Managing the high computational cost of iterative solvers for sparse linear systems is a known challenge in scientific computing. Moreover, scientific applications often face memory bandwidth constraints, making it critical to optimize data locality and enhance the efficiency of data transport. We extend the lattice QCD solver DD-$\alpha$AMG to incorporate multiple right-hand sides (rhs) for both the Wilson-Dirac operator evaluation and the GMRES solver, with and without odd-even preconditioning. To optimize auto-vectorization, we introduce a flexible interface that supports various data layouts and implement a new data layout for better SIMD utilization. We evaluate our optimizations on both x86 and Arm clusters, demonstrating performance portability with similar speedups. A key contribution of this work is the performance analysis of our optimizations, which reveals the complexity introduced by architectural constraints and compiler behavior. Additionally, we explore different implementations leveraging a new matrix instruction set for Arm called SME and provide an early assessment of its potential benefits.

The near-threshold photo- and electroproduction of heavy vector quarkonia off the proton provides direct access to its gluonic structure. In particular, the cross section for $J/\Psi$ photoproduction near threshold is governed by the proton's gluon gravitational form factors (GFFs). In this work, we employ the generalized parton distribution framework together with gluon GFFs calculated in a light-front gluon-spectator model inspired by soft-wall AdS/QCD to predict both the differential and total cross sections for near-threshold $J/\Psi$ and $\Upsilon$ photoproductions. Our results for $J/\Psi$ photoproduction show good agreement with recent experimental data from the $J/\Psi$-007 and GlueX Collaborations at Jefferson Lab, as well as with earlier measurements from SLAC and Cornell.

Effective interaction models of quantum chromodynamics, based on quark degrees of freedom, have been successfully employed to compute the properties of a large array of ground and excited meson and baryon states, along with their electromagnetic form factors, distribution functions and thermal behavior. Amongst them, the contact-interaction model, while non-renormalizable, implements confinement, satisfies Lorentz covariance and correctly describes chiral symmetry and its dynamical breaking pattern. Original studies focused on the light hadron sector in the isospin limit and were thereafter extended to heavy mesons and baryons. The strong effective couplings, as well as infrared and ultraviolet regulators, are flavor-dependent model parameters adjusted to reproduce hadronic observables. In contrast, in this study we combine SU(4) flavor-symmetry breaking couplings, obtained from one-loop vacuum polarization amplitudes in the presence of background constituent quark currents, with the contact-interaction model. This allows us to reduce the number of mass-dimensioned parameters and to consistently relate all flavored couplings to a single mass scale, while the masses and weak decay constants of the pions, kaons, $D$ and $D_s$ mesons are in good agreement with average reference values. Allowing for realistic isospin breaking, $m_d/m_u = 1.7$, in conjunction with the effect of the flavored couplings, leads to a mass splitting, $m_{\pi^+}- m_{\pi^0} \approx 0.3$ MeV, that agrees with lattice QCD values. For the kaons, the mass difference is $m_{K^0}- m_{K^\pm} \approx 2.3$ MeV, whereas $m_{D^\pm} - m_{D^0} \approx 0.5$ MeV and the $\eta_c$ is 6\% lighter than the experimental mass.