Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Which long-baseline neutrino experiments are preferable?   We discuss the physics of superbeam upgrades, where we focus on T2KK, a NuMI
beam line based experiment NOvA*, and a wide band beam (WBB) experiment
independent of the NuMI beam line. For T2KK, we find that the Japan-Korea
baseline helps resolve parameter degeneracies, but the improvement due to
correlated systematics between the two detectors (using identical detectors) is
only moderate. For an upgrade of NOvA with a liquid argon detector, we
demonstrate that the Ash River site is preferred compared to alternatives, such
as at the second oscillation maximum, and is the optimal site within the U.S.
For a WBB experiment, we find that high proton energies and long decay tunnels
are preferable. We compare water Cherenkov and liquid argon technologies, and
find the break-even point in detector cost at about 4:1. In order to compare
the physics potential of the different experimental configurations, we use the
concept of exposure to normalize the performance. We find that experiments with
WBBs are the best experimental concept. NOvA* could be competitive with
sufficient luminosity. If $\sin^2 2\theta_{13}$ > 0.01, a WBB experiment can
perform better than a neutrino factory.

19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
36
The categories of this paper are: cmp-lg
25
The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
3
The categories of this paper are: physics