\subsection{Expectations ahead of the Neutrino Factory}

If a decision were to be taken after the completion of the Reference
Design Report (RDR), say, in 2013, it would be necessary to evaluate
the knowledge of the parameters that govern neutrino oscillations at
this time and to assess the scientific risks for the Neutrino
Factory.
In anticipation, therefore, we describe the expectations for the
status of measurements of $\theta_{13}$, leptonic CP violation, and
the mass hierarchy that will pertain after the the Interim Design
Report (IDR), but ahead of any decision to initiate the Neutrino
Factory project.

\subsubsection{Between IDR and RDR}

Here we discuss the likely evolution of measurements of neutrino
oscillations in the period between the completion of the IDR and the
RDR, i.e., the time from now until the end of 2012.  
The most important
question is whether $\theta_{13}>0$ will have been discovered over
this period.  
To address this question, we show in figure
\ref{fig:evoldisc} the discovery potential as a function of
$\theta_{13}>0$ for those experiments in operation or under
construction during 2009 which may provide useful information before
the time that the RDR will be prepared (marked by the arrow).  
It may be
seen from the figure that the key player is expected to be the Daya Bay
experiment, which has a $\theta_{13}$ discovery reach of $\stheta
\gtrsim 0.02$ at the $3 \sigma$ CL ($\stheta \gtrsim 0.01$ at the 90\%
CL).  
Even if the anticipated timescale is not met, it is clear from the
figure that T2K and NO$\nu$A will discover $\theta_{13}$ for the
median $\delta$ within a few years of the publication of the RDR.
Therefore, we assume that around the time of the RDR, we will know
whether $\stheta \gtrsim 0.01$ (``$\theta_{13}$ discovered'') or
$\stheta \lesssim 0.01$ (``$\theta_{13}$ not discovered'').
\begin{figure}
\begin{center}
\includegraphics[width=0.85\textwidth]{01-PPEG/Figures/evoldiscNH3sNF}
\end{center}
\caption{\label{fig:evoldisc} Evolution of the $\theta_{13}$ discovery
  potential as a function of time ($3\sigma$~CL), i.e., the smallest
  value of $\theta_{13}$ that can be distinguished from zero at
  $3\sigma$.  The bands reflect the (unknown) true value of
  $\delta$. Normal hierarchy assumed. Figure taken from
  reference \cite{Huber:2009cw}.}
\end{figure}
\begin{figure}
\begin{center}
\includegraphics[width=0.45\textwidth]{01-PPEG/Figures/dcvi}
\includegraphics[width=0.45\textwidth]{01-PPEG/Figures/dmhi}
\end{center}
\caption{\label{fig:tsl} CP violation (left panel) and mass hierarchy
  (right panel) discovery potentials as a function of true $\stheta$
  and fraction of true $\delta$ at the 90\%~CL from T2K, NO$\nu$A
  (reactor experiments, Double Chooz and Daya Bay, are included in the
  evaluation to constrain $\theta_{13}$).  The dashed curves
  refer to NO$\nu$A with neutrino running only, whereas the shaded
  contours refer to the nominal NO$\nu$A neutrino-anti-neutrino plan.
  If no contour is shown for a specific year, there is no sensitivity.
  Note the different scales on the vertical axes. Inverted hierarchy
  assumed. Figure taken from reference \cite{Huber:2009cw}.}
\end{figure}

The most interesting question is whether CP violation and the mass
hierarchy can be measured by the time the RDR is finished.  We show in
figure \ref{fig:tsl} the potential for the discovery of CP violation
(left panel) and the mass hierarchy (right panel) as a function of
$\stheta$ and the fraction of true $\delta$ at the 90\%~CL from T2K,
NO$\nu$A and including data from reactor experiments (Double
Chooz and Daya Bay) to improve the constraint on $\theta_{13}$. 
The figure 
shows that even under optimistic conditions, such as at the 90\% CL,
for very large $\stheta$ close to the current bound, and for the
inverted mass ordering (for which the combined performance is better),
there cannot be any information on these performance indicators before
the RDR even from a combined fit to all data.  Since no next
generation experiment beyond the ones discussed here are under
construction at the moment, we do not expect any information on CP
violation and the mass hierarchy from measurements of neutrino
oscillations before the RDR is prepared.

\subsubsection{Between RDR and data taking at the Neutrino Factory}

After the RDR has been delivered, the precision with which $\stheta$
is known will improve rather slowly.
Indeed, the ultimate precision will only be a factor of two or so
better than the precision acheived at the time of the RDR since
there is no experiment under construction which could improve this
bound significantly (see figure \ref{fig:evoldisc}). 
However, at the time the RDR is prepared, there may be a decision in
favour of an alternative next-generation experiment, such as a
super-beam upgrade, which may start data taking earlier or on a
similar timescale as the Neutrino Factory.  
Therefore, we discuss the results to be expected from the experiments
that will be in operation at the time the RDR is prepared and the
results from potential upgrades separately. 
We assume that data taking at the Neutrino  Factory may start as early
as 2020

If $\stheta \gtrsim 0.01$ is discovered before the RDR is delivered,
there is a chance that CP violation may be observed and the mass
hierarchy determined.
This chance is quantified in figure \ref{fig:tsl}. 
If one believes the hint for $\stheta \simeq 0.06$ in reference
\cite{Fogli:2008jx}, CP violation and the mass hierarchy might be
discovered for about 30\% of all values of $\delta$ at the 
90\% CL for the inverted hierarchy. 
Therefore, it is clear that a high confidence level discovery in
advance of the start of data taking at the Neutrino Factory 
is extremely unlikely and could only come from a combination of
different data \cite{Huber:2009cw}. 
The next generation of experiments will be needed to confirm
this result and to determine the oscillation parameters with greater
precision.

In summary, if $\theta_{13} > 0$ has not been discovered before
the RDR is prepared, it is quite unlikely to be discovered until data
from the experiments that are now under construction becomes
available. 
Further, the experiments that are either operating or being
constructed now will not be able to access CP violation or the mass
hierarchy for $\stheta \lesssim 0.01$ (see figure \ref{fig:tsl}). 
Therefore, an advanced, high-sensitivity experiment will be needed.

