Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Unraveling higher-order corrections in the spin dynamics of RIXS spectra   Resonant inelastic x-ray scattering (RIXS) is an evolving tool for
investigating spin dynamics of strongly correlated materials, which complements
inelastic neutron scattering. Both techniques have found that
non-spin-conserving (NSC) excitations in quasi-1D isotropic quantum
antiferromagnets are confined to the two-spinon phase space. Outside this phase
space, only spin-conserving (SC) four-spinon excitations have been detected
using O $K$-edge RIXS. Here, we investigate SrCuO$_2$ and find four-spinon
excitations outside the two-spinon phase space at both O $K$- and Cu
$L_3$-edges. Using the Kramers-Heisenberg formalism, we demonstrate that the
four-spinon excitations arise from both SC and NSC processes at Cu $L_3$-edge.
We show that these new excitations only appear in the second-order terms of the
ultra-fast core-hole lifetime expansion and arise from long-range spin
fluctuations. These results thus open a new window to the spin dynamics of
quantum magnets.

10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph
27
The categories of this paper are: comp-gas
15
The categories of this paper are: nucl-ex
14
The categories of this paper are: math-ph
31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con
6
The categories of this paper are: astro-ph
34
The categories of this paper are: chem-ph
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
26
The categories of this paper are: bayes-an