The excitation energy difference between terminating states based on the $f_{7/2}^n$ and $d_{3/2}^{-1}{f}_{7/2}^{n+1}$ configurations has been studied within the cranked relativistic mean field framework. The discrepancy between the experimental data and the theoretical predictions is found to decrease systematically with increasing asymmetry, indicating an improved description of neutron-rich nuclei. By constraining the relevant shell gap and refitting the relativistic mean field parameter set, a new parametrization is obtained that significantly improves the description of single-particle energies near the shell gap without compromising the reproduction of bulk nuclear properties.

In this work, a comprehensive, two-photon-exchange (TPE)-consistent analysis of the unpolarized reduced cross section ${\sigma }_R(\varepsilon ,Q^2)$ for elastic electron-proton ($ep$) scattering is performed to search for possible contributions from a light neutral scalar mediator and to establish quantitative constraints in their absence. The framework incorporates the standard one-photon-exchange (OPE) term, the phenomenological TPE correction, and an additional scalar amplitude whose strength is governed by the dimensionless coupling ratio $\beta ={\alpha }_s/\alpha$, defined as the scalar proton-electron coupling ${\alpha }_s$ normalized to the electromagnetic fine-structure constant $\alpha$. The scalar strength $S\left(Q^2\right)$ is extracted from linear Rosenbluth fits to world ${\sigma }_R$ data at 134 $Q^2$ points spanning $0.0155\le Q^2\le 5.5{\mathrm{GeV}}^2$. The data exhibit no statistically significant deviation from the $\mathrm{OPE}+\mathrm{TPE}$ baseline, and the global profile likelihood saturates the physical boundary $\widehat{\beta }=0$ for all scanned mediator masses. One-sided 95% confidence-level upper limits ${\beta }_{95}\left(m_s\right)$ are obtained using a profile-likelihood construction over the mass range $0.04\le m_s\le 10\mathrm{GeV}$. Accordingly, the primary result of this work is the determination of quantitative exclusion limits on the scalar coupling, rather than evidence of a nonzero contribution. The resulting exclusion curve lies at the level of a few $\times {10}^{-3}$ to ${10}^{-2}$ depending on $m_s$, with systematic uncertainties increasing the limits by only 5–10% across most of the mass range. These limits improve upon, or are comparable to, previously reported electromagnetic-form-factor-based scalar constraints in the low- to intermediate-mass region and constitute the first dedicated, TPE-consistent ${\sigma }_R$-based search for light scalar exchange in elastic $ep$ scattering. No evidence for a scalar contribution is observed within the present experimental sensitivity.

The impact of Coulomb core polarization on the neutron density distribution of ${}^{48}\mathrm{Ca}$ is investigated. The Coulomb boundary radius is located before the neutron skin region, leading to proton admixture and establishing neutron skin impurity as an intrinsic feature of the density profile. Using the ${(}^3\mathrm{He},t)$ isobaric analog state (IAS) reaction at 420 MeV, the impurity-induced modification of the probed neutron distribution is quantified. For a neutron skin of 0.144 fm, consistent with the CREX thin-skin scenario, Coulomb core polarization enhances the probed neutron distribution by approximately 0.052 fm. This value is remarkably close to the difference between the CREX and RCNP neutron skin determinations, providing a physical mechanism to reconcile the discrepancy between electroweak and hadronic probes in ${}^{48}\mathrm{Ca}$. These findings provide new insights into the CREX-PREX puzzle, highlight the importance of accounting for Coulomb core polarization in neutron distribution analyses, and motivate future IAS charge-exchange measurements as a complementary hadronic probe.

The halo nucleon-core system is, by definition, a shallow state nucleus. The nucleon, in most cases a neutron, is loosely bound to the other nucleons forming the core. Accordingly, the system is located inside the universal window; the halo nucleon most likely resides far from the rest of the nucleons, showing a remarkable insensitivity to details of the interaction with the core. The system can be described using a simple nucleon-core interaction, and this description can be extended to the nucleon-nucleon-core system. Specifically, treating the neutron-core and the neutron-neutron-core systems with a Gaussian interaction as a reference, we show trajectories inside the universal window governed by interaction parameters determined from low-energy observables, such as the neutron-core binding energy, scattering length, and effective range. In this way, we can relate properties of different halo nuclei that might seem uncorrelated. In particular, we determine the three-body parameter, the binding momentum at the unitary limit, and show that the two-neutron halo nuclei emerge from that limit following a linear trajectory depending on the neutron-core range.

Short-range correlated (SRC) nucleon pairs provide a sensitive probe of the short-distance structure of atomic nuclei and the underlying nucleon-nucleon (NN) interaction. We present a simple numerical method to estimate the number of two- and three-nucleon SRC clusters using an independent-particle shell model with a harmonic-oscillator basis. The relative abundances of proton-neutron (pn), proton-proton (pp), and neutron-neutron (nn) SRC pairs are calculated for Al, Fe, and Pb nuclei, normalized to carbon, and compared with existing analytical predictions and available extractions from experimental data. We extend the analysis to the isotopes ${}^{40}\mathrm{Ca}, {}^{48}\mathrm{Ca}$, and ${}^{54}\mathrm{Fe}$ (collectively, the CaFe nuclei), which have been recently studied experimentally. These isotopes provide insight into the role of $1f_{7/2}$ shell occupancy in SRC-pair formation. Finally, we present a reference baseline for three-nucleon (3N) SRC cluster abundances across the studied nuclei, assuming 3N clusters originate from independent two-nucleon (2N) interactions. The predicted baseline is about 3.5% 3N-SRC/2N-SRC ratio for all medium and heavy nuclei. Deviations from this baseline may indicate the presence of additional short-range nuclear dynamics.

We examined the ratios of neutron and proton transition matrix elements, $M_n/M_p$, for the $0_{gs}^{+}\to 2_1^{+}$ transitions in 48 even-even stable nuclei with $N>20$ for which electromagnetic matrix elements were compiled by Pritychenko et al. and for which high-quality inelastic proton-scattering data were available. Several deformed rare-earth nuclei have $(M_n/M_p)/(N/Z)$ values significantly below 1.0, which is not consistent with a simple liquid-drop picture. However, this phenomenon can be explained using a schematic picture in which $M_p$ reaches a maximum at proton midshell ($Z=66$) and $M_n$ reaches its maximum at neutron midshell ($N=104$). Several midmass vibrational nuclei have $M_n/M_p$ values significantly below $N/Z$, which is not consistent with the expectation that $M_n/M_p=N/Z$ in such nuclei. A shell-model investigation of these observations might yield insights about this behavior.

A microscopic statistical model based on the relativistic density functional theory (RDFT) is developed to calculate the nuclear level density (NLD). The approach employs self-consistent single-particle levels obtained from RDFT as input, incorporates pairing correlations within a finite-temperature Bardeen-Cooper-Schrieffer theory, and accounts for rotational and vibrational collective enhancement effects. The spin cut-off parameter is calculated from the single-particle levels, thereby naturally retaining the shell effects and the structural characteristics of different nuclei. Using the shape-coexisting nucleus ${}^{98}\mathrm{Sr}$ as a representative example, the microscopic origin of the deformation effect on the NLD is investigated. In addition, the calculated NLDs are systematically compared with those from various phenomenological and microscopic models, as well as with available experimental data. The results indicate that although certain discrepancies exist among different models, they exhibit consistent overall evolutionary trends. Meanwhile, the RDFT-based microscopic statistical approach is capable of providing a reasonable description of the experimental NLDs as well as the $s$- and $p$-wave neutron resonance spacings.

Background: Recent studies of the β decay of fission fragments by total absorption spectroscopy have found less decay energy attributed to leptons than previously believed, with studies of ${}^{105}\mathrm{Mo}$ and ${}^{105}\mathrm{Tc}$ being particularly impactful for reactor decay heat. These results are also crucial for interpreting measurements of reactor antineutrino energy spectra.

Purpose: To obtain complete $\beta$-decay patterns of ${}^{105}\mathrm{Mo}$, ${}^{105}\mathrm{Tc}$, ${}^{105}\mathrm{Ru}$, and ${}^{105}\mathrm{Rh}$. Determine the impact on reactor decay heat for all four isotopes and the impact on ${\overline{\nu }}_e$ emission calculation for ${}^{105}\mathrm{Mo}$ and ${}^{105}\mathrm{Tc}$.

Method: The complete $\beta$-decay intensities of ${}^{105}\mathrm{Mo}$, ${}^{105}\mathrm{Tc}$, ${}^{105}\mathrm{Ru}$, and ${}^{105}\mathrm{Rh}$ were measured with the Modular Total Absorption Spectrometer (MTAS) at Argonne National Laboratory. A beam of radioactive isobars with mass number A = 105 was produced by the CARIBU source and delivered to MTAS. Specifically, for ${}^{105}\mathrm{Mo}$, a multireflection time-of-flight device was employed to isolate a pure beam of ${}^{105}\mathrm{Mo}$ nuclides before delivery to MTAS. Highly-efficient silicon $\beta$-trigger has substantially aided the purification of the collected spectra.

Results: The mean $\beta$ and $\gamma$ energies of ${}^{105}\mathrm{Mo}$ and ${}^{105}\mathrm{Tc}$ are found to be consistent with previous TAS measurements. Differences are found in the extracted $\beta$-feeding intensities in commonly used evaluations of ${}^{105}\mathrm{Mo}$ and ${}^{105}\mathrm{Tc}$, which results in substantial differences in reactor antineutrinos detectable via inverse $\beta$ decay. Improved half-lives for ${}^{105}\mathrm{Ru}$ and ${}^{105}\mathrm{Mo}$ are also determined.

Conclusions: The number of reactor antineutrinos detectable via inverse $\beta$ decay for ${}^{105}\mathrm{Mo}$ is found to decrease by 86%, while a 37% increase is found for ${}^{105}\mathrm{Tc}$. An improved precision in the half-lives of ${}^{105}\mathrm{Ru}$ and ${}^{105}\mathrm{Mo}$ has been determined to be 4.4644(13) h, and 35.5(8) s, respectively.

The fission fragment mass and total kinetic energy (TKE) distributions of neutron deficient ${}^{193}\mathrm{Tl}$, populated in the ${}^{28}\mathrm{Si}+{}^{165}\mathrm{Ho}$ and ${}^{34}\mathrm{S}+{}^{159}\mathrm{Tb}$ reactions, have been measured at overlapping excitation energies. By employing a two-dimensional unbinned maximum likelihood fitting procedure, a substantial asymmetric fission fraction was identified across all measured energies with fragment mass centroids pointing toward the influence of deformed shell gaps near $Z\approx 36$. The extracted TKE values consistently cluster into two distinct groups, where the higher TKE associated with the asymmetric mode indicates a more compact scission configuration. While both entrance channels yield compatible asymmetric fractions, the experimental mass widths exhibit a systematic increase below the Coulomb barrier. This enhancement is more pronounced in the ${}^{28}\mathrm{Si} + {}^{165}\mathrm{Ho}$ system, potentially reflecting a “double-deformation” influence from the oblate projectile and highly prolate target. Comparisons with the general description of fission observables (GEF) model show a systematic underprediction of the asymmetric component in ${}^{193}\mathrm{Tl}$, highlighting the potential for continued development of model parameters within this transitional mass region. These results provide critical empirical constraints and demonstrate that while shell effects govern the modal structure, entrance-channel deformations significantly influence the sub-barrier fission dynamics.

Dynamical fission calculations show that the post-scission configurations resemble two collinear pear-shaped fragments whose juxtaposed surface bulges subside relatively quickly, as the fragments acquire smoother shapes. The associated rapid speed of the healing bulge surface may boost nucleons in the fragment to energies sufficient for emission. The present study explores this mechanism by following the fate of nucleons that are reflected off the inwards moving bulge surface. The simulations suggest that the mechanism may produce high-energy neutrons at the level of a few percent.

Equations of a boost-invariant and cylindrically symmetric perfect hydrodynamics are solved numerically for initial conditions inspired by the wounded nucleon model. The energy-momentum and spin tensors are used in the form that describes a relativistic massive gas governed by Boltzmann statistics. In contrast to one-dimensional boost-invariant expansion, we find a coupling between the azimuthal and longitudinal components of the electric and magnetic components of the spin polarization tensor. This feature is similar to that found earlier for the Gubser symmetry; however, our treatment allows for a more general form of initial conditions and expansion geometry. Defining the freeze-out hypersurface by the constant temperature condition, we evaluate the Pauli-Lubański four-vector and find that for the assumed geometry the only nonzero total polarization may be induced by the longitudinal component of the magnetic part of the spin polarization tensor, coupled with the azimuthal electric component. The obtained results may serve as a reference point for more realistic models of hydrodynamic expansion.

We present variable precision GP (VarP-GP), a new cost-efficient Bayesian emulator for expensive computational models with variable statistical precision. We focus on the interpretation of measurements of the quark-gluon plasma (QGP) generated in high-energy nuclear collisions, through comparison to numerical models using Bayesian Inference. Such inference calculations are computationally expensive and require surrogate model emulation, which is commonly implemented using machine learning-based Gaussian processes (GPs). Emulator training data are generated by Monte Carlo simulations whose numerical precision depends on the computational resources utilized; improved precision entails greater computational cost. This study utilizes JETSCAPE simulations of inclusive hadron and jet measurements in nuclear collisions at Relativistic Heavy Ion Collider and the Large Hadron Collider. The VarP-GP emulator combines information from multiple simulation runs with varying precision across the model parameter space, taking advantage of the smoothness in that space of quantum chromdynamics-driven processes. Comparison to a traditional emulator approach shows a marked reduction in emulator uncertainty at fixed computational cost, indicating that knowledge of the overall contours of the parameter design space is more important for precise emulation than detailed information at a more limited number of design points. As an initial application of VarP-GP, a computationally expensive model parameter sensitivity study of jet quenching data is reported. The VarP-GP emulator enables new multimodel and many-observable calibrations of QGP data and modeling, which would otherwise not be possible with achievable computing resources.

We present a data-driven analysis within a quantum evolutionary microscopic framework to constrain the in-medium bottomonium potential. In relativistic heavy-ion collisions, bottomonium bound states serve as invaluable probes of the quark-gluon plasma (QGP) owing to their negligible production in the QGP phase. Meanwhile, their nonrelativistic nature allows a straightforward theoretical description via effective field theories such as potential models. Recent lattice QCD calculations of the bottomonium interaction potential have yielded qualitatively distinct results. These discrepancies motivate a data-driven extraction of the potential based on heavy-ion experiments. In this work, we perform a Bayesian analysis to constrain the bottomonium interaction potential. The relationship between potential parameters and observables is established by numerically solving the nonrelativistic time-dependent Schrödinger equation. By comparing these simulations with experimental measurements, our Bayesian framework provides the effective potential that is readily testable in future experiments.

I discuss the peculiarities of scattering in a three-proton system induced by the presence of an entangled proton-proton Bell-like state in the initial configuration. I formulate the problem using the standard spin formalism of nuclear physics in order to follow in detail the reaction pathways leading to the teleportation of a quantum-mechanical state within this system. By performing numerical simulations of the system and calculations based on a realistic nucleon-nucleon potential, I evaluate the relevant spin observables and search for a simple, experimentally feasible signal that could provide clear evidence of quantum teleportation. For the case in which proton 2, belonging to the entangled proton pair 23, interacts with hydrogen target 1, thereby triggering the teleportation process, I find clear evidence of teleportation through measurements of the final polarization of proton $3^{\prime }$, even for small values of the polarization of target proton 1. The dominant component of this polarization is transferred almost entirely from target proton 1 to proton $3^{\prime }$ in the angular region characterized by strong entanglement. For an unpolarized target proton 1, quantum teleportation is no longer possible. The only unambiguous signature of the residual quantum correlations would be provided by measurements of the spin correlations within the strongly entangled final-state proton pair $1^{\prime }{2}^{\prime }$. Indirect evidence may also be obtained from measurements of the polarization of proton $2^{\prime }$ in the final state, although the corresponding effect is relatively weak.

We study fluctuations and correlations of conserved charges in QCD using a string-based description of the hadronic mass spectrum. Mesons and baryons are modeled as open relativistic strings with quark-antiquark and quark-diquark endpoints, respectively, leading to an exponential Hagedorn growth of states with a limiting temperature fixed by the string tension. We find that continuous Hagedorn spectra constrained by experimentally established hadrons underestimate net-baryon number fluctuations obtained in lattice QCD (LQCD) calculations. By extracting the Hagedorn string spectrum directly from lattice QCD through a fit to the second-order net-baryon number susceptibility, we obtain a consistent description of a broad set of fluctuations of conserved charges from LQCD with the Hagedorn temperature $T_H\simeq 323\mathrm{MeV}$, without introducing additional free parameters. Our results provide thermodynamic evidence in support of a string quark-diquark picture of baryons in the confined phase of QCD.

For a long time, studies of femtoscopic correlations have provided information about space-time characteristics of particle sources in high-energy collisions. Recently, the correlation functions have also been used to determine interaction parameters of correlated particles, which is especially important for short-lived particles, for which scattering experiments are impossible. The abundance of experimental data and their high accuracy require an improved theoretical approach to femtoscopic correlations. The aim of this paper is to systematically discuss relativistic effects and their role in femtoscopy. Since a general relativistic approach is currently unavailable due to serious theoretical difficulties, the correlation functions must be computed in the center-of-mass frame where the correlated particles are mostly nonrelativistic. This requires transforming the source function to this frame, the consequences of which are discussed. Since the deuteron formation has a similar physical origin to femtoscopic correlations, relativistic effects are also discussed in the former process. The considerations are illustrated with calculations of some correlation functions and the deuteron coalescence coefficient to demonstrate the magnitude of relativistic effects. It is also argued that a discrepancy between the coalescence coefficient computed with the source radii inferred from the baryon-baryon correlation functions and the experimental data can be removed by taking into account the relativistic elongation of the source radius in the center of mass of correlated particles.

The gap equations lie at the core of the Bardeen-Cooper-Schrieffer (BCS) theory, a standard tool in the description of superfluidity. As a set of non-inear integral equations, the gap equations' inherent difficulties oftentimes hinder even the crudest descriptions of superfluid states. Hard-core potentials, high-density superfluids, and coupled-channel pairing are all reasons that have historically required one to provide special treatment to the gap equations to get a solution. In this paper we present a new method for solving the gap equations that holds the promise of being an efficient universal solver that requires the minimum amount of a priori knowledge of the targeted solutions. With theoretical evidence of exotic nuclear superfluidity posing new questions to our understanding of this fundamental property of nuclear systems, the presented method can be a valuable tool when exploring new pairing states, finite-temperature properties, or the development of sophisticated descriptions of nuclear superfludity.

We report new data from a ${}^{150}\mathrm{Nd}(p,t){}^{148}\mathrm{Nd}$ experiment performed at the John D. Fox Accelerator Laboratory of Florida State University. In total, 54 excited states of ${}^{148}\mathrm{Nd}$ were observed up to an excitation energy of 3500 keV. In this work, we focus on $0^{+}$ states and their band members. In contrast to previous work, the $0_3^{+}$ band is proposed as the candidate for the two-phonon octupole vibrational band. Supporting $spdf$ IBM-1 calculations are presented. To test the robustness of the IBM calculations, several observables were interrogated and are discussed in this publication. In addition, we make the case that neither the $0_2^{+}$ nor the $0_3^{+}$ states of the other $N=88$ isotones are likely good candidates for two-phonon octupole states. Based on our new data for ${}^{148}\mathrm{Nd}$, we propose candidates in ${}^{150}\mathrm{Sm}$ and ${}^{152}\mathrm{Gd}$. Using available $\gamma$-decay data for states with moderate spins in the yrast sequence and a comparison to IBM calculations, we also show how the staggering of the $B\left(E1\right)/B\left(E2\right)$ ratios in the yrast sequence can possibly be used to probe the appearance of bands with multiple octupole phonons.