Studies of generalized transverse momentum dependent gluon distributions in diffractive processes

QCD in high energy collisionsThis chapter is dedicated to giving a brief overview of the fundamental concepts of QCD and high-energy collisions.In Sec.2.1, we examine the behavior of the running strong coupling as a result of QCD's non-Abelian symmetry.The section also delves into two important QCD phenomena: confinement and asymptotic freedom, which stem from the non-Abelian gauge theory.Sec.2.2 explores high-energy Deep Inelastic Scattering (DIS) as a tool to study the internal structure of the proton.We then discuss collinear Parton Distribution Functions (PDFs) in Sec.2.3, which serve as the foundation for further analysis of the proton's internal structure in subsequent chapters.We also emphasize the importance of Wilson lines and the gauge invariance of correlation functions.