PoS(NuFact2019)099 https://pos.sissa.it/ ∗ appearance by the DeepCore sub-array of the IceCube τ ν oscillation measurements, and new measurements are required. τ ν paradigm can be tested with precision measurements of the unitarity of the Pon- ν [email protected] Speaker. The 3 tecorvo–Maki–Nakagawa–Sakata (PMNS) neutrino mixing matrix. However, suchpered tests by are ham- the low precision of A recent world-leading measurement of neutrino observatory is presented, asUpgrade. well as the future prospects from the upcoming IceCube ∗ 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). The 21st international workshop on neutrinosAugust from 26 accelerators - (NuFact2019) August 31, 2019 Daegu, Korea Niels Bohr Institute, Blegdamsvej 17, 2100E-mail: Copenhagen, Denmark. Tom Stuttard for the IceCube collaboration Neutrino oscillations and PMNS unitarity with IceCube-DeepCore and the IceCube Upgrade PoS(NuFact2019)099 , τ µ ν → channel e ν τ ν , ], identified e 4 ν → measurements. produced in CC µ → µ (50%) relative to ν τ ν e O ν beam [ µ 5 GeV and providing and ν ∼ e sector remains relatively ν ] collaborations have ex- 6 τ ] sub-array in the deepest, clear- appearance events being observed 9 cross section is τ τ oscillations via the ν ν τ Tom Stuttard for the IceCube collaboration ν sector of the PMNS matrix significantly ] and IceCube [ 5 τ neutrinos, whilst the are not individually identified, but the appearance 1 µ τ ν 25 GeV crossing the Earth’s diameter maximally os- ∼ ] consists of 5160 Digital Optical Modules (DOMs) in- 8 candidates appearing in the CNGS τ 1 TeV. Worse still, the short lifetime of the with ν ∼ µ ]. The PMNS matrix is expected to be unitary, meaning that it ν 2 , production via pion or kaon decays and suppresses the charged 1 ), this mixing is characterised by the Pontecorvo–Maki–Nakagawa τ τ τ ν ν and ], resulting in significant numbers of 7 µ 3 matrix [ events. × τ -ice interactions, this vast 1 Gton instrument observes huge rates of neutrinos of ν appearance. cross section below ν τ τ ]. ν ν 3 is observed statistically. , and at these energies the suppression to the CC τ τ paradigm. lepton decay topology utilising an emulsion cloud chamber detector to achieve sub-mm ν ν cross sections [ ν τ appearance in IceCube-DeepCore µ , e τ The IceCube neutrino observatory [ This lack of experimental data constraining the To date, three experiments have been able to measure Testing the unitarity of the PMNS matrix requires measurements of all 9 matrix elements, The observation of neutrino oscillations, where a neutrino produced as one flavor may be appearance), albeit with precision significantly below that achieved in ν ν τ ν via the est ice is instrumented moresensitivity densely, to lowering the detection threshold to spatial precision. Separately, the Super-Kamiokande [ cillate to of many 2. reduces the precision with whichlepton its mass, unitarity which can forbids becurrent (CC) tested, and is ainteractions consequence causes it of to the decay large afteridentification travelling of only microscopic distances in a detector, hampering ( The OPERA experiment observed 10 ploited the large naturally occurring fluxEarth’s of atmosphere. neutrinos produced Atmospheric by cosmic ray interactions with the the in these massive underground detectors. The strumenting a cubic-km ofcontaining glacial a single ice photomultiplier deep tube below (PMT).secondaries Via the of the geographic Cherenkov light South produced Pole, by the with charged each DOM atmospheric and astrophysical origin. The 10 Mton DeepCore [ completely describes the mixing between states, andpresence any of deviation Beyond from Standard unitarity could Model indicate (BSM) the Measurements physics, of including PMNS additional matrix ‘sterile’ neutrinos unitarity states. thereforeof provide the a 3 powerful and model-independent test ideally via measurements of all possible neutrino oscillation channels (e.g. detected some time later as another,well implies mixing as between non-zero the masses neutrino for flavor atflavor and least states mass states, two (electron, as of the neutrino mass states. For the three known neutrino Neutrino oscillations and PMNS unitarity with IceCube 1. PMNS unitarity and –Sakata (PMNS) 3 etc). However, the vastthe appearance majority or of disappearance global of electron neutrino or oscillation measurements are derived from unexplored [ PoS(NuFact2019)099 , with a τ ν N ] are shown Figure 6 , consistent with the ex- CC cross section relative CC cross section. normalisation, ] experiments are shown for 24 30 τ . . µ 4 τ ν 0 0 ν ν 700 new and enhanced multi- − + ∼ 73 . Tom Stuttard for the IceCube collaboration ] and OPERA [ 5 produced, in contrast to the more spherical µ appearance measurements [ τ and 90% uncertainty, in two DeepCore analyses using 2 . The second analysis obtains a consistent result. ν normalisation of 0 σ σ τ normalisation than measured by OPERA and Super- ν τ ν 9 CC events at the best fit point, an order of magnitude more than any contribution. This scaling is known as the CC interactions can be identified due to the elongated track-like topology ± τ µ ν normalisation, including 1 ν τ ν ]. The results of the Super-Kamiokande [ 6 appearance measurement is performed by fitting Monte Carlo (MC) simulation to de- normalisation can also be interpreted as a deviation of the τ τ Measured ν ν The Neutrino oscillations are measured in DeepCore by reconstructing the energy and zenith angle The IceCube Upgrade, to be deployed in 2022-23, will feature The The results of two independent DeepCore . Three years of DeepCore data were used, achieving world-leading precision. The lead analysis Kamiokande, though the tension is mildyears given of the DeepCore large uncertainties. data is A currently new underway. measurement using 8 The DeepCore results indicate a lower pectation for a unitary PMNS matrix within 1 Figure 1: 3 years of data [ previous measurement, corresponding to a observed a total of 1804 comparison. to the theoretical prediction.many This theoretical cross similarities section with the is much poorly more known precisely experimentally, measured although shares 1 (a proxy for neutrino travelsition distance) to of the the detected expected neutrinos, atmosphericstructed, and but neutrino crucially comparing flux. the flavor Theof compo- flavor the composition deposited cannot light be produced fully by recon- the long-lived Neutrino oscillations and PMNS unitarity with IceCube 3. The IceCube Upgrade PMT optical sensors inas a a dense suite configuration of within new calibrationmeasurements. the devices, already and dense The will be DeepCore increased utilised array, light to as perform observed well precision from neutrino oscillation neutrino interactions in the new detector is cascade-like topology observed for all other neutrino interactions. tector data, scaling the value of 1 expected for ain unitary neutrino PMNS oscillation matrix. parameters, Nuisance parameters atmosphericoptical representing neutrino sensor the efficiency, flux, ice uncertainty neutrino properties and interaction atmospheric cross muon sections, background are included. PoS(NuFact2019)099 . 4 CC track-like events will also be µ CC (cascade-like) events in DeepCore ν e ν appearance is shown in the left panel of Tom Stuttard for the IceCube collaboration τ ν CC interaction in the DeepCore (left) and IceCube µ ν 3 normalisation is achieved after only a single year of τ ν 1 GeV neutrinos, probing the second neutrino oscillation disappearance with a precision comparable to current long- ∼ . The ability to identify µ 3 ν more precise than the current DeepCore result. In addition, the IceCube × , along with the existing DeepCore array. This will significantly increase the rate 2 disappearance sensitivity after 3 years is shown in the right panel of Figure µ Histogram of the zenith angle reconstruction error for Event displays showing the same 30 GeV ν , where a precision of 10% on the 4 The performance of reconstructions of the neutrino energy and direction will be significantly The expected sensitivity of the IceCube Upgrade to 25 GeV expected, shown in Figure Figure 3: data taking, more than 3 enhanced in this new detector,∼ with a factor 3 improvement in cascade zenith angle resolution at Upgrade will also be able to measure maximum and potentially providing sensitivity to the neutrino mass ordering via matter effects. improved. (left) and the IceCube Upgradethe (right), median shown performance, as whilst a the function dotted of red neutrino lines energy. show The the solid region enclosing red the line central indicates 68% of events. Figure baseline accelerator neutrino experiments, atUpgrade an order of magnitude higher energy. The IceCube of detected neutrinos in the DeepCoreprovide energy high range, statistics measurements as of well as lowering the detection threshold to Figure 2: Neutrino oscillations and PMNS unitarity with IceCube Upgrade (right) sub-arrays. The whitephoton spheres hits represent on optical the sensors, sensors. whilst The the red colored line spheres shows indicate the path of the neutrino. shown in Figure PoS(NuFact2019)099 ν Journal of ]. 12 disappearance measurement µ ν , 870 (1962). disappearance (right), assuming µ 28 ν Tom Stuttard for the IceCube collaboration (2016). 93 appearance (left) normalisation during the next decade. (2018). 4 τ τ ν ν 120 ] oscillation parameters, with the exception that the atmo- , 615–624 (2012). , 211801 (2018). (2019). 10 (2019). , 113007 (2002). 35 99 66 120 (2018). Progress of Theoretical Physics oscillations are essential to achieve this goal. The DeepCore , 429 (1957). [Zh. Eksp. Teor. Fiz.33,549(1957)]. 6 Fit 4.0 [ τ 98 , P03012 (2017). ν ν Physical Review D 12 , 106 (2019). Phys. Rev. D JINST 2019 Phys. Rev. Lett. , , Physical Review Letters Physical Review D PoS (ICRC2019) 928 Astroparticle Physics , , , , et al. Sov. Phys. JETP et al. Physical Review D et al. et al. et al. et al. , et al. Sensitivity of the IceCube Upgrade to appearance in 2019 using three years of data, and the under-construction IceCube Upgrade High Energy Physics Measuring the unitarity of the PMNS neutrino mixing matrix is a powerful test of the 3 The IceCube Upgrade will also feature a broad particle physics program, providing world- τ ] are assumed in the right panel. References to external results can be found in [ ν [8] M. G. Aartsen, [9] R. Abbasi, [1] B. Pontecorvo, [2] Z. Maki, M. Nakagawa, S.[3] Sakata, S. Parke, M. Ross-Lonergan, [4] N. Agafonova, [5] Z. Li, [6] M. Aartsen, [7] S. Kretzer, M. H. Reno, 11 [12] A. Ishihara, [ [11] M. Aartsen, Figure 4: spheric mixing angle and mass splitting measured in the 2018 DeepCore Neutrino oscillations and PMNS unitarity with IceCube normal neutrino mass ordering and 4. Conclusions paradigm, and measurements of sub-array of the IceCube neutrino observatory hasof produced the world’s most precise measurement will provide better than 10% precision on the [10] I. Esteban, M. C. Gonzalez-Garcia, A. Hernandez-Cabezudo, M. Maltoni, T. Schwetz, leading sensitivity to a rangeof of the BSM entire physics, IceCube and array pave initiating the a way new for era in IceCube astroparticle Gen2,References physics. an expansion