Left-Right Symmetry: from LHC to Neutrinoless Double Beta Decay (1011.3522v2)

Abstract: The Large Hadron Collider has a potential to probe the scale of left-right symmetry restoration and the associated lepton number violation. Moreover, it offers hope of measuring the right-handed leptonic mixing matrix. We show how this, together with constraints from lepton flavor violating processes, can be used to make predictions for neutrinoless double beta decay. We illustrate this deep connection in the case of the type-II seesaw.

• The paper demonstrates that left-right symmetric models can significantly enhance neutrinoless double beta decay rates through right-handed current contributions at the TeV scale.
• The paper employs a type-II seesaw framework to relate LHC observables with lepton flavor violation constraints, refining the predicted mass spectra of new particles.
• The paper shows that distinctive same-sign lepton signatures at the LHC could serve as practical indicators of parity restoration and Majorana neutrino behavior.

Left-Right Symmetry: Insights from LHC to Neutrinoless Double Beta Decay

The paper "Left-Right Symmetry: from LHC to Neutrinoless Double Beta Decay" presents an extensive analysis of the implications of left-right (LR) symmetric theories in the search for new physics, particularly focusing on the potential of the Large Hadron Collider (LHC) and its connection to neutrinoless double beta decay ($0\nu2\beta$). The theoretical groundwork for these investigations lies in the pursuit to explore Majorana neutrinos and their contributions to lepton number violation processes, manifest in phenomena beyond the Standard Model (BSM).

The essential thesis of the paper revolves around the application of LR symmetry-based models, particularly in the context of the type-II seesaw mechanism, to illuminate pathways for detecting new physics at the TeV scale, potentially accessible by current experiments at the LHC. The interaction of this new physics with lepton flavor violating (LFV) processes can inform predictions and constraints on $0\nu2\beta$ decay, thereby providing a cohesive framework to explore unexplored territories in particle physics.

Core Contributions and Findings

• Neutrinoless Double Beta Decay and Its Implications: Neutrinoless double beta decay is critical in probing the Majorana nature of neutrinos, signifying lepton number violation. The decay amplitude, traditionally expected to vary with light neutrino mass, may, under LR symmetric models, gain significant contributions from the right-handed sector, thereby inversely impacting neutrino mass hierarchies.
• Right-Handed Physics Contribution: The analysis reveals that the right-handed charged current processes could dominate the $0\nu2\beta$ rate under certain configurations, with new physics at $\Lambda \sim$ TeV scale contributing significantly. This is contingent upon the mass of right-handed neutrinos and the mixing matrices.
• Predictions for Lepton Flavor Violation: The paper provides a detailed parameter space analysis wherein LFV processes constrain the masses and mixings within the model. The branching ratios for processes like $\mu \rightarrow 3e$ become pivotal in delineating the viable mass spectra of the new hypothetical particles.
• LHC's Potential Role: With the capacity of the LHC to investigate beyond the TeV mass scale, the paper underscores the collider's prospects in detecting heavy right-handed neutrinos through distinctive same sign lepton pair signatures—an unambiguous indicator of lepton number violation and parity restoration.

Implications and Future Directions

The implications of the research extend beyond mere theoretical postulations, presenting measurable, experimental avenues for uncovering BSM physics. Observations at the LHC pertaining to right-handed gauge bosons and neutrinos could alter prevailing paradigms of neutrino mass hierarchies and provide alternate explanations for $0\nu2\beta$ decay rates.

Practically, the success of such experimental endeavors could bridge the gaps in our understanding of fundamental symmetries in particle physics and aid in constructing more comprehensive models that predict phenomena currently unaccounted for by the Standard Model. Theoretically, these insights would drive future modeling efforts towards incorporating these symmetry principles, especially leveraging data from ongoing and future neutrino oscillation and double beta decay experiments.

In conclusion, the paper effectively integrates LR symmetry concepts with empirical strategies, providing a robust platform for probing the underlying nature of neutrinos and challenging existent paradigms with new tools and methodologies, fostering symbiotic growth between theoretical predictions and experimental validations.