Holographic Light-front Wavefunction Research Articles

Exclusive diffractive J/ψ and ψ(2S) production in dipole model using a holographic AdS/QCD light-front wavefunction with longitudinal confinement

We use anti-de Sitter/quantum chromodynamics based holographic light-front wavefunction (LFWF) for vector meson, in conjunction with the dipole model to investigate the cross sections data for the diffractive and exclusive J/ψ and ψ(2S) production. We confront the experimental data using a new explicit form of the holographic LFWF, where the longitudinal confinement dynamics in the light-front Schrödinger equation is captured by the ’t Hooft equation of (1+1)-dim, in large Nc approximation, in addition to the transverse confinement dynamics governed by the confining mass scale parameter κ in vector mesons. We obtain the LFWF parameters from fitting to the exclusive J/ψ electroproduction data from the electron-proton collision at the Hadron Electron Ring Accelerator collider for mc=1.27 GeV. Our results suggest that the dipole model together with holographic meson LFWFs with longitudinal confinement is able to give a successful description for differential scattering cross section for exclusive J/ψ electroproduction for H1 and ZEUS data. We also predict the rapidity distributions of differential scattering cross section and total photoproduction of J/ψ and ψ(2S) states in proton-proton ultraperipheral collisions (UPCs) at center of mass energy s=7,13 TeV. Using the minimum set of parameters, our predictions for the UPCs are in good agreement with the recent experimental observations of UPCs at ALICE and LHCb Collaborations. Published by the American Physical Society 2024

Nucleon electroweak form factors using spin-improved holographic light-front wavefunctions

We construct spin-improved holographic light front wavefunctions for the nucleons (viewed as quark-diquark systems) and use them to successfully predict their electromagnetic Sachs form factors, their electromagnetic charge radii, as well as the axial form factor, charge and radius of the proton. The confinement scale is the universal mass scale of light-front holography, previously extracted from spectroscopic data for light hadrons. With the Dirac and Pauli form factors normalized using the quark counting rules and the measured anomalous magnetic moments respectively, the masses of the quark and diquark are the only remaining adjustable parameters. We fix them using the data set for the proton's Dirac-to-Pauli form factor ratio, and then predict all other data without any further adjustments of parameters. Agreement with data at low momentum-transfer is excellent. Our findings support the idea that light (pseudoscalar and vector) mesons and the nucleons share a nonperturbative universal holographic light-front wavefunction which is modified differently by their spin structures.

Dynamical spin effects in the holographic light-front wavefunctions of light pseudoscalar mesons

We quantify the importance of dynamical spin effects in the holographic light-front wavefunctions of the pion, kaon, $\eta$ and $\eta^\prime$. Using a universal AdS/QCD scale and constituent quark masses, we find that such effects are maximal in the pion where they lead to an excellent simultaneous description of a wide range of data: the decay constant, charge radius, spacelike EM and transition form factors, as well as, after QCD evolution, both the parton distribution function and the parton distribution amplitude data from Fermilab. These dynamical spin effects lead up to a $30\%$ chance of finding the valence quark and antiquark with aligned spins in the pion. The situation is very different for the kaon, where a simultaneous description of the available data (decay constant, radius and spacelike EM form factor) prefer no dynamical spin effects at all. The situation is less clear for the $\eta$ and $\eta^\prime$: while their radiative decay widths data are consistent with dynamical spin effects only in $\eta^\prime$, the data on their spacelike transition form factors clearly favor maximal dynamical spin effects in both mesons.

QCD-Constrained Dynamical Spin Effects in the Pion Holographic Light-Front Wavefunction

Using light-front holography, we predict simultaneously the pion decay constant and the pion charge radius by taking into account (higher twist) dynamical spin effects whose relative importance is constrained by QCD.

Spin effects in the pion holographic light-front wavefunction

We account for dynamical spin effects in the holographic light-front wavefunction of the pion in order to predict its mean charge radius, decay constant, spacelike electromagnetic form factor, twist-2 Distribution Amplitude and the photon-to-pion transition form factor. Using a universal fundamental AdS/QCD scale of 523 MeV and a constituent quark mass of 330 MeV, we find a remarkable improvement in describing all observables.

Diffractiveρandϕproduction at HERA using a holographic AdS/QCD light-front meson wave function

We use an anti-de Sitter/Quantum Chromodynamics (AdS/QCD) holographic light-front wavefunction for the $\rho$ and $\phi$ mesons, in conjunction with the Color Glass Condensate (CGC) dipole cross-section whose parameters are fitted to the most recent 2015 high precision HERA data on inclusive Deep Inelastic Scattering (DIS), in order to predict the cross-sections for diffractive $\rho$ and $\phi$ electroproduction. Our results suggest that the holographic meson light-front wavefunction is able to give a simultaneous description of the $\rho$ and $\phi$ production data provided we use a set of light quark masses with $m_{u,d}$ < $m_{s}$ ~ 0.14 GeV.

Heavy quarkonium in a holographic basis

We study the heavy quarkonium within the basis light-front quantization approach. We implement the one-gluon exchange interaction and a confining potential inspired by light-front holography. We adopt the holographic light-front wavefunction (LFWF) as our basis function and solve the non-perturbative dynamics by diagonalizing the Hamiltonian matrix. We obtain the mass spectrum for charmonium and bottomonium. With the obtained LFWFs, we also compute the decay constants and the charge form factors for selected eigenstates. The results are compared with the experimental measurements and with other established methods.

The application of light front holographic QCD to B physics

Light front holography is a formalism developed by Brodsky and de Téramond in which analytic forms for the hadronic bound state wavefunctions can be obtained. We have used the holographic light front wavefunctions thus obtained to calculate the distribution amplitudes of the light vector mesons ρ and K∗. As a result, we are able to calculate the form factors for B → ρ, K∗ transitions as well as ΛQCD/mb contributions in radiative B(s) → (ρ, K∗)γ decays. We compare our predictions to the available experimental data.