Ismail Zahed

Experimental access to the gluonic origin of the proton mass

Zein-Eddine Meziani, Ismail Zahed

Most of the proton mass originates not from the Higgs mechanism but from the quantum structure of the QCD vacuum. The dominant contribution arises from the gluonic trace anomaly as…

Anomalies, Topology, and Hadron Structure in QCD

Ismail Zahed

Quantum Chromodynamics (QCD) provides a remarkable realization of how quantum effects reshape the symmetries of a classical field theory. The axial anomaly links chirality to gauge…

Faddeev description of baryons in two-dimensional QCD with $N_{c} = 3$ . I. Chiral spectrum, isospin, and strangeness

Ismail Zahed, Haocheng Zhang

We develop a light-front Faddeev description of baryons in two-dimensional QCD at $N_{c} = 3$ , in which an exact coupled-channel representation identifies the quark--diquark picture as…

Chiral Structure and Selection Rules in Light-Front Nucleon-Pentaquark Mixing

Fangcheng He, Edward Shuryak, Wan Wu +1

We present a light-front Hamiltonian analysis of nucleon-pentaquark mixing induced by $σ$ - and $π$ -type transition operators in a fully Pauli-consistent five-quark basis. The penta…

Hybrid hadrons at rest and on the light front

Edward Shuryak, Ismail Zahed

We present a unified description of heavy hybrid hadrons based on a constituent-gluon picture embedded in the Born-Oppenheimer (BO) framework. In this approach, the gluonic excitat…

The Hadron-Parton Bridge, From the QCD Vacuum to Partons

Edward Shuryak, Ismail Zahed

Quantum Chromodynamics (QCD) exhibits complementary descriptions of hadrons: a rest-frame picture based on confinement, chiral symmetry breaking and interquark forces, and a high-e…

Pentaquarks on the light front, and their mixture with baryons

Nicholas Miesch, Edward Shuryak, Ismail Zahed

In previous papers we developed the light front formulation for Hamiltonians and wave functions (WFs) for mesons and baryons, with both confinement and chiral symmetry breaking. Fo…

The color force acting on a quark in the pion and nucleon

Wei-Yang Liu, Edward Shuryak, Ismail Zahed

In the Operator Product Expansion (OPE) of hard scattering amplitudes, the twist-3 operators describe local colored Lorentz forces acting on a quark, thereby providing a measure of…

Light S-wave pentaquarks on the light front

Fangcheng He, Edward Shuryak, Wan Wu +1

We construct an explicit basis set for pentaquark states on a regular 4-simplex, that diagonalizes the Hamiltonian for light pentaquarks with confinement on the light front (LF). T…

Pentaquarks made of light quarks and their admixture to baryons

Nicholas Miesch, Edward Shuryak, Ismail Zahed

This paper is a continuation of our studies of multiquark hadrons. The anti-symmetrization of their wavefunctions required by Fermi statistics is nontivial, as it mixes orbital, co…

D-shell mixing in light baryons and its effect on the orbital motion

Nicholas Miesch, Edward Shuryak, Ismail Zahed

The standard description of the nucleon in the non-relativistic quark model is an $1 S, L = 0$ state without orbital motion. Yet, there are several indications from phenomenology that…

hep-ph2025★ 4 cited

Tomography of the Rho meson in the QCD Instanton Vacuum: Transverse Momentum Dependent Parton Distribution Functions

Wei-Yang Liu, Ismail Zahed

We analyse the rho meson unpolarized and polarized transverse momentum dependent parton distribution functions (TMDPDFs) in the instanton liquid model (ILM). The corresponding TMDs…

Tomography of Pions and Kaons in the QCD Vacuum: Transverse Momentum Dependent Parton Distribution Functions

Wei-Yang Liu, Ismail Zahed

We evaluate the pion and kaon transverse momentum dependent parton distribution functions (TMDPDFs) in the instanton liquid model (ILM), a model of the QCD vacuum at low resolution…

hep-ph2025★ 4 cited

Collins-Soper Kernel in the QCD Instanton Vacuum

Wei-Yang Liu, Ismail Zahed, Yong Zhao

We outline a general framework for evaluating the non-perturbative soft functions in the QCD instanton vacuum. In particular, from the soft function we derive the Collins-Soper (CS…

Nucleon electric dipole form factor in QCD vacuum

Wei-Yang Liu, Ismail Zahed

In the QCD vacuum, the nucleon form factors receive contributions from the underlying ensemble of topological pseudoparticles, which are sensitive to a finite vacuum angle $θ$ . We…

Polarized $ϕ$ meson rates with viscous corrections at RHIC

Eduardo Grossi, Andrea Palermo, Ismail Zahed

We discuss the emission of $ϕ$ mesons with longitudinal and transverse polarization in ultra-relativistic heavy ion collisions. In the hadronic phase and in leading order in the ka…

Threshold photo-production of $J /Ψ$ off light nuclei

Fangcheng He, Ismail Zahed

We analyze threshold photoproduction of heavy mesons off a deuteron and Helium-4, using the QCD factorization method. Assuming large skewness, the production amplitude is dominated…

Helium-4 gravitational form factors: exchange currents

Fangcheng He, Ismail Zahed

We evaluate the leading exchange corrections to the Helium-4 gravitational form factors (GFFs) upto momenta of the order of the nucleon mass. We use both the K-harmonic method with…

hep-ph2024★ 13 cited

Pion gravitational form factors in the QCD instanton vacuum II

Wei-Yang Liu, Edward Shuryak, Ismail Zahed

We revisit the hard QCD contributions to the pion gravitational form factors (GFFs), in terms of the twist-2,3 pion distribution amplitudes (DA), including novel semi-hard contribu…

hep-ph2024★ 14 cited

Pion gravitational form factors in the QCD instanton vacuum I

Wei-Yang Liu, Edward Shuryak, Christian Weiss +1

The pion form factors of the QCD energy-momentum tensor (EMT) are studied in the instanton liquid model (ILM) of the QCD vacuum. In this approach the breaking of conformal symmetry…