Papers

Pion production in intermediate-energy heavy-ion collisions (HICs) provides a sensitive probe of the nuclear equation of state and of the isospin dependence of reaction dynamics. In particular, pion production near threshold is strongly affected by the nucleon-nucleon ($NN$) inelastic cross sections and by the high-momentum components of the nucleon momentum distribution. To explore the influence of these two ingredients on pion production and charged-pion ratios, the in-medium $NN$ inelastic cross sections calculated within the relativistic Boltzmann-Uehling-Uhlenbeck transport theory and the short-range-correlation-induced high-momentum tail (HMT) are introduced into the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model. By simulating Au+Au collisions at intermediate energies, we find that the in-medium modification of the $NN$ inelastic cross sections suppresses the pion multiplicity by reducing the probability of $N\Delta$ production in dense matter. The HMT, on the other hand, enhances the high-momentum components of nucleons and modifies the available energy in individual $NN$ collisions, thereby affecting $NN\rightarrow N\Delta$ reactions and the subsequent pion production. With the simultaneous inclusion of these two effects, the pion yields measured by HADES and the $\pi^-/\pi^+$ ratio measured by FOPI can be reasonably reproduced. These results highlight the need to incorporate both in-medium reaction cross sections and short-range-correlation-induced high-momentum components consistently in transport-model studies of pion production in heavy-ion collisions.

The impact parameter and transverse charge densities provide spatially resolved information on hadron structure and probe the interplay between dynamical chiral symmetry breaking and SU(3)-flavor symmetry breaking. We investigate the valence-quark distributions of the pion and kaon using their unpolarized vector GPDs at nonzero skewness $\xi$ within the covariant Nambu–Jona-Lasinio model, with ultraviolet divergences regulated by the Schwinger proper-time scheme. Increasing $\xi$ shifts the distributions toward smaller $x$, reduces their central magnitude at $b_\perp=0$, and broadens their transverse profiles. These results provide insight into the spatial structure of the pion and kaon and offer stringent tests of nonperturbative QCD dynamics, with relevance to forthcoming measurements at Jefferson Lab and the Electron-Ion Collider.

Nuclear excitation by electron capture (NEEC) provides a unique pathway for coupling electronic and nuclear dynamics, but its description in dense matter commonly relies on electronic structures of isolated ions. Here we show how dense environments reshape the available NEEC capture channels. Using a finite-temperature average-atom model, we assess channel availability by jointly considering electronic localization, resonance energy matching, and vacancy availability. Near solid density, the shallow $6p$ states remain sufficiently localized to support resonant electron capture that drives the 8.356-eV isomeric transition in $^{229}$Th, whereas higher valence-like states merge into the continuum and no longer constitute localized capture channels. Calculations at different temperatures and densities reveal distinct windows of channel availability arising from the interplay among pressure-induced delocalization, shifts in resonance energy, and vacancy formation. Coupling the reconstructed channels to particle-in-cell simulations of laser-driven $^{229}$Th further shows that electronic structure at finite density can substantially alter the predicted cumulative NEEC yield. These results demonstrate how the electronic environment governs resonant capture pathways, highlighting its essential role in nuclear excitation driven by electrons in dense matter.

Thermal photons and dileptons provide complementary information on the temperature and collective expansion of matter created in relativistic heavy-ion collisions. Their combination has been proposed as an electromagnetic probe of radial flow: a comparatively flow-insensitive dilepton invariant-mass inverse slope is used to infer the photon inverse slope expected without transverse flow and compared with the observed photon slope. Here the physical basis and leading limitation of this construction are examined using a controlled expanding-fireball calculation. The dilepton and flow-free photon inverse slopes are tightly correlated because they respond similarly to changes of the underlying thermal scale, although the numerical relation depends on the spectral window and electromagnetic source. The flow-induced change of the photon inverse slope correlates more strongly with the photon-emission-weighted velocity component along the photon momentum than with a bulk-like radial-flow average. Prethermal source variations can bias the inferred flow-free photon reference and generate apparent flow even when the direct photon spectral-flow signal vanishes, while multiple photon and dilepton windows provide independent response patterns that can help diagnose this source ambiguity. These results clarify both what photon–dilepton radial-flow tomography measures and the source consistency required for its interpretation.

We present a systematic study of nuclear ground-state properties obtained with the Skyrme quark-meson coupling (SQMC) energy density functional and compare them with results from the SLy4d Skyrme parameterisation. The SQMC functional is constructed using the quark-meson coupling (QMC) model, which incorporates the internal quark structure of the nucleon and results in a significant reduction in the number of free parameters. We investigate binding energies, two-nucleon separation energies, charge radii, and quadrupole deformations across a broad range of nuclei. Particular attention is devoted to the isovector dependence of the spin-orbit interaction derived within the QMC model, and its impact on the binding energies of neutron-rich nuclei relevant to the r-process. We find that the SQMC functional provides a reasonable description of nuclear ground-state properties in comparison with SLy4d.

The synthesis of superheavy nuclei (SHNs) lies at the forefront of nuclear physics, enabling researchers to probe the limits of nuclear stability and the influence of shell effects. This review summarizes recent theoretical advances in understanding SHN formation and decay, emphasizing time-dependent density functional theory (TDDFT) and its extensions as microscopic tools to describe heavy-ion dynamics. Hybrid approaches combining TDDFT with coupled-channels, Langevin, and statistical models are discussed as means to connect microscopic predictions with experimental observables. The roles of fusion hindrance, quasi-fission, and multinucleon transfer are examined in terms of dissipation, shell structure, and deformation effects. Recent progress in computational power has enabled three-dimensional time-dependent mean-field (and beyond) simulations that include pairing and fluctuation dynamics. Perspectives are given on future developments toward a fully predictive description of superheavy element synthesis and the exploration of the upper limits of the nuclear landscape.

Radiative capture in a non-relativistic system can become non-perturbative even when the underlying transition interaction is weak. We demonstrate this mechanism in a simple quantum-mechanical two-channel model with a systematic power counting, where strong mixing between scattering and bound states develops in a narrow region around a finite momentum $k_0$, leading to a perturbative violation of unitarity. In this regime, the enhanced contributions factorize, reducing the dynamics to a free scattering state interacting through a strong local coupling. Under RG evolution in the factorization scale, this local interaction approaches a unitary fixed point, analogous to that of systems with an anomalously large scattering length. This motivates an EFT organized around the finite-momentum surface $|\mathbf{k}|=k_0$, describing fermions at unitarity with a linear dispersion relation. The resummation resulting from the EFT restores unitarity and provides a systematic expansion for both elastic scattering and radiative capture.

We test the system-size dependence of bottomonium suppression using the same open-quantum-system transport framework for Pb-Pb, O-O, and Ne-Ne collisions. The microscopic transport coefficients are retained from previous Pb-Pb analyses. Using QTraj, we solve the next-to-leading-order pNRQCD Lindblad equation in anisotropic hydrodynamic backgrounds and calculate integrated $\Upsilon$ double ratios. The QGP-induced evolution reproduces the observed sequential hierarchy and overall magnitude of the O-O suppression measured by CMS and LHCb. We quantify the sensitivity to both transport coefficients and to the termination temperature of the in-medium evolution. The Ne-Ne measurement favors somewhat stronger suppression than predicted, although the present experimental uncertainty is large. The extension from Pb-Pb to light ions supports, at least for observables less sensitive to cold nuclear matter effects, a common microscopic origin of bottomonium suppression in deconfined matter, characterized by the same temperature-dependent transport coefficients despite the large change in collision-system size.

Gravity (g) modes are the only neutron-star oscillations that report on the composition of dense matter rather than on its stiffness, and work on hybrid stars has established that a first-order quark transition raises their frequency. Quarkyonic matter does the opposite. Quark-nucleon chemical equilibrium is maintained by the strong interaction, so the quarks acquire no thermodynamic freedom on an oscillation period and $c_s^2-c_e^2$ reduces to a positive-definite quadratic form in the lepton gradients alone. The nucleon momentum shell stiffens both sound speeds together instead of separating them, so the buoyancy factor collapses by a factor of 9.5 to 19 at an early transition and the core is left only weakly stratified. Solving the $l=2$ relativistic Cowling problem for ten equations of state that share one isoscalar sector, seven quarkyonic and three nucleonic controls at matched symmetry-energy slope, we found the g-mode confined to the nucleonic shell outside the core, with the horizontal flow that it lives on excluded from the core while the core is displaced almost rigidly. Its frequency falls from 158-522 Hz across the controls to $81-254$~Hz across the quarkyonic models, and by 14% at 1.4$M_\odot$ for the matched pair at $L=50\mev$; more important than the shift, it decreases with mass where the controls rise. Writing each frequency as the dynamical frequency $(GM/R^3)^{1/2}$ times a dimensionless remainder separates structure from composition. The $f$ and $p_1$ trends prove to be inherited from the mass–radius relation; the $g_1$ remainder, constant to $2-9\%$ along a nucleonic sequence, falls by a quarter to a third along a quarkyonic one and departs by a factor of two from the nucleonic $g$-mode relation at fixed compactness and $L/K_0$. These are Cowling values, lower bounds at the ten-per-cent level, and the sign of the trend survives a correction of that size.

We introduce a new method for extracting resonance pole positions that does not require non-Hermitian extensions of a Hamiltonian. The complex resonance poles are extracted from unitary time evolution of a persistent state, a compact trial state chosen such that its survival amplitude is governed by a single exponential over an extended time window. We solve several two- and three-body systems interacting via short- and long-range forces on a lattice and show that the pole positions obtained using the persistent state method converge approximately exponentially with the linear size of the system. We also consider a gate-based quantum implementation of our method using the Rodeo algorithm and a Hamiltonian variational ansatz, and outline an extension to two-cluster scattering.

We establish a universal scaling law for $\alpha$-decay half-lives based on the variable $X_a = Z^a/\sqrt{Q_\alpha}$, which collapses experimental and theoretical data spanning over twenty orders of magnitude onto a single linear correlation. Global optimization over the complete set of even-even $\alpha$ emitters reveals a uniquely sharp optimum at $a \simeq 2/3$. This exponent is theoretically motivated by the leading geometric scaling of heavy nuclei and emerges quantitatively from the correlated nuclear systematics, driven by the correlated $(Z, Q_\alpha)$ manifold of the nuclear chart. Strikingly, five structurally distinct semi-empirical models and an independent microscopic WKB calculation, when independently optimized with respect to the exponent $a$, yield values clustered around $2/3$, while the corresponding $a=2/3$ correlations remain highly linear without refitting the original model parameters. This emergent scaling law implies smooth variations of decay times along the heavy $r$-process path. We demonstrate analytically that, given a roughly uniform distribution of this variable, the scaling law naturally supports a quasi-power-law radioactive heating rate ($\dot{\epsilon} \propto t^{-1.24}$), consistent with full network calculations. Furthermore, integrating these scaling predictions directly into nuclear source terms for radiative-diffusion models yields multimessenger observables that accurately reproduce the kilonova AT2017gfo associated with the gravitational-wave event GW170817, demonstrating that the $Z^{2/3}/\sqrt{Q_\alpha}$ scaling coordinate provides a robust tool for modeling the radioactive engines of neutron-star mergers.

Ultracentral high-energy collisions between identical nuclei are very sensitive to the size and shape of the frozen configuration of nucleons at the instant of the collision, an information that is encoded in the ground state wave functions of the colliding nuclei. The relative standard deviation of the size of the colliding system soon after the collision has recently been inferred from event-by-event fluctuations of the momentum per particle in collisions of $^{208}$Pb nuclei at the LHC, and since a single collision event produces thousands of particles, this information is very precise. We connect this measurement to the magnitude of the zero-point fluctuations of the radius of the lead nucleus. The value that is extracted from the data is compatible with predictions from nuclear-structure calculations, but is overestimated by classical Glauber-type modeling of high-energy collisions. The role of the Pauli principle in suppressing the fluctuations is underlined. It leads to a distinctive $A$ dependence that could be checked in collisions of smaller systems.

Connecting nuclear experiments to neutron star composition requires controlling the extrapolation of experimental information beyond the densities probed in the laboratory. We combine a broad set of nuclear structure observables and INDRA-FAZIA isospin-transport data within a Bayesian inference of the dense matter equation of state (EoS). To limit uncontrolled extrapolation to high density, we employ a flexible asymptotically causal metamodel whose neutron star posteriors are comparable to those obtained with agnostic EoS models. The nuclear structure information is propagated through its full multidimensional distribution of correlated nuclear matter parameters, while the density-dependent INDRA-FAZIA likelihood is evaluated directly along each sampled metamodel symmetry energy curve. These two sources of laboratory information give compatible constraints on the symmetry energy, and their combination preserves agreement with finite nuclear observables. When combined with ab initio chiral effective field theory calculations and astrophysical observations, all these constraints substantially improve the determination of central proton fractions in low-mass neutron stars, while leaving larger uncertainties for massive stars. Within the adopted nucleonic metamodel, the reduced probability of large proton fractions strongly disfavors electronic direct-Urca onset at or below $1.4\,M_\odot$: its posterior probability falls from $\sim20\%$ with chiral and astrophysical constraints alone to below $1\%$ when the laboratory information is included.

Solid-state frequency standards are generally limited by strong decoherence, rendering conventional interrogation schemes inefficient. The $^{229}$Th nuclear clock provides a unique and timely platform for solid-state optical metrology and nuclear cavity quantum electrodynamics (QED), featuring a coherence time many orders of magnitude shorter than the radiative lifetime in current experiments. Here, we propose and analyze three cavity QED-enhanced clock interrogation schemes that turn this timescale mismatch into an advantage, leveraging collective coupling of thorium nuclei to nanophotonic modes to enable fast interrogation and detection despite the long population lifetime. We reveal the central role of collective cooperativity in determining the clock frequency instability, and derive the optimal conditions (power, working-point detuning, thorium density) for clock operation.

We study the Semi-Inclusive Deep Inelastic Scattering (SIDIS) cross-section at large values of hadron transverse momentum $P_t \gtrsim Q$, with $Q^2$ being the photon virtuality. This kinematic regime of SIDIS allows for a collinear factorization in terms of parton distribution functions (PDFs) and collinear fragmentation functions (FFs). On the other hand, at high energies, i.e., at small Bjorken $x$, the same SIDIS process can also be factorized within the Color Glass Condensate (CGC) framework in terms of eikonal dipole amplitudes. In this work, we perform a systematic comparison of the leading-order (LO) and next-to-leading-order (NLO) collinear and the LO CGC factorizations of this process based on the COMPASS and HERA data. We further provide comparisons of these two factorization frameworks for nucleon and nuclear large-$P_t$ SIDIS in the expected Electron Ion Collider (EIC) kinematics. We find, within the present theoretical uncertainties, that it might be difficult to distinguish between these two factorization schemes for nuclear SIDIS at the EIC. We also observe a significant dependence of the LO eikonal CGC predictions on the choice of longitudinal momentum fraction $x_g$, suggesting significant beyond-eikonal corrections for the EIC kinematics.

Dark matter (DM) direct detection searches look for nuclear recoils as a result of weakly interacting massive particles (WIMPs) scattering off nuclei. Calculating the rate associated with this WIMP-nucleus elastic scattering process involves input from several components, which include the direct detection experimental response functions, the high energy physics content employed, the DM halo velocity distribution, and the target nuclear structure information. Uncertainties in any of these components can impact the interpretation of experimental signals, and affect analysis of rate predictions. In this work, we focus on the uncertainties present due to the nuclear structure modelling of silicon and germanium targets, where a comprehensive set of nuclear form factors are employed through a non-relativistic effective field theory (NREFT) formalism. We show that these uncertainties, obtained from large-scale shell model calculations, impact the nuclear form factors and thus experimental exclusion limits for a SuperCDMS-like experiment. The impact of high energy physics content (through particle physics coefficients) on the magnitude of the nuclear uncertainties is also explored for several WIMP-nucleus scattering responses. Non-negligible nuclear uncertainties are present for several direct detection nuclear responses, indicating that nuclear structure must be accounted for in experimental analysis and interpretation.

It has long been a puzzle why the nuclear modification factor in relativistic $p$Pb collisions is consistent with unity, while the high-$p_T$ elliptic flow is significantly positive. The latter is traditionally interpreted as path-length-dependent energy loss, whereas the former is consistent with zero energy loss. In this Letter, we propose that even at high $p_T$ a hard parton coalesces with a boosted thermal medium parton whose energy is correlated with the angle-dependent radial flow. We compare this flow for $pp$, $p$Pb, $p$O, OO and PbPb collision systems and conclude in particular that the $p$Pb flow is large and anisotropic. The collective medium pushes out the hard partons, and more so in $p$Pb, or in-plane, than in $pp$ collisions, or out-of-plane. The mechanism qualitatively agrees with experiment and predicts a significantly smaller elliptic flow signal for jets than for hadrons.

We study the spectroscopy and decays of the $B_c$ meson in a nonrelativistic quark model in which all observables follow from a single set of wave functions, with spin-dependent effects included directly in the bound-state equation. With parameters calibrated to the measured $B_c(1S)$ and $B_c(2S)$ masses, we predict the $S$-, $P$-, and $D$-wave spectrum up to $n=5$, the pseudoscalar and vector decay constants with one-loop QCD corrections, the E1 and M1 radiative widths, and the radial Regge trajectories of ten spin-parity families. The $1P$ multiplet is predicted at 6692–6746~MeV with the normal fine-structure ordering, compatible with lattice QCD and located in the region of the two structures observed by LHCb in the $B_c^+\gamma$ spectrum. The $1D$ states lie near 7008~MeV, below the $BD$ threshold, and all four $D$-wave families are provided. The decay constant $f_{B_c}=507.1$~MeV is consistent with recent QCD sum-rule results and corresponds to $\mathcal{B}(B_c\to\tau\nu_\tau)\approx3\%$. The E1 widths follow the expected angular weights, while their magnitudes are governed mainly by the radial overlap. The $1P\to1S$ (81–112~keV) and $1D\to1P$ (71–93~keV) widths suggest the $1D\to1P\to1S$ cascade as a promising route toward the first $D$-wave $B_c$ state. The Regge trajectories are nearly linear, with slopes decreasing from about 5.8~GeV$^2$ for the $S$-wave to 4.7–4.8~GeV$^2$ for the $D$-wave states. These results may guide forthcoming measurements at the LHC and future $e^+e^-$ facilities.

We study secondary pairing in the two-flavor color-superconducting (2SC) phase, where the residual ungapped quarks form a same-chirality $J^P=1^+$ condensate driven by an attractive instanton-induced interaction. We determine its symmetry realization, quasiparticle structure, anomaly matching, and low-energy effective theory. The pairing gap is necessarily nodal; in particular, the complex axial state has two point nodes and realizes a spinful relativistic superfluid. This state preserves the full chiral symmetry ${\rm SU}(2)_{\rm L}\times{\rm SU}(2)_{\rm R}$ while breaking the modified baryon-number symmetry ${\rm U}(1)_{\tilde{\rm B}}$ and spatial rotations, with rotations about the nodal axis locked to the condensate phase. This locking gives rise to a Berry term, the Mermin-Ho relation, and a type-B orientational Nambu-Goldstone mode in addition to the superfluid phonon. We also show how anomaly matching is reorganized by secondary pairing: the perturbative mixed ${\rm SU}(2)_{\rm L,R}^2{\rm U}(1)_{\tilde{\rm B}}$ anomaly is realized by a Wess-Zumino coupling of the superfluid phonon, whereas the ${\rm SU}(2)_{\rm L}$ and ${\rm SU}(2)_{\rm R}$ Witten anomalies are carried by the point-node Bogoliubov-de Gennes flavor doublets. The resulting theory provides a concrete dense-QCD realization of a spinful relativistic superfluid with nodal fermions required by anomaly matching.

We apply our complex-scaled time-evolution operator to the two-proton decay of $^{6}$Be. The nucleus is described as an $\alpha+p+p$ three-body system with explicit Jacobi-coordinate rearrangement and the realistic Argonne $v8'$ NN interaction for the proton-proton subsystem. Starting from a confined initial wave packet, the decay dynamics are described by expansion over the complex-scaled eigenstates of the final Hamiltonian. The decay width extracted from the late-time survival probability agrees closely with that obtained from the CSM resonance pole. The time-dependent densities in different Jacobi coordinates reveal complementary aspects of the evolving three-body geometry, while the spin-singlet component remains dominant during the decay. In particular, the correlated two-proton configuration persists even in the presence of the strong short-range repulsion of the realistic NN interaction. These results demonstrate the applicability of the complex-scaled time-evolution framework to explicit three-body decay dynamics and provide a consistent description of the decay width, spatial evolution, and spin correlations of $^{6}$Be.

An unresolved mixture of beta-decaying ground and isomeric states populates a common daughter nucleus through different excitation-energy and spin-parity distributions. A framework is developed to determine when such data admit conventional $\beta$-Oslo and Shape analyses and which quantities remain identifiable. The physical primary-$\gamma$ distribution is an average of separately normalized branching kernels; the global parent fraction does not, in general, equal the fraction in an excitation-energy bin or an accepted primary-$\gamma$ sample. Population invariance, Oslo factorization, and recovery of the total nuclear level density are separated. An exact log-linear compatibility test and a lower-cascade replacement identity isolate factorization and first-generation-subtraction effects. For Shape analysis, matched final-state spins and parities remove common angular-momentum factors but can retain excitation-dependent E1/M1 weights. A graph representation gives consistency conditions and exposes the information lost when only one fixed final-state separation is measured. Deterministic spin-parity-resolved cascade benchmarks reproduce the population-invariant limit and exhibit both exact factorization with an effective, rather than total, level density and small matrix residuals accompanied by appreciable shape errors. Evaluated $\rb\rightarrow\sr$ properties specify a relevant application, including two $2^+$ candidate final states and time-dependent parent mixing. The numerical examples are controlled synthetic tests, not an extraction from $^{90}$Rb data. The results provide criteria for interpreting unresolved-parent measurements and for identifying the additional observations required for population-aware inference.

High-resolution in-beam ${\gamma}$-ray spectroscopy of $^{53}$Ca was performed at the Radioactive Isotope Beam Factory (RIBF) at RIKEN. Excited states in $^{53}$Ca were populated via one-neutron and one-proton removal reactions from a $^{55}$Sc radioactive beam, and the emitted ${\gamma}$ rays were detected using the HiCARI hybrid germanium detector array. The lifetime of the first excited $5/2^{-}$ state in $^{53}$Ca was measured for the first time through an analysis of Doppler-roadened ${\gamma}$-ray line shapes arising from relativistic recoil velocities. A lifetime of ${\tau} = 11.3_{-11.3}^{+5.3(stat)+3(sys)}$ ps was deduced, corresponding to a reduced transition probability of $B(E2;5/2^{-}{\rightarrow}1/2^{-}) > 2.6 e^{2}fm^{4}$ at the 1${\sigma}$ level, with a best-fit value of $4.5 e^{2}fm^{4}$. The measured transition strength is compared with state-of-the-art shell-model and ab initio calculations, providing a stringent benchmark for shell-model Hamiltonians and effective charges and modern ab initio descriptions of the neutron-rich calcium isotopes approaching the potential $N$ = 40 shell closure.

In this paper, we present a data-driven artificial neural network (ANN) model for describing the double differential cross sections (DDCS) of neutron emission in nuclear spallation reactions. The ANN model is found to be precise, flexible, and efficient in predicting differential cross sections of nuclear reactions and in learning the complex dependence of neutron DDCS on the projectile energy ($T_p$), target nucleus ($A$ and $Z$), neutron energy ($T_n$), and neutron emission angle ($\theta_n$). The model is trained on replicas of experimental data that incorporate uncertainties. Several regularization schemes are examined during ANN training. The input variables of the constructed ANN framework are also investigated, and the following six key variables are selected for the input layer of the ANN model: $\theta_{n}$, ${\rm log}(T_n/T_p)$, $T_n/T_p$, ${\rm log}(T_p)$, $A^{2/3}$, and $N/Z$. The ANN predictions are compared with training data provided by various experimental collaborations, showing excellent agreement. The resulting model is further tested on test data with projectile energies, target nuclei, and neutron emission angles different from those in the training data, indicating strong predictive power and generalization capability of the ANN framework. As an illustration, the neutron DDCS as functions of $T_n$, $\theta_n$, and projectile energy $T_p$ are predicted and presented for copper target. The proposed high-precision ANN model is expected to be beneficial for accelerator-driven system (ADS) design and many other applications in nuclear physics, astrophysics, and nuclear technology development.

The microscopic approach of the triaxial projected shell model (TPSM) is employed to investigate the properties of the $8^-$ isomer in the six isotones of $^{128}$Xe, $^{130}$Ba, $^{132}$Ce, $^{134}$Nd, $^{136}$Sm, and $^{138}$Gd. The observed decay pattern of the isomer for these isotones is unexpected with the hindrance factor decreasing with atomic number. It is shown in the present work that multi-quasiparticle mixing into the ground-state configuration is responsible for the observed decreasing trend of the hindrance factor. We have also calculated the excitation energies and in-band $B(E2)$ transition probabilities of the yrast and the band built on the $8^-$ isomer for the six isotones, and it is shown that TPSM approach reproduces the measured quantities quite satisfactorily.

The pair transverse momentum ($k_T$) and collision-energy ($\sqrt{s_{NN}}$) dependent difference between $\pi^{+}\pi^{+}$ and $\pi^{-}\pi^{-}$ femtoscopic correlations was observed by the HADES and STAR Collaborations. We investigate how much of the observed splitting can be accounted for by Coulomb dynamics in 0-10% central Au+Au collisions at $\sqrt{s_{NN}}=2.42$-5.2 GeV. Using the UrQMD model and the CRAB programme, three transport scenarios that successively include baryon-baryon, baryon-meson, and meson-meson Coulomb interactions are considered. In a separate calculation based on the baryon-baryon reference, we reconstruct the time-dependent effective charge $Z_{\rm{eff}}(t)$ and radius $R_{\rm{eff}}(t)$ of the residual charged source and propagate each pion from its individual last strong-interaction point through the evolving field. The calculations reproduce the main $k_{T}$ and $\sqrt{s_{NN}}$ dependences of the radii. Baryon–meson Coulomb interactions generate most of the additional charge splitting in the microscopic calculation. The residual-source treatment also enhances the longitudinal and sideward radius ratios relative to the reference, whereas the outward ratio changes little, and the enhancement generally decreases with increasing $\sqrt{s_{NN}}$. Within the present framework, this contribution does not fully account for the data, motivating further investigation of the charged-source geometry and its interplay with strong-interaction dynamics.

We study the hydrodynamics of a charged fluid with spin degrees of freedom. We argue that, in a conformal field theory in 3+1 dimensions, the spin density is related to a linear combination of standard second-order transport coefficients, and an additional term quadratic in the gauge- and mixed gauge-gravitational anomaly coefficients. We compute the spin density in several free and holographic theories and compare the results.

We present a phenomenological study of the near-threshold $\pi^- p \to J/\psi n$ reaction, focusing on the interference effects between the $s-$channel $P_{c \bar c}$ resonances and non-resonance background. This reaction provides a complementary probe to photoproduction for investigating the nature of the hidden-charm pentaquark states. Using an effective Lagrangian approach, we construct scattering amplitudes for $J^P=1/2^-$ and $3/2^-$ $P_{c\bar c}$ states under two spin-parity scenarios, with the background dominated by the $t-$channel $\rho$ meson exchange. We find that the interference can produce peaks, dips, or complex line shapes depending on the relative phase, in contrast to the simple resonance peaks commonly reported in previous theoretical studies. The two spin-parity scenarios yield qualitatively similar patterns, indicating that our main conclusion is robust. Given the current scarcity of experimental data for the pion-induced channel, we emphasize the urgent need for future measurements at J-PARC to understand the dynamics of the $J/\psi N$ interaction near threshold and to search for the heavy pentaquark states.

We investigate QCD thermodynamics in the intermediate-temperature regime using a gas of confining strings supplemented by excluded volume (EV) corrections. In this description, the discrete hadron resonance spectrum is replaced by an exponentially growing open-string spectrum characterized by a Hagedorn temperature $T_H$, related to the confining string tension. With a common EV parameter shared by mesons and baryons, the model gives a good description of bulk lattice-QCD thermodynamics above the pseudocritical temperature. Among the values considered, $T_H \simeq 300\,\text{MeV}$ provides the best agreement, lower than the value $T_H \simeq 320\!-\!340\,\text{MeV}$ inferred from ideal-string-gas fits to the vacuum hadron spectrum. A simultaneous calibration of the mesonic and baryonic EV parameters gives $b_M \simeq 0.19\,\text{fm}^3$ and $b_B \simeq 0.73\,\text{fm}^3$. Within the present spectral ansatz, the larger baryonic EV parameter indicates that stronger effective suppression is required in the baryon sector, although noticeable tensions remain in several conserved-charge observables.

We investigate how the transverse initial energy-density distribution controls the second sine harmonic of longitudinal $\Lambda$ polarization in Pb–Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.36\,\mathrm{TeV}$. We use (3+1)-dimensional Particle-In-Cell Relativistic ideal hydrodynamics and the Becattini–Buzzegoli–Palermo isothermal local-equilibrium prescription. Across the twelve selected initial states, the kinematic-vorticity contribution $P_{z,s2}^{\omega}$ is negative, whereas the kinematic-shear contribution $P_{z,s2}^{\Xi}$ is positive. Changing the initial energy-density normalization $e_{\mathrm{peak}}$, transverse smoothing width $\sigma_\perp$, or reduced impact parameter $b_0$ modifies the relative magnitudes of the two contributions rather than merely rescaling their sum. Reducing the transverse smoothing width $\sigma_\perp$ generally strengthens both contributions, whereas increasing the initial energy-density normalization $e_{\mathrm{peak}}$ can preferentially weaken $P_{z,s2}^{\Xi}$ and reverse the total harmonic. At fixed $e_{\mathrm{peak}}$, the impact-parameter dependence is mainly shear driven for narrower transverse smoothing and mainly vorticity driven for broader transverse smoothing. Applying the Liu–Yin prescription to the two tested hydrodynamic backgrounds reverses the total sign, showing that the sign depends on the polarization formula as well as on the fluid fields. Our results obtained with ideal hydrodynamics and the ILE prescription have the same sign and order of magnitude as the ALICE measurements for peripheral Pb–Pb collisions in the $50$–$70\%$ centrality interval, showing that such a positive harmonic can arise from an initial-state-controlled, shear-dominated balance at decoupling.

We apply the gradient-flow framework to determine the nonperturbative medium contribution to the jet transport coefficient $\hat q$ using quenched lattice QCD in the temperature range $0.76T_c \leq T \leq 2.25T_c$. The calculation focuses on the leading-twist contribution at leading order for an asymptotically energetic quark propagating through a thermal pure-gluon plasma. In the infinite-energy limit, the operator-product expansion expresses $\hat q/T^3$ in pure gauge theory as the product of a perturbative short-distance coefficient and the entropy density $s/T^3$. The latter is determined from the gradient-flow energy-momentum tensor at three lattice spacings for each temperature and the former is estimated perturbatively at one-loop order. We find that $\hat q/T^3$ is strongly suppressed below $T_c$, rises rapidly across the deconfinement transition, and remains approximately constant at $\hat q/T^3\simeq1.1$ throughout the deconfined temperature range studied. This is statistically consistent with the previous quenched lattice determination based on a different renormalization procedure, providing a nontrivial validation of the gradient-flow framework for the jet transport coefficient. The systematic treatment of operator renormalization and matching provided by gradient flow becomes particularly important in full QCD, because the need to renormalize quark operators and account for their mixing with the gluonic sector can likewise be addressed within the same framework.