sign in sign up
<<
Home , MAJORANA, Neutralino, Technicolor (physics)

Physics Within and Beyond the Three Flavor Oscillation

Mikhail Shaposhnikov

NuFact'11 XIIIth Workshop on Neutrino Factories, Superbeams and Beta-beams Nufact, 5 August 2011 – p. 1 Outline

Three flavour oscillations: within

Three flavour oscillations: beyond GUT see-saw, scale 1010−16 GeV EWSB, scale 102−3 GeV νMSM, scale keV to GeV eV scale

Conclusions

Nufact, 5 August 2011 – p. 2 Three flavour oscillations scenario

Neutrinos have non-zero masses - how to incorporate this into the ? Effective field theory approach, no new degrees of freedom: low energy Lagrangian can contain all sorts of higher-dimensional SU(3)×SU(2)×U(1) invariant operators, suppressed by some unknown scale Λ:

∞ On L = L + . SM n−4 nX=5 Λ

Majorana neutrino mass: from five-dimensional operator

¯ ˜ † c O5 = Aαβ Lαφ φ Lβ    Neutrino mass matrix: v2 Mν ∼ Aαβ Λ Nufact, 5 August 2011 – p. 3 Neutrino physics within three flavour oscillations

Mν depends on 9 physical parameters which potentially can be determined experimentally in low energy neutrino experiments.

They are: 3 absolute values of ν masses, (only mass square differences can be determined in experiments, and 2 2 δmsol, δmatm are known with good accuracy); 3 mixing angles

θ23, θ12 and θ13, 1 Dirac CP-violating phase and 2 Majorana phases.

4 parameters out of these 9 are not known (absolute value of neutrino masses and 3 CP-violating phases).

Nufact, 5 August 2011 – p. 4 Ultimate experimental goal within 3 family scenario - determine all 9 parameters with as high accuracy as possible, and check its consistency, such as unitarity of PMNS mixing matrix.

Methods: long and short baseline neutrino oscillation experiments, search for neutrinoless , determination of the end point of spectra in β decays....

Experiments: T2K, MINOS, GERDA, CUORE, NOνA, MiniBooNE, Majorana, Double , Opera, NEMO, RICE, KATRIN, SNO, RENO, IceCube, LAGUNA-LBNO, Daya Bay, LSND, Karmen, ... Theoretical challenges - Alexey Smirnov talk

Nufact, 5 August 2011 – p. 5 Neutrino physics beyond three flavour oscillations

Crucial questions for theory and experiment:

What is the physics behind non-renormalizable terms? What is the value of Λ ?

Nufact, 5 August 2011 – p. 6 Most probably, origin of neutrino masses - existence of new unseen ; complete theory is renormalisable

Nufact, 5 August 2011 – p. 7 Most probably, origin of neutrino masses - existence of new unseen particles; complete theory is renormalisable

Singlet Majorana - effective contribution to neutrino mass

Higgs triplet with hypercharge 2 - direct contribution to neutrino mass

A combination of the two mechanisms

...

Nufact, 5 August 2011 – p. 7 Most probably, origin of neutrino masses - existence of new unseen particles; complete theory is renormalisable

Singlet Majorana fermions - effective contribution to neutrino mass

Higgs triplet with hypercharge 2 - direct contribution to neutrino mass

A combination of the two mechanisms

...

φ φ

N ν ν ?

φ φ

ν ν

Nufact, 5 August 2011 – p. 7 Realisation: SM + 3 sterile

To reduce uncertainties, let’s assume the validity of this theory up to the Planck scale. May be a safe bet: no SUSY, or , or technicolor are seen at the LHC...

Nufact, 5 August 2011 – p. 8 Most general renormalizable Lagrangian

µ MI c Lsee−saw = LSM + N¯I i∂µγ NI − FαI L¯αNI Φ − N¯ NI + h.c., 2 I Extra coupling constants:

3 Majorana masses of new neutral fermions Ni, 15 new Yukawa couplings in the leptonic sector

(3 Dirac neutrino masses MD = FαI v, 6 mixing angles and 6 CP- violating phases), 18 new parameters in total. The number of parameters is almost doubled in comparison with the SM.

Y 2 = T race[F †F ]

Nufact, 5 August 2011 – p. 9 New mass scale and Yukawas

Nufact, 5 August 2011 – p. 10 GUT see-saw

P. Minkowski; M. Gell-Mann, P. Ramond and R. Slansky, T. Yanagida, R. N. Mohapatra, G. Senjanovic

Theoretical discussion: Rabindra Mohapatra talk.

Key assumption: Yukawa couplings of N to the Higgs and left-handed doublets are similar to those in or charged lepton sector (say, f ∼ 1, as for the ). 16 Then, if MN is roughly of the GUT scale MGUT ∼ 10 GeV, active neutrino masses are in the correct range of a fraction of eV.

“Cutoff” scale Λ”:

v2 Λ ≃ ≃ 6 × 1014 GeV matm Nufact, 5 August 2011 – p. 11 GUT see-saw: attractive features

Yukawas in lepton and quark sectors are similar

Λ is close to the GUT scale: extra may be the consequence of the GUT structure, e.g. SO(10)

Leptogenesis leading to baryogenesis, see Nikolaos Mavromatos talk

Nufact, 5 August 2011 – p. 12 GUT see-saw: challenges

Hierarchy problem: Λ is much larger than EW scale: one has to understand not only why MW ≪ MPl, but also why

MW ≪ MN and why MN ≪ PPl.

Stabilisation of hierarchy mH ≪ MN requires low energy SUSY.

If SUSY is not discovered at LHC then so large MN is “unnatural” and requires enormous fine-tuning

No Dark candidate

Nufact, 5 August 2011 – p. 13 Experimental neutrino physics within GUT see-saw: identical with neutrino physics within three flavour oscillations. Extra experimental consequences - decay due to GUT physics

Nufact, 5 August 2011 – p. 14 EWSB scale

Kersten, Smirnov; Pilaftsis; Ibarra et al, Senjanovic et al Key assumption: The masses of new Majorana leptons are related to (unknown) physics of electroweak symmetry breaking and are thus of the order of 100 GeV - 1 TeV. In general, Yukawa coupling are too small to make these particles experimentally observable. However, extra symmetries may allow them to be of the order of 1. If true, LHC can find them.

Resonant leptogenesis is possible (Pilaftsis), but no candidate.

See talk by Goran Senjanovic for more details. Low energy signatures: Alejandro Ibarra talk at WG1

Nufact, 5 August 2011 – p. 15 The νMSM

Asaka, M.S. Approach driven by neutrino experiments and cosmology: Require that three new particles - Majorana leptons - explain simultaneously neutrino masses and oscillations, Dark matter, and asymmetry of the Universe. Get the parameters of the model, make predictions, and identify the way how and where to search for new particles.

Nufact, 5 August 2011 – p. 16 Constraints on DM , N1

Production. N1 are created in the early Universe in reactions l¯l → νN1, qq¯ → νN1 etc. We should get correct DM abundance.

Structure formation. If N1 is too light it may have considerable free streaming length and erase fluctuations on small scales. This can be checked by the study of Lyman-α forest spectra of distant quasars and structure of dwarf galaxies.

X-rays. N1 decays radiatively, N1 → γν, producing a narrow line which can be detected by X-ray telescopes (such as Chandra or XMM-Newton). This line has not been seen yet.

Nufact, 5 August 2011 – p. 17 motn:D trl etiopouto eurstepre the large, requires production neutrino sterile DM Important: e.I a nyb rdcdi the in produced be only can It MeV. 2 θ sin (2 1) 10 10 10 10 10 10 10 10 10 10 -15 -14 -13 -12 -11 -10 -7 -6 -9 -8 ∆ / > L/L

Phase-space density constraints

1

BBN limit: L limit: BBN NRP Ω Ω 2 N N 1 1 > < × Ω Ω 10

DM DM

6

− BBN

3 2500 =

L L L

6

6 6

max

=25 =70 etnaymtya temperature at asymmetry lepton

M =700 1 [keV] 5 ν 10 MSM. X-ray constraints 50 ec of sence uat uut21 .18 p. – 2011 August 5 Nufact, T ∼ 100 Prediction: active neutrino masses

Asaka, Blanchet, M.S: The minimal number of sterile neutrinos, which can explain the dark matter in the Universe and neutrino oscillations, is N = 3. Only one sterile neutrino can be the dark matter. Lightest active neutrino: −3 m1 ≤ 2 10 eV.

Normal hierarchy: +0.2 −3 2 m2 = [9.05−0.1] 10 eV ≃ ∆msolar , +0.6 −2 p 2 m3 = [4.8−0.5] 10 eV ≃ ∆matm , p +0.6 −2 Inverted hierarchy: m2,3 = [4.7−0.5] 10 eV .

Nufact, 5 August 2011 – p. 19 Prediction: neutrinoless double β decay

F. Bezrukov: Effective Majorana mass mββ

Normal hierarchy: 1.3 meV < mββ < 3.4 meV

Inverted hierarchy: 13 meV < mββ < 50 meV

Knowing mββ experimentally will allow to fix Majorana CP-violating phases in neutrino mass matrix, provided θ13 and Dirac phase δ are known.

Nufact, 5 August 2011 – p. 20 How to find DM sterile neutrino

Boyarsky et al: Flux from DM decay N1 → νγ:

fov ΓradMdm ΓradΩfov Fdm = 2 ≈ I, I = ρdm(r)dr 8πDL 8π Z line of sight

(Valid for small redshifts z ≪ 1, and small fields of view Ωfov ≪ 1) Strategy: Use X-ray telescopes (such as Chandra and XMM Newton) to look for a narrow γ line against astrophysical background. Choose astrophysical objects for which:

The value of line of sight DM density integral I is maximal

The X-ray background is minimal

Result: Look at Milky Way and dwarf satellite galaxies Nufact, 5 August 2011 – p. 21 John Womersley: Do neutrinos play a role in dark matter, especially if there is no light neutralino?

Answer: Yes, sterile neutrino with mass from 1 keV to 50 keV is an excellent warm or cold DM candidate. Search for it with X-ray telescopes in space!

Nufact, 5 August 2011 – p. 22 Constraints on BAU sterile neutrinos N2,3

BAU generation requires out of equilibrium: mixing angle of N2,3 to active neutrinos cannot be too large

Neutrino masses. Mixing angle of N2,3 to active neutrinos cannot be too small

BBN. Decays of N2,3 must not spoil Nucleosynthesis

Experiment. N2,3 have not been seen yet.

Nufact, 5 August 2011 – p. 23 - CHARM - CHARM 10 6 10 6 BEBC BEBC NuTeV NuTeV BBN 10-8 PS191 10-8 BAU 2 2 BAU U U PS191 BBN see-saw - - - 10 10 see saw 10 10

BAU BAU 10-12 10-12 0.1 0.2 0.5 1.0 2.0 5.0 10.0 0.1 0.2 0.5 1.0 2.0 5.0 10.0 M @GeVD M @GeVD

Constraints on U 2 coming from the baryon asymmetry of the Universe (solid lines), from the see-saw formula (dotted line) and from the big bang nucleosynthesis (dotted line). Experimental searched regions are in red - dashed lines. Left panel - normal hierarchy, right panel - inverted hierarchy. Gorbunov, M.S., Canetti

Nufact, 5 August 2011 – p. 24 Prediction: degeneracy between N2 and N3

106

1000 D eV @

M 1 M D

0.001

10-6 0.001 0.01 0.1 1 10 M@GeVD

Values of ∆MM - M that leads to the observed baryon asymmetry for the normal hierarchy and for the inverted one. Main ‘fine tuning’ of the νMSM.

Nufact, 5 August 2011 – p. 25 Sachio Komamiya: θ13 and δ are similar to Vub and CP phase in the quark sector. In heavy flavors, angles are not really the interesting thing - CP violation there is found to be insufficient to generate baryogenesis. How about neutrinos? We know about lepto-genesis, is there further fundamental physics in neutrinos beyond the numerical values of the angle and phase?

Answer: The knowledge of θ13 and δ is necessary, but not sufficient to find theoretically baryon asymmetry of the Universe. It is not zero even if θ13 = 0 or δ = 0. To compute it, one must find N’s and determine their properties experimentally.

Nufact, 5 August 2011 – p. 26 Experimental signatures 1

2 −7 GeV Challenge - from baryon asymmetry: θ . 5 × 10 M  Peak from 2-body decay and missing energy signal from 3-body decays of K,D and B (sensitivity θ2) Example:

+ + 2 2 K → µ N,MN = (pK − pµ) = 0

Similar for charm and beauty.

MN < MK : NA62

MK < MN < MD: charm and τ factories

MN < MB: B-factories (planned luminosity is not enough to get into cosmologically interesting region)

Nufact, 5 August 2011 – p. 27 Experimental signatures 2

Two charged tracks from a common vertex, decay processes N → µ+µ−ν, etc. (sensitivity θ4 = θ2 × θ2) First step: proton beam dump, creation of N in decays of K,D or B mesons: θ2 Second step: search for decays of N in a near detector, to collect all Ns: θ2

MN < MK : Any intense source of K-mesons (e.g. from proton targets of PS.)

MN < MD: Best option: SPS beam + near detector

MN < MB: Project X (?) + near detector

MN > MB: extremely difficult

Nufact, 5 August 2011 – p. 28 N2,3 production and decays

2 | | 2 Uτ4 |Uτ4|

+_ τ Ds - e + Proton beam, 450 GeV/c e ν 4 Z ν Target τ

Steel, earth NOMAD detector shielding

Type on neutrino mass hierarchy - from branching ratios of N2,3 decays to e, µ,τ .

CP asymmetry can be as large as 1% - from BAU and DM

Nufact, 5 August 2011 – p. 29 CERN SPS is the best existing machine to uncover new physics below the . Sensitivity is proportional to total delivered on target

10−5 CHARM BEBC NuTeV 10−6 ExperimentsPS191 10−7 BAU SPS 10−8 NA62

2 20 2 2.5x10 PoT N

ν PS θ 10−9

10−10 BBN

10−11 See−saw

10−12 0.1 1 10 M2 [GeV] Nufact, 5 August 2011 – p. 30 eV scale: ‘canonical’ sterile neutrinos

Key assumption: New scale coincides with that found in neutrino oscillations. Existence of eV sterile neutrinos that can be used to explain a number of experiments indicating that 3 neutrino oscillation paradigm may not be complete.

Theory and : A. De Gouvea; Holanda, Smirnov;... talks by Carlo Giunti and Alexey Smirnov; talks by Pilar Hernandez and by He Zhang at WG1

Experiment: talks by Bill Louis and Francis Halzen.

Nufact, 5 August 2011 – p. 31 Conclusions

eV ν N ν MH direct experi− anoma− BAU DM mass masses lies stability search ment GUT 10−16 YES NO YES NO NO NO _ see−saw 10 GeV

2−3 EWSB 10 GeV YES NO YES NO YES YES LHC

keV − a’la ν MSM GeV YES NO YES YES YES YES CHARM

ν a’la eV YES YES NO NO YES YES scale LSND

Nufact, 5 August 2011 – p. 32 Back up slides

Nufact, 5 August 2011 – p. 33 νMSM prediction for the LHC

Higgs and nothing else in the mass interval

Mmin < MH < Mmax

Mmin = 129.5 ± 2.6(exp) ± 2.2(theor) GeV

Mmax ≃ 174 GeV

Wetterich, M.S.:If gravity is asymptotically safe and gravity contribution to the anomalous dimension of scalar coupling is positive, then

MH = 129.5 ± 2.6(exp) ± 2.2(theor) GeV

Nufact, 5 August 2011 – p. 34 Previous searches at CERN

A. M. Cooper-Sarkar et al. [WA66 Collaboration] “Search For Heavy Neutrino Decays In The Bebc Beam Dump Experiment”, 1985

J. Dorenbosch et al. [CHARM Collaboration] “A search for decays of heavy neutrinos in the mass range 0.5-GeV to 2.8-GeV”, 1985

G. Bernardi et al., “Search For Neutrino Decay”, 1986; “Further Limits On Heavy Neutrino Couplings”, 1988

P. Astier et al. [NOMAD Collaboration], “Search for heavy neutrinos mixing with neutrinos”, 2001

P. Achard et al. [L3 Collaboration], “Search for heavy neutral and charged leptons in e+e− annihilation at LEP”, 2001

Nufact, 5 August 2011 – p. 35 Nufact, 5 August 2011 – p. 36