CPandTviolation tests in neutrino oscillation

Abstract

We examine how large violation effects of CP and T are allowed in long baseline neutrino experiments. When we attribute only the atmospheric neutrino anomaly to neutrino oscillation we may have large CPviolation effects. When we attribute both the atmospheric neutrino anomaly and the solar neutrino deficit to neutrino oscillation we may have sizable T violation effects proportional to the ratio of the two mass differences; it is difficult to see CP violation since we cannot ignore the matter effect. We give a simple expression for T violation in the presence of matter. ͓S0556-2821͑97͒00903-X͔ PACS number͑s͒: 14.60.Pq, 11.30.Er † Electronic address: joe@icrhp3.icrr.u-tokyo.ac.jp 1 We assume m 1 Ͻm 2

LeptonicCPviolation

“…It is also important to note that, if the order-one phase corresponds to the largest ∆m 2 kj , then ∆P CP αβ ≃ 0 (Barger et al, 1980c;Bilenky and Niedermayer, 1981 (3.10)]. Therefore, a measurement of the CP-odd asymmetry in neutrino oscillations can be performed only in long-baseline experiments (Arafune and Sato, 1997;Bilenky et al, 1998;Minakata and Nunokawa, 1997;Tanimoto, 1997), as long as |J 21 eµ | is not too small.…”

Neutrino Oscillations With Two Sterile Neutrinos

“…an extension of the 4x4 [7,8] theory with one serile neutrino, which used the 3x3 formalism of Ref [5], to a 5x5 matrix formalism. From Eq(2), multiplying the nine 5x5 O matrices, we obtain the matrix U.…”

“…In the present work we use a U-matrix approach, introduced for active neutrinos with a 3x3 U-matrix [5], and extended to a 4x4 U-matrix with one sterile neutrino in a recent study of P(ν µ → ν e ), the transition probability for a muon neutrino to oscillate to an electron neutrino [7,8]. We introduce a 5x5 U-matrix for three active and two sterile neutrinos, using the parameters found in Refs.…”

CP and T trajectory diagrams for a unified graphical representation of neutrino oscillations

“…[5] and [6]. Therefore, it is one of the most important issues to achieve a complete understanding of the interplay between the CP-phase and the matter effects in parameter regions relevant for such experiments.…”