamma ,n)$ equilibrium in which nuclei rapidly exchange neutrons but change charge much more slowly by beta decay. Freeze-out from this equilibrium shapes the final abundances but does not significantly alter the overall global abundance pattern; therefore, it is important to understand the details of $(n,\gamma \left)\text{−}\right(\gamma ,n)$ equilibrium both because it is the main evolution phase that determines the final abundance pattern and because it is the starting point for the freeze-out. Through use of a simple but realistic phenomenological nuclear physics model, we show that isotopic abundances versus neutron number in $(n,\gamma \left)\text{−}\right(\gamma ,n)$ equilibrium are well approximated as Gaussians. Nuclear pairing causes isotopic abundances to alternate between two Gaussians, and shell effects cause the isotopic abundances to shift from one Gaussian to another when the neutron number crosses a magic number. More complex neutron-separation energy curves versus mass number can be generated by adding a spike function to a linearly declining curve. In such a case, the equilibrium abundance curve jumps from one Gaussian to another for each added spike. Insights from our model can help shed light on how detailed theoretical or experimental nuclear data affect $r$-process nucleosynthesis during the $(n,\gamma )\text{−}(\gamma ,n)$ equilibrium phase.

Minijets, created by perturbative hard QCD collisions at moderate energies, can represent a significant portion of the total multiplicity of a heavy-ion collision event. Since their transverse momenta are initially larger than the typical saturation scale describing the bulk of the equilibrating quark-gluon plasma (QGP), they ought to be described through the physics of parton energy loss. Indeed, their typical stopping distances are larger than the usual hydrodynamization time, so they do not in general hydrodynamize at the same pace than the bulk of the collision. Therefore, in general minijets cannot be described solely by a unique preequilibrium stage that bridges the initial, overoccupied glasma state, with the hydrodynamical evolution. In this work we make use of a new concurrent minijet$+$hydrodynamic framework in which the properties of the hydrodynamically evolving QGP are modified due to the injection of energy and momentum from the minijets. We study the system for different choices of the minimum transverse momentum associated with minijet production. In order to achieve a realistic description of charged particle multiplicity, the amount of entropy associated to the low-$x$ initial state needs to be reduced. Moreover, the fact that the injected momentum from the randomly oriented minijets is not correlated with the spatial gradients of the system reduces overall flow, and the value of the QGP transport coefficients needs to be reduced accordingly in order to describe the measured flow coefficients in experiments. They are, in effect, an important new source of fluctuations, resulting in a spikier, notably modified hydrodynamical evolution when compared to the scenario in which the presence of minijets is ignored. We avow that their abundance makes it necessary to include their physics in holistic descriptions of heavy-ion collisions. We discuss the impact of the minijets on a number of observables, such as $p_T$ spectra and $p_T$-differential flow $v_n$ for a wide range of centrality classes. In contrast to elliptic, triangular or quadrangular flow, we find that directed flow, $v_1$, has the strongest potential to discriminate between different minijet production rates.

The competition between the quenching of pairing due to the repulsive Coulomb interaction and dynamic pairing correlations added by particle number symmetry restoration has been studied in a selected set of Fermium and Nobelium isotopes by using a hierarchy of Hartree-Fock-Bogoliubov–based approximations and a restricted variation after particle number projection, all of them based on the $\mathrm{D}1{\mathrm{M}}^{*}$ parametrization of the Gogny force. It is found that Coulomb antipairing is partially compensated by beyond-mean-field pairing correlations. However, the compensation is not perfect and a modulation of the spontaneous fission half-lives, as functions of the neutron number, indicates that the combined effect on fission dynamics of Coulomb antipairing and restricted particle number symmetry restoration cannot be overlooked. Neither can it be accounted for by the Coulomb Slater approximation.

Mean values of the number of protons and neutrons of the primary fission fragments at scission are determined for the asymmetric fission of 16 fissioning isotopes, from ${}^{219}\mathrm{Ac}$ up to ${}^{238}\mathrm{Np}$. Our results confirm that the main asymmetric fission mode around the heavier uranium isotopes is indeed characterized by an average atomic number around $\langle Z_{\mathrm{H}}\rangle =54$ in the heavy fission fragments. However, they also unambiguously show a stabilization effect in the light fission fragments around $\langle N_{\mathrm{L}}\rangle =52–54$ in the neutron-deficient thorium and actinium isotopes. This is a clear signature that these deformed proton and neutron shell closures around 54 play a major role in the nuclear fission process. The evolution along the thorium chain shows that the neutron shell appears to be dominant in the asymmetric fission of the lighter thorium isotopes, in contrast to the heavier thorium isotopes for which the stabilization originates from the proton shell.

A large number of the presently running neutrino and dark-matter experiments use thallium-doped cesium-iodide CsI[Tl] crystals, sodium-doped cesium-iodide CsI[Na] crystals, or thallium-doped sodium-iodide NaI[Tl] crystals. In the present paper we calculate elastic and inelastic cross sections for neutral-current supernova-neutrino scattering off ${}^{127}\mathrm{I}$ and ${}^{133}\mathrm{Cs}$, relevant for experiments using CsI[Tl], CsI[Na], or NaI[Tl] crystals. We study also the cross sections folded with two-parameter Fermi-Dirac distributions of the supernova-neutrino spectrum. The adopted nuclear-theory framework is the microscopic quasiparticle-phonon model, able to operate in large single-particle valence bases and use G-matrix based two-nucleon interactions with a phenomenological renormalization.

The isoscalar giant resonances for ${}^{86}\mathrm{Ge}$ are studied by the quasiparticle finite amplitude method based on the covariant density functional theory. In addition to the well-known monopole-quadrupole coupling that splits the isoscalar giant monopole resonance in axially deformed nuclei, a monopole-quadrupole-hexadecupole coupling is identified in the neutron-rich triaxially deformed nucleus ${}^{86}\mathrm{Ge}$, leading to the emergence of a distinct resonance peak at the low energy side of the isoscalar monopole strength function. The transition density of the triaxiality-induced resonance peak shows a strong interplay among monopole, quadrupole, and hexadecupole vibrations. The resonance peak responds to monopole, quadrupole, and hexadecupole perturbations simultaneously, which could be regarded as a fingerprint of the triaxiality in ${}^{86}\mathrm{Ge}$.

The physics interpretation of the recent measurements of the spin polarization of $\mathrm{\Lambda }$ hyperons produced in relativistic heavy-ion collisions is discussed. We suggest that the polarization measured in the $\mathrm{\Lambda }$ rest frame should be projected along the direction of the total angular momentum that is first transformed to the same frame, and only then averaged over $\mathrm{\Lambda }$'s with different momenta in the center-of-mass frame. While this procedure does not affect the current measurements done in a broad transverse-momentum range, it may become important (representing a correction of about 10%) for the most energetic hyperons under study (with transverse momenta reaching $4–5\mathrm{GeV}/c$). The proposed treatment is generally more appropriate for relativistic $\mathrm{\Lambda }$'s. Throughout the paper, we deliver explicit expressions for various boosts, rotations, and transformations of angular distributions, which may help to compare model predictions with the experimental results.

We report a comprehensive shell-model study of the $logft$ values for the forbidden ${\beta }^{-}$ decay transitions in the region northeast of ${}^{208}\mathrm{Pb}$. For this we have considered ${}^{210\text{–}215}\mathrm{Pb}$ $\to$ ${}^{210\text{–}215}\mathrm{Bi}$ and ${}^{210\text{–}215}\mathrm{Bi}$ $\to$ ${}^{210\text{–}215}\mathrm{Po}$ transitions. We have performed shell-model calculation using the KHPE interaction in valence shells 82-126 for protons and 126-184 for neutrons without any truncation. We have also calculated half-lives and $Q$ values for the concerned nuclei. Recently several $logft$ values were observed corresponding to ${\beta }^{-}$ decay from the ($8^{-}$) isomeric state of ${}^{214}\mathrm{Bi}^m$ at the CERN-ISOLDE facility [Andel et al., Phys. Rev. C 104, 054301 (2021)], and for the first time we have reported shell-model results for these transitions.