Apparent multiple Delta m^2_32 in muon anti-neutrino and muon neutrino survival oscillations from non-standard interaction matter effect

TL;DR

This paper explores how non-standard neutrino interactions in matter can cause apparent differences in measured oscillation parameters for neutrinos and antineutrinos, potentially explaining discrepancies observed in experiments like MINOS.

Contribution

It demonstrates that non-standard interactions can induce apparent differences in neutrino oscillation parameters, offering an explanation for experimental anomalies.

Findings

Non-standard interactions can cause different apparent Δm^2 for neutrinos and antineutrinos.

The scenario can explain the MINOS neutrino-antineutrino disparity.

NSI effects may evade traditional atmospheric neutrino analyses.

Abstract

Neutrinos propagating through matter may participate in forward coherent neutral-current-like scattering arising from non-standard interactions as well as from the Mikheyev-Smirnov-Wolfenstein matter potential $V_e$. We show that at fixed long baselines through matter of constant density, the non-standard interaction potential $\epsilon_{\mu\tau} V_e$ can contribute an additional term to the oscillation phase whose sign differs for $\anumu$ versus $\numu$ propagation in matter. Its presence can cause different apparent $\Delta m^2$ to be erroneously inferred on the basis of oscillations in vacuum, with values lying above (for $\anumu$) or below (for $\numu$) the actual $\Delta m^2_{32}$ for the case where $\epsilon_{\mu\tau}$ is predominantly real-valued and of sign opposite to $\Delta m_{32}^2$. An NSI scenario invoking only $\Re(\epsilon_{\mu\tau})$ is shown to be capable of accounting for a disparity recently reported between oscillation survival for $\anumu$ and $\numu$ fluxes measured at $735~\mathrm{km}$ by the MINOS experiment. Implications for mantle traversal by atmospheric neutrinos are examined. The NSI matter potential with non-maximal mixing could evade conventional atmospheric neutrino analyses which do not distinguish $\numu$ from $\anumu$ on an event-by-event basis.