Neutrino Horizons in the 21st Century · Outline • Global ﬁt to present oscillation data in the three-neutrino framework impact of new data from the last 12 months • LSND puzzle

Neutrino Horizons in the 21st Century

Status of neutrino oscillations

Thomas Schwetz-Mangold

CERN

T. Schwetz, Neutrino Horizons, 17 April 2008 – p.1

Outline

• Global fit to present oscillation datain the three-neutrino frameworkimpact of new data from the last 12 months

• LSND puzzle in the light of MiniBooNE resultsthe fate of sterile neutrino oscillation schemes


Global data and three-neutrino oscillations

Maltoni, TS, Tortola, Valle, hep-ph/0405172 v6; TS, 0710.5027


Neutrino oscillation experiments

natural neutrino sources:• solar neutrinos

Homestake, SAGE+GNO, Super-K, SNO, Borexino

• atmospheric neutrinosSuper-Kamiokande

artificial neutrino sources:• reactor neutrinos

Chooz (1 km), KamLAND (180 km)

• long-baseline accelerator experimentsK2K (250 km), MINOS (735 km)


3-flavour oscillation parameters

∆m231 ∆m2

21

U =

0

B

B

@

1 0 0

0 c23 s23

0 −s23 c23

1

C

C

A

0

B

B

@

c13 0 e−iδs13

0 1 0

−eiδs13 0 c13

1

C

C

A

0

B

B

@

c12 s12 0

−s12 c12 0

0 0 1

1

C

C

A

atmospheric+LBL Chooz solar+KamLAND

3-flavour effects are suppressed because∆m2

21 ≪ |∆m231| and θ13 ≪ 1

⇒ dominant oscillations are well described by effectivetwo-flavour oscillations


The “solar” parameters ∆m221, θ12


The solar neutrino flux


Solar neutrino experiments


Solar neutrino experiments

SNO: νe + d → p + p + e−

νx + d → p + n + νx

φCC

φNC= 0.340 ± 0.023 ± 0.030

7σ evidence for a non-zero νµ,τ flux from the sunT. Schwetz, Neutrino Horizons, 17 April 2008 – p.9

’Solar’ parameters


The LMA-MSW solution

adiabatic evolution of the neutrino state from thecenter of the sun to the surface

0.1 1 10Eν [MeV]

0.2

0.3

0.4

0.5

0.6

0.7

0.8P

ee

1 - 1/2 sin22θ

sin2θ

Ere

s

strongmatter

vacuum

SNO CC/NC


First data from Borexino

0708.2251 [astro-ph] measurment of the Be7 neutrino line at0.862 MeV by eν → eν scattering (⇒)

47 ± 7(stat) ± 12(sys) ev/(day x 100t), without osc.: 75 ± 4

Energy [keV]300 400 500 600 700 800

Counts/(10 keV × day × 100 tons)

0

0.5

1.0

1.5

2.0

2.5Fit: χ2/NDF = 41.9/477Be: 47±7±12 cpd/100 tons210Bi+CNO: 15±4±5 cpd/100 tons85Kr: 22±7±5 cpd/100 tons210Po: 0.9±1.2 cpd/100 tons


First data from Borexino

0708.2251 [astro-ph] measurment of the Be7 neutrino line at0.862 MeV by eν → eν scattering (⇒)

47 ± 7(stat) ± 12(sys) ev/(day x 100t), without osc.: 75 ± 4

0.1 1 10Eν [MeV]

0.2

0.3

0.4

0.5

0.6

0.7

0.8P

ee

1 - 1/2 sin22θ

sin2θ

Ere

s

strongmatter

vacuum

SNO CC/NC

Borexino


The KamLAND reactor neutrino experiment

Kamioka Liquid scinitillator Anti- Neutrino Detector

detection of ν̄e produced insurrounding nuclear powerplants

70 GW of nuclear power(7% of world total) isgenerated at a distance175 ± 30 km from Kamioka


KamLAND update

New data released this summer:

• 2881 ton yr data4 times more than previous 2004 data

• reduced syst. error due to full volume calibrationfrom 4.7% to 1.8%dominating error for ∆m2 determination is now theuncertainty on the energy scale of 1.5%

observed number of events: 985

expectation without oscillations:1550 reactor neutrino events + 63 background


The KamLAND energy spectrum

evidence for oscillations in 1/Eν


KamLAND vs solar data

90% and 99.73% CL contours

★

0.2 0.4 0.6 0.8

sin2θ12

0

5

10

15

20

∆m2 21

[ 10

-5eV

2 ]

"solar" parameters

KamLAND

globalsolar

∆m221:

measured byKamLAND

sin2 θ12:measured by SNO

∆m221 = 7.6 ± 0.20 × 10−5 eV2, sin2 θ12 = 0.32 ± 0.023


The “atmospheric” parameters ∆m231, θ23


Super-K atmospheric neutrino data

��

��

��!��


Super-K atmospheric neutrino data

��

��

��!��

consistent with νµ → ντ osc. with∆m2 ≃ 2.5 × 10−3 eV2, sin2 θ ≃ 0.5


Long-baseline experiments

first generation of LBL experiments(νµ-disappearance)


Long-baseline experiments

first generation of LBL experiments(νµ-disappearance)

K2K MINOSsource KEK Fermilabdetector Super-K Soudanbaseline 250 km 735 kmneutrino energy 1.3 GeV 3 GeVEν/L [eV2] 5.2 × 10−3 4.1 × 10−3

obs. events 112 563

expect. w/o osc. 158.1+9.2−8.6 738 ± 30


MINOS energy spectrum

0 5 10 15 20

Rat

io o

f Dat

a / P

redi

ctio

n

0

0.5

1

1.5

2

Reconstructed Neutrino Energy (GeV)

20-

30 G

eV

30-

50 G

eV

> 5

0 G

eV

MINOS Data

Neutrino Oscillation Best Fit

NC subtracted

MINOS Preliminary

arxiv:0708.1495, 2.5 × 1020 potT. Schwetz, Neutrino Horizons, 17 April 2008 – p.20

Super-K + K2K + MINOS

90%, 99.73% CL regions

★

0 0.25 0.5 0.75 1

sin2θ23

0

1

2

3

4

5

∆m2 31

[10−3

eV

2 ]

atmospheric

MINOS

global

"atmospheric" parameters

∆m231 = 2.4 ± 0.15 × 10−3 eV2, sin2 θ23 = 0.50 ± 0.063


The bound on θ13


The bound onθ13

The bound on θ13 emerges from an interplay of the global data

10-2

10-1

sin2θ13

10-3

10-2

∆m2 31

[eV

2 ]

CHOOZ

90% CL (2 dof)


The bound onθ13


10-2

10-1

sin2θ13

10-3

10-2

∆m2 31

[eV

2 ]

SOL+KAML+CHOOZ

CHOOZ

90% CL (2 dof)


The bound onθ13


10-2

10-1

sin2θ13

10-3

10-2

∆m2 31

[eV

2 ]

SK+K2K+MINOS

SOL+KAML+CHOOZ

CHOOZ

90% CL (2 dof)


The bound onθ13

global data: sin2 θ13 < 0.05 at 3σ

10-2

10-1

sin2θ13

10-3

10-2

∆m2 31

[eV

2 ]

SK+K2K+MINOS

SOL+KAML+CHOOZ

CHOOZ

GLOBAL90% CL (2 dof)


The bound onθ13

sin θ13 = |Ue3| < 0.224 (3σ) ↔ |Vus| = 0.2257 ± 0.0021

10-2

10-1

sin2θ13

10-3

10-2

∆m2 31

[eV

2 ]

SK+K2K+MINOS

SOL+KAML+CHOOZ

CHOOZ

GLOBAL90% CL (2 dof)


Three flavour effects in present data

bound on θ13 depends on δCP and on hierarchy:(atmospheric data)

Gonzalez-Garcia, Maltoni, 0704.1800


Summary 3-flavour oscillation parameters


3-flavour oscillation parameters

bf ±1σ acc. @ 3σ

∆m221 (7.6 ± 0.2) 10−5 eV2 (8%) KamLAND

sin2 θ12 0.32 ± 0.023 (22%) SNO

|∆m231| (2.4 ± 0.15) 10−3 eV2 (17%) MINOS

sin2 θ23 0.50 ± 0.063 (33%) SK atm

sin2 θ13 < 0.05 @ 3σ CHOOZ

Maltoni, TS, Tortola, Valle, hep-ph/0405172 v6; TS, 0710.5027


Three flavour osc. parameters summary

two possibilities for the neutrino mass spectrum

INVERTEDNORMAL

[mas

s]2

3ν

ν2

ν1

ν2ν1

ν3

νe

µν

ντ

∆m231 > 0 ∆m2

31 < 0


3-flavour oscillations

Open questions:



Open questions:

• Increase the precision on sol and atm params(e.g. Is θ23 exactly 45◦?)



Open questions:


• How small is θ13?

• What is the value of the CP phase δ?

• Type of the neutrino mass ordering (sign of ∆m231)



Open questions:


• How small is θ13?

• What is the value of the CP phase δ?

• Type of the neutrino mass ordering (sign of ∆m231)

• Is this basic picture correct?LSND hint?non-standard effects beyond oscillations?


The LSND puzzle and MiniBooNE results

Maltoni, TS, 0705.0107


The LSND signal

π+ µ+ + νµ

e+ + ν

e+ νµ ν

e

oscillations

other

p(ν_

e,e+)n

p(ν_

µ→ν_

e,e+)n

L/Eν (meters/MeV)

Bea

m E

xces

s

Beam Excess

0

2.5

5

7.5

10

12.5

15

17.5

0.4 0.6 0.8 1 1.2 1.4

L ≃ 35 m

evidence for ν̄µ → ν̄e oscillationsA. Aguilar et al., PRD 64 (2001) 112007

87.9 ± 22.4 ± 6.0 excess eventsP = (0.264 ± 0.067 ± 0.045)%

∼ 3.3σ away from zero


Oscillation interpretation of LSND

the problem:

∆m2 ∼ eV2 not consistentwith solar (8 × 10−5) andatmospheric (3 × 10−3)mass splittings for threeneutrinos!

10-2

10-1

1

10

10 2

10-3

10-2

10-1

1sin2 2θ

∆m2 (

eV2 /c

4 )

BugeyKarmen

NOMAD

CCFR

90% (Lmax-L < 2.3)99% (Lmax-L < 4.6)


Check LSND with MiniBooNE

LSND MiniBooNE

energy 30 MeV 500 MeVbaseline 30 m 500 m

same L/Eν valuechannel νµ → νe νµ → νe


MiniBooNE results, April 2007

obs. events minusbackground:

475 < EQEν < 1250 MeV:

22 ± 19 ± 35 events(consistent with zero)

300 < EQEν < 475 MeV:

96 ± 17 ± 20 events(excess at 3.6σ)

even

ts /

MeV

0.5

1.0

1.5

2.0

2.5analysis threshold

oscillationν2

y MiniBooNE data

µνg expected background

µνeν→µν BG + best-fit

backgroundµν

backgroundeν

300 600 900 1200 1500

exce

ss e

vent

s / M

eV0.0

0.2

0.4

0.6

0.8

(MeV)νreconstructed E3000

data - expected background

eν→µν best-fit

µν2=1.0 eV2m∆)=0.004, θ(22 sin

µν2=0.1 eV2m∆)=0.2, θ(22 sin


The MiniBooNE 2-neutrino limit

10-4

10-3

10-2

10-1

100

sin22θ

10-2

10-1

100

101

102

∆m2 [e

V2 ]

LSND 99%LSND 90%KARMEN 90%MiniBooNE 90%

90% CL: ∆χ2 = 4.6

In the 2-neutrino framework MiniBooNE and LSNDare incompatible at the 98% CL Aguilar-Arevalo et al., PRL08


Adding a sterile neutrino

4-neutrino mass schemes:

(2+2) (3+1)

∆m2

sol

∆m2

LSND

∆m2

atm

∆m2

sol

∆m2

atm

∆m2

LSND

νe

νµ ντ νs

m2

i


Adding a sterile neutrino

4-neutrino mass schemes:

(2+2) (3+1)

∆m2

sol

∆m2

LSND

∆m2

atm

∆m2

sol

∆m2

atm

∆m2

LSND

νe

νµ ντ νs

m2

i

rule

dou

t by

sola

r +at

m. o

sc.


MB vs LSND in (3+1)

In (3+1) schemes the SBL appearance probability iseffectively 2-ν oscillations:

Pµe = sin2 2θSBL sin2 ∆m241L

4E

withsin2 2θSBL = 4|Ue4|

2|Uµ4|2

LSND / MiniBooNE inconsistency is the same as inthe 2-flavour analysis presented by the MiniBooNEcollaboration (98% CL)


Appearance vs disappearance in (3+1)

appearance amplitude sin2 2θSBL = 4|Ue4|2|Uµ4|

2

disappearance experiments bound |Ue4|2 and |Uµ4|

2

★

10-3

10-2

10-1

|Ue4

|2

10-2

10-1

100

101

102

∆m2 41

[eV

2 ]

★

10-3

10-2

10-1

|Uµ4|2

Bugey, Chooz

CDHS

atmospheric


(3+1) global

★

10-4

10-3

10-2

10-1

100

sin22θ

SBL

10-1

100

101

∆m2 41

[eV

2 ]

NEV(incl. MB475)

LSND

90%, 99% CL

before MB:χ2

PG = 20.9 (2 dof)

MB incl.:χ2

PG = 24.7 (2 dof)

disagreement atabout 4σ


More sterile neutrinos?


5-neutrino oscillations

(3+2) scheme∆m

2

LSND

∆m2

sol

∆m2

atm

∆m2

LSND

νe

νµ ντ νs

m2

i

Sorel, Conrad, Shaevitz, hep-ph/0305255


(3+2) appearance probability

Pνµ→νe= 4 |Ue4|

2|Uµ4|2 sin2 φ41

+ 4 |Ue5|2|Uµ5|

2 sin2 φ51

+ 8 |Ue4Uµ4Ue5Uµ5| sin φ41 sin φ51 cos(φ54 − δ)

with the definitions

φij ≡∆m2

ijL

4E, δ ≡ arg

(

U ∗e4Uµ4Ue5U

∗µ5

)

.

(3+2) osc. include the possibility of CP violation!

remember: MiniBooNE: neutrinos, LSND: anti-neutrinos


(3+2) appearance data

best fit point spectra:

MiniBooNE LSND

0.3 0.6 0.9 1.2 1.5 3Eν

CCQE [GeV]

0

0.2

0.4

0.6

0.8

1

exce

ss e

vent

s pe

r M

eV

MB300MB475MB data

475 MeV

0.4 0.6 0.8 1 1.2 1.4L/Eν [m/MeV]

0

5

10

15

exce

ss e

vent

s

app data incl. MBbest fit LSND only

background

Perfect fit to appearance data:w/o MB low energy excess: χ2

min = 16.9/(29 − 5)

with MB low energy excess: χ2min = 18.5/(31 − 5)


(3+2) disappearance data

what about the disappearance data?

Pνα→να= 1 − 4

(

1 −∑

i=4,5

|Uαi|2

)

∑

i=4,5

|Uαi|2 sin2 φi1

− 4 |Uα4|2|Uα5|

2 sin2 φ54

⇒ bound |Uei| and |Uµi| (i = 4, 5), similar as in (3+1)

to be reconciled with appearance amplitudes |UeiUµi|


(3+2) app vs disap

projection section

★

10-3

10-2

10-1

|Ue4

Uµ4|

10-3

10-2

10-1

|Ue5

Uµ5

|

10-3

10-2

10-1

|Ue5

Uµ5

|

90%, 99% CL

appearance(MB475)

disappearance

10-3

10-2

10-1

|Ue4

Uµ4|

10-3

10-2

10-1

|Ue5

Uµ5

|10

-3

10-2

10-1

|Ue5

Uµ5

|

95%, 99% (4 dof)

appearance(MB475)

disappearance

χ2

PC = 9.3, ∆m

2

41 = 0.87, ∆m

2

51 = 19.9


(3+2) global

testing consistency of disappearance andappearance data:

χ2PG = 17.2 (4 dof) PG = 0.18%

(without MB: χ2PG = 17.5)

inconsistency at about 3.1σ

parameters in common |Ue4Uµ4|, |Ue5Uµ5|,∆m241,∆m2

51

best fit: ∆m241 = 0.9 eV2, ∆m2

51 = 6.5 eV2, χ2min = 94.5/(107 − 7)

χ2min, global (3+1) − χ2

min, global (3+2) = 6.1/4 dof (81% CL)


the low energy MB excess in the (3+2) fit

the MB low energy excess is not reproduced at theglobal best fit point:

0.3 0.6 0.9 1.2 1.5 3Eν

CCQE [GeV]

0

0.2

0.4

0.6

0.8

1

exce

ss e

vent

s pe

r M

eV

appearance data (MB300)global data (MB300)MB data

475 MeV χ2

MB300 = 104.4/(109− 7)

χ2MB475 = 94.5/(107 − 7)

χ2PG = 25.1/4

PG = 4.8 × 10−5 (4σ)


adding another sterile: (3+3)


(3+3) global fit

0.1 1 1090

95

100

105

110

115

χ2

0.1 1 10

∆m2

41 [eV

2]

90

95

100

105

110

115

0.1 1 100.1 1 10

∆m2

41 [eV

2]

MB300MB475

(3+1)

(3+2)

(3+3)

(3+2)

(3+3)

∆m241 ∆m2

51 ∆m261 χ2

min χ2(3+2) − χ2

(3+3) CL

MB475 0.46 0.83 1.84 92.8 1.7/4 20%

MB300 0.46 0.83 1.84 100.9 3.5/4 52%T. Schwetz, Neutrino Horizons, 17 April 2008 – p.48

All these sterile neutrino schemes

have problems with cosmology

• sterile states contribute to the relativistic degreesof freedom (CMB, BBN)

• conflict with bound on the sum of neutrino massesfrom various cosmological data sets (LSS)


Cosmology

SN Ia, LSS (2dF, SDSS), BAO, CMB (WMAP, BOOMERANG)

68%, 95%, 99% CL

Hannestad, Raffelt, astro-ph/0607101T. Schwetz, Neutrino Horizons, 17 April 2008 – p.50

More ’exotic’ proposals


More exotic proposals

• 3-neutrinos and CPT violation Murayama, Yanagida 01;Barenboim, Borissov, Lykken 02; Gonzalez-Garcia, Maltoni, Schwetz 03

• 4-neutrinos and CPT violation Barger, Marfatia, Whisnant 03

• Exotic muon-decay Babu, Pakvasa 02

• CPT viol. quantum decoherence Barenboim, Mavromatos 04

• Lorentz violationKostelecky, Mews, 04; Gouvea, Grossman, 06; Katori, Kostelecky, Tayloe, 06

• mass varying neutrinosKaplan, Nelson, Weiner 04; Zurek 04; Barger, Marfatia, Whisnant 05

• shortcuts of sterile neutrinos in extra dimensionsPaes, Pakvasa, Weiler 05

• 1 decaying sterile neutrino Palomares-Riuz, Pascoli, Schwetz 05

• 2 decaying sterile neutrinos with CPV• sterile neutrinos and new gauge boson Nelson, Walsh 07

• sterile neutrino with exotic energy dependence Schwetz 07T. Schwetz, Neutrino Horizons, 17 April 2008 – p.52











• sterile neutrino with exotic energy dependence Schwetz 07

KamLAND+atmospheric antineutrino data














KARMEN, TWIST














KARMEN, TWIST

KamL spectrum, NuTeV














KARMEN, TWIST


energy dependence, MiniBooNE?














KARMEN, TWIST



CDHS+atmospheric data?














KARMEN, TWIST




MiniB+KamL+atmospheric?














KARMEN, TWIST





MiniBooNE














KARMEN, TWIST





MiniBooNE

MINOS+atmospheric?


Sterile neutrino oscillations - outlook

• CPV is being tested by MiniBooNE anti-neutrinodata (problem of statistics?)




• the problem of (3+s) schemes heavily relies onSBL disappearance experimentsBugey (ν̄e reactor) and CDHS (νµ accelerator)

• could be worth to look for disappearance at the∆m2 ∼ 1 eV2 scale at future reactor or LBLexperiments (near detectors)




• the problem of (3+s) schemes heavily relies onSBL disappearance experimentsBugey (ν̄e reactor) and CDHS (νµ accelerator)

• could be worth to look for disappearance at the∆m2 ∼ 1 eV2 scale at future reactor or LBLexperiments (near detectors)

• sterile neutrinos with ∆m2 ∼ 1 eV2 might lead tolarge effects for high energy atmosphericneutrinos in IceCube S. Choubey, 0709.1937


Summary


Summary

3-nu oscillations:

★

★

0 0.25 0.5 0.75 1

{sin2θ12, sin

2θ23}

10-4

10-3

{∆m

2 21, ∆

m2 31

} [e

V2 ]

Solar+KamLAND

Atmospheric+LBL


Summary

3-nu oscillations:

★

★

0 0.25 0.5 0.75 1

{sin2θ12, sin

2θ23}

10-4

10-3

{∆m

2 21, ∆

m2 31

} [e

V2 ]

Solar+KamLAND

Atmospheric+LBL

LSND/MiniBooNE issue:

• (3+1): strongly disfavoured

• (3+2): LSND and MB consistentbut: severe tension in theglobal fit

• many exotic “solutions” fail

• the MB excess (if confirmed)is difficult to explain


Summary

3-nu oscillations:

★

★

0 0.25 0.5 0.75 1

{sin2θ12, sin

2θ23}

10-4

10-3

{∆m

2 21, ∆

m2 31

} [e

V2 ]

Solar+KamLAND

Atmospheric+LBL

LSND/MiniBooNE issue:

• (3+1): strongly disfavoured

• (3+2): LSND and MB consistentbut: severe tension in theglobal fit

• many exotic “solutions” fail

• the MB excess (if confirmed)is difficult to explain

Thanks for your attention!


Documents

Neutrino Horizons in the 21st Century · Outline • Global ﬁt to present oscillation data in the three-neutrino framework impact of new data from the last 12 months • LSND puzzle