Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Superconducting gap in BaFe$_{2}$(As$_{1-x}$P$_{x}$)$_{2}$ from
  temperature dependent transient optical reflectivity   Temperature and fluence dependence of the 1.55-eV optical transient
reflectivity in BaFe$_{2}$(As$_{1-x}$P$_{x}$)$_{2}$ was measured and analysed
in the low and high excitation density limit. The effective magnitude of the
superconducting gap of $\sim 5$ meV obtained from the low-fluence-data
bottleneck model fit is consistent with the ARPES results for the $\gamma$-hole
Fermi surface. The superconducting-state nonthermal optical destruction energy
was determined from the fluence dependent data. The in-plane optical
destruction energy scales well with T$_{\mathrm{c}}^{2}$ and is found to be
similar in a number of different layered superconductors.

12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
1
The categories of this paper are: cs
23
The categories of this paper are: solv-int
24
The categories of this paper are: dg-ga
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an
17
The categories of this paper are: q-fin