Speaker
Shinichi Esumi
(University of Tsukuba (JP))
Description
The initial density distribution in a heavy ion collision fluctuates
due to the finite number of participating nucleons, which leads to
higher harmonic flow as recently measured at RHIC and the LHC. Such
spatial fluctuations may be preserved until kinetic freeze-out,
depending on the strength of the initial fluctuations, the flow
profile, the expansion time, and viscosity of the created matter.
Hanbury Brown and Twiss (HBT) interferometry is a powerful tool to
study the space-time extent of a particle emitting source in heavy ion
collisions. PHENIX has measured the azimuthal angle dependence of HBT
radii with respect to the 2\textsuperscript{nd} and
3\textsuperscript{rd}-order event planes in Au$+$Au collisions at
$\sqrt{s_{NN}}= 200$~GeV.
The results for the 2\textsuperscript{nd}-order dependence indicate
that the initial eccentricity is reduced during the medium evolution,
but not reversed in the final state, which is consistent with previous
results. In contrast, the results for the 3\textsuperscript{rd}-order
dependence indicate that the initial triangular shape is signicantly
reduced and potentially reversed by the end of the medium evolution,
and that the 3\textsuperscript{rd}-order oscillations are largely
dominated by the dynamical effects from triangular flow. The
measurement of the HBT radii from different particle correlations such
as charged kaons over the wide $m_T$ ranges give deeper insight on the
emission source dynamics. We will report and discuss these new
comprehensive HBT measurement in Au$+$Au collisions at $\sqrt{s_{NN}}
= 200$~GeV.
| On behalf of collaboration: | PHENIX |
|---|
Primary author
Shinichi Esumi
(University of Tsukuba (JP))
