Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Bulk quantities in nuclear collisions from running coupling
  $k_{T}$-factorization and hybrid simulations   Starting from a Color Glass Condensate (CGC) framework, based on a
running-coupling improved $k_T$-factorized formula, we calculate bulk
observables in several heavy-ion collision systems. This is done in two ways:
first we calculate the particle distribution directly implied from the CGC
model, and we compare this to the case where it is instead used as initial
conditions for a hybrid hydrodynamic simulation. In this way, we can assess the
effects of hydrodynamic and hadronic evolution by quantifying how much they
change the results from a pure initial state approach and, therefore, to what
extent initial condition models can be directly compared to experimental data.
We find that entropy production in subsequent hydrodynamic evolution can
increase multiplicity by as much as 50\%. However, disregarding a single
overall normalization factor, the centrality, energy, and system size
dependence of charged hadron multiplicity is only affected at the $\sim$5\%
level. Because of this, the parameter-free prediction for these dependencies
gives reasonable agreement with experimental data whether or not hydrodynamic
evolution is included. On the other hand, our model results are not compatible
with the hypothesis that hydrodynamic evolution is present in large systems,
but not small systems like p-Pb, in which case the dependence of multiplicity
on system size would be stronger than seen experimentally. Moreover, we find
that hydrodynamic evolution significantly changes the distribution of momentum,
so that observables such as mean transverse momentum are very different from
the initial particle production, and much closer to measured data. Finally, we
find that a good agreement to anisotropic flow data cannot be achieved due to
the large eccentricity generated by this model.

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The categories of this paper are: hep-th
23
The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
10
The categories of this paper are: q-bio
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ex