Study of the Physics of Neutrinos

1. Study of the Physics of Neutrinos (Boris Kayser at the Superbeam Working Group meeting, Jan. 29-30, ‘04) Sponsored by the American Physical Society Divisions of — • Particles and Fields • Nuclear Physics • Astrophysics • Physics of Beams Organizational meeting was held December 2003. www.neutrinooscillation.org/studyaps/ Final report will be completed August 2004.

2. Our blessing — Compelling evidence for neutrino mass and mixing. Our opportunity — To answer the neutrino questions raised by this discovery. Our purpose — To ensure that we make the best possible use of this opportunity.

3. Some of the Open Questions • What physics is responsible for neutrino masses and mixing? • How many neutrino species are there?Are there sterile neutrinos? • What is the neutrino mass spectral pattern? • What is the scale of neutrino mass? • Are neutrinos Majorana particles (n = n)? • What is the leptonic mixing matrix? • Do neutrino interactions violate CP? • Is leptonic CP responsible for the baryon asymmetry in the universe?

4. Are there surprises? • Rapid n decay? • Non-Standard-Model n interactions? • Towers of sterile neutrinos from extra dimensions? • ???

5. The Purposes of the Study — Primary Purpose — To move towards a coherent strategy for answering the open neutrino questions — a clear, unified plan that funding sources can easily consider and promote. To this end, we will— • Identify the most important questions • Evaluate the physics reach of the proposed ways of answering them • Examine how different facilities and experiments complement each other • Create a decision tree • Determine an intelligent sequence of facilities and experiments

6. Our findings will guide the creation of the future neutrino program. To quote our Charge — “The Study will lay scientific groundwork for the choices that must be made during the next few years.” — Secondary Purpose — To explain to our colleagues in other areas of physics, our funding sources, and the general public why neutrino physics is now so exciting.

7. Charge to each Working Group • Analyze the physics reach of your experimental approach. • Consider what your approach can contribute to answering the open questions. • Ensure that the relevant experiments are represented within your group. • Provide independent technical evaluation of ideas.

8. Targets Organizing Committee and Working Group Leaders hold Mid-Course Correction Meeting April 1-2 or 4-5. Purpose: To assess the progress of the Working Groups and to coordinate their activities. Entire Study holds three-day Final General Meeting during June 23-28 in Aspen. By the end of this meeting: • The working group findings • Final cross-working-group coordination • Preliminary study conclusions

9. Our Final Product A ~300 page written report. Contents — • Contributions from individual working group members • A summary for each working group • An integrated summary of the study’s findings, written by the working group leaders, the organizing committee, and a few additional generous study participants

10. The Structure of the Study Chairmen Stuart Freedman, Boris Kayser Organizing Committee Janet Conrad, Guido Drexlin, Belen Gavela, Takaaki Kajita, Paul Langacker, Keith Olive, Bob Palmer, Georg Raffelt, Hamish Robertson, Stan Wojcicki Lincoln Wolfenstein

11. Working Groups — The Central Element Each working group is defined by an experimental approach. The groups, their leaders, and their first meeting — Solar and Atmospheric Neutrino Experiments John Bahcall <jnb@ias.edu>, Josh Klein <jrk@physics.utexas.edu> January 19, by phone Reactor Neutrino Experiments Gabriela Barenboim <gabriela@fnal.gov>, Ed Blucher <blucher@hep.uchicago.edu> February 7-8, Chicago Superbeam Experiments and Development Bill Marciano <marciano@bnl.gov>, Doug Michael <michael@hep.caltech.edu> January 29-30, Fermilab

12. Neutrino Factory and Beta Beam Experiments and Development Stephen Geer <sgeer@fnal.gov>, Michael Zisman <mszisman@lbl.gov> March 3-4, tentatively at Argonne Neutrinoless Double Beta Decay and Direct Searches for Neutrino Mass Steve Elliott <elliotts@lanl.gov>, Petr Vogel <pxv@caltech.edu> February 27-28, Caltech What Cosmology/Astrophysics and Neutrino Physics can Teach Each Other Steve Barwick <barwick@HEP.ps.uci.edu>, John Beacom <beacom@fnal.gov> Tentatively February 5, by phone

13. Theorists participate in all working groups. They will also discuss issues like how best to use future measurements to discriminate among theoretical models. Coordinator of theoretical discussions: Rabi Mohapatra <rmohapat@physics.umd.edu> To also join any other working group, please contact its leaders.

14. Conveying the Excitement The importance of our secondary purpose — conveying the excitement in neutrino physics — has been made apparent by recent statements by government representatives. We will — • Devote part of our final report to this • Organize a Neutrino-Fest, with media presence Neutrino experts who are especially good at writing for, or speaking to, the broader community are being sought.

15. We should be able to make a very strong case for a robust, exciting neutrino program. Both DOE and NSF have made it clear that they will be listening to us. Good Luck!