Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evidence of a multiple boson emission in Sm$_{1-x}$Th$_x$OFeAs   We studied a reproducible fine structure observed in dynamic conductance
spectra of Andreev arrays in Sm$_{1-x}$Th$_x$OFeAs superconductors with various
thorium concentrations ($x = 0.08 - 0.3$) and critical temperatures $T_c =
26-50$\,K. This structure is unambiguously caused by a multiple boson emission
(of the same energy) during the process of multiple Andreev reflections. The
directly determined energy of the bosonic mode reaches $\varepsilon_0 = 14.8
\pm 2.2$\,meV for optimal compound. Within the studied range of $T_c$, this
energy as well as the large $\Delta_L$ and the small $\Delta_S$ superconducting
gaps, nearly scales with critical temperature with the characteristic ratio
$\varepsilon_0/k_BT_c \approx 3.2$ (and $2\Delta_L/k_BT_c \approx 5.3$,
correspondingly) resembling the expected energy $\Delta_L + \Delta_S$ of spin
resonance and spectral density enhancement in $s^{\pm}$ and $s^{++}$ states,
respectively.

2
The categories of this paper are: math
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ
32
The categories of this paper are: atom-ph
23
The categories of this paper are: solv-int
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
25
The categories of this paper are: patt-sol
30
The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc