A remark on the sign change of the four-particle azimuthal cumulant in small systems

Understand

The azimuthal cumulants, $c_2\{2\}$ and $c_2\{4\}$, originating from the global conservation of transverse momentum in the presence of hydro-like elliptic flow are calculated.

• We observe the sign change of $c_2\{4\}$ for small number of produced particles.
• This is in a qualitative agreement with the recent ATLAS measurement of multi-particle azimuthal correlations with the subevent cumulant method.