One-Loop Effects in the Neutrino Matter Potential and Implications for Non-Standard Interactions

TL;DR

The paper investigates electroweak one-loop corrections to the neutrino matter potential, quantified at about $2.0\%$, and their impact on oscillations in the presence of neutrino non-standard interactions (NSIs) within a DUNE-like long-baseline setup. By deriving corrected oscillation probabilities and performing GLoBES-based simulations, the authors quantify degeneracies between SM radiative effects and NSIs, and assess how these corrections modify mass-ordering sensitivity and NSI constraints. They find that neglecting one-loop corrections can mimic NSI signals and bias NSI parameter fits, while including the corrections can either enhance or degrade sensitivity depending on the NSI sector; in several cases, the mass-ordering reach remains substantial, but some NSI scenarios drop to low-significance levels. The work emphasizes the necessity of incorporating electroweak radiative corrections in precision neutrino analyses to reliably disentangle SM effects from BSM NSIs in upcoming experiments.

Abstract

In this work, we emphasize that it is necessary to take into account one-loop corrections of $2.0\%$ to the neutrino matter potential in the precision measurements of neutrino oscillation parameters and in the experimental searches for new physics beyond the Standard Model. With the numerical simulation of the DUNE experiment, we study how radiative corrections to the matter potential affect neutrino oscillation probabilities, and thus, the event rates in the presence of neutrino non-standard interactions (NSIs). We find that neglecting one-loop corrections may lead to wrong conclusions for the discovery of NSIs. The implications for the determination of neutrino mass ordering and constraints on the NSI parameters in future long-baseline accelerator neutrino experiments are explored in a quantitative way.

Figures (6)

• Figure 2: Correlation between the probabilities $P_{\mu e}^{\rm SI}$, $P_{\mu e}^{\rm NSI}$ and $\overline{P}_{\mu e}^{\rm NSI}$. The effect of the NSI parameter $\epsilon_{e\mu}^{}$ is shown by varying $|\epsilon_{e \mu}^{}|$ and $\phi_{e \mu}^{}$ within the ranges $[0, 0.03]$ and $[0, 2\pi]$, respectively. The correlations are shown for $P_{\mu e}^{\rm SI}$ and $P_{\mu e}^{\rm NSI}$ (left panel) and for $P_{\mu e}^{\rm NSI}$ and $\overline P_{\mu e}^{\rm NSI}$ (right panel). The probabilities are computed both at tree-level and including one-loop corrections for the neutrino energy $E_\nu^{} = 2$ GeV. Normal ordering is assumed.
• Figure 3: Effect of one-loop corrections on the difference between the neutrino oscillation probability $P_{\mu e}^{}$ computed for the NSI case and the SI case (left panel). The corresponding difference is also shown for the antineutrino probability $\overline{P}_{\mu e}^{}$ (right panel). For the NSI case, we have assumed $\epsilon_{e\mu} = 0.05$. The probability differences are shown both at tree-level (dashed black curve) and with one-loop corrections (solid red curve). Normal ordering is assumed.
• Figure 4: Differences in the expected number of binned $\nu_{e}^{}$ events (left panel) and $\overline{\nu}_{e}^{}$ events (right panel) as a function of neutrino energy. The events are computed in presence of NSIs and one-loop corrections for DUNE. The NSI effects are obtained for $\epsilon_{e\mu} = 0.05$. Normal ordering is assumed.
• Figure 5: Effect of the one-loop corrections in neutrino matter potential on the fit result for the NSI parameters $\epsilon_{ee}^{} - \epsilon_{\mu\mu}^{}$ (left panel) and $\epsilon_{e\mu}^{}$ (right panel). While the true events are generated with one-loop corrections, the fitted events are computed both at tree-level (dashed black curves) and with one-loop corrections (solid red curves). Normal ordering is assumed.
• Figure 6: Effect of one-loop corrections on the allowed values for the NSI parameters $\epsilon_{ee}^{} - \epsilon_{\mu\mu}^{}$ and $\epsilon_{e\mu}^{}$. The $\Delta \chi^2 = \chi^2_{\rm NSI} - \chi^2_{\rm SI}$ distributions are shown for both the tree-level and one-loop contributions, respectively. True and test events are both computed with same matter potential, which is obtained at tree-level (dashed black curves) and with one-loop corrections (solid red curves). The true mass ordering is assumed to be normal ordering.