Parton distribution functions (DFs) are a preeminent source of hadron structure information; and experiments interpretable in terms of hadron DFs have long been a priority. For much of this time, DFs were inferred from global fits to data and viewed as benchmarks. Such fitting remains crucial, providing input for the conduct of numerous experiments worldwide. But the past decade has seen the...
The Dyson-Schwinger equation is solved in Minkowski space for the quark propagator in a QCD-inspired model. In the rainbow-ladder truncation with a massive gluon and a Pauli-Villars regulator used to tune the infrared physics of the model, we show that it is possible to verify the realization of the dynamical chiral symmetry breaking in the large coupling regime. In this sense, the parameter...
Local quantum field theory (QFT) provides a framework for establishing the non-perturbative constraints imposed on QFTs at non-vanishing temperatures. In this talk, I will outline how the locality of fields in particular has significant implications for understanding the phenomena experienced by particles as they move through a thermal medium. As an application, I will discuss how pion...
I present a brief review of what I think is known and unknown about nucleon structure. One of the known unknowns is how the nuclear medium modifies the structure of the nucleon. The bulk of the talk is on a new model of the EMC effect based on Light-Front Holographic QCD (LFHQCD).
In this talk I will discuss the pion structure within a dynamical model based on the solution of the Bethe-Salpeter equation in Minkowski space. Our analysis consider the pion as quark anti-quark bound state, interacting through a one-gluon exchange. The inputs of the model are the quark and gluon masses, and a scale parameter related to the extended quark-gluon vertex. Within this model, we...
We solve for the light-front wave functions of the nucleon from the light-front quantum chromodynamics (QCD) Hamiltonian, determined for their constituent three quarks and three quarks-gluon Fock components, together with a three-dimensional confinement. The eigenvectors of the light-front effective Hamiltonian provide a good quality description of the nucleon’s valence quark distribution...
Understanding the structure and dynamics of the proton constitute an important remaining challenges in hadron physics. From the theory side, one of the challenges is to extract from Lattice QCD calculations, performed in Euclidean space, Minkowskian quantities such as the proton parton distribution function. It is difficult to do the inversion of Euclidean quantities back to the corresponding...
In the Hamiltonian formulation of QCD one faces many challenges. One of them is the fact that the Hilbert space is rich in structure with subspaces of varying number of particles and interactions that can easily change the number of particles. Another challenge lies in its singular interactions that need renormalization. I will talk about basis light front quantization (BLFQ) as a framework...
We present the description of hadronic three-body systems in valence approximation within a rigorous Light-Front approach [1,2]. The latter has been applied in particular to the analysis
of electron deep inelastic scattering (DIS) on nuclear targets, in the valence region and in the Bjorken limit [3,4].
The approach preserves Poincaré covariance, macroscopic locality, as well as number of...
Hadrons are strongly interacting particles composed of quarks and gluons and described by Quantum Chromodynamics (QCD). Their internal structure can be described in terms of structure functions that encode, for example, the momentum and spin distributions of their constituents. Parton distribution functions (PDFs), for example, describe the quark and gluon momentum distributions inside a...
Studies of the properties and the azimuthal distribution of hadrons produced in the Target Fragmentation Region serve as a test of our complete understanding of the different mechanisms in the Semi-Inclusive Deep Inelastic Scattering production of hadrons and provide additional information on the QCD dynamics that are not accessible with single hadron production in the Current Fragmentation...
I would present the light-front quantization of the fermionic vector Schwinger Model using the formalism of so-called "good fermions and bad fermions" due to Mannheim and Mannheim, Lowdon and Brodsky.
In this talk, I would present the light-front quantization of the Maxwell Chern-Simons Higgs Theory under Broken Symmetry Phase using the Hamiltonian and Path Integral formulations.
We will discuss the QCD running coupling $\alpha_s$, starting from its pQCD definition and then show how it can be extended to the non-perturbative domain using the concept of effective charges. This permits us to measure $\alpha_s$ in the non-perturbative domain, and compute it in the Holographic LF QCD (HLFQCD) approach. We will briefly describe the calculation, compare its result to...
A remarkable property of holographic light-front QCD (HLFQCD) is the emerging superconformal structure which is responsible for the introduction of a mass scale without leaving the conformal group. This symmetry also fixes the effective confinement potential and leads to a massless pion in the chiral limit, without additional assumptions. In this talk, I will briefly review some of these new...
We apply Holographic QCD for study gluon and heavy quark content in the nucleon. In particular, we discuss the following results:
(1) sum rules, small and large x-behavior for the gluon TMDs [1];
(2) light-front representations and numerical results for the heavy quark-antiquark asymmetry, the electromagnetic form factors of nucleons induced by heavy quarks, including their magnetic...
On the light cone the full symmetry is conformal symmetry not just Lorentz symmetry. Spontaneously breaking conformal symmetry gives masses to particles and takes them off the light cone. Canonical quantization specifies equal time commutators on the light cone. Instant time and light-front commutators are very different, but can be shown to be equivalent by looking at unequal time...
In the present study, the phenomenology of deeply virtual Compton scattering (DVCS) is considered. It is a well-known fact that a charged spin zero hadron has five Compton form factors (CFFs), all of which contribute to the DVCS ampli- tude if the absorbed and emitted photons are virtual. If the emitted photon is real, the number of CFFs that contribute is reduced to three. This analysis is...
In this talk we will discuss the connection between available experimental data and the pressure anisotropy within the nucleon, pushing the formalism at next-to-leading order (NLO). We will discuss the feasibility of extracting quark and gluon contributions, and see how future experimental facilities can contribute.
We explore the link between the chiral symmetry of QCD and the numerical results of the light-front quark model, analyzing both the two-point and three-point functions of the pion. Including the axial-vector coupling as well as the pseudoscalar coupling in the light-front quark model, we discuss the implication of the chiral anomaly in describing the pion decay constant, the pion-photon...
How to decompose the mass of a hadronic system in a meaningful way is a question that has been much debated in the last few years. We propose a nutshell summary of the various pictures, discussing their meaning, how they are related to each other, and how they can be measured.
Recent progress has enabled the approximate computation of light-cone correlation functions in lattice QCD by evaluating Euclidean correlation functions. We will briefly discuss those developments as well as their application to GPDs. We will also talk about our latest work where we developed a formalism that makes the lattice calculations of GPDs more efficient.
Lightcone Conformal Truncation (LCT) is a Hamiltonian Truncation scheme which allows us to solve QFTs numerically. In particular, we can use it to determine eigenstate wavefunctions in the non-perturbative regime in both 2d and 3d QFTs. We use these to calculate time-dependent correlation functions in various models. These include 2d gauge theories near the chiral limit, as well as 2d and...
