Measuring Atmospheric Parameters with SuperBeams

Enrique Fernández MartínezDepartamento de Física Teórica and IFT

Universidad Autónoma de Madrid

Outline

Introduction Oscillation parameters Experiments description

Subleading effects in disappearance m2

atm and the sign degeneracy 23 and the octant degeneracy The effects of 13 and

T2K-1 bounds revised Conclusions

The oscillation parameters

What we already know

Solar sector

Atm sector

What we still don’t know sin213 < 0.40

cp

Mass hierarchy

Octant of 23

21.011.012

2

251.19.0

212

39.0tan

eV102.8

m

1.15.023

2

234.16.0

223

1tan

eV102.2

m

223msignsatm

232tan signsoct

M. C. González García hep-ph/0410030

23 = 35º–55º

12 = 28º–38º

Fluxes

T2K-1 SPL

flux from decay at GeVE 75.0

flux from decay flux from decay

GeVE 27.0

GeVE 25.0

L=130Km

Old SPL fluxes courtesy of GilardoniNew fluxes Campagne et al. hep-ex/0411062

L=295Km

T2K fluxes courtesy of J.J. Gómez Cadenas

OA2º

Event Rates

T2K-1 B1 B2 B3 B4 No osc.

N

753 2228

2273

757

Signal N

46 101 381 239

SPL -

+

No osc. N

24245 25467

Signal N1746 1614

L=130Km

5yr exposure with a 22.5Kt water cerenkov detector for T2K-1

2yr + 8yr exposure with a 440Kt water cerenkov detector for the SPL

L=295Km

Statistics dominated Systematics dominated

4 energy bins of 200MeV Between 0.4 – 1.2GeV

The importance of energy resolution

13 = 0º = 0º

T2K-1 SPL

90% CL contours 5% systematic error and backgrounds taken into account

The importance of energy resolution

T2K-1 SPL

13 = 0º = 0º GeVE 27.0

The importance of energy resolution

T2K-1 SPL

13 = 0º = 0º

GeVE 25.0

GeVE 27.0E1 = 0.4 - 0.6GeV

The importance of energy resolution

T2K-1 SPL

13 = 0º = 0º

GeVE 25.0

GeVE 27.0E1 = 0.4 - 0.6GeVE2 = 0.6 - 0.8GeV

The importance of energy resolution

T2K-1 SPL

13 = 0º = 0º

GeVE 25.0

GeVE 27.0E1 = 0.4 - 0.6GeVE2 = 0.6 - 0.8GeVE3 = 0.8 - 1.0GeV

The importance of energy resolution

T2K-1 SPL

13 = 0º = 0º

GeVE 25 .0

GeVE 27 .0E1 = 0.4 - 0.6GeVE2 = 0.6 - 0.8GeVE3 = 0.8 - 1.0GeVE4 = 1.0 - 1.2GeV

The importance of energy resolution

T2K-1 SPL

13 = 0º = 0º

GeVE 25 .0

GeVE 27 .0E1 = 0.4 - 0.6GeVE2 = 0.6 - 0.8GeVE3 = 0.8 - 1.0GeVE4 = 1.0 - 1.2GeV

The disappearance channel

LscL

LsJsL

Ls

atmsol

atmsol

atm

cos2sin2sin2

sincos~

2sin2

2sin22cos2sin2sin1

2322

121224

23

2

22323

2212

232

1322

23232

P

Where

23121313 2sin2sin2sincos~ J

sin 213 < 0.4 05.02

Lsol

E

msol

2

212

E. K. Akhmedov et al. hep-ph/0402175A. Donini et al. hep-ph/0411402

E

matm

2

223

The sign degeneracy

Input:13 = 0º = 0º

L

L

sol

atm

+ O

2

2sin22sin1

2

232 P

Lsol

+ O2

The sign degeneracy

L

LsL

L

sol

atmsol

atm

+ O

2

sin2sin2

2sin22sin1

2

2322

12

232

P

Input:13 = 0º = 0º

The sign degeneracy

Fit assuming inverted hierarchy

Input:13 = 0º = 0º

L

LsL

L

sol

atmsol

atm

+ O

2

sin2sin2

2sin22sin1

2

2322

12

232

P

The octant degeneracy

Input:13 = 0º = 0º

L

LsL

L

sol

atmsol

atm

+ O

2

sin2sin2

2sin22sin1

2

2322

12

232

P

The octant degeneracy

Input:13 = 0º = 0º

L

LsL

L

sol

atmsol

atm

+ O

2

sin2sin2

2sin22sin1

2

2322

12

232

P

The effect of 13

Input:13 = 0º = 0º

L

LsL

L

sol

atmsol

atm

+ O

2

sin2sin2

2sin22sin1

2

2322

12

232

P

The effect of 13

Input:13 = 0º = 0º

Assuming 13 = 0º

L

LsL

L

sol

atmsol

atm

+ O

2

sin2sin2

2sin22sin1

2

2322

12

232

P s 2cos2sin 232

1322

23

sJ cos~ 223

The effect of 13

Input:13 = 0º = 0º

Assuming 13 = 0º, 2º

L

LsL

L

sol

atmsol

atm

+ O

2

sin2sin2

2sin22sin1

2

2322

12

232

P s 2cos2sin 232

1322

23

sJ cos~ 223

The effect of 13

Input:13 = 0º = 0º

Assuming 13 = 0º, 2º, 4º

L

LsL

L

sol

atmsol

atm

+ O

2

sin2sin2

2sin22sin1

2

2322

12

232

P s 2cos2sin 232

1322

23

sJ cos~ 223

The effect of 13

Input:13 = 0º = 0º

Assuming 13 = 0º, 2º, 4º, 6º

L

LsL

L

sol

atmsol

atm

+ O

2

sin2sin2

2sin22sin1

2

2322

12

232

P s 2cos2sin 232

1322

23

sJ cos~ 223

The effect of 13

Input:13 = 0º = 0º

Assuming 13 = 0º, 2º, 4º, 6º, 8º

L

LsL

L

sol

atmsol

atm

+ O

2

sin2sin2

2sin22sin1

2

2322

12

232

P s 2cos2sin 232

1322

23

sJ cos~ 223

The effect of 13

Input:13 = 0º = 0º

Assuming 13 = 0º, 2º, 4º, 6º, 8º, 10º

L

LsL

L

sol

atmsol

atm

+ O

2

sin2sin2

2sin22sin1

2

2322

12

232

P s 2cos2sin 232

1322

23

sJ cos~ 223

The effect of

Input:13 = 8º = 0º

Assuming = 0º

L

LsL

L

sol

atmsol

atm

+ O

2

sin2sin2

2sin22sin1

2

2322

12

232

P s 2cos2sin 232

1322

23

sJ cos~ 223

The effect of

Input:13 = 8º = 0º

Assuming = 0º, 90º

L

LsL

L

sol

atmsol

atm

+ O

2

sin2sin2

2sin22sin1

2

2322

12

232

P s 2cos2sin 232

1322

23

sJ cos~ 223

The effect of

Input:13 = 8º = 0º

Assuming = 0º, 90º, 180º

L

LsL

L

sol

atmsol

atm

+ O

2

sin2sin2

2sin22sin1

2

2322

12

232

P s 2cos2sin 232

1322

23

sJ cos~ 223

T2K-1 errors revised

m2 = (2.43 – 2.60)·10-3 eV2

sin22 > 0.97 tan2 = 0.73 – 1.39

m2 = (2.50 ± 0.06)·10-3 eV2

sin22 > 0.98 Y. Itow et al. hep-ex/0106019

m2 = (2.45 – 2.56)·10-3 eV2

sin22 > 0.98 tan2 = 0.76 – 1.31

Present:m2 = (1.7 – 3.5)·10-3 eV2

sin22 > 0.9 tan2 = 0.53 – 2.04

m2 = (-2.63 – -2.49)·10-3 eV2

Input:13 = 0º 23 = 45º = 0º

90% CL

T2K-1 errors revised

m2 = (2.42 – 2.61)·10-3 eV2

sin22 = 0.94 – 0.99 tan2 = 0.62 – 0.85, 1.21 – 1.66m2 = (2.44 – 2.58)·10-3 eV2

sin22 = 0.95 – 0.99tan2 = 0.63 – 0.81, 1.24 – 1.58

Present:m2 = (1.7 – 3.5)·10-3 eV2

sin22 > 0.9 tan2 = 0.53 – 2.04

m2 = (-2.64 – -2.47)·10-3 eV2

90% CL

Input:13 = 0º 23 = 40º = 0º

Conclusions

The measurement of 13 and will rely heavily on an improvement of the measure of 23 and m2

23 Precision measurements of 23 and m2

23 need energy resolution and events above and below the oscillation peak

The errors on the 23 and m223 are somewhat

larger due to the dependence of the disappearance signal on 13 , and the mass hierarchy

This dependence can be exploited combined with the appearance channel to solve degeneracies

T2K-2

T2K-2T2K-1

5% systematic error

T2K-2

T2K-2T2K-1

2% systematic error

No background and no systematic

Systematic 0%No Background

Systematic 5%With Background

Errors dominated by statistics

10% systematic

Systematic 10%Systematic 5%

Errors dominated by statistics

Energy Resolution

Red histogram for true QE eventsFigure taken fromY. Itow et al. hep-ex/0106019

Double energy resolution

4 bins of 200MeV 8 bins of 100MeV

Double energy resolution

4 bins of 200MeV 8 bins of 100MeV