Minoo Kabirnezhad

Abstract:

The Tokai to Kamioka (T2K) long-baseline neutrino experiment consists of a muon neutrino beam, produced at the J-PARC accelerator, a near detector complex and a large 295-km-distant far detector. The present work utilizes the T2K event timing measurements at the near and far detectors to study neutrino time of flight as a function of derived neutrino energy. Under the assumption of a relativistic relation between energy and time of flight, constraints on the neutrino rest mass can be derived. The sub-GeV neutrino beam in conjunction with timing precision of order tens of ns provide sensitivity to neutrino mass in the few MeV/c2 range. We study the distribution of relative arrival times of muon and electron neutrino candidate events at the T2K far detector as a function of neutrino energy. The 90% C.L. upper limit on the mixture of neutrino mass eigenstates represented in the data sample is found to be m2ν<5.6 MeV2/c4.

Abstract:

This paper reports a measurement by the T2K experiment of the ν μ charged current quasielastic (CCQE) cross section on a carbon target with the off-axis detector based on the observed distribution of muon momentum ( p μ ) and angle with respect to the incident neutrino beam ( θ μ ). The flux-integrated CCQE cross section was measured to be ⟨ σ ⟩ = ( 0.83 ± 0.12 ) × 10 − 38     cm 2 . The energy dependence of the CCQE cross section is also reported. The axial mass, M QE A , of the dipole axial form factor was extracted assuming the Smith-Moniz CCQE model with a relativistic Fermi gas nuclear model. Using the absolute (shape-only) p μ − cos θ μ distribution, the effective M QE A parameter was measured to be 1.2 6 + 0.21 − 0.18     GeV / c 2 ( 1.4 3 + 0.28 − 0.22     GeV / c 2 ).