and
Neutrino Factory 2004, based on
Rob Fardon, A.E.N., Neal Weiner; astro-ph/0309800
David B. Kaplan, A.E.N., Neal Weiner; hep-ph/0401099
Kathryn Zurek, hep-ph/0405141
Kiyoshi Shiraishi, unpublished
1998, First Convincing evidence for Physics
Beyond the Standard Model from
SuperK, evidence for atmospheric neutrino oscillations
“Breakthrough of the Year”
is the
supernovae evidence for the acceleration of the
universe
But, the
Einstein was wrong about having blundered?
(Cosmological Constant?)
“Why Now” and finetuning are evidence for the
Anthropic Principle?
Strong Evidence for two kinds:
1. 23% Dark Matter -> some garden variety pressureless
clumpy fluid
2. 73% “Dark Energy” -> exotic negative pressure smooth
substance
usually attributed to the energy of the vacuum⎯energy
density which does not dilute with expansion and is
therefore equivalent to Einstein’s cosmological constant.
I will assume this is zero.
sometimes assumed to be some weird dynamical
“quintessence” substance with equation of state
parameter w near -1 which nevertheless does not clump
(not your typical nonrelativistic stuff)
“Smooth, Dark, Tension” Sean Carroll
•
•
•
•
Negative Pressure=Tension
Smooth Tension= Oxymoron?
“Normal” Stuff under tension prefers to Clump
Weird particle physics counterexamples:
1vacuum energy
la slowly rolling scalar field (m~H-1~ 10-33 eV)
dfrustrated network of strings/domain walls
4relativistic, freely streaming particles
After Six Years of Surprises, Do we
Almost Completely Understand
Neutrinos Now?
Flavor
Composition
of n Mass
Eigenstates
q13
q13
Absolute mass scale? CP? Majorana or Dirac? LSND outlier?
Why recent Concordance in the
neutrino oscillation Industry?
Neutrinos are Special! Expect exotic physics to be
discovered there! Window on the Dark Sector!
Can mix with ‘dark’ fermions (aka sterile neutrinos)
Can thus experience ‘dark forces’ much more strongly
than other particles
Oscillations are sensitive to tiny GUT suppressed
operators (standard seesaw)
Environment dependence of oscillations is sensitive to
new millimeter range forces which are subgravitational
strength for other particles
Beyond the n Standard Model
Subject still in experimental youth
Neutrino oscillations offer incredible
sensitivity to new forces, high scales,
ultraweak interactions, new states
Conventional Wisdom about neutrinos,
neutrino expts. has always been wrong!
Coincidences?
-3 4
4
 Density of “Dark Energy” ~ (2 10 ) eV
2
-3 2
2
 Solar Neutrino Mass splitting ~ (4 10 ) eV
2
-2 2
2
 Atmospheric Neutrino Mass splitting ~ (3 10 ) eV
 Convincing evidence for Dark Energy found in 1998
 Convincing evidence for Neutrino Oscillations found in
1998
-3
 Low Scale SUSY gravitino mass ~ 10 eV
More CoincidencesWhy so complicated?
Can dark energy be related to
something we know?
Dark Matter? We know scaling behavior of dark
matter from large scale structure. Dark energy
currently scales very differently.
Scaling behavior of dark energy must have recently
changed (Why Now?)
Neutrinos? Could neutrino energy density
scale like dark energy?
Requires neutrino ‘mass’ to increase with scale factor
Isn’t varying neutrino mass crazy?
No
Varying ‘Mass’ is Everywhere!
Index of refraction
KS regeneration
Quasi particles in condensed matter
MSW effect
All Standard Model fermion mass terms depend
on value of Higgs scalar which can vary (slightly)
All known masses depend on environment
The issue is not ‘whether’, but
‘how much’ neutrino mass should vary !
A simple MassVaryingNeutrino Model
Assume “Dark Sector” (= unknown particles with no standard
Model charges) contains
1 A scalar field A
1 A fermion field n
1 A Yukawa coupling A n n
1 A scalar potential V ( A )
Assume “Our sector” contains
1 Active Neutrinos n
1 Higgs Field H
Allow tiny (y =O (10-12) ) coupling y H n n
 Neutrino mass matrix
.
(
0
yH
yH
A
)
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
Neutrino Masses vary as A
n
Neutrino mass matrix n
(
n
0
yH
n
yH
A
-1
)
2
For large <A> light neutrino mass is ( y H) / A
Assume V ( A ) slowly increasing function of A.
V is then slowly decreasing function of the light neutrino mass
V(A (mn) ) ~
(1+w)/ w
n
m
 Neutrino mass increases adiabatically as neutrino density
dilutes
 Combined neutrino + scalar potential energy decreases
slowly
What is the Scale?
We have 2 pieces of evidence suggesting
a milli-eV scale for new physics.
This is also the inverse cosmic neutrino
spacing.
A milli-eV scale for the A potential (and
mass) leads to Dark Energy
Contrast with ‘cosmon’ type quintessence
model, which requires a mass scale of
10-33 eV.
Smoothness of MaVaN Dark Energy
• When n’s go nonrelativistic, they gravitationally clump at
large scales
• MaVaN’s go nonrelativistic very late (z= a few)
• MaVaN’s get lighter and more relativistic inside clumps =>
‘anti-clumping mechanism’
• Dark energy much smoother than neutrinos V ~ (nn) (1+w)
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
Sterile Neutrinos?
Sterile neutrino mass increasing function of
neutrino density
Mixing with sterile neutrino decreasing
function of neutrino density
Simple to reconcile sterile neutrino with
BBN F mass always much heavier than
temperature
May similarly evade Supernovae bounds
Can we test MaVaN Dark Energy?
 Cosmological tests of neutrino mass from large scale
structure: MaVaN mass was much lighter at high
redshift.
 Model independent relation: mn= (1+w) V/nn
(V= dark energy density)
 No terrestrial sources of high scalar neutrino density
(neutrino density weighted by (m/E)), relative to
cosmological, other than nuclear fireball.
 Main interesting astrophysical source of high scalar
neutrino density is supernova.
Generic tests difficult, not impossible.
 A should have coupling to matter
 Loop suppressed and/or
 Planck/String scale suppressed
 Possible very interesting terms:
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
• Recent unofficial, preliminary analysis of
SuperK atmospheric neutrinos by Kiyoshi
Shiraishi assuming no oscillations in air fits all
data well
• Very weak (consistent with LSND?) upper
bound on mass squared difference in rock from
contained, partially contained events, K2K
• reanalysis of upward through going and upward
stopping muons underway, probably yields best
upper bound on Dm2 in rock
Conventional Wisdom: need > 3 neutrinos to get 3 independent
masses squared, and oscillations involving extra dark states
constrained by Bugey, CDHS, Cosmology, and Supernova, so
LSND must be wrong
Constraints
on Standard
Neutrinos
Constraints from
oscillations in High
Density Material
only
To Do: Theorists
 Model building exploration
 MaVaN consequences for Supernova
 How much room for non standard environment
dependence in Solar/atmospheric/terrestial neutrino
oscillations?
 Consequences for flavor dependence/energy spectrum of
astrophysical neutrino sources
 Early Universe cosmology of acceleron
 More general constraints on sterile neutrinos from
supernovae, cosmology
To Do: Experimentalists
 Document and consider environment of neutrino path in neutrino
oscillation experiments
 Consider q13 measurements in reactor experiments with pathlength
in air and in rock
 Consider environment of neutrinos in direct mass search and 0nbb
measurements
 Short baseline experiments to search for heavier sterile neutrinos
with small mixing angles; consider varying density of material in
neutrino path
Effects of environment in neutrino oscillations?
0nbb decay depends on density of source?
Tritium endpoint searches for absolute n mass
depends on density of source?
Cosmologically “impossible” sterile neutrinos?
Cosmologically “inconsistent” neutrino masses?
A MiniBooNE signal for nm disappearance or ne
appearance