Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ultra-Peripheral Collisions with gold ions in STAR   In 2010, the STAR Collaboration collected 38 million low-multiplicity
triggers for ultra-peripheral collision studies. We present new results
involving photonuclear interactions in ultra-peripheral relativistic heavy ion
collisions (UPCs), based on an analysis of 384,000 photoproduced pion pairs,
from $\rho$, $\omega$ and direct $\pi^+\pi^-$ pair production.The $\omega$
component is clearly visible through its interference with the $\rho$ peak. The
relative amplitudes of the three components have been measured, along with the
phase angle between the $\rho$ and $\omega$ components.
  Using a two-year (2010 and 2011) dataset, we explore higher mass final
states, and observe a $\pi^+\pi^-$ state with a mass of $1653 \pm 10$ MeV and a
width of $164\pm 15$ MeV (statistical errors only). The state is at least
roughly compatible with the $\rho_3(1690)$.
  The $\rho^0$ squared momentum transfer ($t$) spectrum exhibits a spectrum
with both coherent and incoherent prodution. The coherent component shows two
characteristic diffraction minima, with positions that are sensitive to the
hadronic radius of the gold nucleus.

14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
17
The categories of this paper are: q-fin
18
The categories of this paper are: econ
0
The categories of this paper are: hep-ph
3
The categories of this paper are: physics
36
The categories of this paper are: cmp-lg
4
The categories of this paper are: cond-mat
28
The categories of this paper are: alg-geom
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
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The categories of this paper are: q-alg
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The categories of this paper are: eess