Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Smallest QCD Droplet and Multiparticle Correlations in pp Collisions   The collective evolution of produced matter in heavy-ion collisions is
effectively described by hydrodynamics from time scales greater than the
inverse of the temperature, $\tau \gtrsim 1/T$. In the context of the Gubser
solution, I show that the hydrodynamization condition $\tau \, T \gtrsim 1$ is
translated into an allowed domain in the spatial system size and the final
multiplicity for hydrodynamics applicability. It turns out that the flow
measurements in pp collisions are inside the domain of validity. I predict that
by approaching the boundaries of the allowed domain the hydrodynamic response
to the initial ellipticity changes its sign. I follow a rather
model-independent approach for the initial state where, instead of modeling the
initial energy density of individual events, the initial system size and
ellipticity event-by-event fluctuation are modeled. The model, initial state
fluctuation+Gubser solution+Cooper-Frye freeze-out, describes the multiplicity
and transverse momentum dependence of two-point and four-point correlation
functions ($c_2\{2\}$ and $c_2\{4\}$) in an accurate agreement with pp
collision experimental measurements. In particular, the sign of the four-point
correlation function is the same as the observation, which failed to be
described correctly in previous studies. I also predict a signal for the sign
change in the hydrodynamic response that can be inspected in future
experimental measurements of two-point and four-point correlation functions at
lower multiplicities.

10
The categories of this paper are: q-bio
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
13
The categories of this paper are: quant-ph
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex