Search for CP-Violating Neutrino Nonstandard Interactions with the NOvA Experiment

Area of Science:

• Particle Physics
• Neutrino Physics
• High Energy Physics

Background:

• Neutrino oscillations are a key phenomenon in particle physics.
• Standard Model extensions are explored to explain neutrino properties.
• Nonstandard Interactions (NSI) offer a potential explanation for observed neutrino behavior.

Purpose of the Study:

• To search for charge-parity (CP) symmetry violating nonstandard interactions (NSI) of neutrinos.
• To investigate the impact of NSI on the determination of standard neutrino oscillation parameters.
• To constrain the magnitudes of specific NSI parameters, ϵ_{eμ} and ϵ_{eτ}.

Main Methods:

• Utilizing data from the NOvA experiment.
• Analyzing neutrino (ν) and antineutrino (ν[over ¯]) oscillations in both muon-neutrino (ν_{μ}) to muon-neutrino (ν_{μ}) and muon-neutrino (ν_{μ}) to electron-neutrino (ν_{e}) channels.
• Measuring the effects of NSI parameters ϵ_{eμ} and ϵ_{eτ}.

Main Results:

• Constraining the magnitudes of NSI couplings at 90% confidence level: |ϵ_{eμ}|≲0.3 and |ϵ_{eτ}|≲0.4.
• Identifying a degeneracy in the parameter space at |ϵ_{eτ}|≈1.8.
• Observing that the presence of NSI diminishes sensitivity to the standard CP phase, δ_{CP}.

Conclusions:

• The NOvA experiment provides stringent constraints on neutrino NSI.
• NSI can introduce significant degeneracies and affect the measurement of fundamental neutrino properties like the CP phase.
• Further studies are needed to fully understand the implications of NSI in neutrino physics.