Signatures of a light sterile neutrino in T2HK

Abstract

We investigate the performance of T2HK in the presence of a light eV scale sterile neutrino. We study in detail its influence in resolving fundamental issues like mass hierarchy, CP-violation (CPV) induced by the standard CP-phase δ 13 and new CP-phase δ 14 , and the octant ambiguity of θ 23 . We show for the first time in detail that due to the impressive energy reconstruction capabilities of T2HK, the available spectral information plays an important role to enhance the mass hierarchy discovery reach of this experiment in 3ν framework and also to keep it almost intact even in 4ν scheme. This feature is also of the utmost importance in establishing the CPV due to δ 14 . As far as the sensitivity to CPV due to δ 13 is concerned, it does not change much going from 3ν to 4ν case. We also examine the reconstruction capability of the two phases δ 13 and δ 14 , and find that the typical 1σ uncertainty on δ 13 (δ 14 ) in T2HK is ∼ 15 0 (30 0 ). While determining the octant of θ 23 , we face a complete loss of sensitivity for unfavorable combinations of unknown δ 13 and δ 14 .

Physics potential of ESSνSB in the presence of a light sterile neutrino

“…The centroids of the two ellipses basically coincide, hence it is clear that the setup cannot discriminate the MH. This is qualitatively different with respect to what occurs in other LBL experiments (T2HK [27] and especially DUNE [22]), where the two ellipses get separated due to the presence of the matter effects. In the 3+1 scheme, two CP phases are present and their variation in the range [−π, π] gives even more freedom.…”

“…In this paper, we focus on the proposed super beam experiment to be performed at the European Spallation Source (ESSνSB), where a very powerful neutrino beam will be shot over a distance of about 540 km. Our present study is complementary to other recent investigations performed about DUNE [19][20][21][22][23][24][25], T2HK [25][26][27], and T2HKK [25,28]. Other studies on the impact of light sterile neutrinos in LBL setups can be found in [29][30][31][32][33][34][35][36][37].…”

“…We think that it is useful to make a comparison between the results obtained here for ESSνSB with those found for T2HK in our work [27]. We notice that in the 3-flavor scheme both experiments have a similar sensitivity to CPV induced by δ 13 , having both a maximal sensitivity of about 8σ for the values δ 13 ±90 0 .…”

“…In fact, one can notice the two following features: i) The deterioration of the sensitivity to the CPV driven by δ 13 when going from the 3-flavor to the 3+1 scheme is much more pronounced in ESSνSB than in T2HK. Taking the values δ 13 = ±90 0 as a benchmark (where the maximal sensitivity is attained) in [27], we found for T2HK only a weak reduction of the sensitivity from 8σ to 7σ (see Fig. 4 in [27]).…”

Exploring the potential of short-baseline physics at Fermilab

“…It has also been shown that this new phase from the seesaw mechanism brings in a new degeneracy that leads to an important ambiguity in extracting the "standard" three-neutrino phase δ CP [18]. Similar ambiguities in the determination of the oscillation parameters can also appear when considering the possibility of having light sterile neutrinos [19,20]. We discuss the potential of our proposed experimental setup for probing this scenario as well.…”