The group SU(3) has applications in several branches of physics. Many of these applications depend on availability of SU(3) coupling and recoupling coefficients. We have developed a modern Fortran library for calculation of the coupling coefficients, for both the SU(3)⊃U(1)×SU(2) and SU(3)⊃SO(3) group chains, and the recoupling coefficients. The library implements the algorithms of Draayer, Akiyama, and Millener, which are laid out in the paper. Performance of the library has been tested and compared to the Akiyama-Draayer (AD) library implementing the same algorithms as well as to a more recent implementation. Our library works for a larger range of SU(3) quantum numbers and provides more accurate coupling coefficients with large quantum numbers than the AD library.
The AmpRed package has been updated with an improved method for analytic continuation of complex integrals. Compared to the previous version, the new implementation significantly enhances computational efficiency for evaluating complex integrals.
We study the proton structure functions F1 and F2 in the context of holography. We develop a general framework that extends previous holographic calculations of F1 and F2 to the case where the bulk geometry stems from bottom-up Einstein-Dilaton models, which are commonly used in the literature to describe some properties of QCD in the strong coupling regime. We focus on a choice of the dilaton potential that leads to a holographic model able to reproduce known lattice QCD results for the glueball masses at zero temperature and pure Yang-Mills thermodynamics above deconfinement. Once the parameters of the background holographic model are fixed, we introduce probe fermionic and gauge fields in the bulk {\it a la} Polchinski and Strassler to determine the corresponding structure functions. This particular realization of the model can successfully describe the proton mass and provide results for F2 at large x in very good agreement with experimental data.
The quark-gluon plasma (QGP) produced in ultrarelativistic heavy-ion collisions has exhibited properties of a mostly perfect fluid. These properties can be observed through the hydrodynamic expansion of the QGP. Experimentally, this was established by measuring azimuthal anisotropies in the final state, known as elliptic flow (v2) or higher order harmonics such as triangular flow (v3). These Fourier harmonic coefficients have been extensively measured in past experiments using inclusive charged particles or identified particles in the soft sector. Interestingly, measuring such coefficients using hard probes, such as quarkonia, brings additional information about heavy-quarks production and thermalization in the QGP. In this study, we investigate quarkonia collectivity using Run 3 data collected in 2023, presenting new flow measurements. We employ different experimental methods to extract flow coefficients, including the scalar product, event plane, and cumulant methods. These results will impose new constraints on theoretical models, enhancing our understanding of quarkonia behavior in heavy-ion collisions.
A comprehensive analysis of the photoproduction of J/Ψ and Υ mesons in peripheral PbPb collisions at the center - of - mass energies of the Large Hadron Collider (LHC) is performed, considering distinct assumptions for the modeling of the nuclear photon flux, photon - nucleus cross - section, overlap function and dipole - proton scattering amplitude. The comparison of these predictions with the ALICE data is also performed. Our results indicate that a detailed analysis of the production of both mesons will be very useful to improve the description of photon - induced processes in peripheral collisions.
We study magnetic properties of the Hadron Resonance Gas in the presence of a strong (0≤B≤0.15GeV2) uniform magnetic field, using physical values of the magnetic moments of hadrons, i.e., including their anomalous parts. The values of these moments are taken from experiment, or when unavailable, from theoretical estimates. We evaluate the conserved charge susceptibilities, finding the expected sizable effects of the anomalous magnetic moments, in particular of the octet baryons, such as the proton and neutron, where they are exceptionally large. We also study in detail the large effects of the magnetic moments of the Δ(1232) states, for which various theoretical estimates and experimental values differ significantly. We compare our model results with the lattice QCD data and find reasonable agreement within the model uncertainty.
We present suppression predictions from our pQCD-based energy loss model, which receives small system size corrections, for high-pTπ, D and B meson RAB as a function of centrality, flavor, sNN, and pT from large to small collision systems at RHIC and LHC. A statistical analysis is used to constrain the effective strong coupling in our model to available high-pT suppression data from central heavy-ion collisions at RHIC and LHC, yielding good agreement with all available data. We estimate two important theoretical uncertainties in our model, stemming from: the transition between vacuum and hard thermal loop propagators in the collisional energy loss, and from the angular cutoff on the radiated gluon momentum. We find, consistently, that the extracted αs remains relatively unchanged across heavy- and light-flavor final states and across central, semi-central, and peripheral collisions. We make predictions from our large-system-constrained model for small systems and find good agreement with photon-normalized RdAuπ0≃0.75 in 0−5% centrality d + Au collisions by PHENIX. However, we find strong disagreement with the measured RpPbh±≳1 in 0−5% centrality p + Pb collisions by ALICE and ATLAS; we argue that this disagreement is due, in large part, to centrality bias. We make predictions for the ratio of suppression in 3He + Au and p + Au collisions, which may in the future be used to disentangle final- from initial-state suppression in small systems. We then compare our results to various subsets of data, which allows us to estimate the preferred: low-pT scale at which non-perturbative processes become important, scales at which the strong coupling runs, and scale at which vacuum propagators transition to thermally modified propagators in collisional energy loss.
Large-Momentum Effective Theory (LaMET) is a physics-guided systematic expansion to calculate light-cone parton distributions, including collinear (PDFs) and transverse-momentum-dependent ones, at any fixed momentum fraction x within a range of [xmin,xmax]. It theoretically solves the ill-posed inverse problem that afflicts other theoretical approaches to collinear PDFs, such as short-distance factorizations. Recently, arXiv:2504.17706 [1] raised practical concerns about whether current or even future lattice data will have sufficient precision in the sub-asymptotic correlation region to support an error-controlled extrapolation -- and if not, whether it becomes an inverse problem where the relevant uncertainties cannot be properly quantified. While we agree that not all current lattice data have the desired precision to qualify for an asymptotic extrapolation, some calculations do, and more are expected in the future. We comment on the analysis and results in Ref. [1] and argue that a physics-based systematic extrapolation still provides the most reliable error estimates, even when the data quality is not ideal. In contrast, re-framing the long-distance asymptotic extrapolation as a data-driven-only inverse problem with ad hoc mathematical conditioning could lead to unnecessarily conservative errors.