Sensitivity to sterile ν mixings at a ν Factory --Side business of a ν Factory -- Osamu Yasuda Tokyo Metropolitan University 009-1-18 @ Miami009 1
1. Introduction. Light sterile neutrinos 3. Summary
1. Introduction 1.1 Affirmative experimental results on ν oscillation (i) solar ν deficit ν e ν e reactor ν deficit ν e νe Homestake, Kam, SK, SNO, GALLEX, SAGE, Borexino KamLAND Δm sin 7 10 θ 0.8 5 ev (ii) atmospheric ν deficit ν μ ν μ accelerator ν deficit ν μ ν μ IMB, Kam, SK, Soudan, MACRO KK, MINOS Δm sin 10 θ 1.0 3 ev 3
(iii) accelerator ν anomaly LSND νμ νe E ν 50MeV L 30m Δm O(1)eV?? - sin θ O(10 ) Δm LSND [ev ] 10 1 10 0 Maltoni et al., hep-ph/040517 (3+1) NEV+atm LSND global LSND DAR 10-1 95% CL 99% CL 10-3 10-10 -1 10 0 sin θ LSND 4
1. N ν =4 schemes Because of the hierarchy: Δm << Δm << Δm sol atm LSND N ν =3 schemes can t explain LSND. N ν =4 schemes may be able to explain all. Δm = 1 = Δmsol,Δm3 = Δmatm,Δm43 ΔmLSND LEP 4 th ν has to be sterile (+)-scheme is excluded by solar + atmospheric ν (3+1)-scheme will be discussed (+)- scheme (3+1)- scheme 5
(3+1)-scheme sin θ Bugey > 4 U e4 (1 U e4 ) 4 U e4 sin θ CDHSW > 4 U μ4 (1 U μ4 ) 4 U μ4 sin θ LSND = 4 U e4 U μ4 must be satisfied (Okada-OY Int.J.Mod.Phys.A1:3669,1997) But there is no overlap between LSND and left side of Bugey+CDHSW 6
Recent status of LSND: Check by MiniBooNE Karagiorgi et al, Phys.Rev.D80:073001,009 ΜΒ ΜΒ LSND ν μ ν e ν μ ν e Neither MiniBooNE (ν or ν) nor disappearance results (CDHSW+Bugey+atm) excludes LSND at 4σ. LSND+MB 7
1.4 Future long baseline experiments Unknown oscillation parameters in ( θ, sgn Δm ), δ the standard 3 flavor scenario: 13 3 Ongoing & Near future experiments Accelerator 06~ MINOS (FNAL Soudan) L=730km, E ~10GeV 08 ~ OPERA ICARUS (CERN GrandSasso) L=730km, E ~0GeV 09 ~ TK (JAERI SK) L=95km, E ~1GeV phase1 (0.75MW,.5kt) Reactor 09~ Double CHOOZ 10 (?)~ Daya Bay Far future experiments Accelerator θ 13 θ 13, ( ), δ sgn Δm ( ( sgn Δm )? ) 3 xx~ TK (JAERI HK) L=95km, E ~1GeV phase (4MW,500kt) yy~ νfactory (??) L ~ 4000km+7500km, E ~0GeV 3 8
ν factory: ν from μ decays μ e + ν μ + μ + e+ + ν μ + ν e ν e Large No. of events Low backgrounds very good sensitivity sensitivity to δ silver channel ν μ ν ν e ν μ ( μ golden channel ν e ν μ ν μ ν μ ν μ ν ν e ν τ ( τ ν e ν τ ν μ ν τ disappearance channel discovery channel 9
K.Long NF roadmap: key decision points Neutrino Factory roadmap International scoping study (ISS) NuFact06 International design study (IDS) Neutrino Factory consortium formation Build Physics Key decision points Seek to instigate IDS Seek to host FP7 DS and/or I3 bids IDS mandate at Nufact06 Submit FP7 bids Form Neutrino Factory consorium Initiate build phase 006 007 008 009 010 011 01 013 014 015 016 017 018 019 00 Ambitious, science-driven schedule Issue now is to establish vibrant R&D programme Vision for International Design Study phase: International collaboration; coordinated effort: Concept development full system Accelerator R&D Detector R&D Nagashima: ISS 3 rd plenary ( 06) @ RAL 10
1.5 Motivation for research on New Physics and τ detection at ν factory Just like at B factories, high precision measurements of ν oscillation at ν factory will allow us to probe physics beyond SM by looking at deviation from SM+massive ν. If θ 13 turns out to be large, search for new physics and test of unitarity will be even more important subjects at ν factory. (cf. sin θ 13 =0.0±0.01@1σ, Fogli et al, arxiv:0905.3549 [hep-ph] ) 11
If 3 flavor unitarity is guaranteed, then roughly speaking, we could guess (discovery) from (golden) + (disappearance) at ν factory from 3 flavor unitarity: P( ν ν ) + P( ν ν ) + P( ν ν ) = 1? μ e μ μ μ τ disappearance channel discovery channel ν e ν μ Probability of the time reversal process could be obtained if we can guess the CP phase. golden channel Intuitively, therefore, τ detection is supposed to be important to test New Physics which violates unitarity. Quantitative estimate is necessary to draw conclusions. 1
New physics which can be probed at a neutrino factory includes: Non standard interactions in propagation Non standard interactions at production / detection Violation of unitarity due to heavy particles Schemes with light sterile neutrinos Scenarios NSI in propagation NSI at production / detection Violation of unitarity due to heavy particles β = e, μ, τ P( ν α ν β ) = 1 3 flavor unitarity Light sterile neutrinos 13
Scenarios NSI at production / detection Violation of unitarity due to heavy particles Light sterile neutrinos Phenomenological bound on deviation of unitarity O(0.1%) O(1%) O(10%) Light sterile neutrinos could be phenomenologically more promising than others! 14
. Light sterile neutrinos (3+1)-scheme w/ LSND: the situation is unclear, but it s worth checking it (3+1)-scheme w/o LSND: still a possible scenario, provided that the mixing angles satisfy all the constraints of the negative results θ 34 : ratio of and in ν atm θ 4 : ratio of and in ν atm θ 14 : mixing angle in ν reactor at L=O(10m) 15
. Constraints on (3+1)-scheme from ν atm and SBL Donini-Maltoni-Meloni-Migliozzi-Terranova, JHEP 071:013, 07 Assumption on rapid oscillations in ν atm : θ 34 : could be relatively large Δm 41 >0.1 ev 16
.3 Sensitivity to θ 14, θ 4, θ 34 at ν factory with far detectors Donini, Fuki, Lopez-Pavon, Meloni, OY, JHEP 0908:041,009 5 10 0 μ +μ + s/yr 4 yrs (Eμ/GeV, L/km)= (50,3000+7500) or (0, 4000+7500) 50kton MIND + 4kton MECC statistical errors + systematic errors + BG efficiency ~ 0.7 for μ, ~0.65 for τ NB. Magnetized Emulsion Cloud Chamber (MECC) active target: iron τ μ decay + τ e decay + τ hadron decay are used 17
golden + silver Donini, Fuki, Lopez-Pavon, Meloni, OY, JHEP 0908:041,009 4 U e4 U μ4 > 5.8x10-6 4 U e4 U τ4 > 3.8x10-5 18
disappearance + discovery Donini, Fuki, Lopez-Pavon, Meloni, OY, JHEP 0908:041,009 E μ =0GeV --- current --- disappearance --- discovery --- combined 4 U μ4 > 7.6x10-4 U μ4 U τ4 > 1.9x10-3 19
Comparison with the present bound Sensitivity to the 4ν mixings with νe is very good compared to the present bound. It could serve as a severe test of LSND/MiniBooNE. nufact (90%) 0
.4 Sensitivity to the new CP phase If sterile neutrino mixings are found, we can search for the new CP phase. Donini, Fuki, Lopez-Pavon, Meloni, OY, JHEP 0908:041,009 disappearance only disappearance + discovery Discovery channel is crucial to measure the new CP phase 1
3. Summary ν factory can search for sterile neutrino mixings. ν factory can offer a powerful test of LSND/MiniBooNE. In absence of 3 flavor unitarity, τ detectors in principle give us important information on New Physics. To measure the new CP phase due to sterile neutrino mixings, discovery channel is crucial.
Backup slides 3
Mattias Blennow @ NSI w/s at UAM 009-1-10 4
Mattias Blennow @ NSI w/s at UAM 009-1-10 5
Direct bounds on prod/det NSI From μ, β, π decays and zero distance oscillations ( μ l γ Pν )( uγ P d ) ud G εαβ β L α μ F L, R G F ε μe αβ ( μ μγ Pν )( ν γ P e) L β α μ L ud ε 0.04 <.6 10 0.087 5 0.05 0.1 0.013 0.04 0.013 0.13 μe ε < 0.05 0.05 0.05 0.03 0.03 0.03 0.03 0.03 0.03 Bounds order ~10 - C. Biggio, M. Blennow and EFM 0907.0097 Enrique Fernandez-Martinez @ NSI w/s at UAM 009-1-10 6