Status of non-standard neutrino interactions (1209.2710v2)

Abstract: The phenomenon of neutrino oscillations has been established as the leading mechanism behind neutrino flavor transitions, providing solid experimental evidence that neutrinos are massive and lepton flavors are mixed. Here we review sub-leading effects in neutrino flavor transitions known as non-standard neutrino interactions, which is currently the most explored description for effects beyond the standard paradigm of neutrino oscillations. In particular, we report on the phenomenology of non-standard neutrino interactions and their experimental and phenomenological bounds as well as future sensitivity and discovery reach.

• The paper demonstrates that NSIs introduce sub-leading corrections to standard neutrino oscillations, affecting flavor transitions.
• It employs theoretical modeling and parameterization to set experimental bounds on NSI parameters using atmospheric, accelerator, and solar neutrino data.
• The study outlines future experimental approaches designed to distinguish NSI signals from conventional oscillation effects.

Overview of "Status of non-standard neutrino interactions" by Tommy Ohlsson

The paper "Status of non-standard neutrino interactions" by Tommy Ohlsson provides a comprehensive review of non-standard neutrino interactions (NSIs), which are proposed to account for sub-leading effects in neutrino flavor transitions beyond the standard model description of neutrino oscillations. The paper lays significant emphasis on the phenomenology of NSIs, experimental data that provide bounds on these interactions, and offers a theoretical outlook for future neutrino experiments.

Abstract Essentials

Neutrino oscillations have established themselves as the primary mechanism behind neutrino flavor transitions, confirming neutrinos' massiveness and lepton flavor mixing. Ohlsson’s work explores the sub-leading effects in these transitions through NSIs, detailing phenomenological impacts, experimental constraints, and the potential discovery reach in upcoming experiments.

The Need for NSIs

Since the initial results from the Super-Kamiokande experiment, the standard model necessitates revision to incorporate the phenomena of massive and mixed neutrinos. NSIs emerge as a potential 'new physics' component within neutrino production, propagation, and detection processes, complementing the conventional oscillation effects.

Framework and Key Concepts

• NSI Formalism: NSIs are formulated as additional interactions between neutrinos and standard matter fermions (e.g., $u$, $d$, $e$). The NSI effects are parametrized through effective operators added to the standard neutrino oscillation Hamiltonian. These interactions transcend the standard charged-current weak interactions encoded in the Mikheyev–Smirnov–Wolfenstein (MSW) effect.
• Parameterization and Bounds: The paper discusses NSI parameters $\varepsilon_{\alpha\beta}$, where experimental constraints are drawn from neutrino oscillations in matter relevant for long-baseline experiments, atmospheric, solar, and supernova neutrino observations. NSI effects should, in principle, manifest as deviations from expected oscillation probabilities.

Theoretical Models

Various beyond-standard-model theories suggest NSI frameworks, such as the seesaw models, supersymmetric extensions, and theories involving extra dimensions. The work mentions specific implementations, such as the triplet seesaw model and the Zee-Babu model, offering detailed insights into how these theories predict NSI parameters.

Experimental Implications

1. Current Constraints: The paper emphasizes experimental bounds on NSI parameters derived from atmospheric (Super-Kamiokande) and accelerator (MINOS) neutrino experiments, noting constraints on specific parameters such as $\varepsilon_{\mu\tau}$ and $\varepsilon_{\tau\tau} - \varepsilon_{\mu\mu}$.
2. Future Prospects: Forthcoming and planned experiments (e.g., neutrino factories, long-baseline setups) promise heightened sensitivity to potential NSI signatures. The approach prepares for disentangling standard oscillations from NSI by leveraging precise measurements of flavor transitions.

Conclusion and Future Directions

The review by Tommy Ohlsson is pivotal in framing NSIs within both the current and future experimental landscapes. It asserts the importance of refining theoretical models and enhancing experimental techniques to explore the sub-leading effects potentially affecting neutrino oscillations. This exploration can illuminate new physics at scales in proximity to the standard neutrino physics and offer deeper insight into the fundamental properties of neutrinos.

This detailed overview encapsulates the core findings and methodologies that underpin Ohlsson's work on non-standard neutrino interactions within the broader context of neutrino physics and its interplay with emerging new physics paradigms.