Conveners
Parallel 1: Renormalization group procedure for effective particles
- Arkadiusz Trawiński
Parallel 1: Field theories in the front form - Gauge theories on the light front
- Wayne Polyzou (University of Iowa)
Parallel 1: Chiral symmetry and QCD at finite temperature
- Urko Reinosa (CPHT - Ecole Polytechnique - CNRS)
Parallel 1: Hadronic structure - Generalized parton distributions
- Hervé Moutarde
Parallel 1: Hadron structure - New parton distributions
- Matthias Burkardt (New Mexico State University)
Parallel 1: Field theories in the front form - Light-front quantization
- Chueng-Ryong Ji (North Carolina State University)
Small-x divergences of a canonical Hamiltonian of Abelian gauge theory in the front form of quantum dynamics, are regulated using a mass parameter for gauge bosons, introduced through a mechanism analogous to the spontaneous breaking of global gauge symmetry [1]. The regularization includes addition of the third polarization state for massive vector bosons. A corresponding family of...
We present preliminary results for form factors and structure functions
of some of spin-$0$, spin-$1/2$ and spin-$1$ heavy quarkonia and triply-heavy
baryons in heavy flavor QCD. Using renormalization group procedure for
effective particles (RGPEP) and gluon mass ansatz, approximate Hamiltonians
for heavy quarkonia and triply-heavy baryons in QCD were found [1,2].
The approximate...
A Wilsonian approach to $\pi\pi$ scattering based in the Glazek-Wilson Similarity Renormalization Group for Hamiltonian is analyzed in the $JI=$00, 11 and 20 channels in momentum space up to a maximal CM energy of $\sqrt{s}=1.4$ GeV. We identify the Hamiltonian by means of the 3D reduction of the Bethe-Salpeter equation in the Kadyschevsky scheme. We propose a new method to integrate the SRG...
The Ward-Takahashi identity in quantum electrodynamics ($QED_4$) first considered by J. C. Ward and Y. Takahashi, correlates the wave function renormalization for the electron to its vertex renormalization function, guaranteeing the cancellation of ultraviolet (UV) divergences to all orders of perturbation theory.
Since QED in the light-cone gauge is a constrained theory that brings a more...
Epstein-Glaser’s ideas for the formulation of a distributional well-defined perturbative causal field theory are developed in light-front dynamics over the invariant null-plane coordinatization introduced by Rohrlich. Explicitly, the causality theorems which warrant the method are shown to remain valid in that dynamics, and the causal distribution splitting formulae are re-derived in...
Recent development of the laser technologies for the production of extreme intensities has made high-power lasers a practical tool for studying subatomic world at the intensity frontier [1], complementary to the energy frontier. From the theoretical point of view, an intense laser field can be normally represented as a classical background plane-wave field. Because of the high intensity, the...
Mass renormalization for gauge theories in light-front perturbation theory (LFPT) has been a longstanding puzzle, leading to apparently inconsistant results in the literature. In this talk, I will show how to implement a fully Poincaré invariant UV regularization for LFPT calculations, like for example dimensional regularization. Within this approach, one obtains consistent and unambiguous...
Lattice simulations of Yang-Mills theories and QCD in the Landau gauge demonstrate that the gluon propagator saturates at vanishing momentum. This can be modelled by a massive deformation of the corresponding Faddeev-Popov Lagrangian known as the Curci-Ferrari model. The latter does not modify the known ultraviolet regime of the theory and provides a successful perturbative description of...
We analize the role played by the thermal $f_0(500)$ state or $\sigma$ in chiral symmetry restoration. The temperature corrections to the spectral properties of that state are included in order to provide a better description of the scalar susceptibility $\chi_S$ around the transition region. We use the Linear Sigma Model to establish the relation between $\chi_S$ and the $\sigma$ propagator,...
In this talk I will consider the boson stars in a theory of complex scalar filed in the presence of gravity and the the U(1) gauge field and the gluon field. I will discuss the results for the phase diagrams of the boson star solutions in this theory.
Deeply Virtual Compton Scattering (DVCS) is the simplest exclusive process to access Generalized Parton Distributions (GPDs). GPDs encode the correlation between the spacial distribution of partons inside the nucleon and their momentum. An upcoming DVCS experiment in Hall C at Jefferson Lab (Virginia, U.S.A.) will provide the highest precision data in a vast Q$^2$- x$_B$ region accessible by a...
In the framework of collinear QCD factorization, we study the
photoproduction of a gamma meson pair with a large invariant mass and a small transverse momentum, as a new way to access generalized parton distributions (GPDs), in both chiral-even and chiral-odd sectors. In the kinematics of JLab~12-GeV, we demonstrate the feasibility of this measurement.
Generalized Parton Distributions (GPDs) describe correlations between the longitudinal momentum and the transverse position of the partons inside the nucleon . GPDs have been studied in many experiments worldwide mainly using Deeply Virtual Compton Scattering (DVCS, ep → e’p’γ).
This talk will highlight the measurement of the time-reversal conjugate process of DVCS, Timelike Compton...
Studying light-cone PDFs through Euclidean correlators is currently an active field of research. In particular, the concept of quasi parton distributions (quasi-PDFs) is at the forefront of numerical calculation of partonic structure of strongly interacting systems on lattice using QCD. Quasi-PDFs converge to their respective standard distributions if the hadron momentum goes to infinity. We...
The light-cone definition of Parton Distribution Functions (PDFs) does not allow for a direct ab initio determination employing methods of Lattice QCD simulations that naturally take place in Euclidean spacetime. In this presentation we focus on pseudo-PDFs where the starting point is the equal time hadronic matrix element with the quark and anti-quark fields separated by a finite distance. We...
Here we discuss the main outcomes of our investigations on the so called double parton distribution functions (dPDFs). These quantities can be obtained via double parton scattering processes (DPS) in high energy proton-proton and proton nucleus collisions. These new and experimentally unknown distributions represent a novel and promising complementary tool, w.r.t. TMDs and GPDs, to access the...
Basis light-front quantization is a nonperturbative approach which has been developed for solving many-body bound state problems in quantum field theories. We have applied this approach to investigate the structure of the pion using a light front effective Hamiltonian in the constituent quark-antiquark representation. The remarkable results for the electromagnetic (EM) form factor,...
We solve for the mass spectrum and structure of the positronium, the bound state formed by an electron and a positron, from the first-principles of QED. We adopt a nonperturbative approach based on light-front Hamiltonian formalism, named Basis Light-front Quantization. In this calculation we include the lowest two Fock sectors, $|e^+e^-\rangle$ and $|e^+e^-\gamma\rangle$, in the basis. We...
We give a survey of a few subtle mathematical points whose correct treatment is necessary for obtaining noncontradictory structure of the front form of the field theory and its physical predictions. First, we show that small imaginary parts in the exponents of the light-front (LF) two-point functions (convergence factors) are mandatory for their correct equal-LF time limit and for vanishing...
In this talk I would consider in details the role of the light-front coordinates in string theory.
