Light Cone 2021: Physics of Hadrons on the Light Front

Session

Plenary Session

29 Nov 2021, 08:30

Emerald Hall A&B (Jeju Booyoung Hotel)

Conveners

Plenary Session: Session 1

• Ho-Meoyng Choi (Kyungpook National University)

Plenary Session: Session 2

• Jianwei Qiu (Jefferson Lab)

Plenary Session: Session 3

• Hyun-Chul Kim (Inha University)

Plenary Session: Session 4

• Stefan Diehl (JLU Giessen and UCONN)

Plenary Session: Session 5

• Hyon-Suk Jo (Kyungpook National University)

Plenary Session: Session 6

• Wally Melnitchouk (Jefferson Lab)

Plenary Session: Session 7

• Kai-Thomas Brinkmann (JLU Gießen)

Plenary Session: Session 8

• Harut Avakian (Jefferson Lab)

Plenary Session: Session 9

• Su Houng Lee (Yonsei University)

Plenary Session: Session 10

• Giovanni Salme' (Istituto Nazionale di Fisica Nucleare)

Plenary Session: Session 11

• Kyungseon Joo (University of Connecticut)

Plenary Session: Session 12

• Craig Roberts (Nanjing University)

Plenary Session: Session 13

• Zein-Eddine Meziani (Argonne National Laboratory)

Plenary Session: Session 14

• Tobias Frederico (Instituto Tecnologico de Aeronautica)

136. Welcome Address

Yunkyu Bang (APCTP)

29/11/2021, 08:30

112. From Instant to Light-Front: Opening LC2021

Chueng Ji (North Carolina State University)

29/11/2021, 08:40

Invited talk

Since Dirac proposed the light-front form of the relativistic dynamics in 1949, the ILCAC put together a white paper entitled "Light-front Quantum Chromodynamics" (LFQCD) as a framework for the analysis of hadron physics in 2013. Its goal was to find solutions that describe hadrons in the theory of strong interactions, QCD. Many progresses have been made toward the specific goals of this...

123. A New Class of Exclusive Processes to Better Measure the $x$-Dependence of DAs and GPDs

Jianwei Qiu (Jefferson Lab)

29/11/2021, 09:10

Invited talk

We propose a new class of exclusive processes for extracting generalized parton distribution functions (GPDs), which provide a powerful theoretical tool to quantify the spatial distribution of quarks and gluons inside a bound hadron. Using exclusive massive-photon-pair production in meson-meson and meson-baryon collisions as an example, we show that the leading non-perturbative contribution to...

135. Novel Properties of Hadron Physics Derived from Holographic Light-Front QCD

Stanley Brodsky (SLAC National Accelerator Laboratory)

29/11/2021, 09:40

Invited talk

I will discuss some new developments in hadron physics which can be derived from light-front holography and superconformal quantum mechanics. This includes new insights into the physics of color confinement, chiral symmetry, the spectroscopy and dynamics of hadrons, as well as surprising supersymmetric relations between the masses and light-front wavefunctions of mesons, baryons, and...

119. Light-Front Quantization as an Effective Field Theory

Xiangdong Ji (University of Maryland)

29/11/2021, 10:30

Invited talk

Light-front quantization focuses on a particular type of modes in full QCD, the soft and collinear modes in a pre-selected direction, which are useful to describe the quark and gluon structure of the hadrons traveling at the speed of light in the direction. The standard approach to obtain the Hamiltonian and Feynman rule is to take the infinite momentum limit before imposing a UV cut-off, a...

87. Basis Light Front Quantization - Progress and Prospects

James Vary (Iowa State University)

29/11/2021, 11:00

Invited talk

Basis Light Front Quantization (BLFQ) has been successfully applied to obtain bound states in both QED and QCD. For QCD applications in limited Fock spaces, one assumes a form of confinement based on light-front holography along with an additional longitudinal confinement. Recent applications include expanding Fock spaces beyond valence fermions to include the dynamical gauge degrees of...

34. QCD Analysis of Pion Parton Distributions

Wally Melnitchouk (Jefferson Lab)

29/11/2021, 11:30

Invited talk

We present recent results from the JAM (Jefferson Lab Angular Momentum) Collaboration's global QCD analysis of pion parton distributions. In particular, we assess the impact of threshold resummation on the behavior of the pion's valence distributions at large parton momentum fractions x.

118. Recent Progress of Hypernuclear Physics

Emiko Hiyama (Tohoku University/RIKEN)

29/11/2021, 13:30

Invited talk

In hypernuclear physics, during two decade, we have been obtaining many epoch-making data which are related to information on hyperon-nucleon and hyperon-hyperon interactions. In this talk, I will introduce the recent progress and future prospect at J-PARC in hypernuclear physics from theory side.

127. Nucleon Parton Distributions from Lattice QCD

Jiunn-Wei Chen (National Taiwan University)

29/11/2021, 14:00

Invited talk

I will update the progress on the determination of nucleon parton distributions on the lattice using the large momentum effective field theory approach.

29. Elementary Example of Exact Effective-Hamiltonian Computation

Stanislaw Glazek (University of Warsaw)

29/11/2021, 14:30

Invited talk

An exact computation of effective Hamiltonians in an elementary model akin to quantum field theory is carried out by solving equations of the renormalization group procedure for effective particles (RGPEP) [1]. The computation exhibits the mechanism by which the weak-coupling expansion and Tamm-Dancoff approximation increase in accuracy along the RGPEP evolution. The model computational...

80. Resonance in Coupled Channel Reactions

Toru Sato (RCNP, Osaka University)

29/11/2021, 15:00

Invited talk

The spectrum and structure of nucleon resonances are investigated analyzing pion, photon and electron induced meson production reactions. The understanding of the GeV lepton induced reaction and of the role of resonances plays important for the long base line neutrino oscillation experiments [1]. In this talk, resonance poles in coupled channel system is discussed [2] using the uniformized...

36. Frame Dependence of Relativistic Charge Distributions

Cédric Lorcé (Ecole polytechnique)

29/11/2021, 15:50

Invited talk

We review and revisit the concept of charge distribution in the relativistic context. Adopting a phase-space perspective allows us to discuss the momentum dependence of these distributions and to connect the well-known pictures in both the Breit frame and the infinite-momentum frame. In particular, we explain why the center of the neutron charge distribution appears to be negative in the...

68. Compton Scattering on ${}^4$He: Kinematical Features

B. L. G. Bakker (Vrije University)

29/11/2021, 16:20

Invited talk

In the literature concerning the Generalized Parton (GPDs) distributions of ${}^4$He, the common opinion is that a single GPD is dominant at high values of the virtuality $Q$. Because the Compton form factors (CFFs) are related to the GPDs by sum rules, this implies that a single CFF must be dominant at high $Q$ and that the data can be safely analyzed in terms of this CFF. In the present study,...

131. FAIR Physics with PANDA

Kai-Thomas Brinkmann (JLU Gießen)

29/11/2021, 16:50

Invited talk

The Facility for Antiproton and Ion Research, FAIR, is under construction near Darmstadt, Germany. Among other large-scale installations, the PANDA (Antiproton annihilations in Darmstadt) experiment is designed to answer pressing questions in the charmonium mass region. At PANDA, an antiproton beam with momenta up to 15 GeV/c circulating in the high-energy storage ring HESR will interact with...

78. Results from the COMPASS Experiment at CERN

Fabienne Kunne (Université Paris-Saclay)

29/11/2021, 17:20

Invited talk

I will present a selection of results from the COMPASS experiment at CERN. They cover measurements related to the nucleon spin and structure, obtained from deep inelastic scattering (DIS) of muons on longitudinally and transversely polarized nucleons, as well as unpolarized hydrogen. The 3D structure of the nucleon is also studied via exclusive reactions: deep virtual Compton scattering...

41. A perturbative expansion for bound states

Paul Hoyer (Helsinki University)

29/11/2021, 17:50

Contributed talk

Bound states are perturbatively expanded in the coupling $\alpha$ around lowest order bound states, not around free states as for scattering amplitudes. The expansion is not unique, as bound state wave functions are non-polynomial in $\alpha$ even in a first approximation. I describe a first-principles, equal-time method based on a Fock expansion where the constituents are bound by the...

73. Baryonic form factor of the pion

Wojciech Broniowski (IFJ PAN & UJK)

29/11/2021, 18:10

Contributed talk

Charged pions obviously carry no baryon number. Nevertheless, they possess a nontrivial baryonic structure stemming from isospin breaking by the $u$ and $d$ quark mass difference and from the EM effects. We obtain estimates for the pion baryonic form factor in two very different ways ways: from simple constituent quark models, and from vector meson dominance fits to the experimental $e^+ e^-...

117. The SoLID Science Program in Hall A at Jefferson Lab

Zein-Eddine Meziani (Argonne National Laboratory)

30/11/2021, 08:30

Invited talk

The science program enabled by the Solenoidal Large Detector Device (SoLID) in Hall A at Jefferson Lab encompasses studies of nucleon structure addressing some of the fundamental questions in hadron structure. It will explore the nucleon origins of mass and spin in the framework of Quantum Chromodynamics at the luminosity frontier. It will also seek signatures of physics beyond the standard...

82. 3D Structure of the Nucleon: from JLab12 to JLab24

Harut Avakian (Jefferson Lab)

30/11/2021, 09:00

Invited talk

The quark-gluon dynamics manifests itself in a set of non-perturbative functions describing all possible spin-spin and spin-orbit correlations. Single and Dihadron semi-inclusive and hard exclusive production, both in current and target fragmentation regions, provide a variety of spin and azimuthal angle dependent observables, sensitive to the dynamics of quark-gluon interactions. Studies...

31. Nucleon Structure Modification from Tagged DIS Measurements at JLab and the EIC

Or Hen (Massachusetts Institute of Technology)

30/11/2021, 09:30

Invited talk

Understanding the origin of the EMC effect - the modification of the internal structure of nucleons bound in nuclei - is an ongoing effort in QCD research with far-reaching implications for our understanding of the fundamental structure of matter. Inclusive measurements have characterized many features of the EMC effect, but are insensitive to the initial state of the nucleus and therefore...

134. Higher-Spin Baryon Photoproduction with Twisted Photons

Carl Carlson (College of William and Mary/JGU-Mainz)

30/11/2021, 10:00

Invited talk

We may anticipate that future accelerator facilities will include the possibility of energetic twisted photons, which are photons with a structured wave front that can allow a pre-defined large angular momentum along the beam direction. Twisted photons are potentially a new tool in hadronic physics, and we consider here the possibility of selective photoproduction of higher-spin baryons using...

63. Abel Tomography: Charge and Energy-Momentum Tensor Densities of the Nucleon

Hyun-Chul Kim (Inha University)

30/11/2021, 10:50

Invited talk

Usual three-dimensional (3D) densities of the nucleon are only meaningful quasi-probabilistically through the Wigner distributions. Taking the infinite-momentum frame, where the nucleon is on the light cone, we can define two-dimensional (2D) distributions of the nucleon, which contain the quantum-mechanically probabilistic meaning. The Abel transformations, on the other hand, allow one to...

37. Novel Hadron Physics by Structure Functions of Spin-1 Hadrons

Shunzo Kumano (KEK/J-PARC)

30/11/2021, 11:20

Invited talk

There are new polarized structure functions, which do not exist for the spin-1/2 nucleons, in a spin-1 hadron such as the deuteron. In the charged-lepton deep inelastic scattering, the new leading-twist structure functions are $b_1$ and $b_2$, which are related by the Callan-Gross type relation $b_2=2x{b}_1$ in the Bjorken scaling limit. There exists a parton-model sum rule for $b_1$ [1]. We...

94. Positronium Structure from Light-Front QED Hamiltonian

Xingbo Zhao (Institute of Modern Physics, Chinese Academy of Sciences)

30/11/2021, 11:50

Invited talk

The positronium is arguably the simplest bound state in QED. It is often used as a model for studying the structure of hadrons. In this talk, I will report our recent progress in solving the structure of the positronium from the light-front QED Hamiltonian in a basis approach. We include one dynamic photon in the basis. We perform the nonperturbative mass renormalization on the level of the...

140. Current Highlights and Future Prospects from CMS

Sezen Sekmen (Kyungpook National University)

30/11/2021, 16:20

Invited talk

Since 2010, the Compact Muon Solenoid (CMS) Experiment at the CERN Large Hadron Collider (LHC) has collected an unprecedented amount of proton-proton collision data in the center of mass energies of 7, 8 and 13 TeV. These data are used to conduct hundreds of analyses that test the validity of the standard model and look for hints of beyond the standard model physics. The biggest highlight so...

126. Highlights from ATLAS and Future Plans

Massimo Corradi (Sapienza Universita e INFN, Roma I)

30/11/2021, 16:50

Invited talk

An overview of the ATLAS physics program is presented, with emphasis on the most recent results obtained fully exploiting the abundant and now well-understood dataset recorded during Run 2 of CERN’s Large Hadron Collider (2015-2018). The talk will also describe the ongoing improvements of the ATLAS detector targeting Run 3 and the subsequent LHC high luminosity phase.

52. Photon-to-Nucleon Transition Distribution Amplitudes and Backward Time-like Compton Scattering

Kirill Semenov-Tian-Shansky (PNPI)

30/11/2021, 17:20

Invited talk

Nucleon-to-meson and nucleon-to-photon transition distribution amplitudes (TDAs) arise in the collinear factorized description of a class of hard exclusive reactions characterized by the exchange of a non-zero baryon number in the cross channel. In this talk, we review the properties of nucleon-to-photon (and photon-to-nucleon) TDAs, which encode the photon content of the nucleon and allow a...

60. Experimental TDA Program at FAIR, JLab and J-PARC

Stefan Diehl (JLU Giessen and University of Connecticut)

30/11/2021, 17:50

Contributed talk

Hard exclusive processes are a well established tool to study the 3D nucleon structure. The QCD factorisation mechanism in the "nearly forward region" ($t/Q^2$ small) can be divided into a hard part, described by perturbative QCD (pQCD) and in two general structure functions, the Generalized Parton Distributions (GPDs) for the nucleon and the pion Distribution Amplitudes (DAs), describing the...

138. Zero Modes and the Vacuum

Matthias Burkardt (New Mexico State University)

01/12/2021, 08:30

Invited talk

I will discuss how a trivial light cone vacuum can be compatible with a nontrivial vacuum in an equal time framework. In particular I will discuss the role of zero modes and their role in the light-front formulation.

1. Simple Light Front Quark Models

Wayne Polyzou (University of Iowa)

01/12/2021, 09:00

Invited talk

I discuss a relativistic light-front model of hadrons based on strong-coupling QCD degrees of freedom that is designed to be simple enough to explore the role of sea quarks in hadronic structure and reaction calculations. The degrees of freedom are confined local and global color singlet systems quarks of antiquarks connected by ``strings'' represented by confining interactions. These bare...

22. A Nonperturbative Perspective on the Light-Front Vacuum

John Hiller (University of Idaho)

01/12/2021, 09:30

Invited talk

As has been seen in recent calculations for ${\varphi }^4$ theory, tadpole contributions are important for symmetry-breaking effects and yet are missing from standard light-front calculations, because they require transitions to and from the vacuum. Inclusion of such vacuum transitions also implies contributions from vacuum bubbles. A perturbative calculation can make the distinction and subtract...

30. Light-Front Quantization from Then Until Now

Philip Mannheim (University of Connecticut)

01/12/2021, 10:00

Invited talk

We trace the development of light-front quantization from its infinite momentum frame origin to its current formulation. We emphasize its difference from the infinite momentum frame approach especially in regard to vacuum loop diagrams. We identify the importance of off mass shell light-front contributions, especially in regard to circle at infinity contributions to vacuum Feynman diagram...

24. Generalized Polarizabilities of the Proton: Overview and New Results

Nikos Sparveris (Temple University)

01/12/2021, 10:50

Invited talk

The Generalized Polarizabilities (GPs) are fundamental properties of the nucleon. They characterize the nucleon's response to an applied electromagnetic field, giving access to the polarization densities inside the nucleon. As such the GPs represent a central path towards a complete understanding of the nucleon dynamics. Previous measurements of the proton electric GP at intermediate...

114. Recent Results on Baryon Structures and Dark Sector Searches at Belle and Belle II

Youngjoon Kwon (Yonsei University)

01/12/2021, 11:20

Invited talk

The Belle experiment using KEKB collider at KEK, Japan, has made immense contribution to heavy flavor physics with observations of CP violation in B systems and rare B-meson decay measurements. The Belle II experiemnt using SuperKEKB is an upgrade of Belle and aims at collecting 50 times more data. In this talk, we present a selection of recent physics results from Belle. In particular, we...

125. Spectroscopic Study of Quark Dynamics in Baryons at J-PARC

Hiroyuki Noumi (Osaka University)

01/12/2021, 11:50

Invited talk

Hadrons are complex systems of quarks (and gluons) first formed and followed by matter evolution in the universe. The strong interaction plays an important role in formation of matter. The quantum chromodynamics (QCD), which is the fundamental theory of the strong interaction, shows highly non-perturbative behaviors in low energy and thus is difficult to solve. A fundamental question, how...

121. Going to the Light Front with Contour Deformations

Gernot Eichmann (LIP & IST Lisboa)

01/12/2021, 16:20

Invited talk

In this talk I present a new method to compute the light-front wave functions for a system of two interacting scalar particles using contour deformations. After solving the two-body Bethe-Salpeter equation, the projection onto the light front is done through a combination of contour deformations and analytic continuation methods. The resulting light-front wave functions and distribution...

113. Canonical Approach for Extreme QCD

Seung-il Nam (Pukyong National University)

01/12/2021, 16:50

Invited talk

In this talk, we present our recent work for a canonical approach for extreme QCD. We discuss the canonical approach for the study of QCD phase at finite densities and temperatures in the confinement phase. The canonical approach, which is a method to extrapolate observables calculated at pure imaginary chemical potentials to those at real chemical potentials, is useful to overcome the sign...

128. Deeply Virtual Compton Scattering on the Neutron with CLAS12 at Jefferson Lab

Silvia Niccolai (CNRS)

01/12/2021, 17:20

Invited talk

A key step to improve our understanding of nucleon structure in terms of Generalized Parton Distributions (GPDs) is the measurement of Deeply Virtual Compton Scattering on the neutron (nDVCS; $ed\to e^{\prime }n\gamma (p)$). This process provides mainly, in the kinematic range covered at Jefferson Lab, an access to the GPD $E$ of the neutron, which is the least known and constrained GPD as of today. The...

93. The BGOOD Experiment at ELSA and Multi-Quark Structures in the uds-Sector

Hartmut Schmieden (University of Bonn)

01/12/2021, 17:50

Invited talk

A leap in our understanding of hadronic structure formation was witnessed during the last decade. The discovery of the $X,Y,Z$ states in the (hidden) charm meson sector first by Belle, and the $P_C$ baryon states by LHCb revealed the existence of multi-quark objects beyond the simple quark-antiquark or 3-quark valence configurations. While the detailed structure of such states is still under...

116. Origins of the Proton Mass

Ian Cloet (Argonne National Laboratory)

03/12/2021, 08:30

Invited talk

The proton, and its isospin partner the neutron, are the building blocks of the visible universe and are responsible for almost the entirety of its mass. While the total mass of the proton is precisely known, the decomposition of this mass into its quark and gluon components touches upon some of the deepest mysteries in QCD. This talk will review this topic, discuss some of the recent theory...

120. Confinement in Two-Dimensional QCD and the Infinitely Long Pion

Gerald Miller (University of Washington, Seattle)

03/12/2021, 09:00

Invited talk

Three current models of QCD in (1+1) dimensions are examined and extended in light-front coordinates. A pion of high momentum is found to have an infinite extent along its direction of motion.

115. Pseudodistributions: PDFs Off the Light Cone

Anatoly Radyushkin (ODU/JLab)

03/12/2021, 09:30

Invited talk

I formulate the basic concepts underlying the development of parton pseudodistributions functions and review its recent applications to the lattice QCD extractions of parton distributions.

124. Foundations of the Parton Model Description of TMDs

Fatma Aslan (University of Connecticut)

03/12/2021, 10:00

Invited talk

Feyman's parton model played an important role for the understanding of the Bjorken scaling in the first DIS experiments and paved the way towards QCD. Various versions of parton model frameworks have been used in literature to study nucleon structure, target mass corrections and other partonic properties. The properties of the quark correlator are determined by the equations of motion of the...

79. Advances in Exploration of the Nucleon Resonance Spectrum and Structure

Victor Mokeev (Thomas Jefferson National Accelerator Facility)

03/12/2021, 10:50

Invited talk

Studies of the nucleon resonance spectrum and structure offer the unique information on strong interaction dynamics which underlies the generation of excited nucleon states with different structural features. The advances in exploration of the $N^{\ast }$ spectrum which result in discovery of several long time awaited new baryon states (previous "missing resonances") will be presented. The prospects...

98. Parton Structures in Backward Photo/Electroproduction of Meson

Byung-Geel Yu (Korea Aerospace University)

03/12/2021, 11:20

Invited talk

We construct a Reggeized model for the $u$-channel baryon exchange to investigate parton contribution to various types of hadron reactions at backward angles. Backward photoproductions of lighter vector mesons ${\rho }^0(770)$, $\omega (785)$, and $\varphi (1020)$ off the proton target are investigated with a common set of parameters for the parton distribution function. Analysis of pion...

59. Jet Physics Program at RHIC

Nihar Sahoo (Shandong University)

03/12/2021, 11:50

Invited talk

Jets are produced in heavy-ion and nucleon-nucleon collisions from hard-scattered patrons of the incoming beams. We can infer the property of hot-dense QCD matter, known as Quark-Gluon Plasma (QGP), by studying the modified jet properties in heavy-ion collisions to their vacuum reference. Relativistic Heavy-Ion Collider (RHIC), at BNL, New York, USA, can collide heavy-ions (like Au+Au and...

139. Future Opportunities with CEBAF Upgrades

Robert McKeown (Jefferson Lab)

04/12/2021, 09:00

Invited talk

132. Mechanical Properties of the Proton

Volker Burkert (Jefferson Lab)

04/12/2021, 09:30

Invited talk

133. Hadron Physics with AMBER at CERN

Jan Friedrich (Technische Universitaet Muenchen)

04/12/2021, 10:00

Invited talk

NA66/AMBER (Apparatus for Meson and Baryon Experimental Research) has been approved at the CERN Super Proton Synchrotron for a broad research program in quantum chromodynamics. The program ranges in a first phase to about the year 2026, from a precision measurement of the proton radius using a 100-GeV muon beam, to investigations of the quark-gluon structure of mesons in Drell-Yan processes....

130. Status and Prospects of the Electron Ion Collider

Abhay Deshpande (Stony Brook University)

04/12/2021, 10:50

Invited talk

In January 2020, the US DOE approved the realization of the Electron Ion Collider (EIC) to be built at Brookhaven National Laboratory (BNL) in partnership with Jefferson Laboratory. An "EIC project" was stood up and it is now leading the realization of the machine and working with the world-wide EIC Users towards the construction of up to two EIC detectors. In this talk, I will review the...

69. Potential Contribution of Korean Groups for the EIC

Yongsun Kim (Sejong University)

04/12/2021, 11:20

Invited talk

The electron ion collider (EIC) is the future particle accelerator to be built at the Brookhaven National Laboratory (BNL). It will collide electrons and various nuclei to precisely measure the internal structure of nuclei, including the spin and momentum distribution of quarks and gluons. It is also expected to provide unprecedented hard probe data to shed light on the strong interaction in...

129. Challenges and Opportunities in Hadron Physics

Craig Roberts (Nanjing University)

04/12/2021, 11:50

Invited talk

Newly operational, anticipated, and planned factilities have the potential to change the hadron physics landscape. Each one of the participants has expressed their perspective on how our community can advance over this new ground. This presentation will attempt to capture some of the excitement surrounding the journeys that are underway or may soon begin.

33. Hadron Mass in the Medium

Prof. Su Houng ­Lee (Yonsei University)

Invited talk

I will first review several topics in hadron mass and chiral symmetry restoration. Then I will discuss the current status of hadron mass shift measurements in nuclear medium. Finally, I will discuss some recent suggestions on $K_1$ and $K^{\ast }$ meson mass measurements both in heavy ion collision and nuclear target experiments.