Probing the CP violation signal at DUNE in the presence of non-standard neutrino interactions

Abstract

We discuss the impact of non-standard neutrino matter interactions (NSI) in propagation on the determination of CP phase in the context of the long baseline accelerator experiments such as Deep Underground Neutrino Experiment (DUNE). DUNE will mainly address the issue of CP violation in the leptonic sector. Here we study the role of NSI and its impact on the question of observing the CP violation signal at DUNE. We consider two scenarios of oscillation with three active neutrinos in absence and presence of NSI. We elucidate the importance of ruling out subdominant new physics effects introduced by NSI in inferring CP violation signal at DUNE by considering NSI terms collectively as well as by exploiting the non-trivial interplay of moduli and phases of the NSI terms. We demonstrate the existence of NSI-SI degeneracies which need to be eliminated in reliable manner in order to make conclusive statements about the CP phase.

Non-unitarity, sterile neutrinos, and non-standard neutrino interactions

“…[72][73][74][75] (for other works on degeneracies among standard and non-standard parameters in DUNE see e.g., refs. [76][77][78][79]). The first degeneracy appears for the wrong octant of θ 23 , which would otherwise be correctly determined by the interplay between the appearance and disappearance channels at DUNE (see e.g., ref.…”

A combined study of source, detector and matter non-standard neutrino interactions at DUNE

“…Many recent studies have explored this question for DUNE [6][7][8][9][10] in the context of matter NSIs. In figure 2, we show the effect of NSIs on the precision measurement of θ 23 and δ when the true values of these parameters are 42 • and −90 • , respectively.…”

Can we probe intrinsic CP and T violations and nonunitarity at long baseline accelerator experiments?

“…Going beyond the recent studies revealing how potential new physics scenarios can hinder the clean determination of this important parameter [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34], we address the issue of clean separation of the intrinsic leptonic CP phase from the extrinsic contribution arising due to SI as well as new physics 7 . We also show the impact of new physics on testing non-unitarity.…”

“…We also probe deviations due to new physics scenarios. We go beyond the SM in two respects -one in which we introduce subdominant effects due to a possible source of new physics dubbed as NSI [17][18][19][20][21][22][23][24][25][26] and another where the presence of extra sterile state can lead to non-unitarity in the 3×3 part even though the overall mixing matrix is still unitary [27][28][29][30][31][32][33][34] and examine consequences relevant to long baseline experiments (For other new physics scenarios such as non-unitarity, see [35][36][37][38][39]). We highlight the regions in L − E space where the effects due to CP and T violation are drastically modified due to new physics.…”

“…Even if it the case, one needs to make sure whether the source of CP violation is genuine or fake (depending on the baseline) [52]. In presence of NSI, this is further disturbed due to the presence of additional parameters (see [17,20,21]). On top of that in case of NSI, there are new genuine sources of CP violation as well as new fake sources of CP violation (aka matter effects) that can change the asymmetries even further.…”