The fluctuations of elliptic flow $\left(v_2\right)$ in relativistic heavy-ion collisions offer a powerful tool to probe the collective behavior and transport properties of the quark-gluon plasma (QGP). The dependence of these fluctuations on particle species further sheds light on the hadronization mechanism. At CERN Large Hadron Collider energies, the ALICE experiment has measured $v_2$ fluctuations for charged pions, kaons, and (anti)protons via the ratio of $v_2$ measured with respect to the spectator plane $\left(v_2\{{\mathrm{\Psi }}_{\mathrm{SP}}\right\})$ and from the four-particle cumulants $\left(v_2\left\{4\right\}\right)$. However, the observed dependencies on transverse momentum and particle type remain not fully understood. In this study, we perform a phenomenological investigation using a multiphase transport model, which allows us to trace the full evolution of flow fluctuations intertwined with the quark coalescence. The results qualitatively reproduce the ALICE measurements and offer deeper insights into the transport dynamics and hadronization of the QGP.

This study investigates the color-charge dependence of parton energy loss in the quark-gluon plasma (QGP) medium and the associated relative modifications of quark and gluon jet fractions compared to vacuum, using jet axis decorrelation observables. Recent CMS jet axis decorrelation measurements in $\text{PbPb}$ collisions at 5.02 TeV are interpreted using Pythia simulations with varied quark/gluon jet compositions and emulated color-charge dependent energy loss. A template-fit procedure is employed to estimate the limits on gluon jet fractions in the published CMS data and average shift in jet momentum due to quenching for quark- and gluon-initiated jets traversing the QGP. The extracted gluon jet fractions and the estimated quark and gluon energy losses based on this study of jet axis decorrelations are found to be consistent with other model calculations based on inclusive observables. This work illustrates the use of jet substructure measurements for providing constraints on the color-charge dependence of parton energy loss and offers valuable insights for jet quenching models.

Prompt photon measurements in relativistic nuclear collisions serve as an essential comparative basis for heavy-ion studies enabling the separation of medium-induced effects. However, the identification of prompt photons is experimentally challenging due to substantial backgrounds from photons produced in hadron decays and jet fragmentation. Appropriate isolation criteria are applied to suppress these background contributions. We analyze prompt photon spectra using the JETPHOX framework to quantify the relative contributions of fragmentation and direct-production mechanisms to the total photon yield. We perform a systematic study of the impact of isolation criteria on prompt photon production in relativistic nuclear collisions with emphasis on their dependence on beam energy and photon transverse momentum. The fragmentation contribution is found to be substantially large, particularly for $p_T<15$ GeV, and the isolation criterion plays a crucial role in the analysis of prompt photons in that $p_T$ region. A dynamical isolation criterion suppresses the fragmentation component more effectively than a fixed one in this region. Furthermore, the isolation criterion shows a stronger dependence on beam energy and photon $p_T$ than on system size. These observations emphasize the importance of employing carefully selected and consistent isolation criteria when comparing experimental data with theoretical calculations especially for observables sensitive to fragmentation.

Our previous studies revealed evidence of the strange molecular partners of $P_c$ states, $N\left(2080\right)3/2^{-}$ and $N\left(2270\right)3/2^{-}$, in $\gamma p\to K^{*+}{\mathrm{\Sigma }}^0/K^{*0}{\mathrm{\Sigma }}^{+}$ and $\gamma p\to \varphi p$ reactions. Motivated by the differential cross-section data for $\gamma p\to K^{+}{\mathrm{\Sigma }}^0$ from CLAS 2010, which exhibits some bump structures at $W\approx$ 1875, 2080, and 2270 MeV, we extend our previous analysis by investigating the effects of $N\left(1535\right)1/2^{-}$, $N\left(1875\right)3/2^{-}$, $N\left(2080\right)1/2^{-},\text{and}3/2^{-}$ and $N\left(2270\right)1/2^{-},3/2^{-},\text{and}5/2^{-}$ as strange partners of $P_c$ molecular states in the reactions $\gamma p\to K^{+}{\mathrm{\Sigma }}^0$ and $\gamma p\to K^0{\mathrm{\Sigma }}^{+}$. The theoretical model employed in this study utilizes an effective Lagrangian approach in the tree-level Born approximation. It contains contributions from the $s$ channel with exchanges of $N$, $\mathrm{\Delta }$, $N^{*}$ (including the hadronic molecules with hidden strangeness), ${\mathrm{\Delta }}^{*}$; $t$ channel; $u$ channel; and the generalized contact term. The results based on the final fitted parameters are in good agreement with all available experimental data of both cross sections and polarization observables for $\gamma p\to K^{+}{\mathrm{\Sigma }}^0$ and $\gamma p\to K^0{\mathrm{\Sigma }}^{+}$. Notably, the $s$-channel exchanges of molecules significantly contribute to the bump structures in cross sections for $\gamma p\to K\mathrm{\Sigma }$ at $W\approx 1900$, 2080, and 2270 MeV and show considerable coherence with contributions from $s$-channel exchanges of general resonances to construct the overall structures of cross sections. More abundant experiments, particularly for the reaction $\gamma p\to K^0{\mathrm{\Sigma }}^{+}$, are necessary to further strengthen the constraints on the theoretical models.

The $\mathrm{\Lambda }$ and $\mathrm{\Sigma }$ single-particle potentials in infinite nuclear matter are analyzed within a recently established chiral hyperon-nucleon ($YN$) interaction up to ${\mathrm{N}}^2\mathrm{LO}$ in combination with a nucleon-nucleon interaction derived in the same scheme. The self-consistent Brueckner-Hartree-Fock method with the continuous choice of the single-particle potential is employed. It is found that the $\mathrm{\Lambda }$ single-particle potential is comparable to the results achieved with the NLO $YN$ interaction from 2019. The resulting $\mathrm{\Sigma }$ potential becomes more attractive compared to the previous NLO results due to the constraint from the recent $\mathrm{\Sigma }N$ differential cross section data measured in the J-PARC E40 experiment. An estimate of the theoretical uncertainty of the single-particle potentials is provided in terms of the truncation error in the chiral expansion.

We present the first direct determination of asymptotic normalization coefficients (ANCs) for the ground and first excited states of ${}^7\mathrm{Be}$ from ${}^3\mathrm{He}+{}^4\mathrm{He}$ elastic scattering phase shifts. The analysis draws upon the classic datasets of two older low-energy measurements, long considered difficult due to internal inconsistencies and the absence of systematic uncertainties. Employing single-level $R$-matrix fits, the mapping between reduced widths and ANCs, and Bayesian inference, we reconstruct posterior distributions and quantify uncertainties. A key innovation of this study is the application and validation of the extrapolation method developed by our group, specifically designed to extract ANC values in cases where direct low-energy information is lacking. Benchmarking against the latest measurements [Paneru et al., Phys. Rev. C 109, 015802 (2024)], which reported only $R$-matrix fits with fixed ANCs, confirms the predictive power and robustness of our approach. Our findings show that ANCs deduced from older scattering measurements are systematically lower than those inferred from radiative capture, thereby confirming earlier indications of a discrepancy between the two methods. This work demonstrates both the originality and reliability of the extrapolation method as a powerful tool for ANC determination in nuclear astrophysics.

Fine-tuning of the binding energies and widths of the quasibound states in three-body systems consisting of antikaon(s) and nucleon(s) was performed. Dynamically exact three-body Faddeev-type Alt-Grassberger-Sandhas equations with three coupled particle channels were solved for the description of the $\overline{K}NN$ and $\overline{K}\overline{K}N$ systems in different spin states. New models of the antikaon-nucleon and pion-nucleon interactions were constructed, and together with my best version of the hyperon-nucleon potential, were used as input. The characteristics of the quasibound $K^{-}pp$ state calculated with my new one-pole $\overline{K}N-\pi \mathrm{\Sigma }-\pi \mathrm{\Lambda }$ potential reproduces the experimental data from the E15 J-PARC experiment.

We discuss the general behavior of the scattering amplitude with channel couplings near the two-body threshold. It is known that the Flatté amplitude, which is often used in the analysis of experimental data involving exotic hadrons, has some constraint in the near-threshold energy region. While the $M$-matrix gives the general expression of the scattering amplitude, it is not smoothly connected to the Flatté amplitude, due to the property of the determinant of the amplitude in channel space. In this paper, based on the effective field theory, we propose new parametrization of the scattering amplitude which gives the general expression near the threshold and has a well-defined limit reproducing the Flatté amplitude. We show that the nonresonant background contribution exists in the general amplitude even in the first order in the momentum. Finally, we quantitatively evaluate the cross sections by changing the strength of the background contribution. We find that the interference with the background term may induce a dip structure of the cross section near the threshold, in addition to the peak and threshold cusp structures.

Noncentral heavy-ion collisions create fireballs with large initial orbital angular momentum that is expected to induce strong vorticity in the hot bulk fluid and generate global spin polarization of the produced particles. As the collision beam energy $\sqrt{s_{\mathrm{NN}}}$ decreases to approach the two-nucleon-mass threshold, this initial angular momentum approaches zero. One may thus expect that the observed global spin polarization should reach a maximum and then drop to zero as increased stopping competes with decreased initial momentum. Recent experimental measurements, however, appear to show a continual rise of hyperon polarization even down to $\sqrt{s_{\mathrm{NN}}}=$ 2.42 GeV, suggesting a peak very near threshold, which is difficult to interpret and calls for a better understanding of angular-momentum initial conditions, especially at low energy. Here, we develop a new Glauber-based initial-state model (“$\mathrm{Glauber}+$”) to investigate the initial distribution of angular momentum with respect to rapidity as well as the dependence of this distribution on initial baryon stopping across a wide range of collisional beam energy. We estimate that the angular momentum per produced final charged particle at midrapidity peaks around 5 GeV, which may present a potential challenge to an interpretation of the spin-polarization measurements near threshold as being a consequence of the initial angular momentum of the colliding system.

We consider separable toy models of the nucleon-nucleon interaction inspired by chiral effective field theory. We show that nonlocality of the long-range forces causes the need for nonlocal counter terms, or even makes the whole approach nonrenormalizable.

Experimental $B\left(E2\right)$ reduced transition strengths in $N=50$, 126 and $Z=82$ semimagic nuclei are compared to the values predicted by the seniority scheme for a single $j=9/2$ orbital. For the first time all available data, both on even- and odd-mass nuclei, were considered in the same framework. The seniority scheme provides a good approximation for all these three regions with the best fit given by the lead isotopes. In addition, shell model calculations using well-established interactions were performed. In the $N=50$ and $Z=82$ nuclei considering all orbitals within a shell provide only a limited improvement in reproducing the data when compared to the seniority scheme. In contrast, the shell model provides much better agreement for $N=126$ nuclei, where the $\pi f_{7/2}$ orbital has increasing effect on the transition strengths as the $j=9/2$ orbital is filled. In order to further test the applicability of the seniority scheme in the lead isotopes, and investigate the possible distorting effect of the $\nu i_{11/2}$ orbital, more experimental information is required, especially for ${}^{214,215,216}\mathrm{Pb}$.

The energy states and electromagnetic transitions of even-even ${}^{202-206}\mathrm{Po}$ and odd-mass ${}^{203,205}\mathrm{Po}$ and ${}^{203,205}\mathrm{At}$ isotopes within the framework of the proton-neutron interacting boson model (IBM-2) and its extension (IBFM-2) are calculated. For odd-$A$ nuclei, the $0h_{9/2},1f_{7/2},1f_{5/2},2p_{3/2},2p_{1/2}$ and $0i_{13/2}$ single-particle orbits are considered as model space. The obtained results are used to assign spins to some uncertain spin states. The $\log ft$ values of the allowed $\beta$ decay are calculated using the model wave function and compared with available experimental values.

The effect of meson-exchange currents on charged-current quasielastic neutrino scattering with single-nucleon emission is computed and analyzed within the relativistic Fermi gas model. This contribution arises primarily from the interference between one-body and two-body currents, where the two-body operator excites a 1p1h state in the presence of a second, spectator nucleon. The results obtained show a reduction of the vector, axial, and vector-axial transverse response functions and, consequently, a decrease in the total neutrino cross section. In addition to a comparison with the nonrelativistic limit, other models are also explored, such as the relativistic mean field model for nuclear matter and superscaling analysis with relativistic effective mass, both of which yield qualitatively similar results.

We calculate the equation of state (EOS) of spin-polarized nuclear matter in the relativistic Hartree-Fock method. To this end, we employ the relativistic point-coupling model, with which the Fock terms are considerably simplified, reducing them to the same form as the Hartree terms. In analogy to the slope parameter $L$ of the isospin-symmetry energy for spin-unpolarized matter, we evaluate the spin slope parameter $L_s$ of the corresponding spin-symmetry energy for spin-polarized matter. We find that the slope parameter $L$ and the spin slope parameter $L_s$ have a negative correlation in the case of isoscalar polarization, where neutrons and protons are spin polarized in the same direction. On the other hand, the spin slope parameter is nearly independent of the slope parameter in the case of isovector polarization, where neutrons are spin-polarized along the opposite direction to protons. We show that these correlations are a natural consequence of the relativistic point-coupling model, which we employ.

Determining the energy dependence of fusion cross sections at extremely low energies is crucial for various astrophysical processes. In the previous study by Jiang et al. [Phys. Rev. C 75, 015803 (2007)], it was concluded that fusion cross sections for the ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ system rapidly drop off as the energy decreases. We here reexamine this hindrance phenomenon. While the previous study fitted the logarithmic slope $L\left(E\right)$ of fusion cross sections with a function of $L\left(E\right)=A+B/E^n$ and sought the optimum value of $A$ and $B$ with $n=1.5$, we refit the data with the same function for $L\left(E\right)$ but by releasing the restriction on $n$. We find that the optimum values of $n$ significantly deviate from $n=1.5$. For the ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ system, the presence or the absence of the hindrance phenomenon depends on a fitting procedure and a selection of data sets. On the other hand, for the ${}^{12}\mathrm{C}+{}^{13}\mathrm{C}$ system, we show that the optimum values of $n$ are smaller than $n=1.5$ regardless of the details of the fitting procedure, indicating the absence of hindrance in the fusion cross sections.

A low-energy calculation of ${}^9\mathrm{Be}$ photodisintegration cross section is presented within an $\alpha \alpha n$ cluster approach. The $\alpha n$ and $\alpha \alpha$ contact interactions are derived from cluster effective field theory. The two-body potentials defined in momentum space are regularized by a Gaussian cutoff. The associated low-energy constants are found by comparing the calculated low-energy $T$ matrix with its effective range expansion. A three-body state-dependent potential is also introduced in the model. First, the ${}^9\mathrm{Be}$ three-body binding energy is studied within the nonsymmetrized hyperspherical harmonics method. Then, the low-energy cross section is calculated via the Lorentz integral transform method, focusing on the dominant electric dipole transitions. A twofold evaluation of the nuclear current matrix element is presented, employing both the electric dipole transition operator (Siegert theorem) and the one-body convection current operator. This approach is adopted to allow for a discussion of the effect of the many-body currents.

We extend our previous work on the spin alignment of the $\varphi$ vector meson in the hadronic phase of the quark gluon plasma, by including effects of nucleon scatterings. The emission rates are calculated in a realistic hydrodynamic background simulated with the code $\text{FLUID}u\text{M}$, for different beam energies. We find that all the effects taken into account cannot explain the out-of-plane spin alignment of the $\varphi$ meson observed experimentally.

We investigate renormalization of chiral nuclear forces in the coupled channel of ${}^3{S}_1-{}^3{D}_1$ of nucleon-nucleon scattering. The one-pion exchange potential is treated nonperturbatively at leading order while subleading potentials are perturbations. Very much like the uncoupled channel of ${}^3{P}_0$, the singular attraction of one-pion exchange gives rise to the so-called genuine exceptional cutoffs, where artificial correlations between subleading contact operators emerge and they result in ill-defined values of the low-energy constants. To address this issue we follow the solution proposed for ${}^3{P}_0$ in [Peng et al., Phys. Rev. C 110, 054001 (2024)] and apply it to ${}^3{S}_1-{}^3{D}_1$. The truncation uncertainty of an effective field theory allows certain degrees of freedom in choosing renormalization conditions, or fitting schemes of the low-energy constants. By exploiting this freedom near the exceptional cutoffs, we are able to remove the said correlations. A much-mitigated cutoff variation of the phase shifts, which is acceptable to the power counting, is thus obtained.

This article aims to derive the exact relativistic orbital-free kinetic energy density functional for one-particle nuclear systems in one-dimensional case. The kinetic energy is expressed as a functional of both vector and scalar densities. The functional derivatives of the kinetic energy density functional are also derived. Both the kinetic energy density functional and its functional derivatives are validated to be correct. This serves as a foundation for further exploration of more general relativistic orbital-free kinetic energy density functionals.

The ongoing quest for the boundaries of the chart of nuclides has led to the discovery of many new heavy nuclei near the drip line, which generally exhibit large shape deformation. To explore the impact of nuclear deformation on ground-state $\alpha$-decay properties, particularly $\alpha$ clustering, we develop a deformed version of the pocket-type dynamical double-folding potential (DDFP) model. By analyzing the geometry of the pocket potential and the systematics of extracted $\alpha$-preformation factors, we find that the effect of deformation on $P_{\alpha }$ can be described by a simple linear correlation with the square of quadrupole-deformation parameter. Based on this finding, we propose an empirical formula for $P_{\alpha }$ that accounts for both shell and deformation effects. Using the deformed pocket-type DDFP and the proposed formula, we predict the $\alpha$-decay half-lives for neutron-deficient Pu, Cm, and Cf isotopes near the proton drip line.