T2K Collaboration(Abe, K. et al), Antonova, M., Cervera-Villanueva, A., Fernandez, P., Izmaylov, A., & Novella, P. (2019). Search for heavy neutrinos with the T2K near detector ND280. Phys. Rev. D, 100(5), 052006–10pp.
Abstract: 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 -> l(alpha)(+/-)pi(-/+) and N -> l(alpha)(+)l(beta)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- flavored 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.
|
T2K Collaboration(Abe, K. et al), Cervera-Villanueva, A., & Novella, P. (2017). Measurement of (nu)over-bar(mu) and nu(mu) charged current inclusive cross sections and their ratio with the T2K off-axis near detector. Phys. Rev. D, 96(5), 052001–15pp.
Abstract: We report a measurement of cross section sigma(nu(mu) + nucleus. -> mu(-) + X) and the first measurements of the cross section sigma((sigma) over bar (mu) + nucleus -> mu(+) + X) and their ratio R(sigma((nu) over bar)sigma(nu)) at (anti) neutrino energies below 1.5 GeV. We determine the single momentum bin cross section measurements, averaged over the T2K (nu) over bar/nu-flux, for the detector target material (mainly carbon, oxygen, hydrogen and copper) with phase space restricted laboratory frame kinematics of theta(mu) < 32 degrees and p(mu) > 500 MeV/c. The results are sigma((nu) over bar) = (0.900 +/- 0.029d (stat) +/- 0.088(syst) x 10(-39) and sigma(nu) = (2.41 +/- 0.022(stat) +/- 0.231(syst)) x 10(-39) in units of cm(2)/nucleon and R(sigma((nu) over bar)/sigma(nu) = 0.373 +/- 0.012(stat) +/- 0.015(syst).
|
HARP Collaboration(Apollonio, M. et al), Burguet-Castell, J., Cervera-Villanueva, A., Gomez-Cadenas, J. J., Martin-Albo, J., Novella, P., et al. (2010). Measurements of forward proton production with incident protons and charged pions on nuclear targets at the CERN Proton Synchroton. Phys. Rev. C, 82(4), 045208–33pp.
Abstract: Measurements of the double-differential proton production cross-section d(2 sigma)/dpd Omega in the range of momentum 0.5 GeV/c <= p < 8.0 GeV/c and angle 0.05 rad <= theta < 0.25 rad in collisions of charged pions and protons on beryllium, carbon, aluminium, copper, tin, tantalum, and lead are presented. The data were taken with the large acceptance HARP detector in the T9 beam line of the CERN Proton Synchrotron. Incident particles were identified by an elaborate system of beam detectors and impinged on a target of 5% of a nuclear interaction length. The tracking and identification of the produced particles was performed using the forward spectrometer of the HARP experiment. Results are obtained for the double-differential cross-sections mainly at four incident beam momenta (3, 5, 8, and 12 GeV/c). Measurements are compared with predictions of the GEANT4 and MARS Monte Carlo generators.
|
T2K Collaboration(Abe, K. et al), Antonova, M., Cervera-Villanueva, A., Izmaylov, A., & Novella, P. (2018). Characterization of nuclear effects in muon-neutrino scattering on hydrocarbon with a measurement of final-state kinematics and correlations in charged-current pionless interactions at T2K. Phys. Rev. D, 98(3), 032003–46pp.
Abstract: This paper reports measurements of final-state proton multiplicity, muon and proton kinematics, and their correlations in charged-current pionless neutrino interactions, measured by the T2K ND280 near detector in its plastic scintillator (C8H8) target. The data were taken between years 2010 and 2013, corresponding to approximately 6 x 10(20) protons on target. Thanks to their exploration of the proton kinematics and of imbalances between the proton and muon kinematics, the results offer a novel probe of the nuclear-medium effects most pertinent to the (sub-)GeV neutrino-nucleus interactions that are used in accelerator-based long-baseline neutrino oscillation measurements. These results are compared to many neutrino-nucleus interaction models which all fail to describe at least part of the observed phase space. In case of events without a proton above a detection threshold in the final state, a fully consistent implementation of the local Fermi gas model with multinucleon interactions gives the best description of the data. In the case of at least one proton in the final state, the spectral function model agrees well with the data, most notably when measuring the kinematic imbalance between the muon and the proton in the plane transverse to the incoming neutrino. Within the models considered, only the existence of multinucleon interactions are able to describe the extracted cross section within regions of high transverse kinematic imbalance. The effect of final-state interactions is also discussed.
|
T2K Collaboration(Abe, K. et al), Cervera-Villanueva, A., Izmaylov, A., Novella, P., Sorel, M., & Stamoulis, P. (2018). Measurement of the single pi(0) production rate in neutral current neutrino interactions on water. Phys. Rev. D, 97(3), 032002–13pp.
Abstract: The single pi(0) production rate in neutral current neutrino interactions on water in a neutrino beam with a peak neutrino energy of 0.6 GeV has been measured using the empty set, one of the subdetectors of the T2K near detector. The production rate was measured for data taking periods when the Pempty setD contained water (2.64 x 10(20) protons-on-target) and also periods without water (3.49 x 10(20) protons-on-target). A measurement of the neutral current single pi(0) production rate on water is made using appropriate subtraction of the production rate with water in from the rate with water out of the target region. The subtraction analysis yields 106 +/- 41 +/- 69 signal events where the uncertainties are statistical (stat.) and systematic (sys.) respectively. This is consistent with the prediction of 157 events from the nominal simulation. The measured to expected ratio is 0.68 +/- 0.26(stat) +/- 0.44(sys) +/- 0.12(flux). The nominal simulation uses a flux integrated cross section of 7.63 x 10(-39) cm(2) per nucleon with an average neutrino interaction energy of 1.3 GeV.
|
