Conveners
Parallel 2: Phenomenological models - Light-front quark models
- Ruben Sandapen (Acadia University)
Parallel 2: Jet physics
- Francois Gelis
Parallel 2: Small-x physics and heavy ions - Saturation and evolution
- Cyrille Marquet (CPHT - Ecole Polytechnique)
Parallel 2: Phenomenological models - Covariant models
- Tobias Frederico (Instituto Tecnologico de Aeronautica)
Parallel 2: Small-x physics and heavy ions - Gluon distributions
- Jean-Philippe Lansberg (IPN Orsay, Paris Saclay U. / IN2P3-CNRS)
We develop a non-perturbative, light-front approach for valence quark x-distribution in the nucleon to explain quark interactions in the mean field of the nucleonic interior. The main motivation for the model is to obtain a mean field description of the valence quarks as a baseline upon which to study the short-range quark-quark interactions that generate the high x tail of valence quark...
The light-front wavefunctions for mesons obtained from holographic light-front QCD are used to obtain light-cone distribution amplitudes and transition form factors for B decays to light mesons. I present our predictions for some rare decay channels of B mesons.
We study the twist-2 distribution amplitudes (DAs) and the decay constants of pseudoscalar as well as the longitudinally and transversely polarized vector heavy ($D$, $D_s$, $B$ and $B_s$) mesons in the light-front quark model with the Coulomb plus exponential-type confining potential $V_{\rm {exp}} = a + b e^{\alpha r}$ in addition to the hyperfine interaction. We first compute the mass...
In the framework of the QCD shock-wave approach, we review our results on the description
of diffractive production of various final states (jets, meson) at next-to-leading order.
This is applied to the description of exclusive diffractive dijet electroproduction at HERA.
In this talk we investigate the use of jets to measure transverse momentum distributions. We study the effect of the election of the axis in the description of the jet. Critically, for an axis insensitive to recoil, the so called Winner-Take-All axis, the jet TMD has the same double-scale renormalization group evolution as TMD fragmentation functions for all radii R. This fact means that TMD...
We study angularity event shape for deep inelastic scattering (DIS) in the framework of soft-collinear effective theory (SCET) tool to push the frontier of the precision jet physics in the future Electron-Ion Collider (EIC). Angularity $\tau_a$ Depends On a continuous parameter $`a'$ whose limiting values at $a=0$ and $a=1$ provide 'thrust' and 'jet broadening' event shapes. The angularity...
Deep Inelastic Scattering (DIS) is the cleanest tool available to probe the content of a fast proton or nucleus. In the regime of low Bjorken x, one enters in the nonlinear regime of gluon saturation, where the gluons are better described as a strong coherent semi-classical field (a.k.a. Color Glass Condensate) than as a collection of quasi on-shell partons. Hence, that regime lies outside the...
We present a model with which we predict the cross sections for exclusive and dissociative photo and electroproduction of light and heavy vector mesons off protons; the model describes correctly available experimental data. The model is based on the color-dipole approach and incorporates geometric fluctuations of the target-proton partonic structure. The fluctuations are generated as randomly...
The Balistky-Kovchegov equation has been solved including the impact-parameter dependence. Previous attempts to include this dependence have been spoiled by the presence of the so-called Coulomb tails produced by the evolution. We show, that using the collinearly-improved kernel to the BK equation, the Coulomb tails are heavily suppressed which allows for a correct description of existing data...
Most of the progress in high-energy Quantum Chromodynamics has been obtained within the eikonal approximation and infinite Wilson-line operators. Evolution equations of Wilson lines with respect to the rapidity parameter encode the dynamics of the hadronic processes at high energy. However, even at high energy many interesting aspects of hadron dynamics are not accessible within the eikonal...
The most known scheme to regulate the rapidity/UV divergences of the Transverse Momentum
Distribution operators due to the infinite light-like gauge links is the Collis Soper Sterman formalism
or the Soft Collinear Effective Theory formalism. An alternative choice is provided by the scheme
used in the small-x physics. The corresponding evolution equations differ already at leading...
The main tools to probe the structure of the hadron in terms of quarks and gluons are the electron elastic and inelastic scattering experiments. In the elastic case, the charge and current distributions of the on-mass-shell target hadron are encoded in the electromagnetic form factors which depend on the virtual photon four-momentum square $q^2=-Q^2$. For the on-mass-shell spin-zero charged...
I present results for the quark mass function in Minkowski space in both the spacelike and timelike regions calculated from the same quark-antiquark interaction kernel used in the latest meson calculations within the Covariant Spectator Theory. This kernel consists of a Lorentz vector effective one-gluon-exchange-type interaction, a vector constant, and a mixed scalar-pseudoscalar covariant...
The status of the chiral-invariant Nambu-Jona-Lasinio (NJL) four-fermi model is quite equivocal. It serves as the paradigm for dynamical symmetry breaking and yet it is not renormalizable. NJL only studied one loop graphs with point vertices, and needed to use an ultraviolet cutoff. We propose to dress the point vertices with scale invariant vertices with anomalous dimensions. We show that if...
We compare the cross section for exclusive $J/\psi$ photoproduction calculated in the NLO collinear factorization approach with HERA and LHCb data. We use the optimum scale formalism together with the subtraction of the low $k_t < Q_0$ contribution from the NLO coefficient function to avoid a crucial double counting and show that the existing global parton distribution functions (PDFs) are...
We explore how the positivity of the $P_T$-integrated $\eta_c$-hadroproduction cross-section computed at NLO in $\alpha_s$ can set up constraints on the $x$ dependence of both gluon PDFs and TMDs at low scales.
Exclusive quarkonium production offers one of the best ways to obtain information about gluon distributions at small $x$, in ultraperipheral heavy-ion collisions and deep inelastic scattering. The quarkonium light-cone wave functions needed in the dipole picture have typically been available only at tree level, either in phenomenological models or in the nonrelativistic limit. In this talk, we...
We present an estimate of azimuthal asymmetry ($cos~2\phi$) in $J/\psi$ production in electron-proton collision within the kinematics of the planned electron-ion collider (EIC). We find a small but a sizable asymmetry in the small $x$ region which can be observed at the EIC. This sizable asymmetry directly probes the Weisz\"{a}ker-Williams (WW) type linearly polarized gluon distribution in...
We explore the possibility of using transverse single spin asymmetries (TSSAs) arising in prompt photon production through scattering of unpolarized beams of protons/ photons off transversely polarized proton target as probes of Gluon Sivers Function (GSF). We present estimates of asymmetry at RHIC energy, both for direct and fragmentation contributions, using recent fits of GSF in case of $p...
