1. Tests of non-standard neutrino interactions (NSI) Cecilia Lunardini Institute for Nuclear Theory University of Washington, Seattle

2. Menu Non Standard neutrino-matter Interactions Accelerator limits Neutrino oscillation sensitivity NSI effects on solar neutrinos Ideas for low energy experiments

3. New interactions: a possibility Not excluded by neutrino coupling measurements Theoretically sensible  New physics  new couplings (new gauge bosons, …)

4. Neutral current, low energy Neutral current  neutrino + q,e  neutrino + q,e Low energy  Momentum transfer << new physics scale 4-fermion interactions  Flavor changing+flavor preserving NSI

5. Accelerator limits (direct only) Direct bounds: CHARM, NuTeV  no SU(2) + charged lepton data  Strong in muon sector  Weak in e-tau sector Zeller et al., PRL 88, 2002 Vilain et al., PLB335, 1994

6. Neutrino oscillation sensitivity NSI contribute to matter effects (MSW)! Example: solar neutrinos  NSI in e-tau sector only

7. Understanding the survival probability Regimes: Vacuum dominates  vacuum mixing Matter dominates  NSI mixing Not zero if NSI are flavor-changing!

9. The survival probability E/MeV Positive coupling: longer step Negative coupling: Flattening 101 NSI on quarks only, same couplings for u and d

10. Regeneration in the Earth: day/night  If Earth effect can be suppressed by small  “Large” flavor changing NSI needed

11. Fit to the data? Good fit needs:  ~ 30% survival of 8B  Flat SK and SNO spectrum No indication of upturn at lower E No evidence of Earth matter effect (< ~ 7%) favored Small mass splitting possible for small

12. Results of data analysis/1 Bounds on NSI  NSI on quarks.  Fit of 2002 KamLAND data + BP04 model+ solar Cl, Ga rates, SK-ES, SNO day- night (phase I) SNO rates (phase II), neutral current SNO free parameter (modified by NSI)  11 =0, -0.32 <  u 12 <0.14 90% C.L.   1, -0.19 <  u 12 <0.11 90% C.L.  u 12 < -0.08 new solution! Best for flat spectrum

13. LMA-0 LMA-I LMA-II  0.41 Results/2 : a new solution! LMA-0 : Day/Night suppressed by (  -  )~ 0.15  u 11 =  d 11 =-0.065 ;  u 12 =  d 12 =-0.15 90,95,99,99.73% C.L.  2 = 79.6  2 = 79.9  2 = 81.7

14. LMA-1 and LMA-0 : Large effects at medium energy! 8 B8 B (Best-fit parameters taken)

15. Update with KamLAND 2004 data Only minor changes  LMA-D excluded by atmospheric neutrinos

16. LMA-1 and LMA-0 compatible with atmospheric+K2K+MINOS Section of 3D region at  e  =-0.15 (others marginalized) ; inverted hierarchy   2 min =48.50 for no NSI Contours:  2 -  2 min =7.81, 11.35, 18.80 (95%,99%, 3.6  ) LMA-0 LMA-1

17. Potential for low energy experiments! Look for suppression of Be7 and pep fluxes

18. NSI at LENS See Grieb & Raghavan, hep-ph/0609030 Plot courtesy of C. Grieb

19. Look for distortions in the shape of the survival probability at intermediate E  Lack of upturn below SK/SNO threshold E/MeV 101

20. FAQs How large NSI are needed?  About 10% of standard coupling per each component of matter (electrons, u,d, quarks) Are these values natural?  Not very… but possible Can these effects be mimicked by other physics?  yes: sterile neutrinos, noise in solar matter, mass varying neutrinos Can other experiments test this?  Neutrino factories, LBL beams, KamLAND high statistics (LMA-0)

21. Conclusions Possible large neutral current NSI of neutrinos in the e-tau sector  allowed by all existing experiments (accelerators, neutrino oscillations exp.) Large NSI could have tiny effects where we have looked so far!  little effect on current solar data (8B), on atmospheric neutrinos and on short-medium baseline neutrino beams (MINOS)

22. But could appear dramatically in lower energy solar neutrino data!  Different shape of probability  Suppression of 7Be, pep Win-win game for low energy detectors!  Negative result?  best constraint on NSI  Positive result?  Another evidence of new physics in neutrinos Different vacuum oscillations parameters (solar mass splitting smaller, atmospheric mixing not maximal)?