The momentum correlation functions of baryon pairs, which reflects the baryon-baryon interaction at low energies, are investigated for multistrangeness pairs ($\mathrm{\Omega }\mathrm{\Omega }$ and $N\mathrm{\Omega }$) produced in relativistic heavy-ion collisions. We calculate the correlation functions based on an expanding source model constrained by single-particle distributions. The interaction potentials are taken from those obtained from recent lattice QCD calculations at nearly physical quark masses. Experimental measurements of these correlation functions for different system sizes will help to disentangle the strong interaction between baryons and to unravel the possible existence of strange dibaryons.

We report the first detection of the second-forbidden, nonunique, $2^{+}\to 0^{+}$, ground-state transition in the $\beta$ decay of ${}^{20}\mathrm{F}$. A low-energy, mass-separated ${}^{20}\mathrm{F}^{+}$ beam produced at the IGISOL facility in Jyväskylä, Finland, was implanted in a thin carbon foil and the $\beta$ spectrum measured using a magnetic transporter and a plastic-scintillator detector. The $\beta$-decay branching ratio inferred from the measurement is $b_{\beta }=[0.41\pm 0.08\left(\mathrm{stat}\right)\pm 0.07\left(\mathrm{sys}\right)]\times {10}^{-5}$ corresponding to $logft=10.89\left(11\right)$, making this one of the strongest second-forbidden, nonunique $\beta$ transitions ever measured. The experimental result is supported by shell-model calculations and has significant implications for the final evolution of stars that develop degenerate oxygen-neon cores. Using the new experimental data, we argue that the astrophysical electron-capture rate on ${}^{20}\mathrm{Ne}$ is now known to within better than 25% at the relevant temperatures and densities.

Background: Statistical model calculations have to be used for the determination of reaction rates in large-scale reaction networks for heavy-element nucleosynthesis. A basic ingredient of such a calculation is the $\alpha$-nucleus optical model potential. Several different parameter sets are available in literature, but their predictions of $\alpha$-induced reaction rates vary widely, sometimes even exceeding one order of magnitude.

Purpose: This paper presents the result of $\alpha$-induced reaction cross-section measurements on gold which could be carried out very close to the astrophysically relevant energy region. The new experimental data are used to test statistical model predictions and to constrain the $\alpha$-nucleus optical model potential.

Method: For the measurements, the activation technique was used. The cross section of the ($\alpha ,n$) and ($\alpha ,2n$) reactions was determined from $\gamma$-ray counting, while that of the radiative capture was determined via x-ray counting.

Results: The cross section of the reactions was measured below $E_{\alpha }=20.0$ MeV. In the case of the ${}^{197}\mathrm{Au}(\alpha ,2n){}^{199}\mathrm{Tl}$ reaction down to 17.5 MeV with 0.5-MeV steps, reaching closer to the reaction threshold than ever before. The cross section of ${}^{197}\mathrm{Au}(\alpha ,n){}^{200}\mathrm{Tl}$ and ${}^{197}\mathrm{Au}(\alpha ,\gamma ){}^{201}\mathrm{Tl}$ was measured down to $E_{\alpha }=13.6$ and 14.0 MeV, respectively, with 0.5-MeV steps above the ($\alpha ,2n$) reaction threshold and with 1.0-MeV steps below that.

Conclusions: The new data set is in agreement with the available values from the literature, but is more precise and extends toward lower energies. Cross sections two orders of magnitude lower than those in previous experiments which used $\gamma$-ray counting only were successfully measured, thus providing experimental data at lower energies than ever before. The new precision dataset allows us to find the best-fit $\alpha$-nucleus optical model potential and to predict cross sections in the Gamow window with smaller uncertainties.

Uncertainties in our knowledge of the properties of dense matter near and above nuclear saturation density are among the main sources of variations in multimessenger signatures predicted for core-collapse supernovae (CCSNe) and the properties of neutron stars (NSs). We construct 97 new finite-temperature equations of state (EOSs) of dense matter that obey current experimental, observational, and theoretical constraints and discuss how systematic variations in the EOS parameters affect the properties of cold nonrotating NSs and the core collapse of a $20\text{−}{M}_{\odot }$ progenitor star. The core collapse of the $20\text{−}{M}_{\odot }$ progenitor star is simulated in spherical symmetry using the general-relativistic radiation-hydrodynamics code GR1D where neutrino interactions are computed for each EOS using the NuLib library. We conclude that the effective mass of nucleons at densities above nuclear saturation density is the largest source of uncertainty in the CCSN neutrino signal and dynamics even though it plays a subdominant role in most properties of cold NS matter. Meanwhile, changes in other observables affect the properties of cold NSs, while having little effect in CCSNe. To strengthen our conclusions, we perform six octant three-dimensional CCSN simulations varying the effective mass of nucleons at nuclear saturation density. We conclude that neutrino heating and, thus, the likelihood of explosion is significantly increased for EOSs where the effective mass of nucleons at nuclear saturation density is large.

The mechanism that restores pseudospin symmetry (PSS) is investigated under the relativistic Hartree-Fock (RHF) approach, by focusing on the in-medium balance between nuclear attractive and repulsive interactions. It is illustrated that the modelings of both the equilibrium of nuclear dynamics and the in-medium effects can be essentially changed by the $\rho$-tensor coupling that plays the role almost fully via the Fock terms, from which the model discrepancy on the PSS restoration is verified. Specifically, the largely different density-dependent behaviors of the isoscalar coupling strengths $g_{\sigma }$ and $g_{\omega }$, deduced from the parametrization of the RHF Lagrangian PKA1, play an essential role in restoring the PSS of the high-$l^{\prime }$ pseudospin doublets around the Fermi levels. Qualitatively, guidance is provided for the modeling of both the equilibrium of nuclear dynamics and the in-medium effects via the PSS restoration.

Background: Elastic electron scattering has been used for decades to paint the most accurate picture of the proton distribution in atomic nuclei. This stands in stark contrast to the neutron distribution that is traditionally probed using hadronic reactions that are hindered by large uncertainties in the reaction mechanism. Spurred by new experimental developments, it is now possible to gain valuable insights into the neutron distribution using exclusively electroweak probes.

Purpose: We aim to assess the information content and complementarity of the following three electroweak experiments in constraining the neutron distribution of atomic nuclei: (a) parity-violating elastic electron scattering, (b) coherent elastic neutrino-nucleus scattering, and (c) elastic electron scattering of unstable nuclei.

Methods: Relativistic mean-field models informed by the properties of finite nuclei and neutron stars are used to compute ground state densities and form factors of a variety of nuclei. All the models follow the same fitting protocol, except for the assumed—and presently unknown—value of the neutron skin thickness of ${}^{208}\mathrm{Pb}$. This enables one to tune the density dependence of the symmetry energy without compromising the success in reproducing well known physical observables.

Results: We found that the ongoing PREX-II and upcoming CREX campaigns at Jefferson Lab will play a vital role in constraining the weak form factor of xenon and argon, liquid noble gases that are used for the detection of both neutrinos and dark matter particles.

Conclusions: Remarkable new advances in experimental physics have opened a new window into ground state densities of atomic nuclei using solely electroweak probes. The diversity and versatility of these experiments reveal powerful correlations that impose important nuclear structure constraints. In turn, these constraints provide quantitative theoretical uncertainties that are instrumental in searches for new physics and insights into the behavior of dense matter.

Background: Nuclear pasta, emerging due to the competition between the long-range Coulomb force and the short-range strong force, is believed to be present in astrophysical scenarios, such as neutron stars and core-collapse supernovae. Its structure can have a high impact, e.g., on neutrino transport or the tidal deformability of neutron stars.

Purpose: We study several possible pasta configurations, all of them minimal surface configurations, which are expected to appear in the mid-density regime of nuclear pasta, i.e., around 40% of the nuclear saturation density. In particular we are interested in the energy spectrum for different pasta configurations considered.

Method: Employing the density functional theory approach, we calculate the binding energy of the different configurations for three values of the proton content $X_P=1/10,1/3$, and $1/2$, by optimizing their periodic length. We study finite temperature effects and the impact of electron screening.

Results: Nuclear pasta lowers the energy significantly compared to uniform matter, especially for $X_P\ge 1/3$. However, the different configurations have very similar binding energies. For large proton content, $X_P\gtrsim 1/3$, the pasta configurations are very stable, for lower proton content temperatures of a few MeV are enough for the transition to uniform matter. Electron screening has a small influence on the binding energy of nuclear pasta, but increases its periodic length.

Conclusion: Nuclear pasta in the mid-density regime lowers the energy of the matter for all proton fractions under study. It can survive even large temperatures of several MeV. Since various configurations have very similar energy, it is to expect that many configurations can coexist simultaneously already at small temperatures.

The almost hermetic coverage of the CMS detector is used to measure the distribution of transverse energy, $E_{\mathrm{T}}$, over 13.2 units of pseudorapidity, $\eta$, for $p\text{Pb}$ collisions at a center-of-mass energy per nucleon pair of $\sqrt{s_{{}_{\mathrm{NN}}}}=5.02\text{TeV}$. The huge angular acceptance exploits the fact that the CASTOR calorimeter at $-6.6<\eta <-5.2$ is effectively present on both sides of the colliding system because of a switch in the proton-going and lead-going beam directions. This wide acceptance enables the study of correlations between well-separated angular regions and makes the measurement a particularly powerful test of event generators. For minimum bias $p\text{Pb}$ collisions the maximum value of $d{E}_{\mathrm{T}}/d\eta$ is $22\text{GeV}$, which implies an $E_{\mathrm{T}}$ per participant nucleon pair comparable to that of peripheral PbPb collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=2.76\text{TeV}$. The increase of $d{E}_{\mathrm{T}}/d\eta$ with centrality is much stronger for the lead-going side than for the proton-going side. The $\eta$ dependence of $d{E}_{\mathrm{T}}/d\eta$ is sensitive to the $\eta$ range in which the centrality variable is defined. Several modern generators are compared to these results but none is able to capture all aspects of the $\eta$ and centrality dependence of the data and the correlations observed between different $\eta$ regions.

We develop a theoretical framework to study the feed-down effect of higher-lying strange baryons on the spin polarization of the $\mathrm{\Lambda }$ hyperon. In this framework, we consider two-body decays through strong, electromagnetic, and weak processes and derive general formulas for the angular distribution and spin polarization of the daughter particle by adopting the helicity formalism. Using the realistic experimental data as input, we explore the feed-down contribution to the global and the local $\mathrm{\Lambda }$ polarizations and find that such a contribution suppresses the primordial $\mathrm{\Lambda }$ polarization, which is not strong enough to resolve the discrepancy between the current theoretical and the experimental results on the azimuthal-angle dependence of $\mathrm{\Lambda }$ polarization. Our paper may also be useful for the measurement of spin polarization of baryons heavier than $\mathrm{\Lambda }$ (e.g., ${\mathrm{\Xi }}^{-}$) in future experiments.

We show that experimental data on cumulants of anisotropic flow in heavy-ion collisions probe the non-Gaussian statistics of the energy-density field created right after the collision. We carry out a perturbative expansion of the initial anisotropies of the system in terms of its density fluctuations. We argue that the correlation between the magnitudes of elliptic flow and triangular flow, dubbed $sc(3,2)$, is generically of the same sign and order of magnitude as the kurtosis of triangular flow in a hydrodynamic picture. The experimental observation that these quantities are negative implies that the distribution of energy around a given point has positive skew.

As part of a continuing effort to test the unitarity of the Cabbibo-Kobayashi-Maskawa matrix, we have measured the branching ratio for the superallowed $0^{+}\to 0^{+}{\beta }^{+}$-decay transition from ${}^{26}\mathrm{Si}$ to be 0.7569(14), a result with 0.18% relative precision. With this result, the $ft$ value for the transition is now established with comparable precision to the well-known superallowed transitions currently used in the determination of $V_{ud}$. It also completes a second pair of mirror superallowed transitions, ${}^{26}\mathrm{Si}$ $\to$ ${}^{26m}\mathrm{Al}$ and ${}^{26m}\mathrm{Al}$ $\to$ ${}^{26}\mathrm{Mg}$, the ratio of whose measured $ft$ values provides a sensitive test of the method used to calculate the isospin-symmetry-breaking correction ${\delta }_C$ needed to determine $V_{ud}$. Like the previously measured ratio for the mass-38 mirror pair, the new result agrees well with the calculation based on Woods-Saxon radial wave functions and strengthens the case for rejecting the calculation that uses Hartree-Fock radial functions.

We develop a novel approach to fusion reactions for synthesis of superheavy elements, which combines the time-dependent Hartree-Fock (TDHF) method with a dynamical diffusion model based on the Langevin equation. In this approach, the distance of the closest approach for the capture process is estimated within the TDHF approach, which is then plugged into the dynamical diffusion model as an initial condition. We apply this approach to hot fusion reactions leading to formation of the element $Z=120$, that is, the ${}^{48}\mathrm{Ca}+{}^{254,257}\mathrm{Fm}$, ${}^{51}\mathrm{V}+{}^{249}\mathrm{Bk}$, and ${}^{54}\mathrm{Cr}+{}^{248}\mathrm{Cm}$ reactions. Our calculations indicate that the distances of the closest approach for these systems are similar to each other and thus the difference in the probabilities of evaporation residue formation among those reaction systems originates mainly from the evaporation process, which is sensitive to the fission barrier height and the excitation energy of a compound nucleus.

Background: The Nijmegen extended-soft-core (ESC) models describe the nucleon-nucleon (NN), hyperon-nucleon (YN), and the $S=-2$ hyperon-hyperon/nucleon ($YY/\mathrm{\Xi }N$) interactions in a unified way using broken SU(3) symmetry. The potentials consist of local and nonlocal potentials due to (i) one-boson exchanges (OBE), which are the members of nonets of pseudoscalar, vector, scalar, and axial-vector mesons, (ii) two pseudoscalar exchange (TPS), (iii) meson-pair exchange (MPE), and (iv) diffractive exchanges. Both the OBE and pair vertices are regulated by Gaussian form factors producing potentials with a soft behavior near the origin. Broken SU(3) symmetry serves to connect the NN, YN, and YY channels. In particular, the meson-baryon coupling constants are calculated via SU(3) using the coupling constants of the NN analysis as input. The assignment of the cutoff masses for the baryon-baryon-meson (BBM) vertices is dependent on the SU(3) classification of the exchanged mesons for OBE and a similar scheme for MPE.

Purpose: The $S=-1$ YN results are presented from a new version ESC16 of the ESC potential model for baryon-baryon (BB) scattering. The obtained two-body BB potentials are applied to the hyperonic many-body systems as well. Next to the standard ingredients of the ESC models, a contribution of the possible short-range repulsion due to the quark Pauli principle in the BB channels is described in a systematic way for the first time.

Methods: Major novel ingredients with respect to the former versions ESC04–ESC08 are the inclusion of (i) short-range Gaussian Odderon potentials corresponding to the odd numbers of gluon exchanges next to the Pomeron potentials due to even gluon exchanges and (ii) short-range repulsion in all NN, YN, and YY channels due to Pauli-forbidden six-quark cluster ${\left(0s\right)}^6$ configurations. Further new elements are (i) the extension of the $J^{PC}=1^{++}$ axial-vector meson coupling, (ii) the inclusion of the $J^{PC}=1^{+-}$ axial-vector mesons, (iii) a completion of the $1/M$ corrections for the meson-pair-exchange (MPE) potentials, and (iv) the treatment of the scalar $\kappa \left(861\right)$ meson within the Gell-Mann-Okubo (GMO) meson-mixing scheme and as a broad meson, like the $\rho \left(760\right)$ and $\epsilon \left(620\right)$. In contrast to ESC04, we do not consider medium strong flavor-symmetry breaking (FSB) of the coupling constants. The charge-symmetry breaking (CSB) in the $\mathrm{\Lambda }p$ and $\mathrm{\Lambda }n$ channels, which is an SU(2) isospin breaking, is included in the OBE, TPS, and MPE potentials. In addition to the usual set of 35 YN data and 3 ${\mathrm{\Sigma }}^{+}p$ cross sections from the recent KEK-E289 experiment, we added 11 elastic and inelastic $\mathrm{\Lambda }p$ and three elastic ${\mathrm{\Sigma }}^{-}p$ cross sections at higher energy. For the ESC16 model, we performed a simultaneous fit to the combined NN and YN scattering data, supplied with constraints on the YN and YY interaction originating from the $G$-matrix information on hypernuclei.

Results: The fitting of NN dominates the determination of the couplings and the cutoff masses. Only a few parameters are strongly influenced by the YN data and by the constraints for the YY interactions following from $G$-matrix analyses of hypernuclei and hyperonic matter. Like in the ESC04 model, the obtained octet and singlet coupling constants and $F/(F+D)$ ratios of the model confirm the predictions of the quark-antiquark pair-creation (QPC) model with dominance of the ${}^{3}P_0$ mechanism. This not only for the OBE couplings but also for the MPE couplings and $F/(F+D)$ ratios. We obtained within this simultaneous fit ${\chi }^2/N{N}_{\mathrm{data}}=1.10$ and ${\chi }^2/Y{N}_{\mathrm{data}}=1.04$. In particular, we were able to fit the precise experimental datum $r_R=0.468\pm 0.010$ for the inelastic ${\mathrm{\Sigma }}^{-}p$ capture ratio at rest very well.

Conclusions: Besides the good results for the fit to the $S=-1$ scattering data, which to a large extent defines the model, also the information of hypernuclear systems, using the $G$-matrix method, is rather important in establishing the complete ESC model. Different versions of the model give somewhat different results for hypernuclei. The reported $G$-matrix calculations are performed for YN ($\mathrm{\Lambda }N$ and $\mathrm{\Sigma }N$) in nuclear matter and also for some hypernuclei. The obtained well depths ($U_{\mathrm{\Lambda }}$, $U_{\mathrm{\Sigma }}$, $U_{\mathrm{\Xi }}$) reveal distinct features of the ESC model. The inclusion of a quark core Pauli repulsion can make the $\mathrm{\Sigma }$-nucleus interaction less attractive, as seems to be required by the available experimental evidence. Furthermore, the ESC16 model gives small spin-orbit splittings in $\mathrm{\Lambda }$ hypernuclei, which is also indicated by experiment.

Background: Correlations from charge correlation, known as charge balance functions, provide critical tests of the chemical evolution of matter in a heavy-ion collision. Comparisons of experimental balance functions with calculations from parametric descriptions of the final state suggest that the charge production in the earliest stages of a heavy-ion collision are consistent with having generated an amount of light up, down, and strange quarks that are largely consistent with expectations for creating a chemically equilibrate quark-gluon plasma.

Purpose: This work describes a full simulation of the evolving correlations superimposed on a state-of-the-art microscopic description of the collision.

Methods: The creation and diffusion of balancing charges is modeled on the background of a hybrid description of the evolution based on hydrodynamics, for when the matter's temperature is above 155 MeV, and a microscopic hadronic simulation, for the breakup stage. The translation of the charge-charge correlation function, indexed by the flavors up, down, and strange, into correlations between specific hadron species is built on the assumption that differential charges enhance differential yields according to statistical equilibrium. Monte Carlo methods are implemented when applicable.

Results: The charge balance functions are predicted for pairs indexed by charge alone or by whether the particle pairs are any combination of pions, kaons, or protons. Comparisons with experiment are remarkably successful except for the proton-kaon balance functions.

Conclusions: This demonstrates first that two-particle correlations from charge conservation can be calculated for a state-of-the-art model of the evolution with moderate amounts of computation. Aside from the magnitude of the proton-kaon correlations, the calculations well describe preliminary experimental results from the STAR Collaboration at the Relativistic Heavy Ion Collider. Ignoring the one disagreement, this suggests that the matter in a heavy-ion collision comes close to maintaining chemical equilibrium during the superhadronic stage of a heavy-ion collision.

Neutron-deficient ${}^{177-185}\mathrm{Hg}$ isotopes were studied using in-source laser resonance-ionization spectroscopy at the CERN-ISOLDE radioactive ion-beam facility in an experiment combining different detection methods tailored to the studied isotopes. These include either α-decay tagging or multireflection time-of-flight gating for isotope identification. The endpoint of the odd-even nuclear shape staggering in mercury was observed directly by measuring for the first time the isotope shifts and hyperfine structures of ${}^{177-180}\mathrm{Hg}$. Changes in the mean-square charge radii for all mentioned isotopes, magnetic dipole, and electric quadrupole moments of the odd-$A$ isotopes and arguments in favor of $I=7/2$ spin assignment for ${}^{177,179}\mathrm{Hg}$ were deduced. Experimental results are compared with density functional theory (DFT) and Monte Carlo shell model (MCSM) calculations. DFT calculations using Skyrme parametrizations predict a jump in the charge radius around the neutron $N=104$ midshell, with an odd-even staggering pattern related to the coexistence of nearly degenerate oblate and prolate minima. This near-degeneracy is highly sensitive to many aspects of the effective interaction, a fact that renders perfect agreement with experiments out of reach for current functionals. Despite this inherent difficulty, the SLy5s1 and a modified $\mathrm{UNEDF}{1}^{\mathrm{SO}}$ parametrization predict a qualitatively correct staggering that is off by two neutron numbers. MCSM calculations of states with the experimental spins and parities show good agreement for both electromagnetic moments and the observed charge radii. A clear mechanism for the origin of shape staggering within this context is identified: a substantial change in occupancy of the proton $\pi h_{9/2}$ and neutron $\nu i_{13/2}$ orbitals.

The deuteron yield in Pb+Pb collisions at $\sqrt{s_{NN}}=2.76\mathrm{TeV}$ is consistent with thermal production at a freeze out temperature of $T=155\mathrm{MeV}$. The existence of deuterons with binding energy of 2.2 MeV at this temperature was described as “snowballs in hell” [P. Braun-Münzinger, B. Dönigus, and N. Löher, CERN Courier, August 2015]. We provide a microscopic explanation of this phenomenon, utilizing relativistic hydrodynamics and switching to a hadronic afterburner at the above-mentioned temperature of $T=155\mathrm{MeV}$. The measured deuteron $p_T$ spectra and coalescence parameter $B_2\left(p_T\right)$ are reproduced without free parameters, only by implementing experimentally known cross sections of deuteron reactions with hadrons, most importantly $\pi d\leftrightarrow \pi np$.

Background: While coupled-cluster theory accurately models weakly correlated quantum systems, it often fails in the presence of strong correlations where the standard mean-field picture is qualitatively incorrect. In many cases, these failures can be largely ameliorated by permitting the mean-field reference to break physical symmetries. Symmetry-broken coupled-cluster, e.g., Bogoliubov-coupled-cluster, theory can indeed provide reasonably accurate energetic predictions, but the broken symmetry can compromise the quality of the resulting wave function and predictions of observables other than the energy.

Purpose: Merging symmetry projection and coupled-cluster theory is therefore an appealing way to describe strongly correlated systems. One indeed expects to inherit and further improve the energetic accuracy of broken-symmetry coupled cluster while retaining proper symmetries.

Methods: Independently, two different but related formalisms have been recently proposed to achieve this goal. The two formalisms are contrasted in this manuscript, with results tested on the Richardson pairing Hamiltonian. While the present paper focuses on the breaking and restoration of $U\left(1\right)$ global-gauge symmetry associated with particle-number conservation, the symmetry-projected coupled-cluster formalism is applicable to other symmetries such as rotational (i.e., spin) symmetry.

Results: Both formalisms are based on the disentangled cluster representation of the symmetry-rotated coupled-cluster wave function. However, they differ in the way that the disentangled clusters are solved. One approach sets up angle-dependent coupled-cluster equations, while the other involves first-order ordinary differential equations. The latter approach yields energies and occupation probabilities significantly better than those of number-projected Bardeen-Cooper-Schrieffer (BCS) and BCS coupled cluster and, when the disentangled clusters are truncated at low excitation levels, has a computational cost not too much larger than that of BCS coupled cluster.

Conclusions: The high quality of results presented in this manuscript indicates that symmetry-projected coupled cluster is a promising method that can accurately describe both weakly and strongly correlated finite many-fermion systems.

We explore the impact of optimizations of the single-particle basis on the convergence behavior and robustness of ab initio no-core shell model calculations of nuclei. Our focus is on novel basis sets defined by the natural orbitals of a correlated one-body density matrix that is obtained in second-order many-body perturbation theory. Using a perturbatively improved density matrix as the starting point informs the single-particle basis about the dominant correlation effects on the global structure of the many-body state, while keeping the computational cost for the basis optimization at a minimum. Already the comparison of the radial single-particle wave functions reveals the superiority of the natural-orbital basis compared to a Hartree-Fock or harmonic oscillator basis, and it highlights pathologies of the Hartree-Fock basis. We compare the model-space convergence of energies, root-mean-square radii, and selected electromagnetic observables for all three basis sets for selected $p$-shell nuclei using chiral interactions with explicit three-nucleon terms. In all cases the natural-orbital basis provides the fastest and most robust convergence, making it the most efficient basis for no-core shell model calculations. As an application we present no-core shell model calculations for the ground-state energies of all oxygen isotopes and assess the accuracy of the normal-ordered two-body approximation of the three-nucleon interaction in the natural-orbital basis.

The longitudinal proton-proton femtoscopy (Hanbury Brown–Twiss) correlation function, based on the idea that in a heavy-ion collision at $\sqrt{s}\lesssim 20\mathrm{GeV}$ stopped protons are likely to be separated in configuration space, is evaluated. It shows a characteristic oscillation which appears sufficiently pronounced to be accessible in experiment. The proposed measurement is essential for estimating the baryon density in the central rapidity region and can be also viewed as an (almost) direct verification of the Lorentz contraction of the fast-moving nucleus.

We calculate the electromagnetic (charge, magnetic, and quadrupole) form factors and the associated static moments of heavy quarkonia (charmonia and bottomonia) using the basis light front quantization (BLFQ) approach. For this work, we adopt light front wave functions (LFWFs) generated by a holographic QCD confining potential and a one-gluon exchange interaction with fixed coupling. We compare our BLFQ results with the limiting case of a single BLFQ basis state description of heavy quarkonia and with other available results. These comparisons provide insights into relativistic effects. Using the same LFWFs generated in the BLFQ approach, we also present the generalized parton distributions (GPDs) for selected mesons including those for radially excited mesons such as ${\psi }^{\prime }$ and ${\mathrm{{\rm Y}}}^{\prime }$. Our GPD results establish the foundation within BLFQ for further investigating hadronic structure such as probing the spin structure of spin-one hadrons in the off-forward limit.