Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observational Evidence for Stochastic Shock Drift Acceleration of
  Electrons at the Earth's Bow Shock   The first-order Fermi acceleration of electrons requires an injection of
electrons into a mildly relativistic energy range. However, the mechanism of
injection has remained a puzzle both in theory and observation. We present
direct evidence for a novel stochastic shock drift acceleration theory for the
injection obtained with Magnetospheric Multiscale (MMS) observations at Earth's
bow shock. The theoretical model can explain electron acceleration to mildly
relativistic energies at high-speed astrophysical shocks, which may provide a
solution to the long-standing issue of electron injection.

15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
7
The categories of this paper are: hep-th
9
The categories of this paper are: nlin
25
The categories of this paper are: patt-sol
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
4
The categories of this paper are: cond-mat
29
The categories of this paper are: funct-an
18
The categories of this paper are: econ