Neutrino Experiments in 2026 Peter Shanahan SAC Neutrino Working - PowerPoint PPT Presentation

Neutrino Experiments in 2026 Peter Shanahan SAC Neutrino Working Group 5 April 2018

Overview • Request from SAC Neutrino WG was to present the future - What we will know in 2026 2 Date Presenter I Presentation Title

Overview • Request from SAC Neutrino WG was to present the future - What we will know in 2026 - What we know we will likely have learned in the decade thereafter 3 Date Presenter I Presentation Title

Overview • Request from SAC Neutrino WG was to present the future - What we will know in 2026 - What we know we will likely have learned in the decade thereafter • Caveat: Prognostications fall in a spectrum Informed Guess Guess 4 Date Presenter I Presentation Title

The Important Questions • Explicit or implicit in the P5 Science Driver: 
 Understand the Physics Associated with Neutrino Mass - What is the origin of neutrino masses? - What is the structure of the mixing? • Is θ 23 maximal ( π /4 )? 
 If not, what is the octant? Lower: θ 23 < π /4 more ν τ in ν 3 , Upper: θ 23 > π /4 , more ν µ in ν 3 - What is the ordering of the masses? • ν 3 heavier (normal) or heavier (inverted) than ν 1, ν 2 - What are the (absolute) masses? - Do neutrinos violate CP symmetry? • CP-phase δ nontrivial? - Are neutrinos their own antiparticle? • Majorana Particles vs. Dirac - Are there additional neutrino types and interactions? • BSM interactions, sterile neutrinos? 5 Date Presenter I Presentation Title

The Important Questions and Long-baseline Oscillations • Explicit or implicit in the P5 Science Driver: 
 Understand the Physics Associated with Neutrino Mass - What is the origin of neutrino masses? - What is the structure of the mixing? • Is θ 23 maximal ( π /4 )? 
 If not, what is the octant? Lower: θ 23 < π /4 more ν τ in ν 3 , Upper: θ 23 > π /4 , more ν µ in ν 3 - What is the ordering of the masses? • ν 3 heavier (normal) or heavier (inverted) than ν 1, ν 2 - What are the (absolute) masses? - Do neutrinos violate CP symmetry? • CP-phase δ nontrivial? - Are neutrinos their own antiparticle? • Majorana Particles vs. Dirac - Are there additional neutrino types and interactions? • BSM interactions, sterile neutrinos? 6 Date Presenter I Presentation Title

The Open Questions and Long-baseline Oscillation Experiments • Long-baseline Muon Neutrino Disappearance - Primarily sensitive to | Δ m 231 |, sin 2 (2 θ 23 ) - Not sensitive to Mass Hierarchy - Probes maximality/degree of non-maximality, but not octant of θ 23 - Not sensitive to CP violation (unless CPT is violated) • Electron (anti)Neutrino Appearance - Sensitive to 
 CP violation through effect of δ CP 
 Mass Hierarchy via the matter effect 
 θ 23 octant due to sin( θ 23 ) in leading term of appearance probability 7 Date Presenter I Presentation Title

ν e and ν e Appearance Probabilities Comparison of neutrino and 
 antineutrino appearance for 
 a specific baseline and energy Assuming - No Matter Effect - No CP Violation - Maximal µ- τ mixing 8 19 September 2017 P. Shanahan I Neutrino Oscillation Results from NOvA

CP Violation and Neutrino Mass Ordering CP Violation - CPT theorem requires ν µ and ν µ 
 disappearance to be equal in vacuum - ν e appearance probabilities vary on 
 an ellipse with δ CP Inverted Mass Ordering Ordering Mass 
 - ν µ disappearance largely sensitive to | Δ m 2 | - ν e appearance is sensitive to 
 Normal sign( Δ m 2 ) via matter effect - due to presence of electrons in matter ν e e √ 2G F N e 2E/ Δ m 2 31 W e ν e - ~22% effect for NOvA baseline, 
 11% for T2K Shown for maximal θ 23 9 19 September 2017 P. Shanahan I Neutrino Oscillation Results from NOvA

θ 23 Octant ν μ disappearance 
 measures sin 2 (2 θ 23 ) ν e appearance depends in 
 leading order on sin 2 ( θ 23 ) θ 2 3 > π θ / 4 2 3 < π / 4 10 19 September 2017 P. Shanahan I Neutrino Oscillation Results from NOvA

The Open Questions and Long-baseline Oscillation Experiments • Long-baseline Muon Neutrino Disappearance - Primarily sensitive to | Δ m 231 |, sin 2 (2 θ 23 ) - Not sensitive to Mass Hierarchy - Probes maximality/degree of non-maximality, but not octant of θ 23 - Not sensitive to CP violation (unless CPT is violated) • Electron (anti)Neutrino Appearance - Sensitive to 
 CP violation through effect of δ CP 
 Mass Hierarchy via the matter effect 
 θ 23 octant due to sin( θ 23 ) in leading term of appearance probability - Sensitivity to the above depends strongly on external constraint for θ 13 (from reactors) - ν µ disappearance improved sensitivity 11 Date Presenter I Presentation Title

The Open Questions and Long-baseline Oscillation Experiments • Long-baseline Muon Neutrino Disappearance - Primarily sensitive to | Δ m 231 |, sin 2 (2 θ 23 ) - Not sensitive to Mass Hierarchy - Probes maximality/degree of non-maximality, but not octant of θ 23 - Not sensitive to CP violation (unless CPT is violated) • Electron (anti)Neutrino Appearance - Sensitive to 
 CP violation through effect of δ CP 
 Mass Hierarchy via the matter effect 
 θ 23 octant due to sin( θ 23 ) in leading term of appearance probability - Sensitivity to the above depends strongly on external constraint for θ 13 (from reactors) - ν µ disappearance improved sensitivity • Neutral Current Disappearance - Sensitivity to effect of sterile neutrinos, e.g. constraints on θ 24 , θ 34 • Non-standard interactions - Alternative interpretation of ν e vs ν e appearance 12 Date Presenter I Presentation Title

Current Long-Baseline Experiments - NOvA 1m P r o t o n ν μ + n → μ + p m 1 M u o n Michel e- ν μ Charged Current Proton ν e + n → e + p Electron ν e Charged Current Proton ν + X → ν + X' _ Horn-current polarity selects high-purity ν µ or ν µ π 0 ( →γγ ) Neutral Current NO ν A Simulation 10 CC / 6E20 POT / kTON / 50 MeV Total 60 m ν µ 1 ν µ ν + ν e e 14 kt 
 Low-Z tracking 
 − 1 10 Far Detector calorimeters − 2 10 Mineral-oil based 
 in Ash River, FLUKA11 ν 3 10 − liquid scintillator 0 5 10 15 Minnesota E (GeV) 15 m NO A Simulation ν 10 CC / 6E20 POT / kTON / 50 MeV Total 810 km 
 ν µ 1 ν µ baseline ν + ν e e 1 10 − 2 10 − 15 m 300 t 
 FLUKA11 ν − 3 10 0 5 10 15 E (GeV) Near Detector at Fermilab 13 Date Presenter I Presentation Title

Recent NOvA Results • Based on all neutrino-mode data to-date - 8.85x10 20 protons-on-target (14-kt equivalent), collected since Feb. 2014 NOvA Preliminary NOvA Preliminary 5 NOvA FD NH Upper octant Normal Hierarchy 90% C.L. 3.2 20 8.85 10 POT equiv. × NH Lower octant 20 NOvA 8.85 10 POT-equiv. ) × 4 σ T2K 2016 IH Upper octant 3 Significance ( ) MINOS 2014 IH Lower octant* 2 eV 3 2.8 -3 (10 2.6 2 32 2 m ∆ 2.4 1 2.2 Joint analysis 0 2 π π 0 3 2 π π 0.4 0.5 0.6 0.7 2 2 sin θ δ 2 23 CP • Compatible with NOvA Preliminary maximal θ 23 at 0.8 σ Low PID Mid. PID High PID Peripheral POT-equiv 20 Core • No significant octant FD data FD data Best Fit prediction Best Fit prediction Observe 
 Total Background Total Background preference 15 Cosmic Background Cosmic Background 126 ν µ on background of 9 20 • Normal Hierarchy is 10 763 +/- 33 without preferred at nearly 2 σ × 10 Events / 8.85 oscillations • Compatible with CP 5 conservation 
 66 ν e on background of 21 Best fit implies strong 
 0 CPV effect 1 2 3 4 1 2 3 4 1 2 3 4 Reconstructed Neutrino Energy (GeV) 14 Date Presenter I Presentation Title

NOvA in the Future • NOvA has been collecting antineutrino-mode data since Feb. 2017 at 700 kW • Working on first antineutrino results with ~7x10 20 protons-on-target • Guidance from Program Planning: expect to run until 2024. • Projected sensitivities: 
 assume 800 kW in FY19, 
 900 kW in FY21, target and 
 analysis improvements • Sensitivities depend heavily 
 on the assumed values of 
 the parameters - Choose scenario that illustrates 
 capabilities on all questions - ~1 sigma from our current best 
 fit point - Other scenarios that are 
 compatible with the data 
 have better or worse sensitivity to 
 Mass Hierarchy, Octant, maximality, 
 generally weaker for CPV 15 Date Presenter I Presentation Title

Current Long-Baseline Experiments - T2K 50 kt Water Cherenkov Far Detector 295 km baseline Neutrino and antineutrino 
 mode from polarity of Via Mark Messier 16 Date Presenter I Presentation Title

T2K Recent Results • 14x10 20 protons-on-target neutrino-mode, 7x10 20 POT antineutrino-mode Mark Hartz, KEK Colloquium, 8/4/17 89 (7) “ ν e ” candidates in (anti)neutrino-mode 240 (68) “ ν µ ” candidates in (anti)neutrino-mode • Compatible with maximal θ 23 • Weak preference for upper octant • CP conservation disfavored at 2 σ • Normal Hierarchy appears to be preferred at nearly 2 σ 17 Date Presenter I Presentation Title

T2K and the Future • T2K-II proposal - Go from approved 78e20 POT to 200e20 POT, with beam upgrades to1.3 MW and running through 2026 - Other beam and analysis improvements, reduction of systematic uncertainties by 1/3 T2K-II CP-Violation Sensitivity by 2026 (arXiv:1609.0411) T2K CPV Sensitivities 
 Δ m 232 =2.5x10 -3 eV 2 , sin2(2 θ 13 )=0.085 18 Date Presenter I Presentation Title