We investigate temperature fluctuations in hot QCD matter using a 3-flavor Polyakov-loop extended Nambu--Jona-Lasinio (PNJL) model. The high-order cumulant ratios $R_{n2}$ ($n>2$) exhibit non-monotonic variations across the chiral phase transition, characterized by slight fluctuations in the chiral crossover region and significant oscillations around the critical point. In contrast, distinct peak and dip structures are observed in the cumulant ratios at low baryon chemical potential. These structures gradually weaken and eventually vanish at high chemical potential as they compete with the sharpening of the chiral phase transition, particularly near the critical point and the first-order phase transition. Our results indicate that these non-monotonic peak and dip structures in high-order cumulant ratios are associated with the deconfinement phase transition. This study quantitatively analyzes temperature fluctuation behavior across different phase transition regions, and the findings are expected to be observed and validated in heavy-ion collision experiments through measurements of event-by-event mean transverse momentum fluctuations.

We develop a bottom-up formulation of spin-kinetic theory for hot and/or dense plasmas. We introduce scalar and axial-vector phase-space functions as dynamical variables that parametrize both spin-averaged and spin-dependent distribution functions. Using spin-dependent Poisson brackets, we derive the corresponding kinetic equations and construct the associated Schwinger-Keldysh action. We further demonstrate how physical observables can be expressed in terms of these dynamical variables through constitutive relations. In the linear response regime, we establish a precise matching between the kinetic-theory and field-theory descriptions of vector and axial Wigner functions under electromagnetic and gravitational perturbations. Our framework provides a complementary approach to describing the dynamics of spin effects in a medium.

We investigate the imprint of $\alpha$ clustering on initial spin fluctuations in relativistic $^{16}\mathrm{O}+{}^{16}\mathrm{O}$ and $^{20}\mathrm{Ne}+{}^{20}\mathrm{Ne}$ collisions at $\sqrt{s_{\mathrm{NN}}}=5.36$~TeV. Utilizing \textit{ab initio} configurations from Nuclear Lattice Effective Field Theory (NLEFT) and phenomenological $\alpha$-cluster models within a Monte-Carlo Glauber framework, we compute the event-by-event variance of the initial net spin polarization. We find that the strong short-range spin--isospin correlations characteristic of $\alpha$ clusters lead to a significant suppression of spin fluctuations compared to a spherical Woods--Saxon baseline with uncorrelated spins. By constructing a scaled fluctuation observable that accounts for trivial finite-size effects, we demonstrate that this suppression exhibits a non-monotonic centrality dependence sensitive to the detailed cluster geometry. Furthermore, we propose the ratio of scaled spin fluctuations between $^{20}\mathrm{Ne}$ and $^{16}\mathrm{O}$ systems as a robust probe. Our results predict distinct percent-level deviations from the baseline for clustered nuclei, suggesting that measurements of final-state $\Lambda$-hyperon spin correlations can provide novel constraints on the ground-state spin structure of light nuclei.

We evaluate pairwise correlations using ground state wave functions for $^4$He and $^6$He obtained by $\textit{ab initio}$ no-core shell model (NCSM) calculations with the Daejeon16 nucleon-nucleon interaction plus Coulomb interaction, to characterize the structures of these two systems. We demonstrate that two-nucleon spatial correlations, specifically the pair-number operator $r^0$ and the square-separation operator $r^2$ projected on two-body spin $S$ and isospin $z$-components encode important details of the halo structure of $^6$He. We also analyze the single-particle state occupancies and the two-body state occupancies for the ground state of $^4$He and $^6$He. Our results indicate that the two valence neutrons in the ground state of $^6$He dominantly form a spin-singlet configuration. The rms pair separations between core nucleons and halo neutrons of $^6$He is about 80% larger than pair separations within the swollen and off-centered "$\alpha$ core". We show that this off-centering effect is primarily responsible for the observed increase in point-proton radius $r_p$ in $^6$He relative to $^4$He.

A recently developed three-dimensional formalism for the nucleon-deuteron breakup channel initially considered only the leading-order term of the Faddeev equations, using the nucleon-nucleon T-matrix to compute the breakup amplitude. In the present study, we extend that formalism by solving the full three-nucleon Faddeev equation without three-nucleon-force contributions in a three-dimensional approach in which momentum vectors are used directly as variables. This formalism is well suited for projectile energies in scattering processes above the pion-production threshold, where partial-wave expansions become inefficient. To treat the moving singularities of the free three-nucleon propagator, we introduce a new method that treats these singularities in a manner analogous to the simple poles appearing in the Lippmann-Schwinger equation. This approach evaluates the moving singularities directly through the center-of-mass energy of the 23-subsystem and eliminates the need to partition the q-domain into intervals. The resulting formulation opens a pathway toward a systematic investigation of the complex singularities in few-body scattering processes within the Faddeev framework.

In the present work, we study nuclear structure properties of the $^{184-194}$Pb isotopes within the framework of the nuclear shell-model. We have performed shell-model calculations using KHH7B and KHHE interactions. We have reported results for energy spectra, electromagnetic properties such as quadrupole moment ($Q$), magnetic moment ($\mu$), $B(E2)$, and $B(M1)$ transition strengths, and compared the shell-model results with the available experimental data. The shell-model results for the half-lives and seniority quantum numbers ($v$) are also reported for the isomeric states.

In this work, we propose dilepton emission rate (DER) as a sensitive probe of QCD critical point based on the extended Polyakov-quark-meson model. The model could successfully capture two main mechanisms for dilepton production, $\pi^\pm$ and quark-antiquark annihilations on one hand, and self-consistently account for chiral transition and (de-)confinement on the other hand. Along the chemical freezeout lines, all the moments of the DER peak show similar extremal features as those of light quark mass, thus the DER can well reflect the change of chiral symmetry and criticality. More importantly, the DER can be directly measured in heavy ion collisions: Compared to the baryon number fluctuations, the DER fluctuations are found to be more drastic in the critical region and more sensitive to the relative location of the critical point. However, recent statistics of DER in heavy ion collision is not large enough to perform event-by-event measurement, instead we propose to study the baseline subtracted DER: For a given dilepton center of mass, the largest deviation shows up around the point where the light quark mass fluctuation is the strongest.

We investigate the $s$-wave $KN$ scattering up to next-to-leading order within a renormalizable framework of covariant chiral effective field theory. Using time-ordered perturbation theory, the scattering amplitude is obtained by treating the leading-order interaction non-perturbatively and including the higher-order corrections perturbatively via the subtractive renormalization. We demonstrate that the non-perturbative treatment is essential, at least at lowest order, in the SU(3) sector of $KN$ scattering. Our NLO study achieves a good description of the empirical $s$-wave phase shifts in the isospin $I=1$ channel. An analysis of the effective range expansion yields a negative effective range, consistent with some partial wave analyses but opposite in sign to earlier phenomenological summaries. For the $I=0$ counterpart, the $KN$ interaction is found to be rather weak and exhibits large uncertainties. Further low-energy $KN$ scattering experiments and lattice QCD simulations are needed to better constrain both $s$-wave channels.

The plasma generated in heavy ion collisions goes through different phases in its time evolution. While early times right after the collision are governed by far-from equilibrium dynamics, later times are believed to be well described by near-equilibrium dynamics. While the regimes of non-equilibrium are prohibitively complicated to describe within QCD, effective descriptions such as hydrodynamics provide a viable approach. In addition, holographic descriptions allow access to the full non-equilibrium dynamics at strong coupling. In this presentation, we review three examples of such hydrodynamic approaches and corresponding holographic descriptions: 1) non-equilibrium shear viscosity, 2) propagation of non-equilibrium sound waves, and 3) the non-equilibrium chiral magnetic effect.

We present an \emph{ab initio} calculation within quantum statistical field theory and linear response theory, of the dissipative correction to the momentum spectrum of scalar particles emitted at decoupling (freeze-out) from a relativistic fluid assuming the initial state to be in local thermodynamic equilibrium. We obtain an expansion of the Wigner function of the interacting quantum field in terms of the gradients of the classical thermo-hydrodynamic fields - four-temperature vector and reduced chemical potential - evaluated on the initial local-equilibrium hypersurface, rather than on the decoupling (freeze-out) hypersurface as usual in kinetic theory. The gradient expansion includes an unexpected zeroth order term depending on the differences between thermo-hydrodynamic fields at the decoupling and the initial hypersurface. This term encodes a memory of the initial state which is related to the long-distance persistence of the correlation function between Wigner operator and stress-energy tensor and charged current that is discussed in detail. We address the phenomenological implications of these corrections for the momentum spectra measured in relativistic nuclear collisions.

We compute the running of the mass of a neutral boson and of its self-coupling in a simple model describing the self-interaction of three scalars, one of them neutral and the other two electrically charged, subject to the effects of a magnetic field, as functions of the field strength, at one-loop order. We resort to the Environmentally Friendly Renormalization Group approach, where the flow variable is taken as that describing the environmental conditions, in this case the strength of the magnetic field. We find the magnetic field dependent mass and coupling beta functions and use them to set up the differential equations satisfied by the neutral scalar mass and coupling. We solve the resulting system of coupled equations both numerically, and also analytically in the small-mass approximation. We find that the neutral scalar mass increases, while the coupling decreases with increasing field strength. The study is intended to set up the ideas to later use them in more sophisticated theories such as QED and QCD.

Clarifying the origin of hadron mass is one of the fundamental problems in particle physics, relevant from hadronic scales to astrophysical observations. At low energies, this issue is reflected in the decomposition of the hadron mass into chiral-variant and -invariant components. In this letter, we propose a method to extract the chiral invariant mass from the gravitational $D$-form factor under the assumption of the lightest-sigma meson dominance. Focusing on the nucleon, we show that a sizable chiral invariant mass is required to reproduce lattice QCD data, consistent with neutron star constraints.

The mass spectrum of hadrons in magnetic fields features avoided level-crossing structures arising from the mixing of spin eigenstates. In this work, we investigate the impact of level-crossing dynamics of charmonia subjected to time-dependent magnetic fields, where we particularly focus on the occupation probabilities of two or more states as they undergo transitions at avoided crossings. Using a static spectrum of charmonia in magnetic fields, we construct a multi-channel Landau-Zener Hamiltonian. Within this framework, we analyze the time evolution under several representative magnetic-field profiles, including linear ramps and Gaussian decays corresponding to single-passage dynamics, as well as Gaussian pulses realizing double-passage dynamics, and compute the occupation probabilities over a wide range of sweep rates and initial conditions. Our results show that nonadiabatic dynamics, including Landau-Zener transitions and Stückelberg interference, strongly influences the occupation probabilities of charmonia. These findings provide new insights into the real-time dynamics of magnetized hadrons and offer useful guidance for future lattice simulation studies.

We report a state-of-the-art lattice QCD calculation of the total gluon helicity contribution to proton spin, $\Delta G$. The calculation is done on ensembles at three different lattice spacings $a=\{0.08, 0.09, 0.11\}$ fm. By employing distillation + momentum smearing for proton external states, we extract the bare matrix elements of the topological current $K^\mu$ under the 5-HYP smeared Coulomb gauge fixing configurations. Furthermore, we apply a non-perturbative $\mathrm{RI/MOM}$ renormalization scheme augmented with the Cluster Decomposition Error Reduction (CDER) technique to determine the renormalization constants of $K^\mu$. The results obtained from different components $K^{t,i}$ (with $i$ being the direction of proton momentum or polarization) are consistent with Lorentz covariance within uncertainties. After extrapolating to the continuum limit, $\Delta G$ is found to be $\Delta G = 0.231(17)^{\mathrm{sta.}}(33)^{\mathrm{sym.}}$ at the $\overline{\mathrm{MS}}$ scale ${\mu}^2=10\ \mathrm{GeV}^2$, which constitutes approximately $46(7)\%$ of the proton spin.

This work presents the Trojan Horse Method (THM) as a powerful technique for measuring nuclear reaction cross sections at astrophysical energies. We then explore the impact of THM-derived reaction rates on the predictions of Standard Big Bang Nucleosynthesis (SBBN) using the PRIMAT code. Primordial abundances are shown for the single rate impact and, for the first time, also for all the THM rates together. The result shows significant differences with the use of THM rates, which in some cases goes in the direction of improving the agreement with the observations with respect to the use of only reaction rates from direct data, especially for the $^7$Li and deuterium abundances, which are still open issues for SBBN.

We present a model calculation to reproduce the differential mass distribution for the $D^*\pi$ system in the reactions $B^- \to D^{*+} \pi^- \pi^-$ and $B^{+}\to D_s^+D^{*-}\pi^{+}$ analyzed by the LHCb Collaboration, which shows a dominant signal for $D_1(2420)$. %\textbf{We} (The idea is to) We consider a model based on coupled channel meson-meson interactions that can describe the properties of $D_1(2420)$ in terms of the underlying dynamics, use it to determine the invariant mass distribution of the $D^*\pi$ system, and compare the results with the experimental data. We also determine the $D^*\pi$ scattering length, for which different values are available from different sources, leading to a controversy. To our knowledge, this is the first attempt to reproduce the mentioned data using model calculations. Our formalism relies on the hadronization of different mesons through a weak decay, allowing for the final-state (strong) interactions among the relevant constituents. We benefit from our previous work when obtaining the amplitudes corresponding to the strong interactions. We hope that our findings can be useful in further investigations of the properties of $D_1(2420)$.

Non-Hermitian operators and exceptional points (EPs) are now routinely realized in few-mode systems such as optical resonators and superconducting qubits. However, their foundations in genuine scattering problems with unbounded Hamiltonians remain much less clear. In this work, we address how the geometric phase associated with encircling an EP should be formulated when the underlying eigenstates are quantum resonances within a one-dimensional scattering model. To do this, we employ the complex scaling method, where resonance poles of the S-matrix are realized as discrete eigenvalues of the non-Hermitian dilated Hamiltonian, to construct situations in which resonant and scattering states coalesce into an EP in the complex energy plane, that is, the resonance pole is embedded into the continuum spectrum. We analyze the self-orthogonality in the vicinity of an EP and the Berry phase. Our results provide a bridge between non-Hermitian spectral theory and the traditional theory of quantum resonances.

We investigate the effects of anisotropy on dispersion relations and convergence in relativistic hydrodynamics. In particular, we show that for dispersion relations with a branch point at the origin (such as sound modes), there exists a continuum of collisions between hydrodynamic modes at complex wavevector. These collisions are then explicitly demonstrated to be present in a holographic plasma. We lay out a criterion for when the continuum of collisions affects the convergence of the hydrodynamic derivative expansion. Finally, the radius of convergence of hydrodynamic dispersion relations in anisotropic systems is bounded from above on the basis of compatibility with microscopic causality.

Recent studies have shown that hadronic multiplicity in deep inelastic scattering is associated with an entanglement entropy. However, such definitions are intrinsically longitudinal and do not capture the full phase--space structure of the proton. In this work, we investigate the Wehrl entropy of the proton constructed from Husimi distribution obtained from the Gaussian smearing of the Wigner distribution. We show that the entanglement entropy naturally emerges from the normalization condition of the Husimi distribution within this framework. In addition, the Wehrl entropy contains a contribution associated with transverse degrees of freedom. Numerical results for the proton Wehrl entropy are presented for different values of the virtuality.

We analyze the mass spectra of hadrons and demonstrate that the physical spectra of mesons and baryons are well described by the exponential spectrum of open strings. The open string spectrum, derived from string theory, is characterized by a unique Hagedorn temperature $T_{\rm H}$ and free from any other parameters. Notably, our fitting to the physical spectra yields consistent values for both mesons and baryons, $T_{\rm H} \simeq 0.34\,\text{GeV}$, which contrasts with previous phenomenological analyses that suggested different values. This obtained value aligns well with typical string tension derived from lattice-QCD calculations and the Regge slope. In the baryonic sector, our results indicate that diquarks play a crucial role in describing the mass spectrum, implying that baryons can be understood as a quark-diquark system, as anticipated by Regge phenomenology. These findings have significant implications for our understanding of quark deconfinement, especially in the possibly existing regime at high temperature and small baryon chemical potential within the QCD phase diagram.

We calculate the in-medium valence quark distribution of the pion immersed in a finite baryon density using the light-cone quark model. The medium-modified pion properties are obtained by using the constituent quark mass-dependent light cone wave functions. To obtain the constituent quark masses at finite baryon density, we employ the two-flavor Nambu--Jona-Lasinio model. We primarily focus on the in-medium electromagnetic form factor, distribution amplitude, and the parton distribution function of the pion. The parton distribution functions are also evolved from the model scale to a perturbative scale using next to leading order Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations. Furthermore, our calculated form factors are compared with available experimental measurements and lattice quantum chromodynamics studies. We also examine the Mellin moments derived from our parton distribution functions in comparison with existing extractions and theoretical model predictions.

In the framework of a macroscopic $\alpha$-cluster model, the structural properties and the spectroscopy of the $^{24}\mathrm{Mg}$ nucleus are investigated. Special attention is devoted to the electromagnetic selection rules imposed by the point-symmetry group $\mathcal{D}_{4h}$ that leaves invariant the adopted $6\alpha$ equilibrium configuration, a square bipyramid. The analysis entails the application of group-theoretical identities and character tables, in a way familiar to quantum chemists. The results show that the occurrence of interband E0, E2, and M1, M2, M3 transitions is strictly regulated by the transformation properties of the excited vibrational modes to which the states in the process belong. Unlike the $^{12}\mathrm{C}$ nucleus in the $\mathcal{D}_{3h}$-symmetric $3\alpha$ arrangement, M1 transition channels are active between states corresponding to a single quantum of vibrational excitation. Conversely, the measured E1 strengths in the $^{24}\mathrm{Mg}$ spectrum are attributable to the excitation of single-nucleon degrees of freedom, as E1 transitions are forbidden by the model. The present investigation is a only part of a wider work, encompassing the spectrum and the whole electromagnetic properties of this nucleus in the considered $\mathcal{D}_{4h}$-symmetric configuration, in preparation.

We generalize the equivalence between off-equilibrium state and gravitational perturbation of equilibrium state from dynamics of macroscopic quantities to that of microscopic particles. We also generalize the equivalence to incorporate off-equilibrium state with vorticity by torsional perturbation to equilibrium state. The equivalence is achieved by mapping kinetic theories of spinless and spinning particles in torsional curved space to flat space through suitable choice of inertial frame that eliminates geodesic forces on particles. The equivalence has been shown for hydrodynamic and elastic regimes. In the latter case, we predict spin polarization induced by time-variation of shear strain in elastic materials. We also provide an order-of-magnitude estimate for the polarization in Dirac semi-metal.

A systematic non-fluid to fluid transition framework and comparative research on Lorenz ratios for graphene and nonrelativistic systems have been studied to identify their Wiedemann-Franz law violation domain. Here, Lorenz ratio is defined as thermal conductivity divided by electrical conductivity times temperature times Lorenz number. In non-fluid framework, Lorenz ratio become exactly one, which means that the Wiedemann-Franz is obeyed within a Fermi Liquid domain. When one enters from Fermi Liquid to Dirac Fluid domain, Lorenz ratio becomes less than one in non-fluid framework but in fluid framework, it always remain greater than one for both domain. By compiling our outcomes and connecting with experimental data, a non-fluid to fluid transition framework is expected during the transition from Fermi Liquid to Dirac Fluid domain.

In the context of the left-right symmetric model, we study the interplay of neutrinoless double beta ($0\nu\beta\beta$) decay, parity-violating Møller scattering, and high-energy colliders, resulting from the Yukawa interaction of the right-handed doubly-charged scalar to electrons, which could evade the severe constraints from charged lepton flavor violation. The $0\nu\beta\beta$ decay amplitude receives additional contributions from right-handed sterile neutrinos. The half-life, calculated in the effective field theory (EFT) framework, allows for an improved description of the contributions involving non-zero mixing between left- and right-handed $W$ bosons and those arising from exchanging a light right-handed neutrino. We find that the relative sensitivities between the low-energy (or high-precision) and high-energy experiments are affected by the left-right mixing. On the other hand, our results show how the interplay of collider and low-energy searches provides a manner to explore regions that are inaccessible to $0\nu\beta\beta$ decay experiments.

We investigate the structural modifications of heavy quarkonia in the presence of strong magnetic fields using a constituent quark model. By incorporating the effects of spin mixing and quark Landau levels, we employ a nonrelativistic Hamiltonian that captures the essential features of quark dynamics in a magnetic field. The two-body Schrödinger equation is solved using the cylindrical Gaussian expansion method, which respects the cylindrical symmetry induced by a magnetic field. We extract the corresponding light-front wave function (LFWF) densities and analyze their transverse and longitudinal structures, revealing characteristic features such as transverse momentum broadening. While the longitudinal structure is only slightly modified within the nonrelativistic Hamiltonian, we discuss some corrections that can significantly affect its longitudinal structure. Furthermore, we discuss the structure modifications of excited states and find notable changes in the LFWF densities, and state reshuffling near avoided crossings. These results demonstrate the sensitivity of hadron structure to external magnetic fields and help bridge our understanding to relativistic approaches.

The stellar compactness, that is, the dimensionless ratio between the mass and radius of a compact star, $\mathcal{C} := M/R$, plays a fundamental role in characterising the gravitational and nuclear-physics aspects of neutron stars. Yet, because the compactness depends sensitively on the unknown equation of state (EOS) of nuclear matter, the simple question: ``how compact can a neutron star be?'' remains unanswered. To address this question, we adopt a statistical approach and consider a large number of parameterised EOSs that satisfy all known constraints from nuclear theory, perturbative Quantum Chromodynamics (QCD), and astrophysical observations. Next, we conjecture that, for any given EOS, the maximum compactness is attained by the star with the maximum mass of the sequence of nonrotating configurations. While we can prove this conjecture for a rather large class of solutions, its general proof is still lacking. However, the evidence from all of the EOSs considered strongly indicates that it is true in general. Exploiting the conjecture, we can concentrate on the compactness of the maximum-mass stars and show that an upper limit appears for the maximum compactness and is given by $\mathcal{C}_{\rm max} = 1/3$. Importantly, this upper limit is essentially independent of the stellar mass and a direct consequence of perturbative-QCD constraints.