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Guy F. de Teramond

Publications and source records attributed to Guy F. de Teramond.

At least 19 recordsLinked to original sources
arXiv2026

Regge spectral generator and form factors from hard exclusive amplitudes in holographic QCD

We show that the infinite tower of hard exclusive amplitudes in holographic light-front QCD leads to a spectral generator $G(α,λ)$ which encodes the full Regge spectrum. The construction assumes a Poisson distribution of Fock-state components, where $λ$ represents the average parton multiplicity above the valence configuration. The resulting generator yields a Regge spectrum invariant under continuous $λ$-deformations. Its even- and odd-twist projections yield the meson and baryon form factors with a single value of $λ$, fixed by the pion charge radius, which in turn determines the full $Q^2$ dependence. The constituent counting rules for both sectors follow from the structure of the spectral generator, which also provides a compact analytic representation of parton distributions.

hep-ph↗
arXiv2025

Limits of applicability of holographic dual descriptions to QCD: virtuality and coherence

Virtuality and coherence determine the limits of applicability of holographic concepts in QCD. In light-front quantization, the invariant mass controls the off-shell behavior of a physical process and thus provides a measure of its virtuality. In impact space, the corresponding quantity is the invariant transverse separation between quarks and gluons, $ζ$, which is identified with the holographic coordinate $z$ in holographic light-front QCD. By embedding the internal structure of hadrons and implementing an effective superconformal symmetry, the mapping between quantum states and classical gravity -- central to the holographic principle -- yields new analytic insights into the strong-interaction dynamics responsible for the emergence of a confinement scale and the observed hadron spectrum. We show that the possible emergence of a gravity dual to physical QCD is restricted to the Regge limit of high-energy scattering, where many partonic degrees of freedom participate coherently. This criterion provides a quantitative definition of the domain of applicability of holographic QCD to dynamical processes and allows it to be tested directly against experimental results. By further enforcing analyticity together with exact QCD constraints at asymptotic infinity, the holographic framework can be consistently extended beyond the infrared domain. To illustrate this procedure, we briefly discuss recent work by the HLFHS collaboration, where the effective strong coupling was extended from the Regge-limit domain, through the near-perturbative transition region, and into the ultraviolet Bjorken-limit domain. The resulting scheme provides a unified and precise nonperturbative description of the strong coupling across all virtuality scales.

hep-th↗
arXiv2025

Holographic light-front QCD

This brief review presents the key components of light-front holographic quantum chromodynamics (HLFQCD). Particular attention is given to the introduction of the QCD color confinement scale within the context of a graded superconformal algebra. A concise overview of applications is provided, including spectroscopy, form factors, parton distributions of hadrons, and the relationship between entanglement entropy and high-energy scattering. While many other recent applications of HLFQCD exist in the literature, they are not included in this short overview of our latest work.

hep-ph↗
arXiv2025

Asymptotic gauge symmetry and UV extension of the nonperturbative coupling in holographic QCD

We extend our recent analytic study of the strong coupling $α_{\rm eff}$ in the nonperturbative and near-perturbative regimes~\cite{deTeramond:2024ikl} by imposing rigorous renormalization-group results from asymptotically free gauge theories at $Q^2 \to \infty$. The asymptotic boundary conditions modify the scaling properties of $α_{\rm eff}$ at large values of the momentum transfer $Q^2$, and lead to a scale-dependent confinement strength $κ(Q^2)$. This requires that both $κ(Q^2)$ and $α_{\rm eff}\left(Q^2, κ(Q^2)\right)$ remain holomorphic in the complex $Q^2$ plane, except at the physical cuts associated with the heavy-quark thresholds and the singularity flow trajectory studied in~\cite{deTeramond:2024ikl}. For color $SU(3)$, a precise connection is found between the scaling exponent of $κ(Q^2)$ in the ultraviolet, the value of the infrared fixed point of the strong coupling, and the number of flavors in agreement with observations. The nonperturbative analytic model gives an accurate description of the strong coupling at all scales, up to the highest available data.

hep-ph↗
arXiv2024

Color symmetry and confinement as an underlying superconformal structure in holographic QCD

Dedicated to the memory of our colleague, Harald Fritzsch, who, together with Murray Gell-Mann, introduced the color quantum number as the exact symmetry responsible for the strong interaction, thus establishing quantum chromodynamics (QCD) as a fundamental non-Abelian gauge theory. A basic understanding of hadron properties, however, such as confinement and the emergence of a mass scale, from first principles QCD has remained elusive: Hadronic characteristics are not explicit properties of the QCD Lagrangian and perturbative QCD, so successful in the large transverse momentum domain, is not applicable at large distances. In this article, we shall examine how this daunting obstacle is overcome in holographic QCD with the introduction of a superconformal symmetry in anti de Sitter (AdS) space which is responsible for confinement and the introduction of a mass scale within the superconformal group. When mapped to light-front coordinates in physical spacetime, this approach incorporates supersymmetric relations between the Regge trajectories of meson, baryon and tetraquark states which can be visualized in terms of specific $SU(3)_C$ color representations of quarks. We will also briefly discuss here the implications of holographic models for QCD color transparency in view of the present experimental interest. Based on the invited contribution to the book dedicated to the memory of Harald Fritzsch.

hep-ph↗
arXiv2024

The strong coupling in the nonperturbative and near-perturbative regimes

We use analytic continuation to extend the gauge/gravity duality nonperturbative description of the strong force coupling into the transition, near-perturbative, regime where perturbative effects become important. By excluding the unphysical region in coupling space from the flow of singularities in the complex plane, we derive a specific relation between the scales relevant at large and short distances; this relation is uniquely fixed by requiring maximal analyticity. The unified effective coupling model gives an accurate description of the data in the nonperturbative and the near-perturbative regions.

hep-ph↗
arXiv2024

Entropy from entangled parton states and high-energy scattering behavior

The relation between the gluon density in a hadron and entanglement entropy can shed a new light on the high energy scattering behavior of hadrons. Using the holographic light-front QCD framework the growth above the classical geometric cross section is directly related to the increase of the internal quantum entropy from the entangled parton distribution in hadrons. A rather consistent picture emerges from the scale dependence of the Pomeron from the QCD evolution of the gluon distribution function $g(x, μ)$, the rising of the integrated cross section in photoproduction of vector mesons, the deep inelastic scattering (DIS) experiments at HERA, hadron multiplicity and quantum entropy. We also point out a possible analogy between parton entanglement entropy and the black-hole entropy of Bekenstein and Hawking.

hep-ph↗
arXiv2022

Emergent phenomena in QCD: The holographic perspective

A basic understanding of the relevant features of hadron properties from first principles QCD has remained elusive, and should be understood as emergent phenomena which depend critically on the number of dimensions of physical spacetime. These properties include the mechanism of color confinement, the origin of the hadron mass scale, chiral symmetry breaking and the pattern of hadronic bound states. Some of these complex issues have been recently addressed in an effective computational framework of hadron structure based on a semiclassical approximation to light-front QCD, and its holographic embedding in anti-de Sitter (AdS) space. This framework also embodies an underlying superconformal algebraic structure which gives rise to the emergence of a mass scale within the superconformal group: It determines the effective confinement potential of mesons, baryons and tetraquarks. The normalizable zero-mass ground state is identified with the pion which has no baryonic supersymmetric partner, a property which is shared for the lowest meson state in each particle family. This new approach to hadron physics leads to relativistic wave equations, similar in their simplicity to the Schroedinger equation in atomic physics, and provides important insights into the confinement mechanism of QCD.

hep-ph↗
arXiv2022

Onset of color transparency in holographic light-front QCD

The color transparency (CT) of a hadron, propagating with reduced absorption in a nucleus, is a fundamental property of QCD (quantum chromodynamics) reflecting its internal structure and effective size when it is produced at high transverse momentum, $Q$. CT has been confirmed in many experiments, such as semi-exclusive hard electroproduction, $e A \to e' πX$ for mesons produced at $Q^2 > 3 ~ {\rm GeV}^2$. However, a recent JLab (Jefferson Laboratory) measurement for a proton electroproduced in carbon $e\, {\rm C}\to e' p X$, where $X$ stands for the inclusive sum of all produced final states, fails to observe CT at $Q^2$ up to 14.2 GeV$^2$. In this paper, the onset of CT is determined by comparing the $Q^2$-dependence of the hadronic cross sections for the initial formation of a small color-singlet configuration using the generalized parton distributions from holographic light-front QCD. A critical dependence on the hadron's twist, $τ$, the number of hadron constituents, is found for the onset of CT, with no significant effects from the nuclear medium. This effect can explain the absence of proton CT in the present kinematic range of the JLab experiment. The proton is predicted to have a "two-stage" color transparency with the onset of CT differing for the spin-conserving (twist-3, $τ=3$) Dirac form factor with a higher onset in $Q^2$ for the spin-flip Pauli (twist-4) form factor. In contrast, the neutron is predicted to have a "one-stage" color transparency with the onset at higher $Q^2$ because of the dominance of its Pauli form factor. The model also predicts a strong dependence at low energies on the flavor of the quark current coupling to the hadron.

hep-ph↗
arXiv2021

Longitudinal dynamics and chiral symmetry breaking in holographic light-front QCD

The breaking of chiral symmetry in holographic light-front QCD is encoded in its longitudinal dynamics with its chiral limit protected by the superconformal algebraic structure which governs its transverse dynamics. The scale in the longitudinal light-front Hamiltonian determines the confinement strength in this direction: It is also responsible for most of the light meson ground state mass consistent with the Gell-Mann-Oakes-Renner constraint. Longitudinal confinement and the breaking of chiral symmetry are found to be different manifestations of the same underlying dynamics as found in 't Hooft large $N_C$ QCD(1 + 1) model.

hep-ph↗
arXiv2020

QCD Hidden-Color Hexa-diquark in the Central Core of Nuclei

Hidden-color configurations are a key prediction of QCD with important physical consequences. In this work we examine a QCD color-singlet configuration in nuclei formed by combining six scalar $[u d]$ diquarks in a strongly bound $\rm SU(3)_C$ channel. The resulting hexadiquark state is a charge-2, spin-0, baryon number-4, isospin-0, color-singlet state. It contributes to alpha clustering in light nuclei and to the additional binding energy not saturated by ordinary nuclear forces in \he as well as the alpha-nuclei sequence of interest for nuclear astrophysics. We show that the strongly bound combination of six scalar isospin-0 $[ud]$ diquarks within the nuclear wave function - relative to free nucleons - provides a natural explanation of the EMC effect measured by the CLAS collaboration's comparison of nuclear parton distribution function ratios for a large range of nuclei. These experiments confirmed that the EMC effect; i.e., the distortion of quark distributions within nuclei, is dominantly identified with the dynamics of neutron-proton (``isophobic'') short-range correlations within the nuclear wave function rather than proton-proton or neutron-neutron correlations.

hep-ph↗
arXiv2020

Light-Front Holography and Supersymmetric Conformal Algebra: A Novel Approach to Hadron Spectroscopy, Structure, and Dynamics

We give an overview of recent progress into the infrared structure of QCD based on the gauge/gravity correspondence and light-front quantization, where the color confining interaction for mesons and baryons is determined by an underlying superconformal algebraic structure. This new approach to hadron physics gives remarkable connections and predictions across the entire mass spectrum of hadrons and also describes the infrared behavior of the strong coupling. More recently, an extensive study of form factors, polarized and unpolarized parton distributions and the sea quark contribution to the nucleon has been carried out by extending the holographic formalism to incorporate the nonperturbative structure of Veneziano amplitudes. Contribution to the report "Strong QCD from Hadron Structure Experiments" Jefferson Lab Workshop, 5-9 November, 2019

hep-ph↗
arXiv2018

Universality of Generalized Parton Distributions in Light-Front Holographic QCD

The structure of generalized parton distributions is determined from light-front holographic QCD up to a universal reparametrization function $w(x)$ which incorporates Regge behavior at small $x$ and inclusive counting rules at $x \to 1$. A simple ansatz for $w(x)$ which fulfills these physics constraints with a single-parameter results in precise descriptions of both the nucleon and the pion quark distribution functions in comparison with global fits. The analytic structure of the amplitudes leads to a connection with the Veneziano model and hence to a nontrivial connection with Regge theory and the hadron spectrum.

hep-ph↗
arXiv2017

Implications of the Principle of Maximum Conformality for the QCD Strong Coupling

The Principle of Maximum Conformality (PMC) provides scale-fixed perturbative QCD predictions which are independent of the choice of the renormalization scheme, as well as the choice of the initial renormalization scale. In this article, we will test the PMC by comparing its predictions for the strong coupling α^s_{g_1}(Q), defined from the Bjorken sum rule, with predictions using conventional pQCD scale-setting. The two results are found to be compatible with each other and with the available experimental data. However, the PMC provides a significantly more precise determination, although its domain of applicability (Q \gtrsim 1.5 GeV) does not extend to as small values of momentum transfer as that of a conventional pQCD analysis (Q \gtrsim 1 GeV). We suggest that the PMC range of applicability could be improved by a modified intermediate scheme choice or using a single effective PMC scale.

hep-ph↗
arXiv2016

Supersymmetry Across the Light and Heavy-Light Hadronic Spectrum II

We extend our analysis of the implications of hadronic supersymmetry for heavy-light hadrons in light-front holographic QCD. Although conformal symmetry is strongly broken by the heavy quark mass, supersymmetry and the holographic embedding of semiclassical light-front dynamics derived from five-dimensional anti-de Sitter (AdS) space nevertheless determines the form of the confining potential in the light-front Hamiltonian to be harmonic. The resulting light-front bound-state equations lead to a heavy-light Regge-like spectrum for both mesons and baryons. The confinement hadron mass scale and their Regge slopes depend, however, on the mass of the heavy quark in the meson or baryon as expected from Heavy Quark Effective Theory (HQET). This procedure reproduces the observed spectra of heavy-light hadrons with good precision and makes predictions for yet unobserved states.

hep-ph↗
arXiv2016

Superconformal Algebraic Approach to Hadron Structure

Fundamental aspects of nonperturbative QCD dynamics which are not obvious from its classical Lagrangian, such as the emergence of a mass scale and confinement, the existence of a zero mass bound state, the appearance of universal Regge trajectories and the breaking of chiral symmetry are incorporated from the onset in an effective theory based on superconformal quantum mechanics and its embedding in a higher dimensional gravitational theory. In addition, superconformal quantum mechanics gives remarkable connections between the light meson and nucleon spectra. This new approach to hadron physics is also suitable to describe nonperturbative QCD observables based on structure functions, such as GPDs, which are not amenable to a first-principle computation. The formalism is also successful in the description of form factors, the nonperturbative behavior of the strong coupling and diffractive processes. We also discuss in this article how the framework can be extended rather successfully to the heavy-light hadron sector.

hep-ph↗
arXiv2016

The Spectroscopy and Form Factors of Nucleon Resonances from Superconformal Quantum Mechanics and Holographic QCD

The superconformal algebraic approach to hadronic physics is used to construct a semiclassical effective theory for nucleons which incorporates essential nonperturbative dynamical features, such as the emergence of a confining scale and the Regge resonance spectrum. Relativistic bound-state equations for nucleons follow from the extension of superconformal quantum mechanics to the light front and its holographic embedding in a higher dimensional gravity theory. Superconformal algebra has been used elsewhere to describe the connections between the light mesons and baryons, but in the present context it relates the fermion positive and negative chirality states and uniquely determines the confinement potential of nucleons. The holographic mapping of multi-quark bound states also leads to a light-front cluster decomposition of form factors for an arbitrary number of constituents. The remarkable analytical structure which follows incorporates the correct scaling behavior at high photon virtualities and also vector dominance at low energies.

hep-ph↗