PhD defense Naghmeh Mohammadi @ UU

10 - 05 - 2017 om 12:45 tot 10 - 05 - 2017 om 13:45

Higher Harmonic Anisotropic Flow of Identified Particles

Naghmeh Mohammadi, promovenda aan het Nikhef, verdedigt haar proefschrift 10 mei 2017 aan de Universiteit van Utrecht.

In this thesis, a measurement of the elliptic, triangular, quadrangular and pentagonal anisotropic flow coefficients are presented for identified particles measured in Pb-Pb collisions at 2.76 TeV with the ALICE detector at the Large Hadron Collider. In this study, we show that the collision geometry contributes to all flow harmonics however this dependence is larger for elliptic flow. In ultra-central collisions, where the collision geometry is isotropic, the measurements show that all harmonics have non-zero values rising from contribution of the event-by-event fluctuations of the position of the participating nucleons. Furthermore, by studying these flow harmonics for different identified particles, one can also probe the effect of the late stage hadronic rescattering phase to the development of flow coefficients as well as different particle production mechanisms such as quark coalescence. Different models used in this thesis show that the dissipative, late stage hadronic rescattering phase also has a significant effect on the development of flow harmonics. This effect is incorporated in the hybrid hydrodynamic model used in this thesis (iEBE-VISHNU) as well as A Multi-Phase Transport Model (AMPT). In particular, AMPT measurements highlight the importance of the final state hadronic rescattering phase in the development of the mass ordering of flow coefficients at low transverse momentum (pT) values. In the intermediate pT values, the measurements show a baryon-meson grouping where baryons show a higher magnitude compared to mesons. This is observed also in the AMPT string melting version which qualitatively demonstrates the effect of quark coalescence as the main particle production mechanism in the intermediate pT region.

De promotie vindt plaats op woensdag 10 mei 2017, om 12.45 in de Senaatszaal in het Academiegebouw, Domplein 29, Utrecht.

Higher Harmonic Anisotropic Flow of Identified Particles (pdf)

Promotor: R.J.M. Snellings
Co-Promotor: Dr. P. Christakoglou

Contact: Naghmeh Mohammadi