Conveners
Parallel session 12: Collective dynamics & small systems I
- Ulrich Heinz
It is known from earlier studies that the hadronic interaction affects the measured yield of short lived resonance e.g. $K^{*0}$. Recent studies [1] show that the directed flow ($v_{1}$) of $K^{*0}$ is strongly affected during the hadronic stage due to asymmetric loss in different sides of the $p_{x}$ axis in momentum space caused by the tilted fireball and density dependent rescattering....
This talk presents recent ATLAS measurements investigating correlations between the 'ridge' - azimuthal correlations between particles in the underlying event that extend over all rapidities - and hard scattering processes in $pp$ and $p$+Pb collisions. To study this soft-hard correlation, measurements of two-particle correlations in with two different particle-pair selections are studied. In...
The first measurement of two-particle angular correlations for charged particles with LEP-II data is presented. The study is performed using archived hadronic $e^+e^-$ data collected by ALEPH at center-of-mass energies up to 209 GeV, above the $WW$ production threshold, which provide access to unprecedented charged-particle multiplicities and more complex color-string configurations if...
It was recently discovered that Israel-Stewart theory is not as causal as we thought [1]. When a fluid expands too fast, as in heavy ion simulations at early times, the large viscous stresses modify the propagation speeds, leading to superluminal signaling [2]. Since we would not trust hydrodynamic information speeds anyway, this may not sound like such disconcerting news, were it not for some...
We present calculations of the shear viscosity in two limits using perturbative QCD and an excluded-volume hadron resonance gas at finite BSQ densities. We then develop a framework that interpolates these two limits to calculate shear viscosity across a wide range of finite BSQ densities. The pQCD and hadron resonance gas calculations have different BSQ densities dependence, leading to a...
