Developing the T2K Neutrino Oscillation Analysis by Using Pion Samples at the Near Detector

The T2K (Tokai to Kamioka) experiment is a long baseline neutrino experiment in Japan that consists of a neutrino source beamline (from J-PARC), a near detector (ND280) and a far water Cherenkov detector (Super-Kamiokande). The neutrino rates between the two detectors are measured and this is used to determine the Pontecorvo–Maki-Nakagawa-Sakata Matrix (PMNS) parameters that describe neutrino oscillations. The current oscillation analysis aims to constrain the δCP parameter using the Markov Chain for 3 flavour fitting (MaCh3) framework. In this thesis, I added pion information at the near detector (ND280) to better restrict the cross section parameters and potentially improve the neutrino oscillation sensitivity. I implemented a new feature that introduced pion tagged samples to the oscillation framework after studying the kinematics of pions at ND280. The impact of this new feature was studied using likelihood scans and fake data studies at the near detector, followed by spectra predictions at the far detector. Finally, I performed a joint data fit and extracted neutrino oscillation parameter sensitivities. During my time on T2K I served as a Data Quality (DQ) expert for the ND280, the work that I did is also described in this thesis

Simultaneous measurement of the muon neutrino charged-current cross section on oxygen and carbon without pions in the final state at T2K

Authors: K. Abe,56 N. Akhlaq,45 R. Akutsu,57 A. Ali,32 C. Alt,11 C. Andreopoulos,54,34 L. Anthony,21 M. Antonova,19 S. Aoki,31 A. Ariga,2 T. Arihara,59 Y. Asada,69 Y. Ashida,32 E. T. Atkin,21 Y. Awataguchi,59 S. Ban,32 M. Barbi,46 G. J. Barker,66 G. Barr,42 D. Barrow,42 M. Batkiewicz-Kwasniak,15 A. Beloshapkin,26 F. Bench,34 V. Berardi,22 L. Berns,58 S. Bhadra,70 S. Bienstock,53 S. Bolognesi,6 T. Bonus,68 B. Bourguille,18 S. B. Boyd,66 A. Bravar,13 D. Bravo Berguño,1 C. Bronner,56 S. Bron,13 A. Bubak,51 M. Buizza Avanzini ,10 T. Campbell,7 S. Cao,16 S. L. Cartwright,50 M. G. Catanesi,22 A. Cervera,19 D. Cherdack,17 N. Chikuma,55 G. Christodoulou,12 M. Cicerchia,24,† J. Coleman,34 G. Collazuol,24 L. Cook,42,28 D. Coplowe,42 A. Cudd,7 A. Dabrowska,15 G. De Rosa,23 T. Dealtry,33 S. R. Dennis,34 C. Densham,54 F. Di Lodovico,30 N. Dokania,39 S. Dolan,12 T. A. Doyle,33 O. Drapier,10 J. Dumarchez,53 P. Dunne,21 A. Eguchi,55 L. Eklund,14 S. Emery-Schrenk,6 A. Ereditato,2 A. J. Finch,33 G. Fiorillo,23 C. Francois,2 M. Friend,16,‡ Y. Fujii,16,‡ R. Fujita,55 D. Fukuda,40 R. Fukuda,60 Y. Fukuda,37 K. Fusshoeller,11 C. Giganti,53 M. Gonin,10 A. Gorin,26 M. Guigue,53 D. R. Hadley,66 J. T. Haigh,66 P. Hamacher-Baumann,49 M. Hartz,62,28 T. Hasegawa,16,‡ S. Hassani,6 N. C. Hastings,16 Y. Hayato,56,28 A. Hiramoto,32 M. Hogan,8 J. Holeczek,51 N. T. Hong Van,20,27 T. Honjo,41 F. Iacob,24 A. K. Ichikawa,32 M. Ikeda,56 T. Ishida,16,‡ M. Ishitsuka,60 K. Iwamoto,55 A. Izmaylov,26 N. Izumi,60 M. Jakkapu,16 B. Jamieson,67 S. J. Jenkins,50 C. Jesús-Valls,18 M. Jiang,32 P. Jonsson,21 C. K. Jung,39,§ X. Junjie,57 P. B. Jurj,21 M. Kabirnezhad,42 A. C. Kaboth,48,54 T. Kajita,57,§ H. Kakuno,59 J. Kameda,56 D. Karlen,63,62 S. P. Kasetti,35 Y. Kataoka,56 Y. Katayama,69 T. Katori,30 Y. Kato,56 E. Kearns,3,28,§ M. Khabibullin,26 A. Khotjantsev,26 T. Kikawa,32 H. Kikutani,55 H. Kim,41 S. King,30 J. Kisiel,51 A. Knight,66 T. Kobata,41 T. Kobayashi,16,‡ L. Koch,42 T. Koga,55 A. Konaka,62 L. L. Kormos,33 Y. Koshio,40,§ A. Kostin,26 K. Kowalik,38 H. Kubo,32 Y. Kudenko,26,∥ N. Kukita,41 S. Kuribayashi,32 R. Kurjata,65 T. Kutter,35 M. Kuze,58 L. Labarga,1 J. Lagoda,38 M. Lamoureux,24 D. Last,43 M. Lawe,33 M. Licciardi,10 R. P. Litchfield,14 S. L. Liu,39 X. Li,39 A. Longhin,24 L. Ludovici,25 X. Lu,42 T. Lux,18 L. N. Machado,23 L. Magaletti,22 K. Mahn,36 M. Malek,50 S. Manly,47 L. Maret,13 A. D. Marino,7 L. Marti-Magro,56,28 T. Maruyama,16,‡ T. Matsubara,16 K. Matsushita,55 V. Matveev,26 C. Mauger,43 K. Mavrokoridis,34 E. Mazzucato,6 N. McCauley,34 J. McElwee,50 K. S. McFarland,47 C. McGrew,39 A. Mefodiev,26 C. Metelko,34 M. Mezzetto,24 A. Minamino,69 O. Mineev,26 S. Mine,5 M. Miura,56,§ L. Molina Bueno,11 S. Moriyama,56,§ Th. A. Mueller,10 L. Munteanu,6 S. Murphy,11 Y. Nagai,7 T. Nakadaira,16,‡ M. Nakahata,56,28 Y. Nakajima,56 A. Nakamura,40 K. Nakamura,28,16,‡ S. Nakayama,56,28 T. Nakaya,32,28 K. Nakayoshi,16,‡ C. E. R. Naseby,21 T. V. Ngoc,20,¶ K. Niewczas,68 K. Nishikawa,16,* Y. Nishimura,29 E. Noah,13 T. S. Nonnenmacher,21 F. Nova,54 P. Novella,19 J. Nowak,33 J. C. Nugent,14 H. M. O’Keeffe,33 L. O’Sullivan,50 T. Odagawa,32 T. Ogawa,16 R. Okada,40 K. Okumura,57,28 T. Okusawa,41 S. M. Oser,4,62 R. A. Owen,45 Y. Oyama,16,‡ V. Palladino,23 V. Paolone,44 M. Pari,24 W. C. Parker,48 S. Parsa,13 J. Pasternak,21 M. Pavin,62 D. Payne,34 G. C. Penn,34 L. Pickering,36 C. Pidcott,50 G. Pintaudi,69 C. Pistillo,2 B. Popov,53,** K. Porwit,51 M. Posiadala-Zezula,64 A. Pritchard,34 B. Quilain,10 T. Radermacher,49 E. Radicioni,22 B. Radics,11 P. N. Ratoff,33 C. Riccio,39 E. Rondio,38 S. Roth,49 A. Rubbia,11 A. C. Ruggeri,23 C. Ruggles,14 A. Rychter,65 K. Sakashita,16,‡ F. Sánchez,13 G. Santucci,70 C. M. Schloesser,11 K. Scholberg,9,§ M. Scott,21 Y. Seiya,41,†† T. Sekiguchi,16,‡ H. Sekiya,56,28,§ D. Sgalaberna,11 A. Shaikhiev,26 A. Shaykina,26 M. Shiozawa,56,28 W. Shorrock,21 A. Shvartsman,26 M. Smy,5 J. T. Sobczyk,68 H. Sobel,5,28 F. J. P. Soler,14 Y. Sonoda,56 S. Suvorov,26,6 A. Suzuki,31 S. Y. Suzuki,16,‡ Y. Suzuki,28 A. A. Sztuc,21 M. Tada,16,‡ M. Tajima,32 A. Takeda,56 Y. Takeuchi,31,28 H. K. Tanaka,56,§ H. A. Tanaka,52,61 S. Tanaka,41 Y. Tanihara,69 N. Teshima,41 L. F. Thompson,50 W. Toki,8 C. Touramanis,34 T. Towstego,61 K. M. Tsui,34 T. Tsukamoto,16,‡ M. Tzanov,35 Y. Uchida,21 M. Vagins,28,5 S. Valder,66 Z. Vallari,39 D. Vargas,18 G. Vasseur,6 W. G. S. Vinning,66 T. Vladisavljevic,54 V. V. Volkov,26 T. Wachala,15 J. Walker,67 J. G. Walsh,33 Y. Wang,39 D. Wark,54,42 M. O. Wascko,21 A. Weber,54,42 R. Wendell,32,§ M. J. Wilking,39 C. Wilkinson,2 J. R. Wilson,30 K. Wood,39 C. Wret,47 K. Yamamoto,41,†† C. Yanagisawa,39,‡‡ G. Yang,39 T. Yano,56 K. Yasutome,32 N. Yershov,26 M. Yokoyama,55,§ T. Yoshida,58 M. Yu,70 A. Zalewska,15 J. Zalipska,38 K. Zaremba,65 G. Zarnecki,38 M. Ziembicki,65 E. D. Zimmerman,7 M. Zito,53 S. Zsoldos,30 and A. Zykova26 (T2K Collaboration)This paper reports the first simultaneous measurement of the double differential muon neutrino chargedcurrent cross section on oxygen and carbon without pions in the final state as a function of the outgoing muon kinematics, made at the ND280 off-axis near detector of the T2K experiment. The ratio of the oxygen and carbon cross sections is also provided to help validate various models’ ability to extrapolate between carbon and oxygen nuclear targets, as is required in T2K oscillation analyses. The data are taken using a neutrino beam with an energy spectrum peaked at 0.6 GeV. The extracted measurement is compared with the prediction from different Monte Carlo neutrino-nucleus interaction event generators, showing particular model separation for very forward-going muons. Overall, of the models tested, the result is best described using local Fermi gas descriptions of the nuclear ground state with RPA suppression

Scintillator ageing of the T2K near detectors from 2010 to 2021

The T2K experiment widely uses plastic scintillator as a target for neutrino interactions and an active medium for the measurement of charged particles produced in neutrino interactions at its near detector complex. Over 10 years of operation the measured light yield recorded by the scintillator based subsystems has been observed to degrade by 0.9-2.2% per year. Extrapolation of the degradation rate through to 2040 indicates the recorded light yield should remain above the lower threshold used by the current reconstruction algorithms for all subsystems. This will allow the near detectors to continue contributing to important physics measurements during the T2K-II and Hyper-Kamiokande eras. Additionally, work to disentangle the degradation of the plastic scintillator and wavelength shifting fibres shows that the reduction in light yield can be attributed to the ageing of the plastic scintillator. The long component of the attenuation length of the wavelength shifting fibres was observed to degrade by 1.3-5.4% per year, while the short component of the attenuation length did not show any conclusive degradation.Ministerio de Ciencia e Innovación SEV-2016-0588, PID2019-107564GB-I00, PGC2018-099388-BI00European Union 713673, 754496, RISE-GA822070-JENNIFER2 2020, RISE-GA872549-SK2HKJSPS KAKENHI (JP16H06288, JP18K03682, JP18H03701, JP18H05537, JP19J01119, JP19J22440, JP19J22258, JP20H00162, JP20H00149, JP20J2030

Conserved Quantities in f(R)f(R) Gravity via Noether Symmetry

This paper is devoted to investigate $f(R)$ gravity using Noether symmetry approach. For this purpose, we consider Friedmann Robertson-Walker (FRW) universe and spherically symmetric spacetimes. The Noether symmetry generators are evaluated for some specific choice of $f(R)$ models in the presence of gauge term. Further, we calculate the corresponding conserved quantities in each case. Moreover, the importance and stability criteria of these models are discussed.Comment: 14 pages, accepted for publication in Chin. Phys. Let

Measurement of the charged-current electron (anti-)neutrino inclusive cross-sections at the T2K off-axis near detector ND280

The electron (anti-)neutrino component of the T2K neutrino beam constitutes the largest background in the measurement of electron (anti-)neutrino appearance at the far detector. The electron neutrino scattering is measured directly with the T2K off-axis near detector, ND280. The selection of the electron (anti-)neutrino events in the plastic scintillator target from both neutrino and anti-neutrino mode beams is discussed in this paper. The flux integrated single differential charged-current inclusive electron (anti-)neutrino cross-sections, dσ/dp and dσ/d cos(θ), and the total cross-sections in a limited phase-space in momentum and scattering angle (p \u3e 300 MeV/c and θ ≤ 45°) are measured using a binned maximum likelihood fit and compared to the neutrino Monte Carlo generator predictions, resulting in good agreement

Simultaneous measurement of the muon neutrino charged-current cross section on oxygen and carbon without pions in the final state at T2K

This paper reports the first simultaneous measurement of the double differential muon neutrino charged-current cross section on oxygen and carbon without pions in the final state as a function of the outgoing muon kinematics, made at the ND280 off-axis near detector of the T2K experiment. The ratio of the oxygen and carbon cross sections is also provided to help validate various models\u27 ability to extrapolate between carbon and oxygen nuclear targets, as is required in T2K oscillation analyses. The data are taken using a neutrino beam with an energy spectrum peaked at 0.6 GeV. The extracted measurement is compared with the prediction from different Monte Carlo neutrino-nucleus interaction event generators, showing particular model separation for very forward-going muons. Overall, of the models tested, the result is best described using local Fermi gas descriptions of the nuclear ground state with RPA suppression

First combined measurement of the muon neutrino and antineutrino charged-current cross section without pions in the final state at T2K

This paper presents the first combined measurement of the double-differential muon neutrino and antineutrino charged-current cross sections with no pions in the final state on hydrocarbon at the off-axis near detector of the T2K experiment. The data analyzed in this work comprise 5.8×1020 and 6.3×1020 protons on target in neutrino and antineutrino mode respectively, at a beam energy peak of 0.6 GeV. Using the two measured cross sections, the sum, difference, and asymmetry were calculated with the aim of better understanding the nuclear effects involved in such interactions. The extracted measurements have been compared with the prediction from different Monte Carlo generators and theoretical models showing that the difference between the two cross sections have interesting sensitivity to nuclear effects

T2K measurements of muon neutrino and antineutrino disappearance using 3.13×1021 protons on target

We report measurements by the T2K experiment of the parameters θ23 and Δm322, which govern the disappearance of muon neutrinos and antineutrinos in the three-flavor PMNS neutrino oscillation model at T2K\u27s neutrino energy and propagation distance. Utilizing the ability of the experiment to run with either a mainly neutrino or a mainly antineutrino beam, muon-like events from each beam mode are used to measure these parameters separately for neutrino and antineutrino oscillations. Data taken from 1.49×1021 protons on target (POT) in neutrino mode and 1.64×1021 POT in antineutrino mode are used. The best-fit values obtained by T2K were sin2(θ23)=0.51-0.07+0.06(0.43-0.05+0.21) and Δm322=2.47-0.09+0.08(2.50-0.13+0.18)×10-3 eV2/c4 for neutrinos (antineutrinos). No significant differences between the values of the parameters describing the disappearance of muon neutrinos and antineutrinos were observed. An analysis using an effective two-flavor neutrino oscillation model where the sine of the mixing angle is allowed to take nonphysical values larger than 1 is also performed to check the consistency of our data with the three-flavor model. Our data were found to be consistent with a physical value for the mixing angle

Improved constraints on neutrino mixing from the T2K experiment with 3.13×1021 protons on target

The T2K experiment reports updated measurements of neutrino and antineutrino oscillations using both appearance and disappearance channels. This result comes from an exposure of 14.9(16.4)×1020 protons on target in neutrino (antineutrino) mode. Significant improvements have been made to the neutrino interaction model and far detector reconstruction. An extensive set of simulated data studies have also been performed to quantify the effect interaction model uncertainties have on the T2K oscillation parameter sensitivity. T2K performs multiple oscillation analyses that present both frequentist and Bayesian intervals for the Pontecorvo-Maki-Nakagawa-Sakata parameters. For fits including a constraint on sin2θ13 from reactor data and assuming normal mass ordering T2K measures sin2θ23=0.53-0.04+0.03 and Δm322=(2.45±0.07)×10-3 eV2 c-4. The Bayesian analyses show a weak preference for normal mass ordering (89% posterior probability) and the upper sin2θ23 octant (80% posterior probability), with a uniform prior probability assumed in both cases. The T2K data exclude CP conservation in neutrino oscillations at the 2σ level