Impact of Scalar NSI on Spatial and Temporal Correlations in Neutrino Oscillations

TL;DR

The paper investigates how scalar non-standard interactions (SNSI) influence spatial and temporal quantum correlations in three-flavor neutrino oscillations, using CHSH and LGtI as nonlocality probes within a DUNE-like setup. It extends prior vector NSI work by introducing a model-independent SNSI parameterization via η_{αβ} and leveraging ESSnuSB bounds alongside NuFIT inputs. Key findings show that SNSI, especially η_{eτ}, enhances LGtI violations at higher energies and can modify CHSH violations in a flavor-pair–dependent manner, with the BC subsystem often exhibiting the strongest correlations. The work demonstrates that quantum-correlation observables provide complementary constraints on SNSI and may offer insights into the absolute neutrino mass scale in beyond-Standard-Model scenarios.

Abstract

Neutrino oscillation experiments are gradually approaching an era of precision, where subleading effects can also be tested. One such subleading effect is Non-Standard Interactions (NSI), which can play a crucial role in neutrino oscillations. Various works have typically discussed vector NSI in the context of quantum correlations. Recently, there have been improvements in the bounds on scalar NSI as well. In light of these developments, we aim to examine the impact of scalar NSI on quantum correlation measures. To analyze this impact, we are considering the strongest measure of quantum correlation, i.e., non-locality. Our study will encompass both spatial and temporal non-locality measures.

Figures (3)

• Figure 1: Nonlocality measures, i.e., LGtI $(K_{3})$ (upper panel) and CHSH (trade-off relation) (lower panel), are plotted as functions of neutrino energy for the $SO$ and $VNSI+SO$ (left), $SNSI+SO$ (center), and $SNSI-SO$ (right) scenarios essnub. These plots are generated using the $3\sigma$ upper bounds of the SNSI parameters within the DUNE experimental setup (baseline $L=1300$ km, beam energy range 1‚Äì10 GeV). The initial state is taken to be a muon neutrino ($\alpha=\mu$). The standard neutrino oscillation parameters and NSI parameters are listed in Table \ref{['Tab1']} and Table \ref{['Tab2']}, respectively. The scalar NSI effects are shown for the $3 \sigma$ upper bounds from Table \ref{['Tab2']}. The color scheme is as follows: black for SM, purple for VNSI, red for SNSI ($\eta_{ee}$), green for SNSI ($\eta_{\mu \mu}$), blue for SNSI ($\eta_{\tau \tau}$), cyan for SNSI ($\eta_{e \mu}$), magenta for SNSI ($\eta_{e \tau}$), and orange for SNSI ($\eta_{\mu \tau}$).
• Figure 2: Spatial non-locality measures for the reduced two-qubit neutrino flavor states. The upper panels show the squares of the maximal CHSH expectation values, $\langle \text{CHSH} \rangle^2$, for the bipartite subsystems AB, AC, and BC, showing the combined effect of standard oscillations and scalar NSI. The lower panels show the corresponding pure scalar NSI effect, calculated as the difference from the standard oscillation case ($\text{SNSI} - \text{SO}$). All curves are for an initial muon neutrino beam ($\alpha = \mu$) and are plotted as a function of neutrino energy for the DUNE baseline. The scalar NSI parameters are set to their $3\sigma$ upper bounds from Table \ref{['Tab2']}. In the upper panels, the black dotted curve represents the Standard Model case with matter effects (SO).In the upper panels, values of $\langle{\rm CHSH}\rangle^{2}$ exceeding 4 indicate a violation of the Bell‚ÄìCHSH inequality.
• Figure 3: The plots show LGtI $(K_{3})$ versus neutrino energy for SNSI parameters: $\eta_{ee}$ (left), $\eta_{\mu \mu}$ (center), and $\eta_{\tau \tau}$ (right) for the (SNSI-SO) scenario. The darker regions represent the $1\sigma$ range (upper bound and lower bound), and the lighter regions indicate the $3\sigma$ range for the SNSI parameters given in Table \ref{['Tab2']}. Other parameters are same as mentioned in Figure \ref{['fig1']}.