The main priorities of the PPEG are the evaluation of the physics performance of the IDS-NF baseline setup, the comparison to its alternatives (such as beta beams), and the building of the physics case, which has been started within the ISS.

a) Physics performance

The PPEG will focus on the evaluation of the physics reach of the neutrino factory setup. This activity will be performed in collaboration with the detector and accelerator working groups, in order to include the updated experimental specifications.

b) Comparison to alternatives

A comparison to alternatives (such as beta beams) or different experiment classes (such as superbeam upgrades) should be performed in collaboration with EUROnu, since there is a strong overlap of interests. The reference for the neutrino factory will be the current IDS-NF baseline setup.

c) Building the physics case and connection to theory

Building the physics case should be a priority on the timescale of the final design report. For that, both the theory community should be included (such as by organizing a workshop), and specific theoretical questions should be posted.

Questions to be answered

The followings list contains open questions which are related to the physics reach of a neutrino factory. Any study concerning these questions will help clarifying the physics case for a neutrino factory.

If you think you have some work which is relevant to these topics, we would be happy to add a link to your paper/article. Email the details to silvia.pascoli@durham.ac.uk

Phenomenological questions

1. What is the physics case for the ECC detector, both concerning standard and non-standard neutrino physics?
2. What kind of new physics a neutrino factory could be sensitive to? (For ex. neutrino decays, decoherence....)
3. Study of the use of the near detector/s for searches of new physics.
4. Study of the potential of the near detector/s in canceling systematical errors.
5. Study of the characteristics of the near detector such as technology, number, ...
6. Study of non-baseline setups for a neutrino factory.
7. Study of the synergy between golden, platinum and silver channels in unveiling standard and non-standard neutrino physics.
8. Do we want a higher muon energy for searches of non-standard physics?
9. Use neutral currents as a physics signal.
10. From the experimental point of view, what are the observables measureable with best precision? The oscillation parameters or some combinatons thereof? Is that somehow relevant for phenomenology?
11. What is the optimal choice for the detector mass and useful-muon decays splitting between shorter and longer baseline?
12. What is the sensitivity reach if the far baseline detector has a smaller mass and /or higher threshold?
13. Simultaneous two-baseline optimization for the IDS baseline setup: where exactly is the L1-L2-optimum?
14. Robustness of baseline wrt changes in luminosity, dm_atm etc.?
15. What is the reason for the worse CPV sensitivity for large theta13 compared to earlier setups? What are the possible experimental strategies to improve the sensitivity?
16. Tests of the impact of systematics (knowledge on cross sections etc.)?
17. Possibly different versions of detection threshold versus backgrounds.
18. How robust is the baseline setup, such as with respect to muon decay splitting between neutrinos and antineutrinos, the value of dm_atm, luminosity, detector mass/muon decay splitting between shorter and longer baseline?
19. Can the physics potential be optimized by different analysis cuts in the far detector?

Theoretical questions

1. Which models would predict theta13, delta, theta23 octant and the deviation from maximal with precision? What is the precision we need to measure these parameters from a theoretical point of view? For a specific model, what is a reasonable precision on the oscillation parameters necessary to gain information about the model?
2. What is the connection between high energy and low energy CP-violation in see-saw models?
3. What models predict neutrino masses as well as new physics at the TeV scale which is testable at the LHC? What is the role of a neutrino factory in testing these models?
4. Study of muon physics.
5. How to search for new physics? Can we use unitarity bounds?
6. Is there a connection between the quark and lepton sector? And if so, would we need to achieve the same precision in the measurements as in the quark sector?
7. Study of tri-bimaximal mixing at a neutrino factory.
8. What would a value of theta13=0 indicate?