VaLOR Off-Axis angle optimisation studies Costas Andreopoulos 1 , 2 ∗ , Giles Barr 4 , Fatih Bay 3 , Thomas Dealtry 2 , 4 , Steve Dennis 2 , 5 , Lorena Escudero 6 , Nick Grant 7 , Silvestro Di Luise 3 , Davide Sgalaberna 3 , Raj Shah 2 , 4 , Dave Wark 2 , 4 and Alfons Weber 2 , 4 . 1 University of Liverpool, 2 STFC Rutherford Appleton Laboratory, 3 ETH Zurich, 4 University of Oxford, 5 University of Warwick, 6 IFIC Valencia, 7 University of Lancaster presented at the 6 th Open Meeting of the HyperK project January 29, 2015 ∗ Contact: costas.andreopoulos@stfc.ac.uk
Outline Quick introduction to the VALOR T2K 3-flavour oscillation fit Motivation δ cp Discovery sensitivity 2D Confidence contours Summary Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 2 / 26
VALOR 3-flavour analysis Joint measurement of: sin 2 θ 13 , sin 2 θ 23 , δ CP and ∆ m 2 32 Implementing the agreed 2013 analysis strategy. Analysis uses the official T2K 2013 inputs with appropriate scaling (MC and flux, cross-section and detector-response error assignments and correlations). Performs an indirect extrapolation by tuning the far detector Monte-Carlo to near detector constraints Neutrino oscillation probabilities calculated in a 3-active-neutrino framework, including matter effects in constant-density matter. Minimization: Binned likelihood ratio method, using MINUIT. Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 3 / 26
Introduction - Updates Analysis Setup 10 years nominal annual exposure of 7.5 MW · 10 7 sec = 1.56 · 10 22 POT Assuming ± 320kA horn current 1:3 FHC-RHC running ratio Consider 93 sources of systematic error : 66 (33 + 33) Near detector correlated for FHC and RHC mode. 1 12 uncorrelated cross-section errors 100% correlated between FHC and 2 RHC. 19 FSI + HK detector errors 100% correlated between FHC and RHC. 3 Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 4 / 26
List of systematics considered Type Systematics Comment N syst N tot f banff - f banff ν µ flux 11 0 24 ν µ flux ¯ 5 ν e flux 7 ν e flux ¯ 2 f banff ND correlated (FHC) CCQE axial mass 1 25 f banff Resonant axial mass 1 26 f banff - f banff CCQE Norm 3 27 28 f banff - f banff CC1 π Norm 2 30 31 NC1 π 0 f banff 1 33 32 ND correlated (RHC) FHC * 1.06 33 π p-distribution (50%) 1 f WShape π less ∆ decay (20%) 1 f π − less ∆ σ CC coherent (50%) 1 f CCcoh σ NC other (30%) 1 f NCoth Uncorrelated σ NC coherent (30%) 1 f NCcoh σ NC π (30%) 1 f NC π σ ν e / σ ν µ (3%) 1 f CC ν e /ν µ f CC ¯ σ ¯ ν /σ ν (6%) 1 ν/ν f pF FermiMomentum (14%) 1 f bindE Bindingenergy (30%) 1 f Wshape PionMomentum (52%) 1 f SF SpectralFunction 1 12 Energy scale 1 f E √ f SK − f SK 1 R µ efficiencies 6 (SK+ FSI)/ 20 0 5 f SK − f SK 1 R e efficiencies 12 19 6 17 93 Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 5 / 26
Motivation 1 Choice of off axis angle can have considerable impact on the beam energy distribution, composition and total flux seen at HK. 2 2.5 ◦ off-axis beam was optimised for T2K experiment. Discovery of θ 13 Precise measurements of 23 sector parameters ∆ m 2 32 and θ 23 3 What about HK goals? CP Sensitivity Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 6 / 26
Motivation Current (2.5 ◦ ) Off-Axis angle spectrum peaks at 0.6 GeV CCQE Cross section is rising in this region σ e x appearance probability for ¯ ν e (and ν e also rising) On axis beam can lead to improved statistics Studied the effect of moving to 2.25 and 2.0 degrees off axis Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 7 / 26
1 R µ Spectra FHC RHC Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 8 / 26
1 R µ FHC Spectra Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 9 / 26
1 R µ RHC Spectra Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 10 / 26
1 R e Spectra FHC RHC Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 11 / 26
1 R e FHC Spectra Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 12 / 26
1 R e RHC Spectra Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 13 / 26
δ cp Sensitivity Studies Create MC spectra for given value of δ CP Do multiple fits to determine χ 2 min ( sin ( δ CP ) = 0) Do fits with δ CP = π, 0 Do each fit with true hierarchy ∆ χ 2 = χ 2 BestFit − χ 2 True Plotted ∆ χ 2 for each value of δ cp Studies assumed 10yr HK data (1.56 x 10 22 pot ) True oscillation parameters: sin 2 ( θ 13 ) = 0 . 0241 , sin 2 ( θ 23 ) = 0 . 5 , sin 2 ( θ 12 ) = 0 . 306 , ∆ m 2 21 = 7 . 5 · 10 − 5 eV 2 , ∆ m 2 32 = 2 . 4 · 10 − 3 eV 2 Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 14 / 26
δ cp Sensitivity Studies - True Normal Hierarchy 20 9 2 � 9 � 225 � 8 8 25 = � 7 7 6 6 5 5 4 4 3 3 2 2 1 1 0 -3 -2 -1 0 1 2 3 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Input � Fraction of CP space cp sin 2 ( θ 13 ) = 0 . 0241 , sin 2 ( θ 23 ) = 0 . 5 , sin 2 ( θ 12 ) = 0 . 306 , ∆ m 2 21 = 7 . 5 · 10 − 5 eV 2 , ∆ m 2 32 = 2 . 4 · 10 − 3 eV 2 Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 15 / 26
δ cp Sensitivity Studies - True Inverted Hierarchy 20 9 2 9 � � � 225 8 8 25 = � 7 7 6 6 5 5 4 4 3 3 2 2 1 1 0 -3 -2 -1 0 1 2 3 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Input Fraction of CP space � cp sin 2 ( θ 13 ) = 0 . 0241 , sin 2 ( θ 23 ) = 0 . 5 , sin 2 ( θ 12 ) = 0 . 306 , ∆ m 2 21 = 7 . 5 · 10 − 5 eV 2 , ∆ m 2 32 = 2 . 4 · 10 − 3 eV 2 Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 16 / 26
δ cp Sensitivity Studies - sin 2 ( θ 23 ) Dependance Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 17 / 26
δ cp Sensitivity Studies - 20%,50% Exposure 20_5 2 σ χ 225_5 ∆ 5 5 25_5 = σ 4 4 3 3 20% 2 2 1 1 0 0 -3 -2 -1 0 1 2 3 0 0.2 0.4 0.6 0.8 1 δ Input Fraction of CP space cp 20_2 2 σ χ 7 225_2 ∆ 7 25_2 = σ 6 6 5 5 4 4 50% 3 3 2 2 1 1 0 -3 -2 -1 0 1 2 3 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 δ Input Fraction of CP space cp sin 2 ( θ 13 ) = 0 . 0241 , sin 2 ( θ 23 ) = 0 . 5 , sin 2 ( θ 12 ) = 0 . 306 , ∆ m 2 21 = 7 . 5 · 10 − 5 eV 2 , ∆ m 2 32 = 2 . 4 · 10 − 3 eV 2 , NH Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 18 / 26
Sensitivity- 2D Contours sin 2 ( θ 13 )- δ cp (90% Confidence) sin 2 ( θ 13 ) = 0 . 0241 , sin 2 ( θ 23 ) = 0 . 5 , sin 2 ( θ 12 ) = 0 . 306 , ∆ m 2 21 = 7 . 5 · 10 − 5 eV 2 , ∆ m 2 32 = 2 . 4 · 10 − 3 eV 2 , δ cp = − π 2 Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 19 / 26
Sensitivity- 2D Contours δ cp -∆ m 2 32 (90% Confidence) sin 2 ( θ 13 ) = 0 . 0241 , sin 2 ( θ 23 ) = 0 . 5 , sin 2 ( θ 12 ) = 0 . 306 , 32 = 2 . 4 · 10 − 3 eV 2 , δ cp = − π ∆ m 2 21 = 7 . 5 · 10 − 5 eV 2 , ∆ m 2 2 Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 20 / 26
Sensitivity-2D Contours sin 2 ( θ 23 )-∆ m 2 32 (90% Confidence) sin 2 ( θ 13 ) = 0 . 0241 , sin 2 ( θ 23 ) = 0 . 5 , sin 2 ( θ 12 ) = 0 . 306 , 32 = 2 . 4 · 10 − 3 eV 2 , δ cp = − π ∆ m 2 21 = 7 . 5 · 10 − 5 eV 2 , ∆ m 2 2 Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 21 / 26
Summary Moving on axis has a much larger effect on 23 sector due to background around oscillation dip δ cp discovery potential unchanged when moving on axis No difference when systematics or statistics limited Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 22 / 26
Backup Slides Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 23 / 26
Sensitivity- 2D Contours sin 2 ( θ 13 )- δ cp (90% Confidence) ) 0.025 13 2.0 θ ( 2.25 2 0.024 sin 2.50 0.023 0.022 0.021 0.02 0.019 -2.4 -2.2 -2 -1.8 -1.6 -1.4 -1.2 -1 -0.8 δ sin 2 ( θ 13 ) = 0 . 0241 , sin 2 ( θ 23 ) = 0 . 55 , sin 2 ( θ 12 ) = 0 . 306 , cp ∆ m 2 21 = 7 . 5 · 10 − 5 eV 2 , ∆ m 2 32 = 2 . 4 · 10 − 3 eV 2 , δ cp = − π 2 Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 24 / 26
Sensitivity- 2D Contours δ cp -∆ m 2 32 (90% Confidence) 0.00245 32 2 2.0 m 0.00244 ∆ 2.25 2.50 0.00243 0.00242 0.00241 0.0024 0.00239 0.00238 0.00237 0.00236 0.00235 -2.4 -2.2 -2 -1.8 -1.6 -1.4 -1.2 -1 -0.8 δ sin 2 ( θ 13 ) = 0 . 0241 , sin 2 ( θ 23 ) = 0 . 55 , sin 2 ( θ 12 ) = 0 . 306 , cp ∆ m 2 21 = 7 . 5 · 10 − 5 eV 2 , ∆ m 2 32 = 2 . 4 · 10 − 3 eV 2 , δ cp = − π 2 Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 25 / 26
Sensitivity-2D Contours sin 2 ( θ 23 )-∆ m 2 32 (90% Confidence) 32 2 2.0 m 2.25 ∆ 0.00244 2.50 0.00242 0.0024 0.00238 0.00236 0.46 0.48 0.5 0.52 0.54 0.56 0.58 θ 2 sin ( ) sin 2 ( θ 13 ) = 0 . 0241 , sin 2 ( θ 23 ) = 0 . 55 , sin 2 ( θ 12 ) = 0 . 306 , 23 ∆ m 2 21 = 7 . 5 · 10 − 5 eV 2 , ∆ m 2 32 = 2 . 4 · 10 − 3 eV 2 , δ cp = − π 2 Raj Shah (Oxford) VALOR HyperK Studies January 29, 2015 26 / 26
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