Calculations of the cross sections of inelastic electron scattering $(e,e^{\prime })$ on a nucleus in the multi-keV energy range strongly depend on the description of the screening of the nuclear Coulomb potential as well as on the deformation of the wave functions of the incoming and outgoing electron in the vicinity of the nucleus. These cross sections are evaluated at values lower than ${10}^{-30}{\mathrm{cm}}^2$, which vary by several orders of magnitude according to the models. Experimental measurements would be required to constrain the models but it is a real challenge to measure such low cross sections. In this study, we demonstrate that inelastic electron scattering is the main nuclear excitation mechanism in a ${}^{181}\mathrm{Ta}$ target irradiated with a new intense 10–30 keV electron beam produced with a biased laser plasma. Calculations show that, through the detection of conversion electrons, it should be possible to measure the nuclear excitation yields. The effect of electron-beam heating and of plasma deposition on the tantalum target are quantified, thus allowing the dimensioning of a possible experimental configuration to study $(e,e^{\prime })$ processes in this range of energy for the first time.

Hyperon ($Y$) mixing in neutron-star matter brings about a remarkable softening of the equation of state (EoS) and the maximum mass is reduced to a value far less than $2M_{\odot }$. One idea to avoid this “hyperon puzzle in neutron stars” is to assume that the many-body repulsions work universally for every kind of baryons. The other is to take into account the quark deconfinement phase transitions from a hadronic EoS to a sufficiently stiff quark-matter EoS. In the present approach, both effects are handled in a common framework. As well as the hadronic matter, the quark matter with the two-body quark-quark interactions are treated within the Brueckner-Bethe-Goldstone theory beyond the mean-field frameworks, where interaction parameters are based on the terrestrial data. The derived mass-radius relations of neutron stars show that maximum masses reach over $2M_{\odot }$ even in the cases of including hadron-quark phase transitions, being consistent with the recent observations for maximum masses and radii of neutron stars by the Neutron Star Interior Composition Explorer (NICER) measurements and the other multimessenger data.

Background: One of the fundamental problems of quantum information science is quantum entanglement. Recently, quantum phase transition in nuclear systems is studied in connection with quantum entanglement.

Purpose: In this paper, the use of entanglement entropy as a suitable signal for the study of quantum phase transition in the even-even and odd-$A$ nuclei is investigated. The effect of the coupling of a single fermion to a boson core on entanglement entropy is studied.

Method: By use of the affine $SU(1,1)$ Lie algebra and through the Schmidt decomposition in the framework of the interacting boson model (IBM) and interacting boson-fermion model (IBFM), entanglement entropy in the even-even and odd-$A$ are obtained. The entanglement entropy is used for tracking and studying the shape phase transition in these nuclei.

Results: The entanglement entropy in the IBM and the IBFM is calculated. The entanglement entropy values of the low-lying states of ${}^{122–134}\mathrm{Xe}, {}^{102–110}\mathrm{Pd}$, and ${}^{123–133}\mathrm{Xe}$ were calculated and analyzed. It is found that entanglement entropy is a suitable order parameter to detect shape phase transition in nuclear systems.

Conclusions: The obtained results indicate that the entropy of entanglement is sensitive to the shape-phase transition between spherical and $\gamma$-unstable regions in nuclei. The results show that entanglement entropy is a powerful tool for identifying shape phase transitions in nuclei. It is found that the coupling of the single fermion with angular momentum $j$ to the even-even system does not change the geometry imposed by the boson core performing the transition and only the entanglement entropy values have been shifted by the addition of the odd particle with respect to the even case.

Neutron transfer reaction measurements, relevant to the neutrinoless double $\beta$ decay candidate ${}^{124}\mathrm{Sn}$ and its daughter ${}^{124}\mathrm{Te}$, have been performed. Precise measurements of both neutron addition $\left[\right(d,p),({}^4\mathrm{He},{}^3\mathrm{He}\left)\right]$ and removal $\left[\right(p,d),({}^3\mathrm{He},{}^4\mathrm{He}\left)\right]$ cross sections have been used to determine the occupation of valence orbitals pertinent to neutrinoless double $\beta$ decay in these two nuclei. This information could be used to constrain calculations of the nuclear matrix element for the neutrinoless double $\beta$ decay of ${}^{124}\mathrm{Sn}$. The change in the ground-state neutron vacancies in proceeding from ${}^{124}\mathrm{Sn}$ to ${}^{124}\mathrm{Te}$ is mainly found in the $d_{3/2,5/2}$ and $h_{11/2}$ orbitals. The occupancies of states near the Fermi level are in reasonable agreement with shell model calculations.

We present a determination of optical potentials for ${}^4\mathrm{He}$-target collisions using the double-folding method. We use chiral effective field theory nucleon-nucleon interactions at next-to-next-to-leading order combined with state-of-the-art nucleonic densities. The imaginary part of the optical potential is obtained from the real double-folding interaction either through a proportionality constant or applying Kramers-Kronig dispersion relations. With these potentials, we compute the elastic scattering of ${}^4\mathrm{He}$ off various targets, from ${}^4\mathrm{He}$ to ${}^{120}\mathrm{Sn}$. We study the sensitivity of our predicted cross sections to the choice of nucleon-nucleon interactions and nuclear densities. Very good agreement is obtained with existing elastic-scattering data for ${}^4\mathrm{He}$ energies between 100 and 400 MeV.

Background: The nature of asymmetric fission of preactinides is not yet understood in detail, despite intense experimental and theoretical studies carried out at present.

Purpose: The study of asymmetric and symmetric fission of ${}^{180,182,183}\mathrm{Hg}$ and ${}^{178}\mathrm{Pt}$ nuclei as a function of their excitation energy and isospin.

Methods: Mass-energy distributions of fission fragments of ${}^{180}\mathrm{Hg}, {}^{178}\mathrm{Pt}$ (two protons less than ${}^{180}\mathrm{Hg}$), and ${}^{182}\mathrm{Hg}$ (two neutrons more than ${}^{180}\mathrm{Hg}$) formed in the ${}^{36}\mathrm{Ar}+{}^{144}\mathrm{Sm}, {}^{142}\mathrm{Nd}$, and ${}^{40}\mathrm{Ca}+{}^{142}\mathrm{Nd}$ reactions were measured at energies near and above the Coulomb barrier. Fission of ${}^{183}\mathrm{Hg}$ obtained in the reaction of ${}^{40}\mathrm{Ca}$ with ${}^{143}\mathrm{Nd}$ was also investigated to see if one extra neutron could lead to dramatic changes in the fission process due to the shape-staggering effect in radii, known in ${}^{183}\mathrm{Hg}$.

The measurements were performed with the double-arm time-of-flight spectrometer CORSET.

Results: The observed peculiarities in the fission fragment mass-energy distributions for all studied nuclei may be explained by the presence of a symmetric fission mode and three asymmetric fission modes, manifested by the different total kinetic energies and fragment mass splits. The yield of symmetric mode grows with increasing excitation energy of compound nucleus.

Conclusions: The investigated properties of asymmetric fission of ${}^{180,182,183}\mathrm{Hg}$ and ${}^{178}\mathrm{Pt}$ nuclei point out the existence of well-deformed proton shell at $Z\approx 36$ and a less deformed proton shell at $Z$ ≈ 46.

In heavy ion collisions, elliptic flow $v_2$ and radial flow, characterized by eventwise average transverse momentum $\left[p_{\mathrm{T}}\right]$, are related to the shape and size of the overlap region, which are sensitive to the shape of colliding atomic nuclei. The Pearson correlation coefficient between $v_2$ and $\left[p_{\mathrm{T}}\right], {\rho }_2$, was found to be particularly sensitive to the quadrupole deformation parameter $\beta$ that is traditionally measured in low energy experiments. Built on earlier insight that the prolate deformation $\beta >0$ reduces the ${\rho }_2$ in ultracentral collisions (UCC), we show that the prolate deformation $\beta <0$ enhances the value of ${\rho }_2$. As $\beta >0$ and $\beta <0$ are the two extremes of triaxiality, the strength and sign of $v_2^2\text{−}\left[p_{\mathrm{T}}\right]$ correlation can be used to provide valuable information on the triaxiality of the nucleus. Our study provide further arguments for using the hydrodynamic flow as a precision tool to directly image the deformation of the atomic nuclei at extremely short timescale ($<{10}^{-24}\mathrm{s}$).

Nuclear matrix elements (NMEs) of neutrinoless double-$\beta$ decay ($0\nu \beta \beta$) from $0_1^{+}$ to $0_1^{+}$ of ${}^{130}\mathrm{Te}\to {}^{130}\mathrm{Xe}$, ${}^{134}\mathrm{Xe}\to {}^{134}\mathrm{Ba}$, and ${}^{136}\mathrm{Xe}\to {}^{136}\mathrm{Ba}$ are calculated in the nucleon pair shell-model framework. It is found that the NMEs of $0\nu \beta \beta$ calculated in the surface-$\delta$ approximation (SDI) and the BCS approximation with the model space truncated into the SD-pair subspace are close to each other and smaller than those predicted by the other models. The inclusion of the $G$ pair does not alter the results significantly. When the single-particle energies are assumed to be degenerate, the calculated results in the SD-pair shell model become close to those of the other models. It is also shown that the NMEs are sensitive to the model parameters.

The zirconium isotopes with $A=92–110$ have one of the most complicated evolution of structure in the nuclear chart. In order to understand the structural evolution of these isotopes, we carry a detailed calculation in a definite symmetry-based framework, the interacting boson model with configuration mixing (IBM-CM). We compare our calculation to a large range of experimental data, such as energy levels, two-neutron separation energies, $E2$ and $E0$ transition rates, isotope shifts, and magnetic moments. The structural evolution of the low lying spectra of these isotopes is explained using the notion of intertwined quantum phase transitions (IQPTs), for which a QPT involving a crossing of two configurations (Type II) is accompanied by a QPT involving a shape evolution of each configuration separately (Type I). In our study, we find the occurrence of Type I QPT within the intruder configuration, changing from weakly deformed to prolate deformed and finally to $\gamma$-unstable, associated with the U(5), SU(3) and SO(6) dynamical symmetry limits of the IBM, respectively. Alongside the Type I QPT, we also find the occurrence of Type II QPT between the normal and intruder configurations, where both Types I and II have a critical point near $A\approx 100$. The good agreement of our calculation with the vast empirical data along the chain of isotopes demonstrates the relevance of IQPTs to the zirconium isotopes, and can serve as a case study to set path for new investigations of IQPTs in other nuclei and other physical systems.

A generalized formula is provided to calculate the $M_n/M_p$ ratio of the multipole transition matrix elements, in the framework of the so-called phenomenological analysis. It takes into account the possible difference between the neutron and proton radii and diffuseness, which can occur especially in exotic nuclei. The validity domain of the original Bernstein formula is discussed in the case of a proton scattering probe at a few tens of MeV. The largest discrepancies are obtained for very neutron-rich nuclei $(N/Z\gtrsim 1.6)$ or when the electromagnetic deformation parameter is larger than the proton scattering one. The reduction of the statistical error bars, and the study of very neutron-rich nuclei at facilities of exotic beams of the new generation, should favor the use of the generalized Bernstein formula.

${}^{83m}\mathrm{Kr}$, with a short lifetime, is an ideal calibration source for liquid xenon or liquid argon detectors. The ${}^{83m}\mathrm{Kr}$ isomer can be generated through the decay of the ${}^{83}\mathrm{Rb}$ isotope, which is usually produced by proton beams bombarding natural krypton atoms. In this paper, we report a successful production of ${}^{83}\mathrm{Rb}/{}^{83m}\mathrm{Kr}$ with a proton beam energy of 3.4 MeV, and the first measurement of the production rate with such low-energy proton beams. Another production attempt is performed using the newly available 20 MeV proton beam in China, and the measured production rate is consistent with previous measurements. The produced ${}^{83m}\mathrm{Kr}$ source has been successfully injected into the PandaX-II liquid xenon detector, yielding enough statistics for detector calibration.

In this article a correspondence has been established between the out of equilibrium system dissipation and the thermodynamic field redefinition of the macroscopic variables through the momentum dependent relaxation time approximation (MDRTA) solution of the relativistic transport equation. Here, it has been shown that the out of equilibrium thermodynamic fields are not uniquely defined and are subjected to include dissipative effects from the medium. A second order relativistic hydrodynamic theory has been developed including such dissipative effects. The necessary conditions for developing a hydrodynamic theory have been fulfilled: (i) the thermodynamic identities incorporating such redefined fields have been shown to conserve the energy-momentum tensor perfectly under MDRTA, (ii) the non-negativity of entropy production remains unaffected by the inclusion of such dissipative contributions in hydrofields as long as the independent transport coefficients remain positive.

This paper introduces the subensemble acceptance method 2.0 (SAM-2.0)—a procedure to correct cumulants of a random number distribution inside a subsystem for the effect of exact global conservation of a conserved quantity to which this number is correlated, with applications to measurements of event-by-event fluctuations in heavy-ion collisions. The method expresses the corrected cumulants in terms of the cumulants inside and outside the subsystem that are not subject to the exact conservation. The derivation assumes that all probability distributions associated with the cumulants are peaked at the mean values but are otherwise of arbitrary shape. The formalism reduces to the original SAM [V. Vovchenko, O. Savchuk, R. V. Poberezhnyuk, M. I. Gorenstein, and V. Koch, Phys. Lett. B 811, 135868 (2020)] when applied to a coordinate space subvolume of a uniform thermal system. As the new method is restricted neither to the uniform systems nor to the coordinate space, it is applicable to fluctuations measured in heavy-ion collisions at various collision energies in different momentum space acceptances. The SAM-2.0 thus brings the experimental measurements and theoretical calculations of event-by-event fluctuations closer together, as the latter are typically performed without the account of exact global conservation.

We present a dynamical description of (anti)proton number cumulants and correlation functions in central Au-Au collisions at $\sqrt{s_{NN}}=7.7–200\mathrm{GeV}$ by utilizing viscous hydrodynamics simulations. The cumulants of proton and baryon number are calculated in a given momentum acceptance analytically, via an appropriately extended Cooper-Frye procedure describing particlization of an interacting hadron resonance gas. The effects of global baryon number conservation are taken into account using a generalized subensemble acceptance method. The experimental data of the STAR Collaboration are consistent at $\sqrt{s_{NN}}\gtrsim 20\mathrm{GeV}$ with simultaneous effects of global baryon number conservation and repulsive interactions in the baryon sector, the latter being in line with the behavior of baryon number susceptibilities observed in lattice QCD. The data at lower collision energies show possible indications for sizable attractive interactions among baryons. The data also indicate sizable negative two-particle correlations between antiprotons that are not satisfactorily described by baryon conservation and excluded volume effects. We also discuss differences between cumulants and correlation functions (factorial cumulants) of (anti)proton number distribution, proton versus baryon number fluctuations, and effects of the hadronic afterburner.

Earlier fourth-order extended Thomas-Fermi calculations with functional BSk24 of pasta phases in the inner crust of neutron stars are here repeated with Strutinsky-integral and pairing corrections included for protons. The main consequence of these corrections is to eliminate the spaghetti phase at zero temperature and significantly reduce the range of densities over which the lasagna phase is found. On the other hand, the microscopic corrections have a negligible impact on the equation of state and on the proton fraction.

Short-range potential has been added into an extended quantum molecular dynamics (EQMD) model. The rms radius, binding energy, and momentum distribution of ${}^{12}\mathrm{C}$ with different initial structures and short-range potential parameters have been checked. The separation energy of ${}^{12}\mathrm{C}(p,2p){}^{11}\mathrm{B}$ reaction is calculated and compared with the experimental data, which indicates that our modified EQMD model can be taken as a reliable tool for studying proton pair knock-out reaction. Furthermore, the short-range correlation effects on emission time and momentum spectrum of two protons are discussed. Finally, the momentum correlation function of the emitted proton pair is calculated by Lednicky and Lyuboshitz's analytical method. The result explains that short-range repulsion causes high momentum tail and weakens the momentum correlation function.

In this work, we study the effects of the nuclear symmetry energy slope on the neutron star dense matter equation of state and its impact on neutron star observables (mass-radius, tidal response). We construct the equation of state within the framework of covariant density functional theory implementing coupling schemes of nonlinear and density-dependent models with viability of heavier non-nucleonic degrees of freedom. The slope of the symmetry energy parameter $\left(L_{\text{sym}}\right)$ is adjusted following the density dependence of isovector meson coupling to baryons. We find that smaller values of $L_{\text{sym}}$ at saturation favor early appearance of $\mathrm{\Delta }$ resonances in comparison to hyperons, leading to latter's threshold at higher matter densities. We also investigate the dependence of $L_{\text{sym}}$ on tidal deformability and the compactness parameter of a $1.4M_{\odot }$ neutron star for different equations of state and observe similar converging behavior for larger $L_{\text{sym}}$ values.

For more than half a century, nucleons were considered to move continuously in the nuclei. Recent electron-scattering experiments indicate about 20–25% of nucleons in heavier nuclei are involved in the neutron-proton short-range correlations. Nucleons in the nuclei thus have abnormal behavior unlike those in the noninteraction fermi gas. In the neutron-rich nuclei, around the Fermi momentum, the neutron-proton short-range correlations lead to a momentum gap in the proton momentum distribution, which is circumstantially supported by the pionic experimental data. Likewise, there should also be a neutron momentum gap in the proton-rich nuclei. Nucleon momentum gap is thought to have profound and extensive implications in the studies ranging from particle physics to neutron stars as well as ultracold atomic gases.