Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Analytical and Numerical study of the out-of-equilibrium current through
  a helical edge coupled to a magnetic impurity   We study the conductance of a time-reversal symmetric helical electronic edge
coupled antiferromagnetically to a magnetic impurity, employing analytical and
numerical approaches. The impurity can reduce the perfect conductance $G_0$ of
a noninteracting helical edge by generating a backscattered current. The
backscattered steady-state current tends to vanish below the Kondo temperature
$T_K$ for time-reversal symmetric setups. We show that the central role in
maintaining the perfect conductance is played by a global $U(1)$ symmetry. This
symmetry can be broken by an anisotropic exchange coupling of the helical modes
to the local impurity. Such anisotropy, in general, dynamically vanishes during
the renormalization group (RG) flow to the strong coupling limit at
low-temperatures. The role of the anisotropic exchange coupling is further
studied using the time-dependent Numerical Renormalization Group (TD-NRG)
method, uniquely suitable for calculating out-of-equilibrium observables of
strongly correlated setups. We investigate the role of finite bias voltage and
temperature in cutting the RG flow before the isotropic strong-coupling fixed
point is reached, extract the relevant energy scales and the manner in which
the crossover from the weakly interacting regime to the strong-coupling
backscattering-free screened regime is manifested. Most notably, we find that
at low temperatures the conductance of the backscattering current follows a
power-law behavior $G\sim (T/T_K)^2$, which we understand as a strong nonlinear
effect due to time-reversal symmetry breaking by the finite-bias.

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The categories of this paper are: hep-ph
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
6
The categories of this paper are: astro-ph
18
The categories of this paper are: econ
19
The categories of this paper are: eess
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph