Two-particle correlation via Bremsstrahlung

초록

Ridge is the well-known structure in two-particle azimuthal correlations at high-energy heavy-ion collisions. This structure is physically understood through elliptic and higher-order flows at nucleus-nucleus collisions. This structure also appears in small systems, such as proton-proton collisions, recently. However, Ridge structure in small system is hard to well-explain using hydrodynamics, since the small system is not regarded as possibly producing Quark-Gluon plasma. Thus, we try to describe this phenomena through kinematic interaction between jets and medium partons. In high-energy heavy-ion collision, the energetic particles called jets go out with specific direction and lose their energy while passing through the medium. During such process, photons/gluons are emitted from interaction between jets and medium partons. We concentrate on energy loss via photon radiations, as known as Bremsstrahlung. The study on scattering between jet and medium is already published in 2012 by C.Y. Wong. In this study, two symmetric double scattering process between jet particle and medium parton produce certain constructive interference. This constructive interference gives collective motion, in which medium partons are aglined along incoming jet particles. We adopt such result of study on scattering between jets and medium patons when we describe the Bremsstrahlung process. Therefore, we calculate the two symmetric diagrams of photon emission and medium parton scattering. We expect these two amplitudes to give constructive interference leading to the collective motion of medium. And we also expect that Ridge behaviour might be explained if we combine our results with jet colliding results.