tests of non-standard neutrino interactions (nsi)
DESCRIPTION
Tests of non-standard neutrino interactions (NSI). Cecilia Lunardini Institute for Nuclear Theory University of Washington, Seattle. Menu. N on S tandard neutrino-matter I nteractions Accelerator limits Neutrino oscillation sensitivity NSI effects on solar neutrinos - PowerPoint PPT PresentationTRANSCRIPT
Tests of non-standard neutrino interactions (NSI)
Cecilia Lunardini
Institute for Nuclear Theory
University of Washington, Seattle
Menu
Non Standard neutrino-matter Interactions Accelerator limits Neutrino oscillation sensitivity NSI effects on solar neutrinos Ideas for low energy experiments
New interactions: a possibility Not excluded by neutrino coupling
measurements
Theoretically sensible New physics new couplings (new gauge
bosons, …)
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
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, 2002Vilain et al., PLB335, 1994
Neutrino oscillation sensitivity NSI contribute to matter effects (MSW)! Example: solar neutrinos
NSI in e-tau sector only
Understanding the survival probability Regimes:
Vacuum dominates vacuum mixing Matter dominates NSI mixing
Not zero if NSI are flavor-changing!
The survival probability
E/MeV
Positive coupling: longer step
Negative coupling: Flattening
101
NSI on quarks only, same couplings for u and d
Regeneration in the Earth: day/night
If Earth effect can be suppressed by small
“Large” flavor changing NSI needed
07.0)22sin(tan)(
)(2
Earth
A
DayNight
DayNight
)(
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 )(
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 <u12<0.14 90% C.L.
1 , -0.19 <u12<0.11 90% C.L.
u12 < -0.08 new solution!
Best for flat spectrum
LMA-0
LMA-I
LMA-II
0.41
Results/2 : a new solution!
LMA-0 : Day/Night suppressed by ( - )~ 0.15 u
11=d11=-0.065 ; u
12 = d12=-0.15
90,95,99,99.73% C.L.
2 = 79.6
2 = 79.9
2 = 81.7
LMA-1 and LMA-0 : Large effects at medium energy!
8 B
(Best-fit parameters taken)
Update with KamLAND 2004 data Only minor changes
LMA-D excluded by atmospheric neutrinos
LMA-1 and LMA-0 compatible with atmospheric+K2K+MINOS Section of 3D
region at e=-0.15 (others marginalized) ; inverted hierarchy
2min=48.50 for no
NSI
Contours: 2 - 2
min=7.81, 11.35, 18.80 (95%,99%, 3.6 )
LMA-0
LMA-1
Potential for low energy experiments! Look for suppression of Be7 and pep fluxes
NSI at LENS
See Grieb & Raghavan, hep-ph/0609030
Plot courtesy of C. Grieb
Look for distortions in the shape of the survival probability at intermediate E Lack of upturn below SK/SNO threshold
E/MeV101
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)
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)
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)?