what is the case for nufact? hitoshi murayama (uc berkeley) intl scoping study meeting of nufact and...

What is the case for nufact?

Hitoshi Murayama (UC Berkeley)

Intl Scoping Study Meeting of

Nufact and SuperbeamBoston University, March

8, 2006

ISS Physics WS Boston 2

The Question

• Neutrino physics has been full of surprises

• We’ve learned a lot in the last ~8 years

• We want to learn more• New projects are more and more expensive

• Is it really worth it?• Especially worth ~B$, B€, 100B¥?


Elevator Pitch

• If you happen to be on an elevator with a powerful senator, can you explain why you want to spend ~B$ on your project in 30 seconds?


What will NOT work

For politicians and taxpayers, these arguments wouldn’t be convincing and/or interesting enough

• Measurements as precisely as we can

• Push limits on 13 as much as we can

• Verify the three-generation framework of neutrino oscillation

• Distinguish different flavor modles• Field needs another machine to sustain itself


Quantum Universe Report

What are neutrinos telling us?

• Of all the known particles, neutrinos are the most mysterious. They played an essential role in the evolution of the universe, and their tiny nonzero mass may signal new physics at very high energies.


Quantum Universe Report

• Einstein’s Dream of Unified Forces– Are there undiscovered principles of nature: new symmetries

, new physical laws?– How can we solve the mystery of dark energy?– Are there extra dimensions of space– Do all the forces become one?

• The Particle World– Why are there so many kinds of particles?– What is dark matter? How can we make it in the laboratory?– What are neutrinos telling us?

• The Birth of the Universe– How did the universe come to be?– What happened to the antimatter?


Outline

• Why Neutrinos?• A few scenarios

– sin2 213 ≪ 0.01– sin2 213 > 0.01– Mini-BooNE confirms LSND– LHC discovers new physics < TeV

• The Big Questions– Scenario to “establish” seesaw/leptogenesis

• Conclusion

Why Neutrinos?


Interest in Neutrino Mass

• So much activity on neutrino mass already.

Why are we doing this?Window to (way) high energy scales beyond the Standard

Model!


Why Beyond the Standard Model

• Standard Model is sooooo successful. But none of us are satisfied with the SM. Why?

• Because it leaves so many great questions unanswered Drive to go beyond the Standard Model

• Two ways:– Go to high energies– Study rare, tiny effects


Rare Effects from High-Energies

• Effects of physics beyond the SM as effective operators

• Can be classified systematically (Weinberg)


Unique Role of Neutrino Mass

• Lowest order effect of physics at short distances

• Tiny effect (m/E)2~(0.1eV/GeV)2=10–20!

• Inteferometry (i.e., Michaelson-Morley)– Need coherent source– Need interference (i.e., large mixing angles)

– Need long baseline

Nature was kind to provide all of them!• “neutrino interferometry” (a.k.a. neutrino oscillation) a unique tool to study physics at very high scales


Ubiquitous Neutrinos

They must have played some important role in the universe!


The Data

de Gouvêa’s classification:

• “Indisputable”– Atmospheric– Solar– Reactor

• “strong”– Accelerator (K2K)

And we shouldn’t forget:

• “unconfirmed”– Accelerator (LSND)


Historic Era in Neutrino Physics

We learned:• Atmospheric s are lost. P=4.2 10–26

(SK) (1998)

• converted most likely to (2000)

• Solar e is converted to either or (SNO) (2002)

• Only the LMA solution left for solar neutrinos (Homestake+Gallium+SK+SNO) (2002)

• Reactor anti-e disappear (2002) and reappear (KamLAND) (2004)


Neutrinos do oscillate!

Proper time


What we learned

• Lepton Flavor is not conserved• Neutrinos have tiny mass, not very hierarchical

• Neutrinos mix a lotthe first evidence for

incompleteness of Minimal Standard Model

Very different from quarks


Typical Theorists’ View ca. 1990

• Solar neutrino solution must be small angle MSW solution because it’s cute

• Natural scale for m223 ~ 10–100 eV2

because it is cosmologically interesting

• Angle 23 must be ~ Vcb =0.04• Atmospheric neutrino anomaly must go away because it needs a large angle

Wrong!

Wrong!

Wrong!Wrong!


The Ivisibles


The Big Questions

• What is the origin of neutrino mass?• Did neutrinos play a role in our existence?

• Did neutrinos play a role in forming galaxies?

• Did neutrinos play a role in birth of the universe?

• Are neutrinos telling us something about unification of matter and/or forces?

• Will neutrinos give us more surprises?Big questions tough questions to answer


Immediate Questions

• Dirac or Majorana? • Absolute mass scale?

• How small is 13?• CP Violation?• Mass hierarchy?

• Is 13 maximal?• LSND? Sterile neutrino(s)? CPT violation?


Tools

• Available tools now:– SuperK, SNO, KamLAND, Borexino, Mini-BooNE, MINOS, Cuoricino, NEMO, SDSS, …

• Available soon (?):– Opera, Double-Chooz, T2K, MINERA, SciBooNE, NOA, reactor 13 expts, KATRIN, PLANCK, new photometric surveys, more 0 expts, …

Do we really need more?What do we need?


Do we really need more?

What do we need?

• The answer depends on what we will find in the near future

• Talk about a few scenarios– sin2 213 ≪ 0.01– sin2 213 > 0.01– Mini-BooNE confirms LSND

– LHC discovers new physics < TeV

sin2 213≪0.01


Obvious case?

• Superbeams will not address 13, mass hierarchy, or CP violation

• A clear case for neutrino factory and/or -beam

• de Gouvêa: Will we get the funds to get a neutrino factory even if all previous investments end up “unsuccessful”?

sin2 213>0.01


sin2 213>0.01

• Reactor/T2K/NOA finds sin2 213 This is my prejudice

• Upgrades (4MW J-PARC to HyperK, Proton Driver+NOA 2nd detector, etc)– Measures sin2 213 precisely– Determines mass hierarchy– Discovers CP violation

What’s left then?


The source of CP violation

• Having seen does not tell us what is causing it (in particular in the presence of “matter effect background”)

• Is it due to the Dirac phase in the MNS matrix?

• Exactly the same question being addressed by B-factories– i.e., K can be explained by the KM phase, but is it?

– Cross check in a different system, e.g., B Yes!– Is there new interaction (e.g. SUSY loop)? future


Testing MNS hypothesis

• One way I know is to use tau modes

• Consequence of CPT and three flavors• Can they be studied at neutrino factory?– I know it is tough even for a neutrino factory, but other facilities will clearly not do it


Testing MNS hypothesis

• A simulation like this will make the case

(e)

(

)

(e)

(

)

w/o new neutrino interaction with new neutrino interaction

Mini-BooNE confirms LSND


The hell breaks loose

• In this case, it is hard to understand what is going on, because there is currently no simple way to accommodate LSND result with other neutrino data– Multiple sterile neutrinos?– Sterile neutrino and CPT violation?– Mass varying neutrinos?– Something even more wild and wacky?


What it takes

• We will need neutrino “oscillation” experiments with multiple baselines, multiple modes– E~10 GeV, L~10km, looking for appearance– Redo CDHSW ( disappearance experiment with L=130 & 885m, E=19.2GeV)

– E~1 GeV, L~1 km, looking for oscillatory behavior and CP violation in e, or better, e

– Some in the air, some in the earth – Probably more– Muon source would help greatly

LHC discovers new physics <TeV


TeV new physics

• Whatever it is,– SUSY, large extra dimensions, warped extra dimension, technicolor, Higgsless, little Higgs

it is hard to avoid the TeV-scale physics to contribute to flavor-changing effects in general

• Renewed strong case for, e.g., super-B• Very strong case for lepton flavor violation, g2– Hence, for a muon storage ring

• Obvious competition with ILC and beyond


For example, SUSY

• High-energy data (LHC/ILC) will provide masses of superparticles– But most likely not their mixings

• Low-energy LFV experiments (e.g., e, AeA) provide rates (T-odd asymmetry if lucky)– Combination of virtual particles in the loop and their mixing

• Put them together– Resolve the mixing– Constrain models of flavor


What about the Big Questions?

• What is the origin of neutrino mass?• Did neutrinos play a role in our existence?

• Did neutrinos play a role in forming galaxies?

• Did neutrinos play a role in birth of the universe?

• Are neutrinos telling us something about unification of matter and/or forces?

• Will neutrinos give us more surprises?Big questions tough questions to answer

Origin of Neutrino Mass,

our existence, even our universe


Neutrinos must be Massless

• All neutrinos left-handed massless• If they have mass, can’t go at speed of light.

• Now neutrino right-handed?? contradiction can’t be massive


Two ways to go

(1) Dirac Neutrinos:– There are new particles, right-handed neutrinos, after all

– Why haven’t we seen them?

– Right-handed neutrino must be very very weakly coupled

– Why?


Extra Dimensions

• All charged particles are on a 3-brane

• Right-handed neutrinos SM gauge singlet Can propagate in the “bulk”

• Makes neutrino mass smallm ~ 1/R if one extra dim R~10m

• An infinite tower of sterile neutrinos

• Or anomaly mediated SUSY breaking

1MPl

d 4(LHu N )


Two ways to go

(2) Majorana Neutrinos:– There are no new light particles

– Why if I pass a neutrino and look back?

– Must be right-handed anti-neutrinos

– No fundamental distinction between neutrinos and anti-neutrinos!


Seesaw Mechanism

• Why is neutrino mass so small?

• Need right-handed neutrinos to generate neutrino massL R

mD

mD

L

R

L R

mD

mD M

L

R

m

mD2

M mD

To obtain m3~(m2atm)1/2, mD~mt,

M3~1015GeV (GUT!)

, but R SM neutral


Grand Unification

• electromagnetic, weak, and strong forces have very different strengths

• But their strengths become the same at 1016 GeV if supersymmetry

• To obtain m3~(m2

atm)1/2, mD~mt

M3~1015GeV!

Neutrino mass may be probing unification:

Einstein’s dream

M3


Leptogenesis

• You generate Lepton Asymmetry first. (Fukugita, Yanagida)

• Generate L from the direct CP violation in right-handed neutrino decay

• L gets converted to B via EW anomaly More matter than anti-matter We have survived “The Great Annihilation”

• Despite detailed information on neutrino masses, it still works (e.g., Bari, Buchmüller, Plümacher)

(N1 iH) (N1 iH) Im(h1 jh1khlk* hlj

* )


Origin of Universe

• Maybe an even bigger role: inflation

• Need a spinless field that – slowly rolls down the

potential– oscillates around it minimum– decays to produce a thermal

bath• The superpartner of right-

handed neutrino fits the bill• When it decays, it produces

the lepton asymmetry at the same time (HM, Suzuki, Yanagida, Yokoyama)

• Decay products: supersymmetry and hence dark matter

Neutrino is mother of the Universe?

QuickTime™ and aCinepak decompressor

are needed to see this picture.





~

ampl

itud

esi

ze o

f th

e un

iver

se

R


Origin of the Universe

• Right-handed scalar neutrino: V=m22

• ns=0.96

• r=0.16• Detection possible in the near future


Can we prove it experimentally?

• Unfortunately, no: it is difficult to reconstruct relevant CP-violating phases from neutrino data

• But: we will probably believe it if the following scenario happens

Archeological evidences


A scenario to “establish” seesaw

• We find CP violation in neutrino oscillation– At least proves that CP is violated in the lepton sector

• Ue3 is not too small– At least makes it plausible that CP asymmetry in right-handed neutrino decay is not unnaturally suppressed

• But this is not all



• LHC finds SUSY, LC establishes SUSY• no more particles beyond the MSSM at TeV scale

• Gaugino masses unify (two more coincidences)

• Scalar masses unify for 1st, 2nd generations (two for 10, one for 5*, times two)

strong hint that there are no additional particles beyond the MSSM below MGUT except for gauge singlets.


Gaugino and scalars

• Gaugino masses test unification itself independent of intermediate scales and extra complete SU(5) multiplets

• Scalar masses test beta functions at all scales, depend on the particle content



• Next generation experiments discover neutrinoless double beta decay

• Say, mee~0.1eV (quasi-degenerate)

• There must be new physics below ~1014GeV that generates the Majorana neutrino mass



• It leaves the possibility for R-parity violation

• Consistency between cosmology, dark matter detection, and LHC/ILC will remove the concern

M 0.756(n 1)x f

n1

g1/ 2annMPl3

3s0

8H02

2 /(TeV )2

ann


Preliminary

High precision even for ILC

= 1014GeV seesaw

Modified

Type-I

Type-IIseesaw

New particles

31 324 15+15*

(mQ2-mU

2)/M1

2

1 1.283 1.078

(mQ2-mE

2)/M1

2

1 1.084 1.026

(mD2-mL

2)/M1

2

1 1.040 1.014

Matt Buckley



• B-mode fluctuation in CMB is detected, with a reasonable inflationary scale

strong hint that the cosmology has been ‘normal’ since inflation (no extra D etc)



Possible additional archeological evidence, e.g.,:

• lepton-flavor violation (e conversion, ) seen at the “reasonable” level expected in SUSY seesaw (even though I don’t believe mSUGRA)

• Bd KS shows deviation from the SM consistent with large bR-sR mixing above MGUT

• Isocurvature fluctuation seen suggestive of N1 coherent oscillation, avoiding the gravitino problem


Conclusions

• Revolutions in neutrino physics• Neutrino mass probes rare/subtle/high-energy physics

• There is a very good chance for further big progress

• Most likely, we will need superbeam, and also neutrino factory and/or beta beam

• Neutrino physics is within the context of particle physics, astrophysics and cosmology

• Big questions can be answered only based on collection of experiments, not oscillation alone

What’s the elevator pitch?

what is the case for nufact? hitoshi murayama (uc berkeley) intl scoping study meeting of nufact and...

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