PoS(ICHEP2016)972 http://pos.sissa.it/ disappearance at the µ ν Appearance) experiment e ν appearance and e ν ] experiments, the collective evidence of the 2 ] and MiniBooNE [ 1 ∗ [email protected] [email protected], [email protected], [email protected] [email protected] appearance are shown, and searches for anomalous [email protected] [email protected] [email protected] τ Speaker. Contradictory evidence has been presentedknown active on neutrinos the and light issue sterile of neutrinolations observed species. neutrino by Apparent the mixing short-baseline LSND between neutrino [ oscil- the three reactor neutrino anomaly, and the galliumat anomaly the all 1 eV point level. towards While sterile thesewith neutrinos results null with are results mass tantalizing, from they other are short-baseline not experiments,baseline conclusive and as and with they atmospheric disappearance are experiments. searches in in tension The long- NOvA (NuMI Off-Axis may help clarify the situation by(Neutrinos searching from for the Main disappearance Injector) of beam active over neutrinos aby baseline NOvA from of to the 810 look NuMI km. for oscillations We describe into thepearance sterile method of neutrinos used neutral-current at the (NC) Far neutrino Detector events, (FD)addition, including through the preliminary the Near results disap- Detector of (ND) this is search.lations well and In suited probing for the searching LSND for and anomalous MiniBooNEfinal short-baseline sterile states. neutrino oscil- We allowed also regions present using a a novel method varietyconvolutional for of neural selecting networks. samples Based with high on purity this at method,ν the the ND sensitivity using to anomalous short-baseline NOvA ND are presented. ∗ Copyright owned by the author(s) under the terms of the Creative Commons c Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). L. Suter Fermi National Accelerator Laboratory Email: S. Kasetti University of Hyderabad, India Email: R. Keloth Cochin University of Science and Technology, India Email: A. Aurisano, A. Sousa, S.University Yang of Cincinnati E-mail: G. K. Kafka Harvard University E-mail: Searches for Sterile Neutrinos with NOvA G. S. Davies Indiana University E-mail: 38th International Conference on High Energy3-10 Physics August 2016 Chicago, USA PoS(ICHEP2016)972 2 ± 71 . G. S. Davies POT of neutrino data anal- beam and a baseline of 810 20 µ ν 10 appearance. × τ ν 05 shows the CVN NC classifier distri- . 1 ] short-baseline experiments saw an excess 2 1 ] event selection algorithm is based on the GoogLeNet 4 ] and MiniBooNE [ appearance and a search for 1 e ν , the observation in data is within one sigma of three-flavour prediction. ) . syst ( 28 . ] showed that only three light active neutrino flavors exist. It is therefore concluded 8 3 disappearance and ± µ ) . ν appearance which can be interpreted as oscillations with a light neutrino with a mass on order stat Neutral-current interactions are not affected by three-flavor oscillations but mixing between The three neutrino paradigm has been used to successfully explain the vast majority of neutrino ( e ¯ ν 15 . active and sterile neutrinos willnot reduce interact the in the rate detector oflearning volume. NC and events This tools at analysis the from takesConvolutional FD, advantage the Visual of as Network computer recent sterile (CVN) vision advances neutrinos [ in community will machine to classify neutrino interactions. The compared to the 3-flavour signal and background simulated prediction. 2. NC Disappearance Analysis convolutional neutral network (CNN) architecture. Figure km. The NOvA NDnote also will briefly be describes sensitive thebetween to NOvA oscillations potential due for to the a short-baseline oscillations 1 using eV a scale joint sterile fit neutrino. This bution for the FD-selected datacosmogenic compared backgrounds to after the preselection three-flavor and predictionplied. cosmic for The NC background CVN events, neutral rejection beam current cutsachieves event and have excellent classifier been is efficiency ap- the (94%) primary andbackgrounds; selector purity 50% for (88%) efficiency the and when signal 72% selection separating purityNOvA and the when observes cosmic NC backgrounds 95 signal are NC from included. candidate beam and-count events analysis between to 0.5 obtain - a9 4 single GeV value in result. the FD Given after the performing extrapolated a prediction cut- ysed of to 83 date. The calorimetric energy distribution of events selected in the FD is show in Fig. of 1 eV. High precision measurementsexperiments [ of the decay width of the Z boson performed by four LEP NOvA sees no evidence for sterile neutrino mixing with the 6 of that any additional neutrinos must beNOvA sterile, is as in an they off-axis must notspectrum long-baseline interact before neutrino through three-flavor experiment. the oscillations, weak predicting force. Thetance the and ND FD flux measures spectrum differences the with derived from105m neutrino corrections simulation). underground. for energy The accep- The FD ND is issited located 1 on 14.6 km the mrad from surface the off in target the Ashrange at central River, of Fermilab, Minnesota. energies axis between Both of 1 detectors the and are for 3 beam, the GeV observing in NOvA neutrinos order baseline. to predominantly matchcomposed in to of The a the cells NOvA first narrow of 3-flavor detectors liquid oscillationing scintillator are maximum for encased functionally a in deficit equivalent polyvinyl of tracking chloride neutral-currentsearch events calorimeters, (PVC) (NC) for extrusions. in light the By three-flavor sterile look- oscillation neutrinosmodel-independent formalism, at NOvA interpretation can of the the FD. results The using NC data disappearance from analysis a in the FD presents a oscillation results, but there are a fewadditional results neutrinos. that The can LSND not [ be explained without the introduction of a Searches for Sterile Neutrinos with NOvA 1. Introduction PoS(ICHEP2016)972 for (3.1) (3.2) (3.3) (3.4) (2.1) 3 G. S. Davies ]. 5 6 appearance can be 5 e ν ) and the predicted NC disappearance probabil- 4 . The three year 90% C.L NOvA Preliminary µ 2 Data ν 2 N ° L eV -3 3 2 41 E = 45 23 1 eV POT-equiv. 4 θ m 20 , ° CC Background ∆ CC Background 10 e µ × = 2.44x10 FD Data NC 3 Flavor Prediction ν ν Cosmic Background < 2 32 L L = 8.5 2 from both of them simultaneously m 13 ∆ θ 6.05 2 2 41 2 41 E E 2 2 L Calorimetric Energy (GeV) 4 4 m m sin m 2 41 χ ∆ E ∆ The distribution of events se- ) 4 m ∆ 2 2 2 . An R-ratio comparison with the stan- 1 | ∆ ) 4 . 2 cosmic sin µ sin . In the 3+1 model, + appearance and 2 U 2 | sin syst µµ 0 e 4 0 5 CC e ( 25 20 15 10 e θ ν

− | µ eV B Events / 0.25 GeV 0.25 / Events NC 2 U 08 13 θ 1 . . | 1 S Σ Figure 2: lected at the NOvA FD.and Red arrows dashed depict lines the calorimetricrange energy 0.5-4.0 GeV selection region. 2 0 0 ( 2 2 2 | 2 + − 2 − > | 4 ) sin 4 . µ 1 µ 2 41 sin − U disappearance can be expressed as: | Data U m 1 | 4 stat = µ N ∆ 4 ( ν = = − = 16 0.8 e , minimizing the total ]. Since both . 1 ν R 6 0 24 and [ → = θ ± µ NOvA Preliminary SBL 24 ν 24 region and is in tension at µ 0.6 θ P θ ν 2 19 2 2 ° . 2 and eV → -3 1 = 45 µ 23 SBL POT-equiv. θ ν sin gives the potential to constrain both of these angles. The NOvA sensi- 14 sin 20 , ° = 1 eV P CC Background CC Background 10 θ e µ × 0.4 = 2.44x10 FD Data NC 3 Flavor Prediction ν ν Cosmic Background 14 2 32 14 = 8.5 24 CVN NC Classifier m 13 R ∆ θ 6.05 θ > θ θ 2 2 2 2 The CVN NC event classifier. m 0.2 and cos ∆ sin = 14 = θ e 0 µµ 5 0 µ 25 20 15 10

0). Further details of the NC disappearance analysis can be found here [

θ θ . Events ) subtracted from the number of data-selected NC events ( ). For clarity R is: 2 2 1 Figure 1: Red dashed line andlection arrow region depict above the the se- CVNfier NC value of classi- 0.2 for this analysis. 2 2 NC = S R cosmic + If a light sterile neutrino exists, one can expect to observe disappearance in muon neutrinos and An R-ratio can be constructed to check consistency with the standard 3-flavour prediction. CC B dard 3-flavor model concludes that thetions NC ( disappearance result is consistent with 3-flavour oscila- appearance in electron neutrinos at the NOvAbetween ND, the due to active oscillations and with mass sterile squared neutrino, difference 3. Short-Baseline Oscillations expressed as: where sin where sin ities are parameterized in with respect to tivity at 90% C.L for short-baselineone oscillations and due three to years light of sterile data99% neutrinos taking. C.L is NOvA’s one results shown year at in 90% Fig. C.L sensitivity excludes LSND 90% and This analysis calculates The R-ratio is a ratio of( the predicted background from all neutrino flavors and cosmic ray muons Searches for Sterile Neutrinos with NOvA signal ( PoS(ICHEP2016)972 1 G. S. Davies 1 − 2 41 10 m ∆ 2 − 10 (2013) 161801 3 − NOvA Simulation τ µ 10 θ 110 2

2 4 − sin 10 POT 90% C.L. τ 20 ν

10 5 → × −

µ ν 18 10 after 3 years. The regions 6 − 90% C.L sensitivity for µτ 10 NOvA Realistic Sel. NOvA Perfect Sel. NOMAD CHORUS E531 CCFR CDHS θ (2001) 112007 2 2 7 − 64 1 1 3 2 − 10 sin

10 (2016) P09001

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2 2 11 Figure 4: and excluded by CDHS,MAD CCFR, and E531, CHORUS are also NO- shown. 3 1 , JINST 1 − 10 shows the 2D exclusion region with a rate-only fit assuming et al. at 90% C.L.; 4 e (2006) 257-454 µ 2 − θ NOvA Simulation

10 e µ [MiniBooNE Collaboration], Phys. Rev. Lett. 427 θ 2 2 (2013) 050 at 90% C.L. The re- 3 − sin 10 et al. 34 θ 1305 4 − [LSND Collaboration], Phys. Rev. D Sensitivity for 10 , Phys. Rept. MiniBooNE 90% C.L MiniBooNE 99% C.L KARMEN 90% C.L NOvA with flux and cross-section syst (1yr) NOvA with flux and cross-section syst (3yr) LSND 90% C.L LSND 99% C.L appearance. Figure , JHEP τ et al. 5 − ν et al. 1 1 2 2 10

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2 2 gions excluded byand KARMEN LSND, are also MiniBooNE shown. Figure 3: profiling over This work was supported by the U.S. Department of Energy; the U.S. National Science Foun- [2] A. A. Aguilar-Arevalo [3] S. Schael [4] A. Aurisano, A. Radovic, D. Rocco [5] G. S. Davies, http://theory.fnal.gov/jetp/talks/jetp_gsdavies_nova-2.pdf (2016) [6] J. Kopp [1] A. Aguilar Searches for Sterile Neutrinos with NOvA sensitivity completely excludes the LSND 90%and and MiniBooNE 99% allowed C.L regions regions. with NOvA one can NOvAalso probe TDR-equivalent probe year the for of LSND data. The NOvaa ND two-flavour can approximation to the 3+1previous experiments model after at 3 short-baselines. years NOvA of running will in be this competitive channel. with dation; the Department ofMSMT Science CR, Czech and Republic; Technology, the India; RAS,the RMES, the and State European RFBR, and Russia; Research University CNPq Council; and ofUniversity FAPEG, of Minnesota. the Brazil; Minnesota and module We assembly aretional facility grateful Laboratory, and for and Ash at the River Fermilab. Laboratory, contributions Fermilab atContract of is No. the the operated Argonne De-AC02-07CH11359 by with staffs Na- the Fermi at U.S. Research the DOE. Alliance, LLC, under References Acknowledgements