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Zhao, Zhiwen

Publications and source records attributed to Zhao, Zhiwen.

SIDIS-RC EvGen: A Monte-Carlo event generator of semi-inclusive deep inelastic scattering with the lowest-order QED radiative corrections

SIDIS-RC EvGen is a C++ standalone Monte-Carlo event generator for studies of semi-inclusive deep inelastic scattering (SIDIS) processes at medium to high lepton beam energies. In particular, the generator contains binary and library components for generating SIDIS events and calculating cross sections for unpolarized or longitudinally polarized beam and unpolarized, longitudinally or transversely polarized target. The structure of the generator incorporates transverse momentum-dependent parton distribution and fragmentation functions, whereby we obtain multi-dimensional binned simulation results, which will facilitate the extraction of important information about the three-dimensional nucleon structure from SIDIS measurements. In order to build this software, we have used recent elaborate QED calculations of the lowest-order radiative effects, applied to the leading order Born cross section in SIDIS. Here, in this paper, we provide details on the theoretical formalism as well as the construction and operation of SIDIS-RC EvGen, e.g., how we handle the event generation process and perform multi-dimensional integration. We also provide example programs, flowcharts, and numerical results on azimuthal transverse single-spin asymmetries.

97 MATHEMATICS AND COMPUTING↗

The TMD Program at JLab

As a part of the general nucleon imaging effort, there have been many efforts to access the transversemomentum dependent parton distributions (TMDs) by using the semi-inclusive deep inelasticscattering (SIDIS) processes. The recently upgraded Continuous Electron Beam AcceleratorFacility (CEBAF) at Jefferson Lab (JLab) provides golden opportunities to study them in valencequark region. The TMDs describe the three-dimensional, spin-correlated distributions of quarksand gluons in the nucleon in momentum space. The corresponding SIDIS measurements requirehigh intensity and polarization with large kinematic coverage which will be provided by severaldifferent detectors. We present an overview of the planned JLab TMD program in the 12 GeVera.

Gao, Haiyan↗

New results on spin and 3D structure measurements

The nucleon spin structure has puzzled the physics community for about 30 years since the originaldiscovery made by the EMC collaboration in late 1980s that the quark spin only contributesa small fraction to the nucleon spin. With major efforts from both theoretical and experimentalsides, the quark spin contribution is relatively well known and the gluon spin contribution is becomingknown in recent years. To fully understand the nucleon spin structure, the study has gonebeyond one dimensional to three dimensional (3D) to probe the confined motion and access theorbital angular momentum of the partons inside the nucleon. In this paper, we briefly review theexperimental status and the progress during the last year on the study of nucleon spin and 3Dstructures.

Gao, Haiyan↗