Wenbin Zhao

We study particle correlations in high energy jets by comparing the measured energy-energy correlator with that constructed from two individual energy flows with respect to the jet axis. This comparison demonstrates that the genuine correlations are stronger at moderate or large angles across all jet energies, indicating that they are coming from correlated splitting. Meanwhile, at small angles, they increase with jet energy, exhibiting a peculiar pattern that can be used to explore jet energy loss in heavy-ion collisions. This method will provide a unique tool to disentangle different physics by comparing the genuine correlations in jet energy-energy correlators between heavy-ion collisions and proton-proton collisions.

Calculating cross sections in the Color Glass Condensate effective theory requires Fourier transforms of multi-Wilson-line correlators from transverse coordinate space to transverse momentum space. Under the common assumption of impact-parameter independence, each transform reduces to a set of Hankel transforms whose Bessel-function kernels oscillate rapidly at phenomenologically relevant momenta, making direct quadrature prohibitively expensive. We present a Filon-type quadrature, applicable to any integrand, that integrates these oscillatory factors in closed form on the stored coordinate grid, reducing each Hankel transform to a precomputed weight vector and the full nested transform chain to a sequence of matrix products. We develop and validate the method on the deep inelastic scattering dijet cross section beyond the correlation-limit approximation. Porting the calculation to GPU, with custom CUDA kernels that fuse the momentum-space contraction directly into the correlator evaluation, brings the runtime for one dipole input down to about two minutes on a single NVIDIA A800, from several hours on a multi-core CPU. We further generalize the algorithm to three sequential Hankel transforms and validate the resulting six-dimensional transform against an analytic Gaussian integrand family with closed-form results at every stage. This general algorithm is directly applicable to next-to-leading-order proton-nucleus and electron-ion scattering cross-section calculations performed without the correlation-limit approximation. The code is publicly available at https://github.com/CCNU-CGC-py/FFT_filon

We perform a global Bayesian analysis of coherent and incoherent diffractive J / ψ photoproduction in γ + p and γ + Pb collisions using a color glass condensate (CGC)-based framework and ultraperipheral collision data from the Large Hadron Collider (LHC), corrected for the expected effect of electromagnetic dissociation (EMD). Using Gaussian-process emulators of the underlying CGC calculations, we infer model parameters from a combined set of HERA and LHC measurements. We find that the γ + Pb data with EMD correction substantially reduce the previously observed tension between proton and nuclear datasets, enabling a consistent simultaneous description of diffractive J / ψ production in γ + p and γ + Pb collisions within the CGC framework.

We study energy-energy correlators (EECs) in e + e − annihilation and deep inelastic lepton-hadron scattering (DIS), focusing on aspects of nonperturbative physics in these observables. We introduce the EEC jet functions and investigate the infrared behavior of both small-angle EECs and angle-integrated EECs by performing explicit one-loop calculations. The factorization and universality of the EECs in these processes are demonstrated. A matching scheme is proposed to smoothly connect kinematic regions where different scaling behaviors with jet energy are observed. In combination with the next-to-leading order correction, this matching provides a good description of the EEC data and simulations in high-energy e + e − annihilation. Predictions for DIS processes for future electron-ion collider kinematics are also presented.

We perform a global Bayesian analysis of diffractive J / ψ production in γ + p and γ + Pb collisions using a color glass condensate (CGC) based calculation framework. As past calculations have shown that CGC-based models typically overpredict the J / ψ production in γ + Pb collisions at high center of mass energy, we address the question of whether it is possible to describe coherent and incoherent diffractive J / ψ data from γ + p collisions at Hadron–Electron Ring Accelerator (HERA) and the LHC, and from γ + Pb collisions at the LHC simultaneously. Our results indicate that a simultaneous description of γ + p and γ + Pb data is challenging, with results improving when an overall K -factor—scaling γ + p and γ + Pb cross sections to absorb model uncertainties—is introduced.