Browsing by Subject "QGP"

Strongly coupled matter called quark–gluon plasma (QGP) is formed in heavy-ion collisions at RHIC [1, 2] and the LHC [3, 4]. The expansion of this matter, caused by pressure gradients, is known to be hydrodynamic expansion. The computations show that the expanding QGP has a small shear viscosity to entropy density ratio (η/s), close to the known lower bound 1/4π [5]. In such a medium one expects that jets passing through the medium would create Mach cones. Many experimental trials have been done but no proper evidence of the Mach cone has been found [6, 7]. Mach cones were thought to cause double-bumps in azimuthal correlations. However these were later shown to be the third flow harmonic. In this thesis a new method is proposed for finding the Mach cone with so called event-engineering. The higher order flow harmonics and their linear response are known to be sensitive to the medium properties [8]. Hence a Mach cone produced by high momentum jet would change the system properties and, thus, the observable yields. Different flow observables are then studied by selecting high energy jet events with different momentum ranges. Considered observables for different momenta are then compared to the all events. Found differences in the flow harmonics and their correlations for different jet momenta are reported showing evidence of Mach cone formation in the heavy-ion collisions. The observations for different jet momenta are then quantified with χ 2 -test to see the sensitivities of different observables to momentum selections.