Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Mixed-order transition in the antiferromagnetic quantum Ising chain in a
  field   The antiferromagnetic quantum Ising chain has a quantum critical point which
belongs to the universality class of the transverse Ising model (TIM). When a
longitudinal field ($h$) is switched on, the phase transition is preserved,
which turns to first-order for $h/\Gamma \to \infty$, $\Gamma$ being the
strength of the transverse field. Here we will re-examine the critical
properties along the phase transition line. During a quantum block
renormalization group calculation, the TIM fixed point for $h/\Gamma>0$ is
found to be unstable. Using DMRG techniques, we calculated the entanglement
entropy and the spin-spin correlation function, both of which signaled a
divergent correlation length at the transition point with the TIM exponents. At
the same time, the bulk correlation function has a jump and the end-to-end
correlation function has a discontinuous derivative at the transition point.
Consequently for finite $h/\Gamma$ the transition is of mixed-order.

30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
1
The categories of this paper are: cs
24
The categories of this paper are: dg-ga
12
The categories of this paper are: nucl-th
15
The categories of this paper are: nucl-ex
31
The categories of this paper are: ao-sci
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
33
The categories of this paper are: plasm-ph
13
The categories of this paper are: quant-ph
17
The categories of this paper are: q-fin
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex