Neutrino Neutrino oscillations oscillations Oleg Lychkovskiy Oleg Lychkovskiy ITEP ITEP 2008 2008
Dec 16, 2015
PlanPlan
Lecture ILecture I IntroductionIntroduction Two-flavor oscillationsTwo-flavor oscillations Three-Three- flavor oscillationsflavor oscillations Matter effectMatter effect
Lecture IILecture II Overview of experiments and observations.
Introduction: acquaintance with neutrinosIntroduction: acquaintance with neutrinos
SM interactions:SM interactions:
Low energy (Low energy (E<<100E<<100 GeV) interactions: GeV) interactions:
ββ – decay: – decay:
(Z, A) (Z, A) (Z+1,A) + e (Z+1,A) + e-- + v + vee
vve e – capture:– capture:
vve e + p + p n + e n + e++
π – decay:π – decay: Deep inelasticDeep inelasticscattering:scattering:
… … and so onand so on
Typical energies: MeV-PeV >> m:Typical energies: MeV-PeV >> m:always always ultrarelativisticultrarelativistic!!
Two-flavor oscillationsTwo-flavor oscillations
Key feature: flavor eigenstates, in which neutrinos are created Key feature: flavor eigenstates, in which neutrinos are created
and detected, do not coincide with mass eigenstates!and detected, do not coincide with mass eigenstates!
mm11 and and mm22 - masses of - masses of vv11 and and vv22
Two-flavor oscillations, wave packet formalismTwo-flavor oscillations, wave packet formalism
(at given t only x=Vt ± a/2 are relevant)
Two-flavor oscillations, plane wave formalismTwo-flavor oscillations, plane wave formalism
Final oscillation probability does not depend on the specificFinal oscillation probability does not depend on the specificform of the wave packet form of the wave packet F(x)F(x)!!
Thus we may put Thus we may put F(x)=1, x=L F(x)=1, x=L and drop the integration over and drop the integration over xx! !
We get the same final result with less calculations:We get the same final result with less calculations:
Three-flavor mixingThree-flavor mixing
• 3 angles: 3 angles: θθ12 12 ,, θθ13 13 , , θθ2323
νe , νμ , ντ - flavor eigenstatesν1 , ν2 , ν3 - mass eigenstates with masses
mm11, m, m22, m, m33
• 2 CP-violating Majorana phases: 2 CP-violating Majorana phases: αα1 1 , α, α22 (physical only if (physical only if ν’s are Majorana fermions) are Majorana fermions)
• 1 CP-violating Dirac phase: 1 CP-violating Dirac phase: δδ
Three-flavor mixingThree-flavor mixing
Unknown: absolute values of masses, Unknown: absolute values of masses, θθ1313 , , δδ, , αα11 , , αα11 , ,
sign of sign of ΔΔmm223232 , octet of , octet of θθ2323
Three-flavor mixingThree-flavor mixing
e e
normal hierarchynormal hierarchy inverted hierarchyinverted hierarchy
mm2232 32
(Mass)(Mass)22
mm222121}}
mm2232 32
mm222121}}
oror
sinsin221313
sinsin221313
Three-flavor oscillationsThree-flavor oscillations
)1(Re2
)(
2/'''
2/3 3
'''
2
2
EmiL
jijlljillill
EmiL
i jjlljillill
ji
ji
eUUUU
eUUUUP
)1(Re2
)(
2/'''
2/3 3
'''
2
2
EmiL
jijlljillill
EmiL
i jjlljillill
ji
ji
eUUUU
eUUUUP
In particular, one can see that Majorana phases do not enter In particular, one can see that Majorana phases do not enter the oscillation probabilitythe oscillation probability
Three-flavor oscillations: Three-flavor oscillations: ννμμ ννl’l’
L L ΔΔmm222121 /4E<< π, /4E<< π, sinsin221313 neglectedneglected
Assume Assume
Then, neglecting and one obtains Then, neglecting and one obtains
Relevant for the majority Relevant for the majority of of accelerator experiments accelerator experiments
and for and for atmospheric neutrinosatmospheric neutrinos
Example: Example: K2KK2K (E=1GeV, L=250km) (E=1GeV, L=250km)
Three-flavor oscillations: Three-flavor oscillations: ννee ννee ,,
sinsin221313 neglectedneglected
Assume the detector registers only electron neutrinosAssume the detector registers only electron neutrinos
ji
jiejeiee EmLUUP 4/sinRe41)( 2222
ji
jiejeiee EmLUUP 4/sinRe41)( 2222
Neglecting Neglecting |U|Ue3e3||22 = |s = |s1313||22 < 0.05 < 0.05 , one obtains, one obtains
The same result one can get in a more illuminating wayThe same result one can get in a more illuminating way
Three-flavor oscillations: Three-flavor oscillations: ννee ννee ,,
sinsin221313 neglectedneglected
Two-flavor mixing effectively!Two-flavor mixing effectively! ==12 12 mm22mm22
2121
Relevant for Relevant for KamLANDKamLAND
Three-flavor oscillations: Three-flavor oscillations: ννee ννee , ,
small baselines, small baselines, 1313 in play in play
http://dayawane.ihep.ac.cn/docs/experiment.htmlhttp://dayawane.ihep.ac.cn/docs/experiment.html
If one does not neglect If one does not neglect ss13132 2 , ,
oscillationsoscillations with small with small amplitude ~ amplitude ~ ss1313
2 2 and small period and small period
LLoscosc = = 4E/4E/ΔΔmm223131 are superimposed are superimposed
on the on the ΔΔmm2121–related oscillations. –related oscillations.
If in addition
one comes to
Relevant for Relevant for Double Chooz, Daya BayDouble Chooz, Daya Bay
Example: Example: Double ChoozDouble Chooz (E=4 MeV, L=1 km) (E=4 MeV, L=1 km)
Matter (MSW) effect in neutrino Matter (MSW) effect in neutrino oscillationsoscillations
ννee-e-e interaction (through W-boson exchange):interaction (through W-boson exchange):
averaging of this Lagrangian over the matter electronsaveraging of this Lagrangian over the matter electronsgives an effective matter potential:gives an effective matter potential:
ννll-e-e interaction through Z-boson exchange does not depend on interaction through Z-boson exchange does not depend on flavor and thus does not influence oscillationsflavor and thus does not influence oscillations
Matter (MSW) effectMatter (MSW) effect
eeeF
e
iii
i
nGV
miH
2ˆ
:,, basis eigenstateflavor the in diagonal is term ninteractioMatter
)(ˆ
:,, basis eigenstate mass the in diagonal is nHamiltonia Vacuum3
1000
321
mmm
VHH
111
0
,,
ˆˆ
basis eigenstatematter
nHamiltonia total theofation Diagonaliz
for the details see lecture notes by Y.Nir, arXiv:0708.1872
Neutrinos in matter, two-flavor case, Neutrinos in matter, two-flavor case, nnee=const=const
Resonance:Resonance: Overwhelming Overwhelming
matter effect:matter effect:
Oscillations with the maximal amplitude!
No oscillations!
Relevance of matter effectRelevance of matter effect
Supernova coreSupernova core::ρ ~ 1012 g/cm3
E ~10 MeVV ~ 0.1 eV
ΔΔmm212122 /2E /2E ~0.5 · · 1010-11 -11 eVeV
ΔΔmm313122 /2E /2E ~ 10 10-10 -10 eVeV
Overwhelming Overwhelming
matter effect!matter effect!
Key parameter:
Sun core: ~ 100 g/cm3
V ~0.5 ·· 10-11eVE ~ (0.5-20) MeV
ΔΔmm212122 /2E /2E ~(0.2-8)1010-11-11 eVeV
relevantrelevant
ΔΔmm313122 /2E /2E ~ (0.6-24) 10 10-10-10 eVeV
irrelevantirrelevant
EarthEarth:: ρ =(1-10) g/cm3
V = (0.4-4) 10-13 eV
Reactors: E ~ few MeVΔΔmm2121
22 /2E /2E ~ (1-10)1010-11 -11 eVeV
ΔΔmm313122 /2E /2E ~ (3-30)10 (3-30)10-10-10 eVeV
Matter effect is irrelevantMatter effect is irrelevant
Accelerators, atmospheric Accelerators, atmospheric neutrinos:neutrinos: E ~ few GeV
ΔΔmm212122 /2E /2E ~ (0.1-1)1010-13-13 eVeV
ΔΔmm313122 /2E /2E ~ (0.3-3)10 (0.3-3)10-12-12 eVeV
Matter effect may be relevantMatter effect may be relevant
Remarks upon the previous lecture
Misprint: Misprint: tree-flavortree-flavor three-flavorthree-flavor MSW effect = Mikheyev-Smirnov-Wolfenstein MSW effect = Mikheyev-Smirnov-Wolfenstein
effecteffect ““octant”=… = 1/4 of the coordinate plane octant”=… = 1/4 of the coordinate plane
Lecture II.Neutrino oscillations.
Overview of experiments and observations.
Based on the review by O.Lychkovskiy, A.Mamonov, L.Okun, M.Rotaev,
to be published in UFN (УФН).
Three-flavor mixingThree-flavor mixing
• 3 angles: 3 angles: θθ12 12 ,, θθ13 13 , , θθ2323
νe , νμ , ντ - flavor eigenstatesν1 , ν2 , ν3 - mass eigenstates with masses
mm11, m, m22, m, m33
• 2 CP-violating Majorana phases: 2 CP-violating Majorana phases: αα1 1 , α, α22 (physical only if (physical only if ν’s are Majorana fermions) are Majorana fermions)
• 1 CP-violating Dirac phase: 1 CP-violating Dirac phase: δδ
SOURSESOURSEν/ν,
flavorrelevant relevant energyenergy
MSWMSWwhat what waswas (can (can be) extractedbe) extracted
SunSun νe 0.5-19 MeV0.5-19 MeVof major
importanceθθ12 12 m2
21
ReactorsReactors νe 1-6 MeV1-6 MeV irrelevantirrelevantm2
21, , θθ1212
θθ1313
Cosmic raysCosmic rays
(atmospheric(atmospheric
ν’s))
νμ, νμ, minor fraction
of other flavors
0.1 GeV -0.1 GeV -
10 TeV10 TeVrelevant
θθ23 23 m232
octant of octant of θθ23 23
AcceleratorsAcceleratorsνμ, νμ,
minor fraction of other flavors
0.5-50 GeV0.5-50 GeV relevantrelevantm2
32, , θθ2323
θθ1313 , , δ
hierarchy, octanthierarchy, octant
SupernovaSupernova all species 1-40 MeV1-40 MeVof major
importancehierarchy, hierarchy, θθ1313
Neutrino oscillations in the matter of the Sun
We are interested in νe νe oscillations and we neglect θθ1313
ne=ne(r), r is the distance from the center of the Sun
Effectively two-flavor case with 1-2 mixing: θθ =θθ1212 , m2=m2
21
, m=m(r), θθ= = θθ(r)(r)
adiabaticity condition holds:
Neutrino oscillations in the matter of the Sun
At the Earth (r=R)
where averaging over the production point r0 is performed
Neutrino oscillations in the matter of the Sun
Probability weakly depends on m221 , but, nevertheless,
is sensitive to its sign!
Radiochemical experiments
Homestake:
ννee + + 3737ClCl 3737Ar + eAr + e--
3737ArAr 3737Cl + eCl + e++ + + ννee
Eth=0.86 MeV
t1/2=35 days
Result: ~ 4 times less neutrinos, than predicted by the SSM
SAGE, GALLEX/GNO:
ννee + + 7171GaGa 7171Ge + eGe + e--
7171GeGe 7171GaGa + e+ e++ + + ννee
Eth=0.23 MeV
t1/2=11.4 days
Result: ~ 2 times less neutrinos, than predicted by the SSM
Cherenkov detector experiments
Kamiokande ((1-3) kt of H2O) and Super-Kamiokande (50 kt of H2O):
ννll + e + e ννll + e + e
SNOSNO: (1 kt of D: (1 kt of D22O):O):
ννee + d + d p + p + e p + p + e
ννll + d + d p + n + p + n + ννll
ννll + e + e ννll + e + e
EEthth>5 >5 MeVMeV
The total flux was measured, and it coincided with the SSM prediction!The total flux was measured, and it coincided with the SSM prediction!
SSM verified SSM verified the the ννee deficite is due to oscillations! deficite is due to oscillations!
BorexinoMain goal: mono-energetic (E= 862 кэВ) 7Be neutrinos
Scintillation detector: low threshold (Eth= 0.5 MeV),
but no direction measured
!!!First real-time low-energy solar neutrinos:
47 ± 7stat ± 12syst 7Be ν / (day · 100 t)
(arXiv:0708.2251)
Reactor Reactor experiments
νe:• produced in β-decays in nuclear reactors: -decays in nuclear reactors: (A,Z) (A,Z) (A,Z+1) + e(A,Z+1) + e-- + + νe
• detected through νe + p n + n + ee++
• scintillation detectors usedscintillation detectors used• antineutrino energy: few MeVantineutrino energy: few MeV
Long-baseline, Long-baseline, L=O(100) L=O(100) km:km:KamLANDKamLAND
Short-baseline, Short-baseline, L=O(1) L=O(1) km:km:Chooz, Double Chooz,Chooz, Double Chooz,
Daya BayDaya Bay
oscillations
KamLANDKamLAND
• Sources of : 55 Japanese reactorsSources of : 55 Japanese reactors• Baselines: Baselines: L=(140 - 210) L=(140 - 210) kmkm• energies: energies: 1.71.7 MeV MeV < E < 9.3 < E < 9.3 MeVMeV• Probability of survival:Probability of survival:
Sensitive toSensitive to ΔΔmm2221 21 and and θθ1212 Status: runningStatus: running
KamLANDKamLAND!!!The latest result!!!The latest result::
Also 70Also 70±± 2727 geo-neutrinos geo-neutrinos registered!registered!
arXiv: 0801.4589v2 arXiv: 0801.4589v2
ChoozChooz
• Source: Chooz nuclear stationSource: Chooz nuclear station• Baseline: Baseline: L=1.05 L=1.05 kmkm• energies: energies: 33 MeV MeV < E < 9 < E < 9 MeVMeV• Probability of survival:Probability of survival:
The final result: The final result: sinsin222θ2θ13 13 < 0.2< 0.2 90%CL 90%CL Status: finishedStatus: finished
Future experiments:Future experiments: Double Chooz Double Chooz and Daya Bayand Daya Bay
Goal: measuring Goal: measuring θθ1313
Daya BayDaya Bay
sinsin2222θθ13 13 << 0.010.01
by 2013by 2013
Double ChoozDouble Chooz
sinsin2222θθ13 13 << 0.030.03
by 2012by 2012
Double Chooz sensitivity evolutionDouble Chooz sensitivity evolution arXiv:hep-ex/0701020v3
near detectors will be built near detectors will be built
the initial spectrum will be measured, the initial spectrum will be measured, not calculatednot calculated
Atmospheric neutrinosAtmospheric neutrinos• Source: cosmic rays, interacting with the atmosphere.Source: cosmic rays, interacting with the atmosphere.
Major fraction:Major fraction: Minor fraction: Minor fraction: Negligible fraction: Negligible fraction:
• Detection reactions: deep inelastic scatteringDetection reactions: deep inelastic scattering
νμ + N μ + hadrons
• Experiments:Experiments: Kamiokande, IMB, Super-Kamiokande, Amanda, Baikal, MACRO,Kamiokande, IMB, Super-Kamiokande, Amanda, Baikal, MACRO, Soudan, IceCube, …Soudan, IceCube, …
• “ “Baselines”: Baselines”: L=(0 - 13000) L=(0 - 13000) kmkm• Energies: Energies: 0.1 0.1 GeV GeV < E < 10 < E < 10 TeVTeV
Atmospheric neutrinosAtmospheric neutrinos
Original flux and energy spectrum Original flux and energy spectrum are poorly known are poorly known
large theoretical large theoretical flux uncertaintiesflux uncertainties
MSW-effect and 3-flavor oscillationsMSW-effect and 3-flavor oscillationsin play, extended sourcein play, extended source
no simple precise no simple precise expressions!expressions!
Approximate expressions:
SK atmospheric neutrino resultsSK atmospheric neutrino results
Phys.Rev. D71 (2005) 112005Phys.Rev. D71 (2005) 112005, , arXiv:hep-ex/0501064v2
sinsin2222θθ2323 > 0.92 > 0.92
1.5 1.5 · 1010-3-3 < < m232 < 3.4 < 3.4 · 10 10-3-3 eVeV22
90% 90% CLCL
Evidence for appearance!Evidence for appearance!Phys.Rev.Lett.97:171801,2006Phys.Rev.Lett.97:171801,2006,,hep-ex/0607059hep-ex/0607059
Prospects for resolving Prospects for resolving hierarchy ambiguityhierarchy ambiguityarXiv:0707.1218arXiv:0707.1218
Accelerator neutrino experiments
• νμ and νμ are produced in meson decays • energies: few GeVenergies: few GeV• baselines: hundreds of kilometersbaselines: hundreds of kilometers
μ
oscillations
Main goals: appearance observations: search for e or τ
measuring 13
precise measurement of m223 , 23
mass hierarchy CP
Accelerator neutrino experiments К2К
MINOS OPERA
MiniBooNEТ2К
NOVA
LSND
e
m232, sin2223
sterile
13 CP(?)
For К2К, MINOS (?) and OPERA (?)
L L ΔΔmm222121 /4E<< π, /4E<< π, 1313=0=0
approximation is valid
T2К, NOvA and, probably, OPERA and MINOS, will go beyond this approximation!
Next several slides are from the talk by Yury Kudenko at NPD RAS Session
ITEP, 30 November 2007
Accelerator neutrino experiments
L/E 200
L=250 km <E> 1.3 GeV
98.2%e 1.3%
First LBL experiment К2К1999-2005
~1 event/2 days at SK
Predictions of flux and interactions at Far Detector by Far/Near ratio
Signal of oscillation at K2K Reduction of events Distortion of energy spectrum
disappearance
Expected: 158.1 + 9.2 – 8.6Observed: 112
- # Events
Expected shape (no oscillation)
Best fit
Best fit valuessin22 = 1.00m2 [eV2] = (2.80 0.36)10-
3
Kolmogorov-Smirnov testBest fit probability = 37%
Null oscillation probability (shape + # events) = 0.0015% (4.3)
K2K final result
- Shape distortion
PRD74:072003,2006
+
Near Det: 980 tons
Far Det: 5400 tons
735 km
Beam: NuMI beam, 120 GeV Protons - beam
Detectors: ND, FD
Far Det: 5.4 kton magnetized Fe/Sci Tracker/Calorimeter at Soudan, MN (L=735 km)
Near Det: 980 ton version of FD, at FNAL (L 1 km)
Precise study of “atmospheric” neutrino oscillations, using the NUMI beam and two detectors
MINOS
New MINOS result 2.50 POT analyzed ≈ 2x statistics of 2006 result Improved analysis
Comparison of new and old MINOS results
J.Thomas, talk at Lepton-Photon2007
# expected (no osc.) 73830# observed 563
m223 =(2.38 +0.20 -0.16) x 10-3
sin2223=1.00 -0.08
After 5 years running: expected accuracy of m232 and sin2223 10%
chance for first indication of non-zero 13
MINOS: projected sensitivityM.Ishitsuka, talk at NNN07
OPERA
High energy, long baseline beam( E 17 GeV L ~ 730 km )
direct search
pure beam: 2% anti <1% e
P( ) = cos413sin223sin2[1.27m223L(km)/E(GeV) ]
E/L ~ 2.310-2 10m223 (atm)
Pb
Emulsion layers
1 mm
kink
after 5 years data taking:~22000 interactions~120 interactions~12 reconstructed<1 background event
Target mass ~1300t
Second generation LBL experiments
T2KNOVA
Off Axis Neutrino Beams
• Increases flux on oscillation maximum• Reduces high-energy tail and NC backgrounds• Reduces e contamination from K and decay
T2K (Tokai to Kamioka)
~1GeV beam (100 of K2K)
JPARC facility
on-axisoff-axis beam
JPARC MINOS Opera K2KE(GeV) 50 120 400 12Int(1012 ppp) 330 40 24 6 Rate (Hz) 0.29 0.53 0.17 0.45Power (MW) 0.77 0.41 0.5 0.0052
Statistics at SK OAB 2.5 deg, 1 yr = 1021 POT, 22.5 kt~ 2200 tot ~ 1600 charged current e < 0.5% at peak
Principle Goals of T2K
Background uncertainty 10%CP = 0 CP = /2CP = - /2 CP =
- - Search for e appearance 13 sensitivity 1o (90% c.l.)
-Measurement m223
with accuracy of 1%(sin2223) 0.01 (m2
23) < 110-4 eV2
m2=2.5x10-3
NOA
Mass hierarchy can be resolved if 13 near to present limitusing both anti- beams andsin2213 from T2K + reactor experiments
matter effects increase (decrease) oscillations for normal (inverted) hierarchy for
P( e) depends on
sin2213 sign m223 CP
13 sensitivities vs time
A.Blondel et al.,hep-ph/0606111
Short baseline reactor experiments Double-Chooz and Daya Bay 13 ( insensitive to CP)
Daya Bay goal
Summary for accelerator experiments
K2K confirmation of atmospheric neutrino oscillations discovered by SK
MINOS confirmed the SK и K2K results high precision measurements of oscillation parameters
MiniBooNe rules out (98% cl) the LSND result as e
oscilations with m2 ~ 1 eV2 new anomaly appears run with anti- beam OPERA data taking begun in 2007
T2K-I neutrino beam in 2009
Main goal for next 5 years: 13
Matter effect in SupernovaMatter effect in Supernova Adiabaticity almost everywhere, resonant layers are possible Adiabaticity almost everywhere, resonant layers are possible
exeptionsexeptions Three flavors in play, two different resonansesThree flavors in play, two different resonanses
H-H-резонанс: резонанс:
L-L-резонанс:резонанс:
13
231 2cos
2)(2
E
mrnG HeF
12
221 2cos
2)(2
E
mrnG LeF
km 10)158( km 10)53( 44 LH rr
Adiabaticity conditionsAdiabaticity conditions
Adiabaticity ofAdiabaticity of H-resonanceH-resonance depends ondepends on θθ1313 !!
L- resonance is always adiabatical!L- resonance is always adiabatical!
12 ln2tan2sin
dr
nd
E
m e
In resonance layer the adiabaticity parameter reads In resonance layer the adiabaticity parameter reads
1)10(105.2 3/24 EL МэВ/
3/23/4
13
132
3 )10()2(cos
2sin10
EH МэВ/
Mass hierarchy andMass hierarchy and θθ1313
NH=Normal Hierarchy, IH=Inverted HierarchyNH=Normal Hierarchy, IH=Inverted Hierarchy
LL==LLarge arge θθ13 13 : : θθ13 13 >0.03>0.03
SS==SSmall mall θθ13 13 : : θθ13 13 << 0.0030.003
NH, NH, LL IH, IH, LL NH and IH, NH and IH, SS
00 11 11
11 00 11HP
HP
Takahashi, Sato,Takahashi, Sato,hep-ph/0205070hep-ph/0205070R=10 kpcR=10 kpc
Future SN neutrino signal in SK
θθ1313 measurment with SNmeasurment with SNIfIf
and the hierarchy isand the hierarchy isinverted, thaninverted, than
θθ1313 is measurable!is measurable!
015.0003.0 13 )106.0( 13
oo
Takahashi, Sato,Takahashi, Sato, hep-ph/0205070hep-ph/0205070
Conclusions
Present knowledge: central value 2 interval m2
12 (10-5 eV2) 7.6 7.1 - 8.3 m2
31 (10-3eV2) 2.4 2.0 - 2.8 sin212 0.32 0.26 - 0.40sin223 0.50 0.34 - 0.67sin213 0.0 <0.05
5-year goals: • to increase the sensitivity for m2
12 , m231 , sin212 , sin223 up to (1-10)%
• sin213 sensitivity at the level 0.003
• mass hierarchy, (?)