Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Crystalline symmetry protected helical Majorana modes in the iron
  pnictides   We propose that propagating one-dimensional Majorana fermions will develop in
the vortex cores of certain iron-based superconductors, most notably
Li(Fe$_{1-x}$Co$_x$)As. A key ingredient of this proposal are the 3D Dirac
cones recently observed in ARPES experiments [P. Zhang et al., Nat. Phys.
$\textbf{15}$, 41 (2019)]. Using an effective Hamiltonian around the $\Gamma-Z$
line we demonstrate the development of gapless one-dimensional helical Majorana
modes, protected by $C_4$ symmetry. A topological index is derived which links
the helical Majorana modes to the presence of monopoles in the Berry curvature
of the normal state. We present various experimental consequences of this
theory and discuss its possible connections with cosmic strings.

36
The categories of this paper are: cmp-lg
19
The categories of this paper are: eess
15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg
14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
6
The categories of this paper are: astro-ph
11
The categories of this paper are: hep-lat
23
The categories of this paper are: solv-int
18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga