Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Demonstration of one-parameter scaling at the Dirac point in graphene   We numerically calculate the conductivity $\sigma$ of an undoped graphene
sheet (size $L$) in the limit of vanishingly small lattice constant. We
demonstrate one-parameter scaling for random impurity scattering and determine
the scaling function $\beta(\sigma)=d\ln\sigma/d\ln L$. Contrary to a recent
prediction, the scaling flow has no fixed point ($\beta>0$) for conductivities
up to and beyond the symplectic metal-insulator transition. Instead, the data
supports an alternative scaling flow for which the conductivity at the Dirac
point increases logarithmically with sample size in the absence of intervalley
scattering -- without reaching a scale-invariant limit.

34
The categories of this paper are: chem-ph
30
The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
0
The categories of this paper are: hep-ph
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
25
The categories of this paper are: patt-sol
13
The categories of this paper are: quant-ph
21
The categories of this paper are: adap-org
24
The categories of this paper are: dg-ga
28
The categories of this paper are: alg-geom
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas