Study On Transversely Polarized Asymmetry In High Energy Scattering Processes

The study of hadron structure has been an active research field in particle physics.The typical hadron mass scale is in the non-perturbative energy region of quantum chromodynamics(QCD).Understanding the hadronic structure is of great significance for studying the non-perturbative properties of QCD.The transversely polarized asymmetry in high energy scattering processes is one of the powerful tools to investigate the internal 3-dimensional structure,especially the spin structure of hadrons.According to the factorization theorem,the physical observables in the high energy scattering processes involving hadrons can be separated into the short range hard scattering part which can be calculated by perturbation theory and the long range non-perturbative part where the parton distribution function(PDF)and fragmentation function(FF)are usually used.The transversely polarized asymmetry in high energy scattering processes is contributed by the convolution of the corresponding PDF and FF according to the factorization framework.The contributions of PDF and FF can be traced back through the study of asymmetries,so as to obtain the information such as the spin distribution and the spin-orbit coupling of parton in hadrons.In this thesis,by utilizing the transverse momentum dependence(TMD)factorization theoretical framework,the phenomenological study of the semi-inclusive deep inelastic scattering(SIDIS)process and the π-p collision Drell-Yan process is carried out.Specifically,based on some transversely polarized asymmetries appeared in the SIDIS process at the future Electron Ion Collider(EIC)in US and Electron-ion collider in China(EicC),as well as the Drell-Yan process measured by the running COMPASS Collaboration,this thesis does the following three aspects of research:1.We apply the TMD factorization formalism to investigate the transverse single spin dependent Collins asymmetry with a sin(φh+φs)modulation in the Kaon meson produced SIDIS process.The asymmetry is contributed by the convolutions of the transversity distribution function of the target proton and the Collins function of the Kaon in the final state.We adopt the available parametrization of collinear h1(x)of target proton as well as the recently extracted result for the Kaon Collins function.To perform the TMD evolution,the parametrization of the nonperturbative Sudakov form factor of the proton and final state Kaon are utilized.We numerically predict the Collins asymmetry for charged Kaon production at EIC and EicC within the accuracy of next-to-leading-logarithmic order.It is found that the asymmetry could be measured at EIC and EicC.Our result indicates that the sea quark transversity distribution function plays an important role in the Collins asymmetry.We emphasize the importance of planned EIC and EicC in the aspect of constraining sea quark distribution functions as well as accessing the information of the nucleon spin structure and the hadronization mechanism.2.We investigate the transverse momentum weighted azimuthal asymmetry with a sin(3φh-φs)modulation in pion produced SIDIS process where the unpolarized electron scattering off the transversely polarized proton,using the weighted function as W=QT3sin(3φh-φs)/(6M2Mh).The weighted asymmetry is contributed by the product of the second transverse-moment of the proton pretzelosity distribution function and the first transverse-moment of the pion Collins function.Using the extracted result for the proton pretzelosity and the available parametrization for the pion Collins function,we numerically predict the weighted sin(3φh-φs)asymmetry for charged pion production at EIC and EicC.One can find that the weighted asymmetries for the π+production in SIDIS process are positive,while those for the π-production are negative in the kinematics regions of EIC and EicC.We emphasize the importance of the planned high luminosity EIC and EicC in the aspect of constraining pretzelosity in the near future.3.We investigate the weighted azimuthal asymmetries in the single transversely polarized π-p Drell-Yan process.We provide theoretical expression of leading twist asymmetries,namely,the weighted(qT/Mp)sinφs asymmetry,the weighted(qT/Mπ)sin(2φ-φs)asymmetry and the weighted qT3/(6MπMp2)sin(2φ+φs)asymmetry.The asymmetries can be interpreted as products of transverse-moments of TMD PDFs of pion and proton.For Boer-Mulders function and unpolarized distribution function of pion,we adopt the model calculation results from the light-cone wave functions.Using the available parametrization of proton Sivers,transversity,and pretzelosity,we present a systematic calculations for weighted asymmetries at the kinematics of the COMPASS,and compare with COMPASS preliminary experimental data.To test our theoretical results,more precise experimental data are needed.In summary,the phenomenological study of some transverse spin dependent asymmetries in the SIDIS process and the Drell-Yan process is carried out.Our theoretical study is helpful to understand the internal 3-dimensional structure of hadrons,especially the spin structure of nucleon,and to provide some theoretical references for the future experiments.