Light-Cone 2023: Hadrons and Symmetries

18 sept. 2023, 08:00 → 22 sept. 2023, 18:00 America/Sao_Paulo

Rio de Janeiro, Brazil

Ignacio Bediaga (Elisa Carmen Hickman de Bediaga), Tobias Frederico (Instituto Tecnologico de Aeronautica)

The Light-Cone 2023 (LC2023) will be hosted by the Brazilian Center for Physics Research - CBPF from September 18  to 22, 2023  in the city of Rio de Janeiro, Brazil.

 Registration will be open by  June 1st to August  15th, 2023. Extended up to August 31th, 2023. 

The  Brazilian Center for Physics Research (CBPF) is one of the most important institutions in Brazil, where both theoretical and experimental research are developed, offers an ideal and stimulating environment to achieve the goals of the conference, thanks to their active community acting in many aspects of the Standard model and beyond.

The conference continues a series that started in 1991 and, since then, takes place at least once a year under the supervision of the International Light Cone Advisory Committee. 

The scientific goal of the Light Cone conference series is to continuously update the knowledge in light-front theory, its intersections with Euclidean Lattice and continuum approaches towards the phenomenological applications to describe hadrons and nuclei. Light-front theory provides a suitable framework for the calculations of decay rates, scattering amplitudes, correlations, spin effects, phases, distributions and other hadronic observables from first principles, aiming to reveal novel nonperturbative effects predicted by QCD. Notably, it provides the basic concepts and tools for a multidimensional imaging of hadrons from parton distributions accessible in the deep inelastic regime, giving the opportunity to deepen our understanding of the dependence of the spin and mass content of the nucleon, and in general of hadrons, in terms of their fundamental degrees of freedom.

The Light-Cone 2023  will emphasize the phenomenological applications where one can gain fruitful interpretations in terms of hadron-structure observables, matching the experimental efforts, carried on in many facilities around the world.  Part of the program will be also devoted to discuss applications to relativistic few-body systems, within QCD and other Quantum Field Theories, as well as the possible benefits from the interplay with Euclidean Lattice techniques and continuum approaches. Following the tradition of the Light-Cone Conference Series anticipating the opportunities offered by facilities such as the JLab, J-PARC, FAIR at GSI,  the future EIC, among other facilities, we plan to organize a stimulating scientific program  to fosterer the forefront research in nuclear, hadron and particle physics. The scientific program of LC2023 will have invited as well as contributed talks, that will address the following main topics:

• Hadron structure and spectrum
• Parton Physics in hadrons and nuclei
• Mass generation
• Lattice Gauge theories
• QCD at finite temperature and density
• Nonperturbative QFT methods in Minkowski and Euclidean space
• Light-front field theory
• AdS/CFT and holography
• Relativistic Few- and Many-body physics 
• Astroparticle physics
• Fundamental Symmetries and violations
• Present and future facilities 

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lun. 18 septembre

08:00 → 08:30 Registration

08:30 → 08:50 Welcome

08:50 → 10:30 Plenary

McCartor-Session-CJi.pdf

08:50 The electron-ion collider -- A world wide unique collider to unravel the mysteries of visible matter

Understanding the properties of nuclear matter and its emergence through the underlying partonic structure and dynamics of quarks and gluons requires a new experimental facility in hadronic physics known as the Electron-Ion Collider (EIC). The EIC will address some of the most profound questions concerning the emergence of nuclear properties by precisely imaging gluons and quarks inside protons and nuclei such as their distributions in space and momentum, their role in building the nucleon spin and the properties of gluons in nuclei at high energies. In January 2020 the EIC received CD-0 and Brookhaven National Laboratory was selected as site, and June 2021 CD-1. This presentation will give highlights on the EIC science program, introduce the experimental equipment and its integration into the accelerator and give the status of the EIC project, as well what are the next major steps.

Orateur: Dr Elke Aschenauer (BNL)

eca.lightcone2023.pptx

09:30 Enhanced Charm CP Asymmetries from Final State Interactions

Precision CP violation (CPV) measurements are widely recognized as a highly sensitive probe of the Standard Model with new sources needed to account for the mater-antimatter asymmetry observed in the Universe. There is a long-term discussion involving the source of the strong phase needed to generate direct CPV in charmless B and D decays. I will show that the final state interactions (FSI) can be the source needed to explain some observed asymmetries in B → hhh (h = π, K). I will also show in more detail a recent result where FSI and CPT symmetry constraint, one can enhance the charge-parity (CP) violation difference between D0 → π−π+ and D0 → K−K+ decay up to the current experimental value recently observed by the LHCb collaboration.

Orateur: Patricia Magalhaes (Unicamp)

LightCone2023_Patricia_18_9h30.pdf

10:00 Hydrodynamics in small systems in ultra-relativistic hadron collisions

I will give an outline of the evidence of the formation of a "fluid" in small systems in ultra-relativistic hadron collisions (p-p and pA), and argue that this forces us to radically rethink our view of hydrodynamics as an effective theory. I will argue that a re-derivation of hydrodynamics as a field theory can help us in understanding how a system with as few as 20 degrees of freedom can appear hydrodynamic.
I conclude proposing to test the hydrodynamic hypothesis "to the limit", using the hydrodynamic initial state to characterize initial state quark wavefunctions of the hadron

Orateur: Giorgio Torrieri (State University of Campinas (Unicamp),Brasil)

lightcone.pdf

10:30 → 11:00 Coffee-break

11:00 → 12:00 Plenary

McCartor-Session-CJi.pdf

11:00 Light Front Puzzles

I discuss some of the apparent inconsistencies in canonical, covariant
and light-front formulations of quantum field theory and the
resolution of these inconsistencies. The topics that will be
discussed are (1) the problem of inequivalent representations (2) the
problem of the trivial vacuum (3) the problem of ill-posed initial
value problems (4) the problem of rotational covariance (5) the
problem of zero modes and (6) the problem of spontaneously broken
symmetries.

Orateur: Wayne Polyzou (University of Iowa)

11:30 Light-front subtleties: zero modes, operator solutions, correlation functions

A novel approach to the dynamical light-front (LF) zero modes is presented. It is based on quantization of the two-dimensional LF gauge field $A^\mu(x)$ in the covariant (Feynman) gauge. The $A^{\pm}$ components are obtained as a massless limit of the massive vector field and contain an infinite set of dynamical zero modes with finite LF energy. We argue that the same zero modes are present in realistic gauge theories like LF QED(3+1). Its covariant-gauge formulation is briefly described and a few general comments concerning the LF zero modes are presented. Next, operator solution and axial anomaly of the LF Thirring-Wess and Schwinger models is discussed. Finally, we show that contradictions related to the $x^+ = 0$ restriction of the two-point and Pauli-Jordan functions are removed if the scalar field contains regularization terms in the plane-wave factors. The value of the two-point function at coinciding points is then also correctly obtained in the Hamiltonian approach.

Orateur: Lubomir Martinovic (Institute of Physics SAS, Bratislava, Slovakia)

martinovic_rio23.pdf

12:00 → 14:30 Lunch

14:30 → 15:30 Plenary

McCartor-Session-CJi.pdf

14:30 Abnormal solutions with massive exchanges

We will summarize the main properties of the so called ”abnormal solutions” of the Wick-Cutkosky model [1, 2], i.e. scalar particles interacting via massless exchange, within the Bethe-Salpeter equation [3]. These solutions have the property of not existing in the non-relativistic limit, despite of having very small binding energies, and present a genuine many-body character with a vanishing two-body norm in the zero binding limit. These states have already been obtained and discussed in previous works, including previous LCM [4, 5, 6, 7]
We will present in the LCM 2023 new results concerning the massive exchange case, in particular determine under which conditions it is possible to obtain such peculiar solutions without spoiling the model by tachyonic states (M2 < 0).
References
[1] G.C. Wick, Phys. Rev. 96, 1124 (1954).
[2] R.E. Cutkosky, Phys. Rev. 96, 1135 (1954).
[3] E.E. Salpeter, H. Bethe, Phys. Rev. 84, 1232 (1951).
[4] J. Carbonell, V.A. Karmanov, H. Sazdjian, Eur. Phys. J. C (2021) 81:50.
[5] V. A. Karmanov, J. Carbonell, H. Sazdjian, PoS(LC2019) 374 (2020) 050; arXiv:2001.00401.
[6] V. A. Karmanov, J. Carbonell, H. Sazdjian, EPJ Web Conf. 204 (2019) 01014; https://doi.org/10.1051/epjconf/201920401014.
[7] V. A. Karmanov, J. Carbonell, H. Sazdjian, http://ntse.khb.ru/2018/Proc/, p.212; arXiv:1903.02892 [hep-ph].

Orateur: Dr Jaume Carbonell (IPNO)

LCM_Rio_2023.pdf

15:00 Abnormal states with unequal constituent masses

The Bethe-Salpeter equation for system of two oppositely charged particles not only reproduces the Coulomb spectrum, but, for enough large coupling constant ${\cal C}>\frac{\pi}{4}$, predicts additional levels [1,2] not covered by the Schroedinger equation. These relativistic states (called abnormal) are dominated, for more than 90-99 percent, by the exchanged photons [3] (which are scalar in the model [1,2]), while contribution of two massive charged particles themselves is rather small (1-10 percent). These predictions and theoretical clarification of the nature of the abnormal states put on the agenda their experimental detection. Since the carrier of a large (positive) charge is a heavy ion, and the negative charge is provided by electron, the masses of particles, capable of forming the abnormal systems and available in laboratory, are very different. We show that in a system with so different masses the abnormal states still exist. Moreover, the effect of unequal masses is attractive. From the Bethe-Salpeter amplitude we extract the two-body light-front wave function and calculate the balance between contribution to the state vector of two charged constituents and photons. It is weakly sensitive to the mass ratio. The photons still predominate.

[1] G.C. Wick, Phys. Rev. 96, 1124 (1954).
[2] R.E. Cutkosky, Phys. Rev. 96, 1135 (1954).
[3] J. Carbonell, V.A. Karmanov, H. Sazdjian, Eur. Phys. J. C (2021) 81:50.

Orateur: Prof. Vladimir Karmanov (Lebedev Physical Institute of Russian Academy of Sciences)

Karmanov_LC2023.pdf

15:30 → 16:10 Coffee-break

16:10 → 17:30 Plenary

McCartor-Session-CJi.pdf

16:10 Basis Light-Front Quantization: Foundations, Recent Results and Plans

Basis Light Front Quantization (BLFQ) provides a foundation for the development of Hamiltonians and numerical methods to solve both relativistic bound state and scattering applications in 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. For applications limited to valence quarks, an effective one-gluon exchange interaction in light front gauge is employed. Recent developments include expanding Fock spaces beyond valence fermions to include the dynamical gauge degrees of freedom which provide direct access to gluonic contributions to amplitudes and distribution functions. Since the light front wave functions are interpreted as appropriate to a low-resolution scale, calculated observables such as parton distribution functions (PDFs) can be QCD-evolved to higher scales for comparison with experiments. I will survey recent applications to mesons and baryons and discuss prospects for future developments.

Orateur: Prof. James Vary (Iowa State University)

12-23F-LC2023_BLFQ.pdf

17:30 → 20:00 Welcome Cocktail

mar. 19 septembre

08:50 → 10:30 Plenary

McCartor-Session-CJi.pdf

08:50 The proton gluonic gravitational form factors

I will be discussing the proton gluonic gravitational form factors, in particular, those extracted from the J/$\psi$-007 performed in Hall C at Jefferson Lab. In this experiment, the elastic photoproduction of a small dipole (J/$\psi$) is used to probe the gluonic structure of the proton. The gluons' contribution to the mechanical properties of the proton (mass density, pressure, and shear forces) will be presented in several frames (Breit, lightcone). A comparison to lattice calculations will also be presented. The experimental uncertainties as well as the theoretical caveats of this extraction in a nonperturbative region of photon-nucleon center of mass will be considered and discussed. Projections of these form factors with better statistical precision using the SoLID detector in Hall A will be shown.

Orateur: Dr Zein-Eddine Meziani (Argonne National Laboratory)

Light-Cone-2023-meziani.pdf

09:30 Gluon saturation: toward precision using light front and covariant approaches

We use the Color Glass Condensate effective theory of QCD at small x to calculate fully inclusive structure functions as well as single and double inclusive hadron production in DIS at small x at the Next to Leading Order (NLO). We show that calculations of NLO corrections in light front perturbation theory and the traditional covariant perturbation theory agree for processes that have been computed in both approaches. We elucidate the need for and outline an approach for going beyond the small x approximation which may be more convenient in light front perturbation theory.

Orateur: Jamal Jalilian-Marian (Baruch College, CUNY)

JJM-light-cone-2023.pdf

10:00 Resummation in JIMWLK Hamiltonian

The JIMWLK Hamiltonian governs evolution of high energy collision processes. At next-to-leading order, the Hamiltonian features large logarithms, which have to be resummed. We discuss partial resummation of these logarithms into running coupling and DGLAP-like resummation.

Orateur: Michael Lublinsky (Ben-Gurion University of the Negev)

talk_Rio.pdf

10:30 → 11:00 Coffee-break

11:00 → 12:00 Plenary

McCartor-Session-CJi.pdf

11:00 Glue and sea inside proton: A light-front Hamiltonian approach

Basis Light-Front Quantization (BLFQ) provides a nonperturbative framework to solve relativistic many-body bound state problems in quantum field theories. We report our recent progress in applying BLFQ to reveal structure of the nucleon going beyond to its leading Fock sector. We produce the light-front wave functions of the nucleon from the light-front QCD Hamiltonian, determined for its constituent $|qqq\rangle$, $|qqqg\rangle$, and $|qqqq\bar{q}\rangle$ Fock components. The eigenvectors of the light-front QCD Hamiltonian have been successfully employed to compute a wide class of different and related nucleon observables. We discuss the generalized parton distributions functions (GPDs) and the transverse momentum dependent distribution functions (TMDs) of the gluon and sea quarks inside the nucleon.

Orateur: Chandan Mondal (Institute of Modern Physics, Chinese Academy of Sciences)

Chandan_LC2023_highlighted.pdf

11:30 Valence and sea parton correlations in double parton scattering from data

The effective cross section of double parton scattering in proton collisions has been measured by many experiments with rather different results. Motivated by this fact, we assumed that the parton correlations in the transverse plane are different whether we have valence or sea partons. With this simple approach, we were able to fit the available data and found that sea parton pairs are more correlated in the transverse plane than valence--sea parton pairs.

Orateur: Emmanuel de Oliveira (UFSC)

main.pdf

12:00 → 14:30 Lunch

14:30 → 15:30 Plenary

McCartor-Session-CJi.pdf

14:30 Studying chiral pions with massive gluons.

We will show how to obtain a closed expression for the
the calculation of the pion decay constant in the chiral case.
The expression is obtained by using the Curci-Ferrari model which
includes massive gluons. This model also allows to find an infrared safe
trajectory of the renormalisation group. With
which the results of the numerical simulations can be reproduced with good accuracy ussing perturbation theory. This leads to the interpretation that the
development parameter associated with the ghost-gluon coupling constant is a small parameter.
This small parameter allows for a better understanding of which diagrams has to be considered when calculating, for example, the pion decay constant. The numerical solution of the expression gives the region of gluon masses that well reproduce the pion decay constant.

Orateur: Dr Marcela Peláez

LightCone2023.pdf

15:00 Pion Transverse Momentum Distribution in Minkowski space.

I will discuss the pion structure within a dynamical model based on the solution of the Bethe-Salpeter equation in Minkowski space.
The model 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 obtain the full parton distribution function, its contribution due to light-front valence wave function and a comparison with experimental data, after the aplication of a NLO evolution[1]. We also present the unpolarized transverse-momentum dependent quark distributions. In addition, I will show that the model is able to compute other hadronic observables as pion weak decay constant, the valence probability, the LF-momentum distributions, the distribution amplitudes, the probability densities both in the LF-momentum space and the 3D space given by the Cartesian product of the covariant Ioffe-time and transverse coordinates [2]. Finally, we calculated the pion electromagnetic form factor with a good agreement with available experimental data [3].

References:
1. W. de Paula, E. Ydrefors, J. H. Alvarenga Nogueira, T. Frederico and G. Salme, Phys. Rev. D 105 (2022), L071505
2. W. de Paula, E. Ydrefors, J. H. Alvarenga Nogueira, T. Frederico and G. Salme, Phys. Rev. D 103 (2021) no.1, 014002
3. E. Ydrefors, W. de Paula, J. H. A. Nogueira, T. Frederico and G. Salme, Phys. Lett. B 820 (2021), 136494

Orateur: Wayne de Paula (Instituto Tecnologico de Aeronautica)

LC2023dePaula.pdf

15:30 → 16:00 Coffee-break

16:00 → 17:20 Plenary

McCartor-Session-CJi.pdf

16:00 Proton gravitational form factors with basis light-front quantization

We study the gravitational form factors (GFFs) and the mechanical properties like the pressure and shear distribution of quarks using the light-front wave functions (LFWFs) of the nucleon from a basis light-front quantization (BLFQ) approach in the leading Fock-sector representation. Our analysis further expands to include an extra Fock sector, which integrates three quarks and an active gluon. This leads to the study of gluon GFFs and their respective mechanical features. We compare our results with existing experimental data and Lattice outcomes.

Orateur: Sreeraj Nair (The Institute of Modern Physics (IMP) of the Chinese Academy of Sciences)

sreeraj_lc2023.pdf

16:30 Beyond Valence Distributions in meson with Basis Light-Front Quantization

We explore light mesons beyond valence structure in the Basis Light-front Quantization (BLFQ) approach, comprising the quark-gluon interactions from the light-front quantum chromodynamics (QCD) on the Hamiltonian. After fitting the light meson mass spectroscopy, the Hamiltonian eigenvectors provide a good description of the pion and the kaon Decay constants, Electromagnetic Form factor, and Parton distribution function. We will also discuss the parton distributions going beyond the leading twist.

Orateur: Jiangshan Lan (Institute of Modern Physics, Chinese Academy of Sciences)

LC2023JLAN919.pdf

17:00 Quantum stress on the light front

We investigate the gravitational form factors of a strongly coupled scalar theory in the light front Hamiltonian approach. The theory can be used to mimic the non-perturbative interaction between the nucleon and the pion. We renormalize the energy-momentum tensor with a Fock sector dependent scheme. We also systematically analyze the Lorentz structure of the energy-momentum tensor and identify the suitable hadron matrix elements to extract the form factors, avoiding the contamination of spurious contributions. We present results up through the 3-parton Fock sector (i.e bare mock nucleon plus up to two mock pions) for the gravitational form factors of the mock nucleon at strong coupling and over a large range of four-momentum transfer squared. We verify that the extracted form factors obey momentum conservation as well as von Laue’s mechanical equilibrium condition. From the gravitational form factors, we compute the energy and pressure distributions of the system. Furthermore, we show that utilizing the Hamiltonian eigenvalue equation, the off-diagonal Fock sector contributions from the interaction term can be converted to diagonal Fock sector contributions, yielding a systematic non-perturbative light-front wave function representation of the energies and forces inside the system.

Orateur: Xianghui Cao (University of Science and Technology of China)

XianghuiCao_Quantum_stress_on_the_light_front.pdf

mer. 20 septembre

08:50 → 09:00 Plenary: McCartor Award Session - Chueng Ji

McCartor-Session-CJi.pdf

09:00 → 10:30 Plenary

McCartor-Session-CJi.pdf

09:00 Evolution of GPDs as a tool for their extraction

I will present how perturbative evolution offers in theory the possibility of a model independent extraction of generalized parton distributions (GPDs) from exclusive processes such as deeply virtual Compton scattering (DVCS), but falls short of its promises practically at moderate skewness -- a problem illustrated through the concept of shadow GPDs. However, perturbative evolution provides crucial insights to the modeling of GPDs at small x. I will open up on the perspectives provided by non-perturbative evolution computed in lattice QCD.

Orateur: Dr Herve Dutrieux (William and Mary)

Presentation_2023_09_20__Light_Cone_.pdf

09:30 Towards a Hamiltonian first principle approach for baryons

Basis light-front quantization (BLFQ), as a fully relativistic and nonperturbative approach based on a light-front quantized Hamiltonian with Quantum Chromodynamics (QCD) input, has the potential to achieve the first principle calculation. For QCD applications in limited Fock spaces, we implement a form of confinement based on light-front holography and additional longitudinal confinement in our Hamiltonian. Consequently, BLFQ results agree with the global fitting and experimental data. Recent developments include expanding the Fock spaces to the five-particle Fock sectors, such as the five-quark and three-quark-two-gluon Fock sectors, and implementing the relevant QCD interaction to replace the effective confining potential. Using the light-front wave functions produced by BLFQ, one can calculate observables such as parton distribution functions (PDFs) of the gluon and sea quarks at a low-resolution scale and implement QCD-evolved to higher scales for comparison with experiments. At the end of this talk, I also discuss prospects for future developments.

Orateur: Siqi Xu (Institute of Modern Physics, Chinese Academy of Science)

Light_cone_2023.pdf

10:00 cos(2ϕ) and sin(2ϕ-ϕs) azimuthal spin asymmetries in the pion induced Drell-Yan process

The Drell-Yan process, involving the annihilation of a quark and an antiquark into a lepton-antilepton pair, provides valuable insights into the structure and dynamics of hadrons. In this study, we focus on the investigation of azimuthal angular asymmetries, specifically the cos(2ϕ) and sin(2ϕ-ϕs) asymmetries, which probe the spin and transverse momentum-dependent properties of the initial-state hadrons. The cos(2ϕ) asymmetry arises from the convolution of two Boer-Mulders functions in an unpolarized π-p Drell-Yan process. It reflects the polarization of the initial-state quarks and antiquarks, providing information on the distribution of quark spins inside the hadrons. Similarly, the sin(2ϕ-ϕs) asymmetry (with ϕs , the azimuthal angle of target transverse spin) can be obtained through the convolution of the Boer-Mulders function of the pion and the transversity distribution of the proton. By analyzing the sin(2ϕ-ϕs) asymmetry, one can extract valuable information about the transverse spin structure of the nucleons and study the role of spin-orbit correlations. We discuss the theoretical framework and formalism employed for the calculation of these asymmetries, taking into account the pion parton distribution functions from the light-front holographic QCD and proton parton distribution functions from light-front quark-diquark model, and we show the comparison with the COMPASS (2017) and other theoretical studies.

Orateur: Bheemsehan Gurjar (Indian Institute of Technology Kanpur)

Bheemsehan_LC_2023.pdf

10:30 → 11:00 Coffee-break

11:00 → 12:00 Plenary

McCartor-Session-CJi.pdf

11:00 Positronium structure from a basis light-front approach

In this talk I report our recent progress on solving the postronium system in a basis light-front Hamiltonian approach with the light-front QED Hamiltonian as input. Both the leading Fock sector ($|e^+e^-\rangle$) and the higher sector containing one dynamical photon ($|e^+e^-\gamma\rangle$) are included in the basis. We found that the rotation symmetry of the positronium system provides natural cutoffs in momentum space for the particles in the basis. We performed the calculation at the physical electromagnetic coupling. We obtained the mass spectrum and charge radii of the low-lying states which reasonably agree with the results from non-relativistic quantum mechanics. The subleading helicity components of the postronium states naturally appear due to relativistic effects. Finally I will report the photon distribution in the positronium states.

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

Positronium_LC2023_Xingbo_Zhao_230920.pptx

11:30 Positronium in quantum electrodynamics of effective particles

We study numerically spectrum of positronium using effective
(and renormalized) Hamiltonian obtained from QED by means of
the renormalization group procedure for effective particles
(RGPEP). The basis light-front quantization (BLFQ) provides
the framework for numerical computations. Positronium is chosen
as the testing ground for our method and a stepping stone for
future studies in QCD, which is the intended application area
of the method. We obtain reasonable agreement between our and
the well-known perturbative results with controllable
uncertainties. The dependence on the renormalization scale
parameter is also studied.

Orateur: Kamil Serafin (Institute of Modern Physics, Chinese Academy of Sciences)

kserafin20230920lightcone.pdf

jeu. 21 septembre

08:50 → 10:30 Plenary

McCartor-Session-CJi.pdf

08:50 Nuclear Hadronization Studies at JLab: Present and Future

In 2004, the CLAS detector at Jefferson Lab collected experimental data on a broad range of nuclear targets, from heavy nuclei like Lead to lighter ones such as Carbon or Deuterium, employing a 6 GeV electron beam. These data enabled us to investigate various facets of nuclear phenomena, encompassing the nuclear hadronization process, nuclear color transparency, short-range nuclear collations, and two-pion correlations. Notably, the varying sizes of nuclei facilitated an exploration of the phenomenon of nuclear hadronization in relation to nuclear medium size. The studied final hadron types included charged and neutral pions, protons with substantial statistics, and, with fewer statistics, kaons, etas, omegas, and lambdas. Moving forward to the first quarter of 2024, the experiment will be replicated on CLAS12 with CEBAF12, offering higher energy, an expanded kinematic range, and increased statistical precision for diverse types of hadrons. Within the presentation, I will outline the previous experiment, delve into the impending 12 GeV experiment, and elucidate the perspectives and scientific significance of the envisioned 24 GeV experiment.

Orateur: Hayk Hakobyan (Universidad Tecnica Federico Santa Maria)

Talk_Light_Cone_2023.pdf

09:30 Bridge between QCD and LFQM

I will discuss the link between the QCD and the light-front quark model (LFQM) utilizing the interpolation between the instant form dynamics (IFD) and the light-front dynamics (LFD). In the ‘tHooft model, the mass gap solutions, vacuum condensation, spontaneous symmetry breaking of the chiral symmetry and the mass spectra of mesons bearing the feature of the Regge trajectories are found and the Gell-Mann-Oakes-Renner relation for the pionic ground-state in the zero fermion mass limit is confirmed both in IFD and LFD as well as in-betweens. The implication of the link between QCD and LFQM will be discussed for the consistency in the framework of analyzing simultaneously both the mass spectra and the wave-function related physical observables. Independence of current components, polarization vectors, and reference frames will be exemplified in recent LFQM analyses of meson decay constants.

Orateur: Chueng Ji (North Carolina State University)

LC2023-Rio-September-28-2023-CRJi.pdf

10:00 Hot perturbative QCD in a very strong magnetic background

We compute the pressure, chiral condensate and strange quark number susceptibility from first principles within perturbative QCD at finite temperature and very high magnetic fields up to next-to-leading order and physical quark masses. We study the convergence of the perturbative series for the pressure for different choices of renormalization scale in the running coupling. Our results for the chiral condensate and strange quark number susceptibility can be directly compared to recent lattice QCD data away from the chiral transition.

Orateur: Eduardo Fraga (Instituto de Física, UFRJ)

LC2023-fraga.pdf

10:30 → 11:00 Coffee-break

11:00 → 12:10 Plenary

McCartor-Session-CJi.pdf

11:00 Effective models for heavy mesons in a plasma inspired by gauge gravity duality

The advent of the AdS/CFT correspondence led to the development of phenomenological models aimed at describing the behavior of hadrons in non-perturbative regimes of QCD. In particular, the so-called holographic models allow the description of the behavior of quarkonium in a thermal medium, such as the plasma of quarks and gluons formed in heavy ions collisions. We will discuss how quasi-states of bottomonium and charmonium inside a thermal medium can be described holographically in such a way that one can study the effects of temperature, density and presence of magnetic fields on dissociation in the thermal medium. We will also present a recent result on how rotation, which occurs when ion collisions are not frontal, affects the deconfinement temperature.

Orateur: Prof. Nelson Braga (Universidade Federal do Rio de Janeiro)

Braga_LC_2023.pdf

11:30 Exotic Baryons in Hot Neutron Stars

We study the nuclear isentropic equation of state for a stellar matter composed of nucleons, hyperons, and $\Delta$-resonances. We investigate different snapshots of the evolution of a neutron star, from its birth as a lepton-rich protoneutron star in the aftermath of a supernova explosion to a lepton-poor regime when the star starts cooling to a catalyzed configuration. We use a relativistic model within the mean-field approximation to describe the hot stellar matter and adopt density-dependent couplings adjusted by the DDME2 parameterization. We use baryon-meson couplings for the spin-$1/2$ baryonic octet and spin-$3/2$ decuplet determined in a unified manner relying on $\text{SU}(6)$ and $\text{SU}(3)$ symmetry arguments. We observe that $\Lambda$ is the dominant exotic particle in the star at different entropies for both neutrino-free and neutrino-trapped stellar matter. For a fixed entropy, the inclusion of new particles (hyperons and/or delta resonances) in the stellar matter decreases the temperature. Also, an increase in entropy per baryon ($1\;\text{to}\; 2$) with decreasing lepton number density ($0.4\;\text{to}\; 0.2$) leads to an increase in stellar radii and a decrease in its mass due to neutrino diffusion. In the neutrino transparent matter, the radii decrease from entropy per baryon $2$ to $T\,=\,0$ without a significant change in stellar mass.

Orateur: Adamu Issifu (UFSC)

Adamu_LC2023.pdf

11:50 The EMC effect within the light-front Hamiltonian dynamics for few-nucleon bound systems

We present the description of light-nuclei, in valence approximation, within a rigorous Light-Front (LF) approach. The latter, fulfills Poincaré covariance, macroscopic locality,number of particles and momentum sum rules. We applied the analysis to electron deep inelastic scattering (DIS) on $^3$He, $^3$H and $^4$He targets, in the Bjorken limit. For details about the $^3$He case, see Ref. [1]. Within the present framework, the main theoretical ingredient is the LF nuclear spectral function which can be related to the nuclear momentum distribution. The latter quantity has been calculated within the phenomenological Av18 + UIX potential and the chiral potentials called NVIa +3N and NVIb +3N. The evaluated momentum distribution has been used to calculate the structure functions of the considered nuclei. As discussed in Ref. [1], also for $^3$H and $^4$He, our analysis predicts a sizable European Muon Collaboration (EMC) effect [2]. Let us remark that, in the valence region, results are rather independent with respect to the use of different parametrizations of the nucleon DIS structure functions and the nuclear potentials. This investigation represents the first realistic calculations of the EMC effect, for different targets, which fulfills Poincaré covariance and thus preserving all the fundamental sum rules. Therefore, this a relevant study also in view of the present and future experimental scenarios.

REFERENCES

[1] E. Pace, M. Rinaldi, G. Salme', S. Scopetta, PLB 839 (2023) 137810

[2] F. Fornetti, E. Pace, M. Rinaldi, G. Salme', S. Scopetta and M. Viviani, in prep.

Orateur: Filippo Fornetti (INFN Sezione di Perugia and Università degli Studi di Perugia)

Fornetti_LC23.pdf

12:10 → 14:30 Lunch

14:30 → 15:30 Plenary

McCartor-Session-CJi.pdf

14:30 Spectra, from factors and hadronic structure functions from a deformed AdS model

In this talk, I will present recent results from an AdS/QCD model, inspired by AdS/CFT correspondence. In this model, the IR mass scale is introduced in a quadratic exponential deformation of the AdS metric. In contrast with the hard and soft wall models, there is no cut in the AdS space nor any dilaton field in the action. This model proves effective for obtaining discrete spectra for hadrons of any spin, from glueballs to scalar and vector mesons as well as baryons of spins 1/2, 3/2 and 5/2. From this model, we also obtain the pion and nucleon form factors and the structure functions of the proton. These results are compared with the literature and experimental data.

Orateur: Henrique Boschi-Filho (Universidade Federal do Rio de Janeiro)

Seminar_LC23_Boschi.pdf

15:00 A confining holographic QCD model for vector mesons and nucleons

We present a minimal holographic QCD model that allows for a description of asymptotically linear Regge trajectories for vector mesons and nucleons in a way consistent with confinement. We consider a 5d background where the dilaton is quadratic in the infrared (far from the boundary). The background is a solution of 5d Einstein-dilaton gravity and satisfies the confinement criterion. The vector mesons and nucleons are described by a 5d Yang-Mills action and a generalized 5d Dirac action respectively. In our framework all hadron masses depend on a single mass scale related to the infrared parameter of the dilaton. We calculate masses and decay constants and compare our results against experimental data finding a good agreement.

Orateur: Alfonso Ballon Bayona (Rio de Janeiro Federal University)

BallonBayona_LightCone2023.pdf

15:30 → 16:00 Coffee-break

16:00 → 17:30 Plenary

McCartor-Session-CJi.pdf

16:00 Exploring the covariant form factor for spin-1 particles

The spin-1 particles is an admirable two quarks bound state
system to understand electromagnetic properties from hadronic states.
These systems are generally relativistic, and therefore,
need an approach using quantum field theory. In the present work, we will use both the
quantum field theory at the instant form, as well,
quantum field theory on the light-front~(LFQFT).
In general, it is used to calculate the electromagnetic properties of
spin-1 vector particles in the LFQFT formalism, with the plus
component of the electromagnetic current. In the present work, we used, in addition to
the plus component of the electromagnetic current; the minus component
of the current, and we use that
components o the current, to extract the covariant form factors; showing that
to have an equivalence between these we need to add non-valence terms
to the electromagnetic current, in order to restore the covariance, and obtain
exactly the same results when using the instant form quantum field theory.

Orateur: João Pacheco de Melo (Laboratório de Física Teórica e Computacional - UCS - UNICID)

jpachecolc2023v2.pdf

16:30 Structure of spin-1 QCD systems using light-front Hamiltonian approach

We investigate the structure of the spin-1 hadron system, particularly the $\rho$-meson, through the leading-twist momentum-dependent parton distribution functions. We employ the light-front wavefunctions generated from the Basis Light-Front Quantization approach to compute the quark and gluon distribution functions (PDFs), and the transverse momentum-dependent quark distribution functions (TMDs). To extract the wavefunctions, we truncate the Fock space to consider the states of the valence quark-antiquark and quark-antiquark-gluon. Our predictions follow the positivity bounds implied on the PDFs and TMDs of both the quark and the gluon. Further, we evolve the unpolarized and helicity PDFs to a higher scale in order to compare the moments of PDFs with the other theoretical approaches.

Orateur: Satvir Kaur (Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou)

LC-2023-SK.pdf

16:50 Exclusive production of excited light vector mesons with a holographic wave function model

The exclusive photo- and electroproduction of the light vector mesons $\rho, \, \omega \, \text{and } \phi$ are studied within the color dipole picture as function of the center-of-mass energy of the $\gamma p$ collision and the momentum transfer squared $|t|$. The corresponding vector meson wave functions have been computed with the relativistic AdS/QCD holographic approach. This enabled us to obtain a good description of all available data for the ground-state light mesons $\rho (1S), \, \omega (1S),\, \text{and } \phi(1S)$ as well as to make predictions for the excited states $\rho (2S), \, \omega (2S),\, \text{and } \phi(2S)$ with the same formalism. This study revealed the existence of a sizeable theoretical uncertainty coming from modeling the partial dipole amplitude in the non-perturbative kinematical domain. These uncertainties could be deeply investigated with measurements of the light vector meson cross sections in future hadron colliders.

Orateur: Cheryl Henkels de Souza (UFSC)

Presentation_Light_Cone_2023_final-Cheryl.pdf

17:10 Double Parton Scattering in Ultraperipheral Collisions

Double Parton Scattering (DPS) is a important way for which we can investigate the parton distributions of the proton and the nucleus. Although, we know that such scatterings should occur in high energy collisions, the formalism to describe it lack of answers to questions like --- is there a universal effective cross section? In direction to explore such questions, we investigate DPS in ultraperipheral collision (UPC) where the effective cross section is not a constant as usually is in the central collisions, as we point in our results. Furthermore, once we allow the nucleus to break in a ultraperipheral proton--nucleus collision, we provide insights concerning the photon distribution of the nucleus. Also, as the effective cross section have a complex dependence with the longitudinal fraction energy carrying by the photon in the initial state, we evaluate cross sections with photon and gluons in the initial state producing quark--antiquark pairs or dilepton and quark--antiquark in the final state.

Orateur: Bruna de Oliveira Stahlhofer (UFSC)

LC2023.pdf

19:00 → 22:00 Banquet

ven. 22 septembre

08:50 → 10:30 Plenary

McCartor-Session-CJi.pdf

08:50 The search for glueballs

While the Higgs mechanism might be responsible for the masses of the elementary particles, the mass-creation mechanism for hadrons is quite different. Less than 1% percent of the mass of the proton is due to the Higgs mechanism. Particles solely composed of gluons are at the center of the strong interaction. Glueballs themselves would be massless without the strong interaction and their predicted masses arise solely from the strong interaction. Glueballs thus offer a unique way to study the mass creation of strongly interacting particles. In the past years, a new relation between modern superstring theory and QCD has been developed by the AdS/CFT (Anti-de Sitter space/conformal field theory) correspondence. Several groups have studied in the Witten-Sakai-Sugimoto model of strings to investigate glueballs and their behavior. Modern stringy hadron models attempt not only to make predictions for glueballs but also describe and predict other hadronic states including their decay dynamics. This talk describes the experimental situation and the experimental perspectives to provide more information on glueballs and their structure.

Orateur: Prof. Ulrich Wiedner (Bochum University)

Glueballs_wiedner.pdf

09:30 Confirming the action of the Schwinger mechanism in QCD

In this talk, we present a short review of the emergence of a dynamical gluon mass through the action of the Schwinger mechanism. The linchpin of this mechanism is the dynamical formation of longitudinally coupled massless bound-state poles in the vertices of the theory, and especially in the three-gluon vertex. The presence of these poles, in addition to causing the infrared saturation of the gluon propagator, also induces a modification (“displacement”) to the Ward identity of the three-gluon vertex, proportional to the form factor associated with the pole. Here we will show how this displacement signal has been confirmed through a suitable combination of inputs obtained from lattice QCD.

Orateur: Prof. Arlene Cristina Aguilar (IFGW, Unicamp)

LC_2023_aguilar.pdf

10:00 Multigluon correlation functions from lattice QCD

The lattice computation of multigluon correlation functions, namely two, three and four point functions, is reviewed exploring its implications to the QCD dynamics.

Orateur: Orlando Oliveira (University of Coimbra)

MultigluonCorrelationFunctions.pdf

10:30 → 11:00 Coffee-break

11:00 → 12:00 Plenary

McCartor-Session-CJi.pdf

11:00 Dynamical mass generation constrained by gauge symmetries

A nonperturbative approach to derive the dressed quark-gluon vertex is based on longitudinal and transverse Slavnov-Taylor identities, rather than on perturbative dressing or solving the inhomogeneous Bethe-Salpeter equation. The adequate manipulation of these identities with projections leads to the functional form of all form factors of the vertex.

This novel vertex is used in the Dyson-Schwinger (DSE) equation of the quark with lattice QCD simulations for the gluon and ghost propagators. The dynamical chiral symmetry breaking this vertex induces is very large and gives rise to a realistic mass gap for all quark flavors, compatible with those of the usual phenomenological interaction models in DSE calculations. Finally, we test the gauge covariance of our DSE kernel by studying the gauge dependence of the quark mass and wave renormalization function as well as of the quark condensate and the anomalous chromomagnetic moment.

Orateur: Prof. Bruno El-Bennich (Universidade Federal de São Paulo)

Light Cone 2023.pdf

11:30 Spectral analysis of the gauge invariant quark propagator

We explore the Dirac decomposition of the gauge invariant quark propagator, shedding light on the hadronization of a quark as this interacts with the vacuum. Using the spectral representation of the quark propagator, we link the coefficients of the Dirac decomposition of the gauge invariant quark propagator to sum rules governing the chiral-odd and chiral-even quark spectral functions.

In particular, in light-like axial gauges, we obtain a novel sum rule for the quark spectral function associated to the gauge-fixing vector. Based on the gauge invariance of the gauge invariant quark propagator, we demonstrate the formal gauge invariance of the so called jet mass, a color-screened gauge-invariant dressed quark mass) that can be expressed in any gauge as the first moment of the chiral-odd quark spectral function. Lastly, we also present a gauge-dependent formula that connects the second moment of the chiral-even quark spectral function to invariant mass generation and final state rescattering in the hadronization of a quark.

Orateur: Dr Caroline Silva Rocha Costa (JLAB)

LightCone2023.pdf

12:00 → 14:30 Lunch

14:30 → 15:30 Plenary

McCartor-Session-CJi.pdf

14:30 The quark-photon vertex in confining models

We present one-loop results for corrections from Strong Interactions to the quark-photon vertex using different confining models for the exchanged gluon. This calculation allows for the prediction of confinement effects in form factors and observables like the proton anomalous magnetic moment. We show that a range of confining models with dynamical gluon masses and even complex-conjugated poles present predictions that are fully compatible with observables and discuss to what extent model parameters may be constrained by this comparison.

Orateur: Prof. Leticia Palhares (Departamento de Física Teórica, UERJ)

15:00 Radiative Corrections to the Gribov-Zwanziger Effective Model for QCD

Given the well-known limitations of the perturbative approach to Yang-Mills theories in the infrared regime, it is often interesting to resort to nonperturbative methods, such as Lattice QCD, Schwinger-Dyson equations, Renormalization Group Methods, and effective models. In particular, the so-called Refined Gribov-Zwanziger (RGZ) effective model has successfully described a nontrivial infrared behavior of gauge field propagators, being very close to the ones observed in numerical lattice gauge field theory simulations.

We discuss the one-loop correction to the the ghost-anti-ghost-gluon interaction vertex, in the RGZ theory. Our analytical results are fairly compatible with lattice YM simulations. We also discuss our current efforts to calculate the one-loop correction to the RGZ gluon propagator.

Orateur: Bruno Mintz (UERJ - Universidade do Estado do Rio de Janeiro (Brazil))

bruno-mintz-light-cone-2023.pdf

15:30 → 16:00 Coffee-break

16:00 → 16:40 Plenary

McCartor-Session-CJi.pdf

16:00 Klein-Gordon Effective Equation for Yang-Mills SU(2) Classical Theory

The Faddeev-Niemi representation prescription for the Yang-Mills SU(2) gauge theory is explored through a Gauge Induced Variable technique which render the topology implied both interesting and rich on new consequences: effective modes in the classical solutions of the theory emerge in the context of a generalized Klein-Gordon Equation. Traces of mass intervals and fundamental scales appears in the treatment as long as electroweak charge screening.

Orateur: Dr Josenilson Adnei Oliveira Marinho (Universidade Federal Rural da Amazonia)

apresentacao-2.pdf

16:20 Two boson interaction in high energy physics with dipole formalism

In the high energy regime, in light cone coordinates it is possible to calculate the probability of bosons ($\gamma, W^\pm, Z,g $) floating in a quark-antiquark pair, which in turn can be approached through of the dipole formalism in the high energy regime. In this work we present important observables that will be essential to study the background contributions of future electron-positron accelerators, such as contributions from interactions between two bosons in ultraperipheral collisions measured at the LHC.

Orateur: Gabriel Zardo Becker (Universidade Federal de Santa Catarina - UFSC)

Seminario.pdf

16:40 → 16:50 Closing