The CREX and PREX-II measurements of the neutron-skin thickness of ${}^{48}\mathrm{Ca}$ and ${}^{208}\mathrm{Pb}$ challenge standard nuclear energy-density functional (EDF) descriptions of nuclei and nuclear matter. It is shown that the apparent tension arises from an implicit constraint in current EDF parametrizations that ties the density dependence of the functional at the dilute nuclear surface to that of uniform matter near saturation. Relaxing this surface-bulk coupling and independently constraining the dilute-density sector, while preserving realistic saturation properties and the high-density equation of state, yields EDFs that simultaneously reproduce the neutron skins of both nuclei, their electric dipole polarizabilities, and neutron-star mass-radius relations. The established correlation between the neutron-skin thickness and the symmetry-energy slope parameter $L$ at saturation is retained but becomes substantially broader. The results show that current neutron-skin data do not require extreme values of $L$ and highlight an underconstrained degree of freedom associated with low-density nuclear matter.

We derive deterministic equations for the evolution of non-Gaussian fluctuations in relativistic stochastic hydrodynamics. This is achieved by defining the average local Landau frame and corresponding fluctuating hydrodynamic variables. Fully nonlinear stochastic hydrodynamics is expressed in a unified multicomponent matrix form. A relativistic formalism, also manifestly covariant under SO(3) rotations of the local spatial basis in the average local Landau frame, is introduced. The equations describe correlators of all hydrodynamic variables, including fluctuating velocity (or momentum density)—a long-standing problem in relativistic hydrodynamics.

We consider nonequilibrium evolution of non-Gaussian fluctuations in a hydrodynamic system undergoing a boost-invariant expansion described by Bjorken flow. We derive the evolution equations for two- and three-point velocity correlators using the effective field-theory framework and present analytical solutions for them. We show that the average Landau frame is better suited for studying non-Gaussian fluctuations of velocity when relativistic effects are important. In the Bjorken background, the average Landau frame corresponds to the density frame. We demonstrate that the three-point correlators depend nonlinearly on the nonequilibrium dynamics of the two-point functions and exhibit nontrivial effects such as memory. The importance of these effects in the context of the search for the QCD critical point via fluctuations is discussed.

I investigate the low-energy scattering and femtoscopic correlation functions of the $d\text{−}\mathrm{\Lambda }$, $d\text{−}\mathrm{\Sigma }$, and $d\text{−}\mathrm{\Xi }$ systems within a microscopic folding approach. The effective deuteron-hyperon interactions are constructed by folding the HAL-QCD hyperon-nucleon potentials with the deuteron wave function, while the spin and isospin structures are treated through Wigner-$6j$ recoupling coefficients. Using the resulting interactions, I calculate the scattering parameters and momentum correlation functions for all spin channels. No bound states are found for the $d\text{−}\mathrm{\Lambda }$, $d\text{−}\mathrm{\Sigma }$, or $d\text{−}\mathrm{\Xi }$ systems. Nevertheless, the $d\text{−}\mathrm{\Lambda }$ correlation exhibits a pronounced low-momentum enhancement associated with a large scattering length and a near-threshold pole, whereas the $d\text{−}\mathrm{\Sigma }$ correlation is suppressed by its predominantly repulsive interaction. The neutral $d\text{−}{\mathrm{\Xi }}^0$ system shows only a moderate enhancement, while the charged $d\text{−}{\mathrm{\Xi }}^{-}$ correlation is strongly amplified by the attractive Coulomb interaction. I further investigate feed-down effects from ${\mathrm{\Sigma }}^0$, $\mathrm{\Sigma }\left(1385\right)$, and $\mathrm{\Xi }$ decays using Monte Carlo response matrices and demonstrate that these decays clearly modify the observable $d\text{−}\mathrm{\Lambda }$ correlation. The results provide quantitative predictions for future femtoscopic measurements and establish deuteron-hyperon correlations as a sensitive probe of hyperon-nucleus interactions.

Based on nucleons ($p, n$) and hyperons ($\mathrm{\Lambda }, {\mathrm{\Omega }}^{-}$) formed at kinetic freeze-out from a quark combination model, we systematically study the production of light nuclei and hypernuclei in the hadronic coalescence picture. We present the analytical formula of the nucleus momentum distribution of two-body coalescence and that of three-body coalescence. We explain the experimental data of the transverse momentum spectra of deuteron ($d$), triton ($t$), helium-3 (${}^3\mathrm{He}$), and hypertriton (${}_{\mathrm{\Lambda }}{}^3\mathrm{H}$) measured in Au-Au collisions from the RHIC Beam Energy Scans I and II, and also provide the corresponding predictions of different $\mathrm{\Omega }-$hypernuclei $H\left(p{\mathrm{\Omega }}^{-}\right), H\left(n{\mathrm{\Omega }}^{-}\right)$, and $H\left(pn{\mathrm{\Omega }}^{-}\right)$. We further study the production correlations of different species of light (hyper-)nuclei and discuss their interesting behaviors as a function of collision energy.

We investigate the production of the as-yet-undetected true muonium within the quark-gluon plasma formed in relativistic heavy-ion collisions, employing a relativistic Boltzmann transport framework coupled to viscous hydrodynamic simulations. The obtained effective cross sections for central collisions are 1.23 $\mu \text{b}$ in AuAu collisions with $\sqrt{s_{\mathrm{NN}}}=200$ GeV and 14.2 $\mu \text{b}$ in PbPb collisions with $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV, resulting in a yield of $\mathcal{O}\left({10}^4\right)$ and $\mathcal{O}\left({10}^5\right)$ true muonium per billion $AA$ collisions at RHIC and the LHC, respectively. This establishes heavy-ion collisions as a promising process for detecting true muonium.

Quartet correlations in neutron-rich Te isotopes are investigated within the quartet Bardeen-Cooper-Schrieffer (BCS) framework. Taking ${}^{100}\mathrm{Sn}$ as an inert core, we consider two valence protons and valence neutrons occupying the $2d_{5/2}\oplus 1g_{7/2}$ model space, and solve the quartet BCS variational equations with a charge-independent isovector pairing interaction. The effective pairing strength is constrained from empirical neutron pairing gaps in the Te isotopic chain. We find that the valence quartet number increases as the valence neutron number is enlarged from $N_{\mathrm{val}}=2$ to 14. The same increasing behavior is also found for the condensed quartet component. The proton occupation of the $1g_{7/2}$ orbit is strongly enhanced relative to the conventional like-particle BCS reference and is driven close to the degeneracy-weighted limit. These results suggest that additional valence neutrons enhance the quartet admixture in the correlated quartet BCS state, while redistributing the fixed proton weight from pair-like configurations to quartet configurations.

Background: The fission fragment mass distribution (FFMD) has been known as one of the most fascinating observables. Its exploration provides information on fragment properties that reveal multiple interesting aspects of the fission phenomenon. The curiosity of investigating the neutron-deficient sublead nuclei developed after the discovery of unexpected asymmetric fission for ${}^{180}\mathrm{Hg}$ [Andreyev et al., Phys. Rev. Lett. 105, 252502 (2010)]. Numerous experiments involving heavy-ion-induced reactions were conducted to produce a variety of neutron-deficient sublead compound nuclei to study the underlying fission dynamics. These sublead nuclei were generally found to possess flat-topped mass distributions, but the exact number of asymmetric modes involved in generating such structures is still unresolved. Moreover, the role of shell effects in forming asymmetric splits in the sublead nucleus has not yet been fully explored.

Purpose: This article presents the study of fission dynamics for ${}^{192}\mathrm{Hg}$, populated via fusion of ${}^{32}\mathrm{S}$ with ${}^{160}\mathrm{Gd}$. It illustrates the FFMDs of ${}^{192}\mathrm{Hg}$ at excitation energies ($E^{*}\mathrm{s}$) between 49.3 and 67.6 MeV. Moreover, it provides a comparative study of experimentally measured fission-fragment properties and the corresponding gef (GEneral description of Fission observables) model code outcomes.

Method: The carbon-backed ${}^{160}\mathrm{Gd}$ target was bombarded with ${}^{32}\mathrm{S}$ ions at five different laboratory energies, spanning a wide range from 134–156 MeV. Two multiwire proportional counters, each having dimensions 16 cm $\times$ 11 cm, were employed in order to derive velocity information of the fragments. Further, these velocities eventually generated the fission-fragment mass and kinetic energy distributions.

Results: For all energies, the triple-Gaussians satisfactorily fit the experimentally obtained flat-topped FFMDs. Later, the mean number of protons in the light and heavy fragments, extracted from the experimental distributions, was found to be influenced by quadrupole-deformed shell gaps at $Z \approx$ 34, 36, 42, 44, and 46. Similar observations have been made in studies of the Hg isotopic chain. Whereas, a negligible role of octopole-deformed shell gaps ($N \approx$ 52 and 56) in deciding the mean number of neutrons in fragments was registered. Contrary to this, gef predicted the mean number of neutrons in the light fragment around 52, which hinted at the role of octopole-deformed shell gaps. The present study reported the inexistence of the quasifission process. Both experimental and theoretical symmetric fission fractions (SFFs) were observed to increase with increasing $E^{*}$. Generally, the theoretically predicted SFF values were higher than the experimental values. Moreover, the comparison of SFFs for different nuclei at $E^{*} \approx$ 49 MeV indicated that SFFs tend to grow with an increasing $N/Z$ ratio.

Conclusions: The incompetence of a single-Gaussian to fit the experimental distribution verified the existence of an asymmetric fission mode component in addition to the symmetric fission component. The experimental $Z_{\mathrm{peak}}$ values were found to be influenced by the quadrupole-deformed shell gaps. The dominant role of proton shell gaps has also been observed by comparing the present results with the previously available data for a wide range of Hg isotopes. Although gef partially reproduces the experimentally derived $Z_{\mathrm{peak}}$ and $N_{\mathrm{peak}}$ values (with differences of no more than 3), it overpredicts the symmetric contributions. SFF values have been observed to increase with increasing $N/Z$ ratio.

We present a theoretical study of the two-neutrino $0^{+}\to 0^{+}$ double beta decay of ${}^{76}\mathrm{Ge}$ within the no-core configuration-interaction framework based on the Skyrme SV density functional. We analyze three allowed decay scenarios distinguished by the $[n,m]\equiv [{\left(\nu g_{9/2}\right)}^n,{\left(\pi g_{9/2}\right)}^m]$ occupancy of the $0g_{9/2}$ intruder orbital, which remains conserved to high precision, as well as by the triaxiality of the daughter nucleus. The resulting $2\nu \beta \beta$ nuclear matrix element is found to depend strongly on the scenario. For the energetically favored [4,2] occupancy, we obtain $|{\mathcal{M}}^{2\nu }|=0.069\left(7\right) {\mathrm{MeV}}^{-1}$. For the [6,0] occupancy, the matrix element further depends on the triaxiality parameter $\gamma$ of the two coexisting, closely lying minima in ${}^{76}\mathrm{Se}$, yielding $|{\mathcal{M}}^{2\nu }|=0.040\left(4\right) {\mathrm{MeV}}^{-1}$ at $\gamma =17.7^{\circ }$ and $|{\mathcal{M}}^{2\nu }|=0.22\left(2\right) {\mathrm{MeV}}^{-1}$ at $\gamma =41.9^{\circ }$. The latter result is consistent with the empirical value reported by Barabash, $|{\mathcal{M}}^{2\nu }|=0.204\left(14\right) {\mathrm{MeV}}^{-1}$ [Barabash, Universe 6, 159 (2020)], while the two former results are comparable to existing calculations based on energy-density-functional frameworks. Our calculations reveal challenges in the precise determination of $|{\mathcal{M}}^{2\nu }|$ for the ${}^{76}\mathrm{Ge}$ decay. The structural complexity, triaxiality, and shape coexistence identified in the analyzed nuclei imply a strong sensitivity to fine details of the interaction and configuration mixing. This, in turn, explains the difficulties in theoretical modeling of the $|{\mathcal{M}}^{2\nu }|$ matrix elements for the ${}^{76}\mathrm{Ge}$ decay, which vary by almost an order of magnitude in the available literature.

Nuclear shell effects play a crucial role in shaping the solar $r$-process abundance pattern, while the individual contributions of shell effects in various nuclear physics ingredients, including nuclear masses, $\beta$-decay rates, and neutron-capture rates, remain insufficiently understood. We systematically investigate the influence of the $N=82$ and $N=126$ shells on the final abundances, particularly the shell effects of three nuclear physics ingredients. Our results demonstrate that removing the nuclear shell effects disrupts key features of the $r$-process abundance distribution, causing the material to become almost uniformly distributed over a mass range of roughly $30–40$ units. In addition, the $N=82$ and $N=126$ shells exhibit opposite effects on the production of heavy nuclei with $N>126$. We further find that the propagation of shell-structure changes to nuclear masses has the largest impact on the final abundances, followed by neutron-capture rates. In contrast, within the simplified diagnostic tests adopted here, shell-related discontinuities in $\beta$-decay rates at magic numbers have only a minor direct influence on the resulting abundance pattern. In addition to magic shells, relativistic mean field (RMF) models predict the presence of spurious shells at $Z=58$ and $N=92$. We find that an artificial increase of 1 MeV in nuclear binding energy at $N=92$ produces a pronounced enhancement of abundances around $A\approx 140$, potentially altering the overall abundance pattern, whereas the $Z=58$ spurious shell has only a minor effect, causing merely a small change near the $A\approx 155$ region.

The ${}^{45}\mathrm{Sc}(p,\gamma ){}^{46}\mathrm{Ti}$ reaction plays an important role in both hydrostatic and explosive nucleosynthesis. During hydrostatic oxygen and silicon burning in massive stars, including dynamic processes such as convective carbon-oxygen (C-O) shell mergers, it acts as a bottleneck that regulates the reaction flow in the Sc-Ti mass region. In oxygen-neon (ONe) novae, the ejecta indicate the production of elements up to the Fe group, as observed in V1974 Cygni, and the ${}^{45}\mathrm{Sc}(p,\gamma ){}^{46}\mathrm{Ti}$ reaction links nuclei above Ca to the Fe region. In core-collapse supernovae (CCSNe), it influences the production of the radioactive isotope ${}^{47}\mathrm{Sc}$. At present, the thermonuclear reaction rate is based on statistical model calculations. In this work, we report on measurements of the ${}^{45}\mathrm{Sc}(p,\gamma ){}^{46}\mathrm{Ti}$ reaction performed using the 5 MV accelerator at the Nuclear Science Laboratory, University of Notre Dame, over a laboratory proton energy range of 526–1275 keV. We present the first direct measurements of the resonance strengths for six resonances at $E_{\mathrm{R}}^{\mathrm{lab}}=917.4$, 1026.0, 1031.1, 1049.7, 1059.4, and 1257.5 keV, together with integrated resonance strengths at $E^{\mathrm{lab}}=555$, 630, 700, 761, and 871 keV. For resonance energies below the lowest directly measured energy, available transfer-reaction data were used to estimate the resonance strengths. An updated thermonuclear reaction rate is derived, and its astrophysical implications are discussed.

The possible existence of a bound state in the charmonium-neutron-${}^{10}\mathrm{Be}$ system is investigated within a three-cluster model in which the system is treated as $c\overline{c}+n+{}^{10}\mathrm{Be}$. The three-body problem is solved using a hyperspherical-harmonics expansion within the coupled Faddeev-equation framework. The neutron-${}^{10}\mathrm{Be}$ interaction is described by an $l$-dependent Woods-Saxon potential that provides a satisfactory description of the low-energy properties of ${}^{11}\mathrm{Be}$. The effective ${}^{10}\mathrm{Be}\text{−}c\overline{c}$ interactions are constructed by folding the $S$-wave charmonium-nucleon potentials obtained from the HAL QCD Collaboration at nearly physical pion mass with the ${}^{10}\mathrm{Be}$ matter density. Bound three-body states are obtained for all three spin-dependent charmonium-nucleon interactions considered. The central three-body binding energies are 3.297(493) MeV for $J/\psi N\left({}^{4}S_{3/2}\right)$, 4.650(632) MeV for $J/\psi N\left({}^{2}S_{1/2}\right)$, and 2.009(325) MeV for ${\eta }_{c}N\left({}^{2}S_{1/2}\right)$, with corresponding nuclear matter rms radii of 2.542(24), 2.474(17), and 2.680(42) fm, respectively. These results demonstrate that the attractive charmonium-nucleon interactions obtained from lattice QCD can generate bound $c\overline{c}+n+{}^{10}\mathrm{Be}$ configurations within the present three-body framework, while the predicted binding energies retain a substantial sensitivity to the spin dependence of the underlying interaction.

We perform a systematic study of the structure and properties of the krypton isotopic chain including both even-even and odd-$A$ nuclei based on the axially deformed relativistic Hartree-Bogoliubov approach. Five effective interactions of three families of covariant density functionals, i.e., PC-L3R, DD-PCX, DD-PC1, DD-MEX, and DD-ME2, are employed to calculate potential energy surfaces of krypton isotopes. ${}^{74,75}\mathrm{Kr}$ and ${}^{90,91,92}\mathrm{Kr}$ are determined as typical candidates of shape coexistence. The potential surfaces originating from the PC-L3R, DD-PCX, and DD-MEX interactions exhibit an abrupt shape transition from oblate to prolate for ${}^{73-74}\mathrm{Kr}$, whereas DD-PC1 and DD-ME2 preserve an oblate ground-state shape. Such discrepancies are attributed to the occupations of single-particle levels at the vicinity of the Fermi surface described by these functionals. Moreover, the comparison between spherical and deformed calculations verifies the indispensability of deformation degrees of freedom in this region. The consideration of deformation effects improves the description of two-neutron separation energies, of which its evolution clearly demonstrates the $N=50$ and 82 shell closures. Interestingly, PC-L3R predicts a more extended two-neutron drip line up to ${}^{132}\mathrm{Kr}$, in agreement with the ${\mathrm{NL}3}^{*}$ and PC-PK1 nonlinear effective interactions, whereas other functionals estimate a rather short isotopic chain up to ${}^{119}\mathrm{Kr}$. This anomalous extension implies a significant softening or even collapse of the traditional $N=82$ shell closure near the neutron-rich drip line, highlighting the need for future studies based on triaxial deformation and beyond-mean-field correlations in this nuclear region.

The nature of low-energy enhancement in the radiative strength function (RSF), which is known as the upbend resonance (UBR) and has a crucial role in the description of neutron-capture cross section and stellar nucleosynthesis, is still under debate. The present Letter extends the exact thermal pairing plus phonon damping model to explore the microscopic nature of the UBR and its thermodynamic origin over a wide mass range of odd-odd, odd-$A$, and even-even systems, from ${}^{44}\mathrm{Sc}$ to ${}^{153}\mathrm{Sm}$, whose experimental RSFs, including the UBRs, are available. The results of our calculations indicate that the UBR arises from noncollective particle-particle and hole-hole excitations with a strength three times stronger than that of the giant dipole resonance. Moreover, the emergence of the UBR at finite temperature provides additional theoretical evidence for the invalidity of the Brink-Axel hypothesis in the very low $E_{\gamma }$ region. Last, but not least, a global relation between the integrated strength of the RSF in the UBR region to that of the total RSF and the mass number is reported, for the first time, within the present study.

In nuclear matter, for interparticle separations larger than the healing distance (a characteristic long-distance scale of finite-density fermionic systems), the in-medium two-body wave function is essentially a free wave function. In terms of the renormalization group (RG), this implies that the running of the effective field theory (EFT) couplings freezes for $r$-space cutoffs above this distance (or $p$-space cutoffs below the corresponding healing momentum scale). As a consequence the leading-order EFT description of nuclear matter (understood here as the infrared limit of the RG) corresponds to the mean-field approximation and a set of tree-level (i.e., perturbative) leading contact-range couplings. Though the contacts do in principle inherit the power counting they had in the vacuum, their iteration is suppressed in the infrared, explaining why they become perturbative in nuclear matter. In addition to the contact-range potential, RG evolution requires the inclusion of density-dependent terms in the equation of state that can be represented by a pseudopotential, which (unlike the genuine contacts) should not be iterated. The leading order EFT description ends up being a subset of Skyrme forces previously identified by the Orsay group.

We present an automated, GPU-accelerated framework for many-body perturbation theory (MBPT) calculations of the zero-temperature nuclear equation of state (EOS) based on chiral nucleon-nucleon and three-nucleon (3N) interactions. Automated diagram generation and evaluation enable the computation of all diagrams up to fifth order in the MBPT expansion at the normal-ordered two-body level in infinite matter, with residual three-body contributions explicitly included up to third order. Multi-GPU acceleration of 3N normal ordering, a novel Monte Carlo integrator (called PVegas), and further advances in high-performance computing enable us to evaluate all 840 fifth-order diagrams with controlled numerical uncertainties. We investigate the MBPT convergence up to fifth order in pure neutron matter and symmetric nuclear matter for two sets of chiral interactions, study neutron-star matter, and present fourth-order results for asymmetric matter including normal-ordered 3N forces. The framework enables systematic MBPT studies with harder interactions and benchmarks against nonperturbative methods. It can be further extended to finite-temperature EOS calculations and to improved uncertainty quantification using emulation and resummation techniques.

Background: Pseudospin symmetry (PSS) in proton resonant states remains largely unexplored due to the long-range Coulomb interaction and the inherent difficulties in modeling resonant phenomena.

Purpose: We aim to clarify the interplay between the Coulomb field and nuclear shell effects in governing PSS breaking, by systematically studying the Po isotopic chain ($A=190–220$) across the $N=126$ neutron shell closure.

Method: We employ the relativistic mean-field theory with complex momentum representation (RMF-CMR), incorporating the Landé subtraction to handle the Coulomb singularity in momentum space, which enables a unified description of both bound and resonant proton states.

Results: Our calculations reveal that resonance energies and widths decrease monotonically with neutron number, with PSS becoming progressively restored near the continuum threshold. We identify a robust correlation between the energy splitting and a newly defined momentum-space wave function splitting, $\mathrm{\Delta }G$. By systematically varying the Coulomb strength, we observe that most pseudospin doublets exhibit enhanced breaking with increasing Coulomb repulsion (e.g., the $3\tilde{p}$ splitting increases by a factor of $\sim 2.8$), whereas the inverted $1\tilde{i}$ doublet shows the opposite behavior, evolving toward degeneracy—both trends arising from the same underlying mechanism, namely that the energies of the $j_{<}$ states increase faster than those of the $j_{>}$ states as the Coulomb strength is increased. Crucially, at the magic number $N=126$, both energy and wave function splittings exhibit a local suppression, providing direct evidence that shell stabilization counteracts Coulomb-induced symmetry breaking.

Conclusions: PSS breaking in proton resonances is governed by a delicate competition among the $\mathrm{\Sigma }$ potential, Coulomb repulsion, and shell closure. By focusing on the role of shell stabilization across a magic neutron number—an aspect not addressed in previous studies—our results establish a quantitative picture of how Coulomb repulsion and shell effects compete in governing PSS breaking in proton resonances. The predicted local minimum in PSS splitting near ${}^{210}\mathrm{Po}$ offers a clear signature for experimental verification via transfer reactions. The RMF-CMR method is demonstrated as a powerful tool for future investigations of deformed and paired systems near the proton drip line.

We report high-resolution measurements of the ${}^{94}\mathrm{Mo}(n,\gamma ){}^{95}\mathrm{Mo}$ cross section in the neutron energy range from a few eV up to about 250 keV, performed at the n_TOF facility (CERN), and of the ${}^{94}\mathrm{Mo}(n,\mathrm{tot})$ cross section up to 32 keV, measured at GELINA (JRC Geel). A combined $R$-matrix analysis of capture and transmission data yields significantly improved neutron-resonance parameters for ${}^{94}\mathrm{Mo}$. A total of 186 resonances were observed in this analysis, of which 127 were not present in latest evaluations. The resulting Maxwellian-averaged cross section at stellar temperatures relevant to the slow neutron-capture process ($s$-process) is approximately 25% lower than previous evaluations and literature values. To assess the astrophysical impact of the revised cross section, we performed $s$-process nucleosynthesis calculations for low-mass asymptotic giant branch stars. Despite the substantial reduction in the ${}^{94}\mathrm{Mo}(n,\gamma ){}^{95}\mathrm{Mo}$ rate, the final yields vary by only 3%–4%. This demonstrates that the isotopic budget of ${}^{94}\mathrm{Mo}$ in asymptotic giant branch stars is primarily governed by the branching flow at ${}^{94}\mathrm{Nb}$ rather than by the neutron-capture destruction on ${}^{94}\mathrm{Mo}$ itself. The new cross section thus helps disentangle nuclear cross-section uncertainties from branching-flow effects in the $s$-process production of ${}^{94}\mathrm{Mo}$.

This work combines the generalized liquid drop model (GLDM) with the Bayesian neural network (BNN) to systematically investigate the $\alpha$-decay half-lives of nuclei in the superheavy region. By training the BNN to learn the nonlinear relation between the residuals of theoretical results and experimental data and the input characteristic parameters, the GLDM results are optimized. Using the GLDM-BNN, the standard deviation of the $\alpha$-decay half-lives for all nuclei decreases from 1.107 to 0.480, corresponding to a relative difference of $56.6\%$, indicating that the BNN effectively captures hidden physical information. Furthermore, the maximal information coefficient (MIC) is employed to analyze the correlation between each input feature and the $\alpha$-decay half-life. Among them, the $\alpha$-decay energy exhibits the highest MIC value of 0.490, highlighting its dominant role in determining the $\alpha$-decay half-life. Finally, the GLDM-BNN is used to predict the $\alpha$-decay half-lives of experimentally new superheavy nuclei with atomic numbers $Z=113–118$. The predicted results provide strong evidence supporting $N=184$ as the next neutron magic number after $N=126$.

Ultrarelativistic heavy nuclei traversing a solid target undergo successive nuclear encounters separated by atomic lattice spacings. At sufficiently high beam energies, Lorentz contraction reduces the proper time between collisions to $\mathcal{O}\left({10}^4\right)\mathrm{fm}/c$ in the center-of-mass frame of the first interaction. We then consider the fragmentation region of this first collision and show that short-lived hadrons produced in this region, with additional Lorentz boost, can reach the next nucleus before decaying. We show that this geometry enables secondary hadron–nucleus collisions involving species that cannot be realized as conventional secondary beams or in subsequent hadron–nucleus interactions in cosmic-ray cascades. For a 2.76-TeV-per-nucleon Pb beam incident on a solid Pb lattice, we determine which forward-produced hadrons can survive to a second interaction, estimate their collision probabilities, and analyze potential observable consequences. In particular, we identify some representative hadrons whose proper lifetimes are of order ${10}^3$ fm/c, e.g., specific mesons (${\eta }^{\prime }$) and heavy-flavor resonances ($J/\psi ,D^{*}\left(2010\right)$), as projectile species that become accessible through this collision space-time geometry. At substantially higher beam energies (for example, with 10-TeV-per-nucleon Pb beam), the survival probabilities are significantly enhanced. This can make even very short-lived hadrons with lifetimes of a few tens of fm [$\mathrm{\Xi }$(1530), $\omega$(782), $\varphi$(1020)] available for this secondary hadron–nucleus collision, providing an additional motivation for future ultrarelativistic fixed-target heavy-ion experiments.