Angular power spectrum in publically released ALICE events

作者：Llanes Estrada Felipe J^*; Munoz Martinez Jose L

来源：Nuclear Physics A, 2018, 970: 107-132.

DOI：10.1016/j.nuclphysa.2017.11.005

• Heavy ion collisions
• Cosmic microwave background
• Angular correlations
• Angular power spectrum

We study the particles emitted in the fireball following a Relativistic Heavy Ion Collision with the traditional angular analysis employed in cosmology and earth sciences, producing Mollweide plots of the number and p(t) distribution of a few actual, publically released ALICE-collaboration events and calculating their angular power spectrum. We also examine the angular spectrum of a simple two-particle correlation. While this may not be the optimal way of analyzing heavy ion data, our intention is to provide a one to one comparison to analysis in cosmology. With the limited statistics at hand, we do not find evidence for acoustic peaks but a decrease of C-l that is reminiscent of viscous attenuation, but subject to a strong effect from the rapidity acceptance which probably dominates (so we also subtract the m = 0 component). As an exercise, we still extract a characteristic Silk damping length (proportional to the square root of the viscosity over entropy density ratio) to illustrate the method. The absence of acoustic-like peaks is also compatible with a crossover from the QGP to the hadron gas (because a surface tension at domain boundaries would effect a restoring force that could have driven acoustic oscillations). Presently we do not understand a depression of the l = 6 multipole strength; perhaps ALICE could reexamine it with full statistics.

• 出版日期2018-2