Neutrino Oscillation Prospects with a Dual-Baseline Beam from BNL to SNOLAB and SURF

Abstract

The Electron-Ion Collider (EIC) is a next-generation accelerator primarily designed to study the internal structure of nucleons through high-precision electron-hadron collisions. In this work, we explore the feasibility of employing a 1 MW fraction of the EIC proton beam to generate a high-intensity GeV-scale neutrino beam for long-baseline oscillation studies. We have simulated proton-target interactions and optimize the resulting neutrino fluxes for water-based liquid scintillator (WbLS) detectors located at distinct baselines of 900 km and at 2900 km. Oscillation analyses performed with GLoBES show that extended baselines allow access to multiple oscillation maxima, significantly enhancing sensitivity to leptonic CP violation. The study also examines the interplay between matter effects and the intrinsic CP violating phase in shaping observable asymmetries. These results suggest that the EIC proton beam could provide a novel and complementary source for precision neutrino physics, extending the scientific reach of the EIC program.

Figures (10)

• Figure 1: This shows the $\nu_{\mu}$ flux at 1 km from EIC for six different horn currents (shown in the keys in units of kA). $\text{P}_{\mu e}$ (with arbitrary scaling) for 900 km and 2900 km are overlaid in red and blue shades respectively.
• Figure 2: The top row shows the $\nu_{\mu}$ flux $\Phi_{{\nu_{\mu}}}$; $\nu_{e}$ cross-section $\frac{\sigma_{{\nu_e}}}{E}$; and the transition probabilities $\text{P}_{\mu e}$ at EIC-SURF baseline of 2900 km, and at EIC-SNO baseline of 900 km. The bottom row shows the relevant products of these quantities for three different types of interactions, -namely inclusive charge current (CC), quasielastic charge current (CCQE), non-quasielastic charge current (CCNQE).
• Figure 3: The solid curves show the quantities $\Delta P_{\mu e}^{\text{I}}, \Delta P_{\mu e}^{\text{II}}$ and $\Delta P_{\mu e} = (\Delta P_{\mu e}^{\text{I}} + \Delta P_{\mu e}^{\text{II}})$ from Eq. \ref{['eq:acp']} as functions of energy for the three baselines (900 km, 1300 km, 2900 km). The dotted red curves indicate the intrinsic CP asymmetry $(\Delta P_{\mu e} - \Delta P_{\mu e}^{\delta_{\text{CP}}=0})$ originating only from the phase $\delta_{\text{CP}}$ and free from matter effects. The pair of black dotted vertical lines in each panel indicates the relevant $E^{\text{max}}_{1}$ and $E^{\text{max}}_{2}$.
• Figure 4: The top row shows the heatplots of the CP asymmetry $\Delta P_{\mu e} = (\text{P}_{\mu e} -\bar{\text{P}}_{\mu e})$ for the three baselines (900 km, 1300 km, 2900 km) in the parameter space of the CP phase $\delta_{\text{CP}}$ and energy E. The bottom row shows the heatplots of the intrinsic CP asymmetry $(\Delta P_{\mu e} - \Delta P_{\mu e}^{\delta_{\text{CP}}=0})$. The pair of black dotted vertical lines in each panel indicates the relevant $E^{\text{max}}_{1}$ and $E^{\text{max}}_{2}$.
• Figure 5: Electron neutrino appearance events at THEIA for the EIC to SURF baseline (2900 km). Here we show only signals (dotted) as well as events (signal + background).