We report measurements of the flux-integrated (nu) over bar (mu) and (nu) over bar (mu) + nu(mu) charged-current cross -sections on water and hydrocarbon targets using the T2K anti-neutrino beam with a mean beam energy of 0.86 GeV. The signal is defined as the (anti -)neutrino charged-current interaction with one induced mu(+/-) and no detected charged pion or proton. These measurements are performed using a new WAGASCI module recently added to the T2K setup in combination with the INGRID Proton Module. The phase space of muons is restricted to the high-detection efficiency region, p(mu) > 400 MeV/c and theta(mu) < 30 degrees, in the laboratory frame. An absence of pions and protons in the detectable phase spaces of p(pi) > 200 MeV/c, theta(pi) < 70 degrees and p(p) > 600 MeV/c, theta(p) < 70 degrees is required. In this paper, both the <(nu)over bar>(mu), cross-sections and (nu) over bar (mu) + nu(mu), cross-sections on water and hydrocarbon targets and their ratios are provided by using the D'Agostini unfolding method. The results of the integrated (nu) over bar (mu), cross-section measurements over this phase space are sigma(H2O) = (1.082 +/- 0.068(stat.)(+0.145)(-0.128)(syst.)) x 10(-39) cm(2)/nucleon, sigma(CH) = (1.096 +/- 0.054 (stat.)(+0.132)(-0.117)(syst.)) x 10(-39) cm(2) /nucleon, and sigma(H2O)/sigma(CH) = 0.987 +/- 0.078 (stat.)(+0.093)(-0.090)(syst.). The (nu) over bar (mu), + nu(mu), cross-section is sigma(H2O) = (1.155 +/- 0.064(stat.)(+0.148)(-0.129)(syst.)) x 10(-39) cm(2)/nucleon, sigma(CH) = (1.159 +/- 0.049(stat.)(+0.129)(-0.115)(syst.)) x 10(-39) cm(2)/nucleon, and sigma(H2O)/sigma(CH) = 0.996 +/- 0.069(stat.)(+0.083)(-0.078)(syst.).

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) × 10^20 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 PMNS parameters. For fits including a constraint on from reactor data and assuming normal mass ordering T2K measures sin^2θ_23 = 0.53^+0.03_-0.04 and Δm^2_32 = (2.45 ± 0.07) × 10^-3 eV^2c^-4. The Bayesian analyses show a weak preference for normal mass ordering (89 posterior probability) and the upper sin^2θ_23 octant (80 probability), with a uniform prior probability assumed in both cases. The T2K data exclude CP conservation in neutrino oscillations at the 2σ level.

This paper reports the first T2K measurement of the transverse kinematic imbalance in the single-$\pi^+$ production channel of neutrino interactions. We measure the differential cross sections in the muon-neutrino charged-current interaction on hydrocarbon with a single $\pi^+$ and at least one proton in the final state, at the ND280 off-axis near detector of the T2K experiment. The extracted cross sections are compared to the predictions from different neutrino-nucleus interaction event generators. Overall, the results show a preference for models which have a more realistic treatment of nuclear medium effects including the initial nuclear state and final-state interactions.

We report measurements of the flux-integrated ν̅_μ and ν̅_μ+ν_μ charged-current cross-sections on water and hydrocarbon targets using the T2K anti-neutrino beam, with a mean neutrino energy of 0.86 GeV. The signal is defined as the (anti-)neutrino charged-current interaction with one induced μ^± and no detected charged pion nor proton. These measurements are performed using a new WAGASCI module recently added to the T2K setup in combination with the INGRID Proton module. The phase space of muons is restricted to the high-detection efficiency region, p_μ>400 MeV/c and θ_μ<30^∘, in the laboratory frame. Absence of pions and protons in the detectable phase space of "p_π>200 MeV/c and θ_π<70^∘", and "p_ p>600 MeV/c and θ_ p<70^∘" is required. In this paper, both of the ν̅_μ cross-sections and ν̅_μ+ν_μ cross-sections on water and hydrocarbon targets, and their ratios are provided by using D'Agostini unfolding method. The results of the integrated ν̅_μ cross-section measurements over this phase space are σ_ H_2O = (1.082±0.068( stat.)^+0.145_-0.128( syst.)) × 10^-39 cm^2/nucleon, σ_ CH = (1.096±0.054( stat.)^+0.132_-0.117( syst.)) × 10^-39 cm^2/nucleon, and σ_ H_2O/σ_ CH = 0.987±0.078( stat.)^+0.093_-0.090( syst.). The ν̅_μ+ν_μ cross-section is σ_ H_2O = (1.155±0.064( stat.)^+0.148_-0.129( syst.)) × 10^-39 cm^2/nucleon, σ_ CH = (1.159±0.049( stat.)^+0.129_-0.115( syst.)) × 10^-39 cm^2/nucleon, and σ_ H_2O/σ_ CH = 0.996±0.069( stat.)^+0.083_-0.078( syst.).

We report measurements of the flux-integrated $\overline{\nu}_\mu$ and $\overline{\nu}_\mu+\nu_\mu$ charged-current cross-sections on water and hydrocarbon targets using the T2K anti-neutrino beam with a mean beam energy of 0.86 GeV. The signal is defined as the (anti-)neutrino charged-current interaction with one induced $\mu^\pm$ and no detected charged pion or proton. These measurements are performed using a new WAGASCI module recently added to the T2K setup in combination with the INGRID Proton Module. The phase space of muons is restricted to the high-detection efficiency region, $p_{\mu}>400~{\rm MeV}/c$ and $\theta_{\mu}<30^{\circ}$, in the laboratory frame. An absence of pions and protons in the detectable phase spaces of $p_{\pi}>200~{\rm MeV}/c$, $\theta_{\pi}<70^{\circ}$ and $p_{\rm p}>600~{\rm MeV}/c$, $\theta_{\rm p}<70^{\circ}$ is required. In this paper, both the $\overline{\nu}_\mu$ cross-sections and $\overline{\nu}_\mu+\nu_\mu$ cross-sections on water and hydrocarbon targets and their ratios are provided by using the D’Agostini unfolding method. The results of the integrated $\overline{\nu}_\mu$ cross-section measurements over this phase space are $\sigma_{\rm H_{2}O}=(1.082\pm0.068(\rm stat.)^{+0.145}_{-0.128}(\rm syst.)) \times 10^{-39}\,{\rm cm^{2} / nucleon}$, $\sigma_{\rm CH}=(1.096\pm0.054(\rm stat.)^{+0.132}_{-0.117}(\rm syst.)) \times 10^{-39}\,{\rm cm^{2} / nucleon}$, and $\sigma_{\rm H_{2}O}/\sigma_{\rm CH} = 0.987\pm0.078(\rm stat.)^{+0.093}_{-0.090}(\rm syst.)$. The $\overline{\nu}_\mu+\nu_\mu$ cross-section is $\sigma_{\rm H_{2}O} = (1.155\pm0.064(\rm stat.)^{+0.148}_{-0.129}(\rm syst.)) \times 10^{-39}\,{\rm cm^{2} / nucleon}$, $\sigma_{\rm CH}=(1.159\pm0.049(\rm stat.)^{+0.129}_{-0.115}(\rm syst.)) \times 10^{-39}\,{\rm cm^{2} / nucleon}$, and $\sigma_{\rm H_{2}O}/\sigma_{\rm CH}=0.996\pm0.069(\rm stat.)^{+0.083}_{-0.078}(\rm syst.)$.

K. Abe, N. Akhlaq, R. Akutsu, A. Ali, C. Alt, C. Andreopoulos, 33 M. Antonova, S. Aoki, T. Arihara, Y. Asada, Y. Ashida, E.T. Atkin, Y. Awataguchi, G.J. Barker, G. Barr, D. Barrow, M. Batkiewicz-Kwasniak, A. Beloshapkin, F. Bench, V. Berardi, L. Berns, S. Bhadra, A. Blanchet, A. Blondel, 12 S. Bolognesi, T. Bonus, B. Bourguille, S.B. Boyd, A. Bravar, D. Bravo Berguño, C. Bronner, S. Bron, A. Bubak, M. Buizza Avanzini, S. Cao, S.L. Cartwright, M.G. Catanesi, A. Cervera, D. Cherdack, G. Christodoulou, M. Cicerchia, ∗ J. Coleman, G. Collazuol, L. Cook, 27 D. Coplowe, A. Cudd, G. De Rosa, T. Dealtry, C.C. Delogu, S.R. Dennis, C. Densham, A. Dergacheva, F. Di Lodovico, S. Dolan, D. Douqa, T.A. Doyle, J. Dumarchez, P. Dunne, A. Eguchi, L. Eklund, S. Emery-Schrenk, A. Ereditato, A.J. Finch, G. Fiorillo, C. Francois, M. Friend, † Y. Fujii, † R. Fukuda, Y. Fukuda, K. Fusshoeller, C. Giganti, M. Gonin, A. Gorin, M. Grassi, M. Guigue, D.R. Hadley, P. Hamacher-Baumann, D.A. Harris, M. Hartz, 27 T. Hasegawa, † S. Hassani, N.C. Hastings, Y. Hayato, 27 A. Hiramoto, M. Hogan, J. Holeczek, N.T. Hong Van, 26 T. Honjo, F. Iacob, A.K. Ichikawa, M. Ikeda, T. Ishida, † M. Ishitsuka, K. Iwamoto, A. Izmaylov, N. Izumi, M. Jakkapu, B. Jamieson, S.J. Jenkins, C. Jesús-Valls, P. Jonsson, C.K. Jung, ‡ P.B. Jurj, M. Kabirnezhad, H. Kakuno, J. Kameda, S.P. Kasetti, Y. Kataoka, Y. Katayama, T. Katori, E. Kearns, 27, ‡ M. Khabibullin, A. Khotjantsev, T. Kikawa, H. Kikutani, S. King, J. Kisiel, T. Kobata, T. Kobayashi, † L. Koch, A. Konaka, L.L. Kormos, Y. Koshio, ‡ A. Kostin, K. Kowalik, Y. Kudenko, § S. Kuribayashi, R. Kurjata, T. Kutter, M. Kuze, L. Labarga, J. Lagoda, M. Lamoureux, D. Last, M. Laveder, M. Lawe, R.P. Litchfield, S.L. Liu, A. Longhin, L. Ludovici, X. Lu, T. Lux, L.N. Machado, L. Magaletti, K. Mahn, M. Malek, S. Manly, L. Maret, A.D. Marino, L. Marti-Magro, 27 T. Maruyama, † T. Matsubara, K. Matsushita, C. Mauger, K. Mavrokoridis, E. Mazzucato, N. McCauley, J. McElwee, K.S. McFarland, C. McGrew, A. Mefodiev, M. Mezzetto, A. Minamino, O. Mineev, S. Mine, M. Miura, ‡ L. Molina Bueno, S. Moriyama, ‡ Th.A. Mueller, L. Munteanu, Y. Nagai, T. Nakadaira, † M. Nakahata, 27 Y. Nakajima, A. Nakamura, K. Nakamura, 15, † Y. Nakano, S. Nakayama, 27 T. Nakaya, 27 K. Nakayoshi, † C.E.R. Naseby, T.V. Ngoc, ¶ V.Q. Nguyen, K. Niewczas, Y. Nishimura, E. Noah, T.S. Nonnenmacher, F. Nova, J. Nowak, J.C. Nugent, H.M. O’Keeffe, L. O’Sullivan, T. Odagawa, T. Ogawa, R. Okada, K. Okumura, 27 T. Okusawa, R.A. Owen, Y. Oyama, † V. Palladino, V. Paolone, M. Pari, W.C. Parker, S. Parsa, J. Pasternak, M. Pavin, D. Payne, G.C. Penn, L. Pickering, C. Pidcott, G. Pintaudi, C. Pistillo, B. Popov, ∗∗ K. Porwit, M. Posiadala-Zezula, A. Pritchard, B. Quilain, T. Radermacher, E. Radicioni, B. Radics, P.N. Ratoff, C. Riccio, E. Rondio, S. Roth, A. Rubbia, A.C. Ruggeri, C. Ruggles, A. Rychter, K. Sakashita, † F. Sánchez, G. Santucci, C.M. Schloesser, K. Scholberg, ‡ M. Scott, Y. Seiya, †† T. Sekiguchi, † H. Sekiya, 27, ‡ D. Sgalaberna, A. Shaikhiev, A. Shaykina, M. Shiozawa, 27 W. Shorrock, A. Shvartsman, K. Skwarczynski, M. Smy, J.T. Sobczyk, H. Sobel, 27 F.J.P. Soler, Y. Sonoda, R. Spina, S. Suvorov, 50 A. Suzuki, S.Y. Suzuki, † Y. Suzuki, A.A. Sztuc, M. Tada, † M. Tajima, A. Takeda, Y. Takeuchi, 27 H.K. Tanaka, ‡ Y. Tanihara, M. Tani, N. Teshima, L.F. Thompson, W. Toki, C. Touramanis, T. Towstego, K.M. Tsui, T. Tsukamoto, † M. Tzanov, Y. Uchida, M. Vagins, 4 S. Valder, D. Vargas, G. Vasseur, C. Vilela, W.G.S. Vinning, T. Vladisavljevic, T. Wachala, J. Walker, J.G. Walsh, Y. Wang, D. Wark, 41 M.O. Wascko, A. Weber, 41 R. Wendell, ‡ M.J. Wilking, C. Wilkinson, J.R. Wilson, K. Wood, C. Wret, J. Xia, K. Yamamoto, †† C. Yanagisawa, ‡‡ G. Yang, T. Yano, K. Yasutome, N. Yershov, M. Yokoyama, ‡ T. Yoshida, Y. Yoshimoto, M. Yu, A. Zalewska, J. Zalipska, K. Zaremba, G. Zarnecki, M. Ziembicki, M. Zito, and S. Zsoldos

We report measurements by the T2K experiment of the parameters $\theta_23$ and $\Delta m^2_{32}$ which govern the disappearance of muon neutrinos and antineutrinos in the three-flavor PMNSneutrino oscillation model at T2K's 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 $1.49\times 10^{21}$ protons on target (POT) in neutrino mode and $1.64\times 10^21$ POT in antineutrino mode are used. Assuming the normal neutrino mass ordering the best-fit values obtained by T2K were $\sin^2\theta_{23}=0.51^{+0.06}_{-0.07}$ $(0.43^{+0.21}_{-0.05})$ and $\Delta m^2_{32}=2.47^{+0.08}_{-0.09} (2.50^{+0.18}_{-0.13})$ $eV^2/c^4$. 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-flavour neutrino oscillation model where the sine of the mixing angle is allowed to take non-physical 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.

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' 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.

Abstract 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 > 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.

We report the measurements of single and double differential cross section of muon neutrino charged-current interactions on carbon with a single positively charged pion in the final state at the T2K off-axis near detector using $5.56\times10^{20}$ protons on target. The analysis uses data control samples for the background subtraction and the cross section signal, defined as a single negatively charged muon and a single positively charged pion exiting from the target nucleus, is extracted using an unfolding method. The model dependent cross section, integrated over the T2K off-axis neutrino beam spectrum peaking at $0.6$~GeV, is measured to be $\sigma = (11.76 \pm 0.44 \text{(stat)} \pm 2.39 \text{(syst)}) \times 10^{-40} \text{cm}^2$~$\text{nucleon}^{-1}$. Various differential cross sections are measured, including the first measurement of the Adler angles for single charged pion production in neutrino interactions with heavy nuclei target.

We have measured new observables based on the final state kinematic imbalances in the mesonless production of $\nu_\mu+A\rightarrow\mu^-+p+X$ in the $\text{MINER}\nu\text{A}$ tracker. Components of the muon-proton momentum imbalances parallel ($\delta p_\mathrm{Ty}$) and perpendicular($\delta p_\mathrm{Tx}$) to the momentum transfer in the transverse plane are found to be sensitive to the nuclear effects such as Fermi motion, binding energy and non-QE contributions. The QE peak location in $\delta p_\mathrm{Ty}$ is particularly sensitive to the binding energy. Differential cross sections are compared to predictions from different neutrino interaction models. The Fermi gas models presented in this study cannot simultaneously describe features such as QE peak location, width and the non-QE events contributing to the signal process. Correcting the GENIE's binding energy implementation according to theory causes better agreement with data. Hints of proton left-right asymmetry are observed in $\delta p_\mathrm{Tx}$. Better modeling of the binding energy can reduce bias in neutrino energy reconstruction and these observables can be applied in current and future experiments to better constrain nuclear effects.

Electron antineutrino appearance is measured by the T2K experiment in an accelerator-produced antineutrino beam, using additional neutrino beam operation to constrain parameters of the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) mixing matrix. T2K observes 15 candidate electron antineutrino events with a background expectation of 9.3 events. Including information from the kinematic distribution of observed events, the hypothesis of no electron antineutrino appearance is disfavored with a significance of 2.40σ and no discrepancy between data and PMNS predictions is found. A complementary analysis that introduces an additional free parameter which allows non-PMNS values of electron neutrino and antineutrino appearance also finds no discrepancy between data and PMNS predictions.

We study neutrino-induced charged-current (CC) pi(0) production on carbon nuclei using events with fully imaged final-state proton-pi(0) systems. Novel use of final-state correlations based on transverse kinematic imbalance enables the first measurements of the struck nucleon's Fermi motion, of the intranuclear momentum transfer (IMT) dynamics, and of the final-state hadronic momentum configuration in neutrino pion production. Event distributions are presented for (i) the momenta of neutrino-struck neutrons below the Fermi surface, (ii) the direction of missing transverse momentum characterizing the strength of IMT, and (iii) proton-pion momentum imbalance with respect to the lepton scattering plane. The observed Fermi motion and IMT strength are compared to the previous MINER.A measurement of neutrino CC quasielastic-like production. The measured shapes and absolute rates of these distributions, as well as the cross section asymmetries, show tensions with predictions from current neutrino generator models.

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 x 10(20) and 6.3 x 10(20) 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.

Elastic neutrino scattering on electrons is a precisely-known purely leptonic process that provides a standard candle for measuring neutrino flux in conventional neutrino beams. Using a total sample of 810 neutino-electron scatters after background subtraction, the measurement reduces the normalization uncertainty on the muon neutrino NuMI flux between 2 and 20 GeV from 7.5% to 3.9%. This is the most precise measurement of neutrino-electron scattering to date, will reduce uncertainties on MINERvA's absolute cross section measurements, and demonstrates a technique that can be used in future neutrino beams such as LBNF.

In this document, we present the Technical Design Report of the Upgrade of the T2K Near Detector ND280. The goal of this upgrade is to improve the Near Detector performance to measure the neutrino interaction rate and to constrain the neutrino interaction cross-sections so that the uncertainty in the number of predicted events at Super-Kamiokande is reduced to about 4 to improve the physics reach of the T2K-II project. This goal is achieved by modifying the upstream part of the detector, adding a new highly granular scintillator detector (Super-FGD), two new TPCs (High-Angle TPC) and six TOF planes. Details about the detector concepts, design and construction methods are presented, as well as a first look at the test-beam data taken in Summer 2018. An update of the physics studies is also presented.

This paper reports on the search for heavy neutrinos with masses in the range $140 < M_N < 493$ MeV/c$^2$ using the off-axis near detector ND280 of the T2K experiment. These particles can be produced from kaon decays in the standard neutrino beam and then subsequently decay in ND280. The decay modes under consideration are $N \to \ell^{\pm}_{\alpha} \pi^{\mp}$ and $N \to \ell^+_{\alpha} \ell^-_{\beta} \nu (\bar\nu)$ ($\alpha,\beta=e,\mu$). A search for such events has been made using the Time Projection Chambers of ND280, where the background has been reduced to less than two events in the current dataset in all channels. No excess has been observed in the signal region. A combined Bayesian statistical approach has been applied to extract upper limits on the mixing elements of heavy neutrinos to electron-, muon- and tau- flavoured currents ($U_e^2$, $U_{\mu}^2$, $U_{\tau}^2$) as a function of the heavy neutrino mass, e.g. $U_e^2 < 10^{-9}$ at $90\%$ C.L. for a mass of $390$ MeV/c$^2$. These constraints are competitive with previous experiments.