We present a mechanism to efficiently preselect the number of intrinsic many-body states that are used to define the many-body wave functions within the discrete generator coordinate method (GCM). This procedure, based on the proper definition of a natural basis of orthonormal states, does not require the evaluation of the nondiagonal Hamiltonian kernels to do the selection and helps to reduce the numerical instabilities. The performance of the method is analyzed in detail in the ground state and $0^{+}$ excited states of some selected nuclei computed with the Gogny energy density functional.

By applying a relativistic mean-field description of neutron star matter with density dependent couplings, we analyze the properties of two different matter compositions: nucleonic matter with $\mathrm{\Delta }$ baryons and nucleonic matter with hyperons and $\mathrm{\Delta }$ baryons. The $\mathrm{\Delta }$-meson couplings are allowed to vary within a wide range of values obtained by experimental data, while the hyperon-meson couplings are fitted to hypernuclear properties. Neutron star properties with no deconfinement phase transition are studied. It is verified that many models are excluded because the effective nucleon mass becomes zero before the maximum mass configuration is attained. Hyperon-free compact stars with $\mathrm{\Delta }$-dominated composition are possible: the deltic stars. It is found that with a convenient choice of parameters the existence of deltic stars with 80% of $\mathrm{\Delta }$ baryons at the center of the star is possible. However, the presence of hyperons lowers the $\mathrm{\Delta }$ baryon fraction to values below 20% at the center and below 30% at 2–3 saturation densities. It is discussed that, in the presence of $\mathrm{\Delta }$ baryons, the hyperon softening is not so drastic because $\mathrm{\Delta }$'s couple more strongly to the $\omega$ meson, and the stiffness of the equation of state is determined by the $\omega$ dominance at high densities. The speed of sound reflects very well this behavior. The compactness of the pulsar RX J0720.4-3125 imposes $x_{\sigma \mathrm{\Delta }}>x_{\omega \mathrm{\Delta }}>1$ and favors $x_{\rho \mathrm{\Delta }}>1$.

A technique for broadband high-precision mass measurements of short-lived exotic nuclides is reported. It is based on the isochronous mass spectrometry (IMS) and realizes simultaneous determinations of revolution time and velocity of short-lived stored ions at the cooler storage ring CSRe in Lanzhou. The technique, named the $B\rho$-defined IMS or $B\rho$-IMS, boosts the efficiency, sensitivity, and accuracy of mass measurements, and is applied here to measure masses of neutron-deficient $fp$-shell nuclides. In a single accelerator setting, masses of ${}^{46}\mathrm{Cr}$, ${}^{50}\mathrm{Fe}$, and ${}^{54}\mathrm{Ni}$ are determined with relative uncertainties of (5–6)$\times {10}^{-8}$, thereby improving the input data for testing the unitarity of the Cabibbo-Kobayashi-Maskawa quark mixing matrix. This is the technique of choice for future high-precision measurements of the most rarely produced shortest-lived nuclides.

Excited states of the ${}^{203}\mathrm{Po}$ ($Z=84,N=119$) have been investigated after populating them through ${}^{194}\mathrm{Pt}({}^{13}\mathrm{C},4n)$ fusion-evaporation reaction at ${\mathrm{E}}_{\mathrm{beam}}=74$ MeV and using a large array of Compton-suppressed HPGe clover detectors as the detection setup for the emitted $\gamma$ rays. Standard techniques of $\gamma$-ray spectroscopy have been applied towards establishing the level structure of the nucleus. Twenty five new $\gamma$-ray transitions have been identified therein, through $\gamma \text{−}\gamma$ coincidence measurements, and spin-parity assignments of several states have been determined or confirmed, following the angular correlation and linear polarization measurements on the observed $\gamma$ rays. The excited states have been interpreted in the framework of large basis shell-model calculations, while comparing their calculated and experimental energies. They have been principally ascribed to proton population in the $h_{9/2}$ and $i_{13/2}$ orbitals outside the $Z=82$ closure and neutron occupation of the $f_{5/2}$, $p_{3/2}$, and $i_{13/2}$ orbitals in the $N=126$ shell.

We investigate the degree of $\alpha$ (${}^4\mathrm{He}$ nucleus) clustering in the ground-state density profiles of ${}^{44}\mathrm{Ti}$ and ${}^{52}\mathrm{Ti}$. Two types of density distributions, shell- and cluster-model configurations, are generated fully microscopically with the antisymmetrized quasi-cluster model, which can describe both the $j-j$ coupling shell and $\alpha$-cluster configurations in a single scheme. Despite both the models reproducing measured charge radius data, we found that the $\alpha$ clustering significantly diffuses the density profiles near the nuclear surface compared to the ideal $j-j$ coupling shell-model configuration. The effect is most significant for ${}^{44}\mathrm{Ti}$, while it is less for ${}^{52}\mathrm{Ti}$ due to the occupation of the $0f_{7/2}$ orbits in the ${}^{48}\mathrm{Ca}$ core. This difference can be detected by measuring proton-nucleus elastic scattering or the total reaction cross section on a carbon target at intermediate energies.

The real-space density-constrained time-dependent Hartree-Fock-Bogoliubov method is exploited to obtain the dynamic potential energy and several experimental variables of fission fragments. The resultant predictions of collective variables, especially the total kinetic energy and total excitation energy of the fission fragments, finely match the experimental data. It is demonstrated that scission dynamics including the shell effects and pairing correlations should be the focus of further studies.

Elastic scattering, total reaction, and fusion cross section measurements for the radioactive ${}^7\mathrm{Be}$ nucleus on a light and a heavy target, are treated in a global approach at near and sub-barrier energies for probing the optical potential and describing fusion at low energies. Elastic scattering data of ${}^7\mathrm{Li}$ on the same target were analyzed under the same context to support this analysis. It is found that for low mass targets, dispersion relations are not adequate for describing the potential or the fusion. On the contrary this is possible for heavy targets, where the standard potential threshold anomaly and fusion enhancement is observed. The consequences of the above on fusion hindrance at deep sub-barrier energies is discussed.

We have studied the classical and quantum expressions of electrical conductivity and their numerical estimation in the presence of a magnetic field for hadron resonance gas (HRG) and massless quark matter. Classical results of transport coefficients of HRG matter in the presence of a magnetic field were studied previously by Dash et al. [Phys. Rev. D 102, 016016 (2020)] using the standard relaxation time approximation in the Boltzmann equation. In the same reference, the transition from isotropic transport coefficients to anisotropic coefficients in the presence of a magnetic field was also estimated for massless and HRG matter. This led to an upper limit or Stefan-Boltzmann (SB) type limit to the nonperturbative domain transition of transport coefficients. In a similar context, the present work has concentrated on the classical to quantum transition of HRG transport from the domain of high temperature and low magnetic field to that of low temperature and high magnetic field. We have also compared the quantum modification of HRG results with that of massless quark matter, where we observed an opposite trend. A similar kind of quantum effect is also noticed between mesons and baryons due to their different particle distribution functions. Despite the fact that HRG contains both mesons and baryons, Landau quantization of its net magnetothermodynamic phase space reveals meson- or boson-dominated quantum modification. That is why the quantum modification of HRG results reveals the opposite trend from that of massless quark matter, which faces fermionic quantum modification.

Jets produced in high energy heavy ion collisions are quenched by the quark gluon plasma. Measurements of these jets are influenced by the methods used to suppress and subtract the large, fluctuating background and the assumptions inherent in these methods. We compare the measurements of the background in Pb+Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV by the ALICE Collaboration (Abelev et al., J. High Energy Phys. 03 (2012) 053) to calculations in tenngen (a data-driven random background generator) and pythia angantyr. A detailed understanding of the width of these fluctuations is important for reducing uncertainties due to unfolding and extending measurements to lower momenta and larger resolution parameters. The standard deviation of the energy in random cones in tenngen is approximately in agreement with the form predicted in the ALICE paper, with deviations of 1–6%. The standard deviation of energy in random cones in angantyr exceeds the same predictions by approximately 13%. Deviations in both models can be explained by the assumption that the single-particle $d^{2}N/dyd{p}_T$ is a gamma distribution in the derivation of the prediction, whereas the model uses a different distribution. This indicates that model comparisons are potentially sensitive to the treatment of the background. We demonstrate that unfolding methods used to remove background fluctuations from jets can affect the comparisons between models and data, even in the absence of detector effects. Our findings suggest the need to more carefully consider methods for comparing simulations and data.

In this paper, we describe an experiment measuring low-$Q^2$ elastic electron-proton scattering using a newly developed cryogenic supersonic gas jet target in the A1 three-spectrometer facility at the Mainz Microtron. We measured the proton electric form factor within the four-momentum transfer range of $0.01\le Q^2\le$ $0.045{(\mathrm{GeV}/c)}^2$. The experiment showed results consistent with the existing measurements. The data we collected demonstrated the feasibility of the gas jet target and the potential of future scattering experiments using high-resolution spectrometers with this gas jet target.

We theoretically investigate the fate of a neutron-alpha $p$-wave resonance in dilute neutron matter, which may be encountered in neutron stars and supernova explosions. While ${}^5\mathrm{He}$ is known as a resonant state that decays to a neutron and an alpha particle in vacuum, this unstable state turns into a stable bound state in the neutron Fermi sea because the decay process is forbidden by the Pauli-blocking effect of neutrons. Such a resonance-to-bound transition assisted by the Pauli-blocking effect can be realized in cold atomic experiments for a quantum mixture near the heteronuclear Feshbach resonance.

In a previous analysis of electroproduction of hypernuclei the cross sections were calculated using the distorted-wave impulse approximation where the momentum of the initial proton in the nucleus was set to zero (the “frozen-proton” approximation). In this paper we go beyond this approximation, assuming a nonzero effective proton momentum due to proton Fermi motion inside the target nucleus, discussing also other kinematical effects. To this end we have derived a more general form of the two-component elementary electroproduction amplitude (Chew-Goldberger-Low-Nambu-like) which allows its use in a general reference frame moving with respect to the nucleus rest frame. The effects of Fermi motion were found to depend on kinematics and elementary amplitudes. The largest effects were observed in the contributions from the longitudinal and interference parts of the cross sections. The extension of the calculations beyond the frozen-proton approximation improved the agreement of predicted theoretical cross sections with experimental data, and, once we assumed the optimum on-shell approximation, we were able to remove an inconsistency which was previously present in the calculations.

We extend the applicability of the hydrodynamics, perturbative QCD and saturation -based EKRT (Eskola-Kajantie-Ruuskanen-Tuominen) framework for ultrarelativistic heavy-ion collisions to peripheral collisions by introducing dynamical freeze-out conditions. As a new ingredient compared to the previous EKRT computations we also introduce a nonzero bulk viscosity. We compute various hadronic observables and flow correlations, including normalized symmetric cumulants, mixed harmonic cumulants, and flow–transverse-momentum correlations, and compare them against measurements from the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC) . We demonstrate that the inclusion of the dynamical freeze-out and bulk viscosity allows a better description of the measured flow coefficients in peripheral collisions and enables the use of an extended centrality range when constraining the properties of QCD matter in the future.

Background: An ultralow $Q$-value $\beta$ decay can occur from a parent nuclide to an excited nuclear state in the daughter such that $Q_{\text{UL}}\lesssim$ 1 keV. These decay processes are of interest for nuclear $\beta$-decay theory and as potential candidates in neutrino mass determination experiments. To date, only one ultralow $Q$-value $\beta$ decay has been observed—that of ${}^{115}\mathrm{In}$ with $Q_{\beta }=147\left(10\right)$ eV. A number of other potential candidates exist, but improved mass measurements are necessary to determine if these decay channels are energetically allowed and, in fact, ultralow.

Purpose: To perform precise $\beta$-decay $Q$-value measurements of ${}^{112,113}\mathrm{Ag}$ and ${}^{115}\mathrm{Cd}$ and to use them in combination with nuclear energy level data for the daughter isotopes ${}^{112,113}\mathrm{Cd}$ and ${}^{115}\mathrm{In}$ to determine if the potential ultralow $Q$-value $\beta$-decay branches of ${}^{112,113}\mathrm{Ag}$ and ${}^{115}\mathrm{Cd}$ are energetically allowed and $\lesssim 1$ keV.

Method: The Canadian Penning Trap at Argonne National Laboratory was used to measure the cyclotron frequency ratios of singly charged ${}^{112,113}\mathrm{Ag}$ and ${}^{115}\mathrm{Cd}$ ions with respect to their daughters ${}^{112,113}\mathrm{Cd}$ and ${}^{115}\mathrm{In}$. From these measurements, the ground-state to ground-state $\beta$-decay $Q$ values were obtained.

Results: The ${}^{112}\mathrm{Ag}\to {}^{112}\mathrm{Cd}$, ${}^{113}\mathrm{Ag}\to {}^{113}\mathrm{Cd}$, and ${}^{115}\mathrm{Cd}\to {}^{115}\mathrm{In}\beta$-decay $Q$ values were measured to be $Q_{\beta }\left({}^{112}\mathrm{Ag}\right)=3990.16\left(22\right)$ keV, $Q_{\beta }\left({}^{113}\mathrm{Ag}\right)=2085.7\left(4.6\right)$ keV, and $Q_{\beta }\left({}^{115}\mathrm{Cd}\right)=1451.36\left(34\right)$ keV. These results were compared to energies of excited states in ${}^{112}\mathrm{Cd}$ at 3997.75(14) keV, ${}^{113}\mathrm{Cd}$ at 2015.6(2.5) and 2080(10) keV, and ${}^{115}\mathrm{In}$ at 1448.787(9) keV, resulting in precise $Q_{\text{UL}}$ values for the potential decay channels of $-7.59\left(26\right)$ keV, 6(11) keV, and 2.57(34) keV, respectively.

Conclusion: The potential ultralow $Q$-value decays of ${}^{112}\mathrm{Ag}$ and ${}^{115}\mathrm{Cd}$ have been ruled out. ${}^{113}\mathrm{Ag}$ is still a possible candidate until a more precise measurement of the 2080(10) keV, $1/2^{+}$ state of ${}^{113}\mathrm{Cd}$ is available. In the course of this work we have found the ground state mass of ${}^{113}\mathrm{Ag}$ reported in the 2020 Atomic Mass Evaluation [Wang et al., Chin. Phys. C 45, 030003 (2021)] to be lower than our measurement by 69(17) keV (a $4\sigma$ discrepancy).

An ambitious goal of the astrophysical community is not only to constrain the equation of state (EOS) of neutron star (NS) matter by confronting it with astrophysics observations, but ultimately also to infer the NS composition. Nevertheless, the composition of the NS core is likely to remain uncertain unless we have an accurate determination of the nuclear symmetry energy at suprasaturation density $(\rho >{\rho }_0)$. We investigate how the nucleonic direct Urca (dUrca) processes can be used as an effective probe to constrain the high density nuclear symmetry energy. A large number of minimally constrained EOSs has been constructed by applying a Bayesian approach to study the correlations of the symmetry energy at different densities with a few selected properties of a NS. The nuclear symmetry energy above the baryon density 0.5 ${\mathrm{fm}}^{-3}$ $(\approx 3{\rho }_0)$ is found to be strongly correlated with NS mass at which the onset of nucleonic dUrca neutrino cooling takes place in the core. This allows us to constrain the high density behavior of nuclear symmetry energy within narrow bounds. The pure neutron matter pressure constraint from chiral effective field theory rules out the onset of nucleonic dUrca in stars with a mass $\lesssim$1.4 $M_{\odot }$. The onset of dUrca inside 1.6 ${\mathrm{M}}_{\odot }$ to 1.8 ${\mathrm{M}}_{\odot }$ NS implies a slope of the symmetry energy $L$ at $\approx 2.5{\rho }_0$, respectively, between 54 and 48 MeV.

Recent proposals for the use of light nuclei as dark-matter direct detection targets necessitate a strong theoretical understanding of the nuclear physics involved. We perform relevant calculations for dark-matter–light-nucleus scattering in a combined pionless effective field theory and large-$N_c$ expansion, where $N_c$ is the number of quark colors. We include a general set of one-nucleon currents that have been used in other effective theories, as well as novel two-nucleon contact currents. First, we obtain constraints for the relative sizes of the dark-matter couplings to the one- and two-nucleon currents through the large-$N_c$ expansion. Then, we use these constraints to make predictions for the relative sizes of spin-dependent and spin-independent cross sections for dark-matter scattering off of a nucleon, a deuteron, a triton, and helium-3.

Dipole and quadrupole strength distribution of ${}^{204}\mathrm{Pb}$ was investigated via a nuclear resonance fluorescence experiment using bremsstrahlung produced using an electron beam at a kinetic energy of 10.5 MeV at the linear accelerator ELBE. We identified 136 states resonantly excited at energies from 3.6 to 8.4 MeV. Spins of the excited states were deduced by angular distribution ratios of $\gamma$ rays observed at scattering angles of ${90}^{\circ }$ and ${127}^{\circ }$ with respect to the incident $\gamma$ beam. The analysis of the measured $\gamma$-ray spectra includes the quasicontinuum of levels at high energy. Monte Carlo simulation of $\gamma$-ray cascades were performed to obtain the intensities of inelastic transitions and branching ratios of the ground-state transitions. The present experimental results were used to investigate the electric dipole $\left(E1\right)$ strengths by comparison with predictions from the quasiparticle-phonon model with the self-consistent energy density functional.

We describe a path-integral ground-state quantum Monte Carlo method for light nuclei in continuous space. We show how to efficiently update and sample the paths with spin-isospin dependent and spin-orbit interactions. We apply the method to the triton and $\alpha$ particle using both local chiral interactions with next-to-next-to-leading-order and the Argonne interactions. For operators, like the total energy, that commute with the Hamiltonian, our results agree with Green's function Monte Carlo and auxiliary field diffusion Monte Carlo calculations. For operators that do not commute with the Hamiltonian and for Euclidean response functions, the path-integral formulation allows straightforward calculation without forward walking or the increased variance typical of diffusion methods. We demonstrate this by calculating density distributions, root-mean-square radii, and Euclidean response functions for single-nucleon couplings.

We study the one-dimensional boost-invariant Boltzmann equation in the relaxation-time approximation using special moments of the distribution function for a system with a finite particle mass. The infinite hierarchy of moments can be truncated by keeping only the three lowest moments that correspond to the three independent components of the energy-momentum tensor. We show that such a three-moment truncation reproduces accurately the exact solution of the kinetic equation after a simple renormalization that takes into account the effects of the neglected higher moments. We derive second-order Israel-Stewart hydrodynamic equations from the three-moment equations, and show that, for most physically relevant initial conditions, these equations yield results comparable to those of the three-moment truncation, albeit less accurate. We attribute this feature to the fact that the structure of Israel-Stewart equations is similar to that of the three-moment truncation. In particular, the presence of the relaxation term in the Israel-Stewart equations, yields an early-time regime that mimics approximately the collisionless regime. A detailed comparison of the three-moment truncation with second-order nonconformal hydrodynamics reveals ambiguities in the definition of second-order transport coefficients. These ambiguities affect the ability of Israel-Stewart hydrodynamics to reproduce results of kinetic theory.

Collective structures in ${}^{186}\mathrm{Os}$ have been investigated through the ${}^{186}\mathrm{W}({}^4\mathrm{He},4n){}^{186}\mathrm{Os}$ reaction, at a beam energy of 48 MeV. The low-lying bands built on the excited $0{}_2^{+}, 2{}_2^{+}$, and $4{}_3^{+}$ states have been extended up to spins of ${12}^{+}, {15}^{+}$, and $8^{+}$, respectively, and a number of new linking transitions were identified. The features of the collective bands in ${}^{186}\mathrm{Os}$, such as level energies, are presented in the context of a systematic study of the neighboring even-even ${}^{182–192}\mathrm{Os}$ isotopes. In addition, the validity of the $K$-selection rule, stemming from a description based on axial symmetry of the nuclear shape, is examined. The observed decays between the rotational bands support a description where $K$ is conserved. However, some $K$-forbidden decays were also identified, suggesting that a model allowing for small $K$ admixtures is probably required. The experimental data are further compared with calculations using a five-dimensional collective Hamiltonian based on covariant density functional theory. The calculations predict that the collective bands are associated with different nuclear shapes, varying in quadrupole deformation, triaxiality, and softness.