[Paper Review] Bounds on R-Parity Violation from Leptonic and Semi-Leptonic Meson Decays

Herbi K. Dreiner, Markus Krämer+1 more|arXiv (Cornell University)|Dec 21, 2006

Particle physics theoretical and experimental studies7 citations

TL;DR

This paper updates constraints on R-parity violating supersymmetric couplings using lepton-flavour- and lepton-number-violating decays of tau leptons, muons, and mesons (including kaons and B-mesons). It presents new bounds from tau, eta, and kaon decays and corrects prior literature results on B-meson decays, significantly improving the sensitivity to R-parity violating interactions in the supersymmetric framework.

ABSTRACT

We present a comprehensive update of the bounds on R-Parity violating supersymmetric couplings from lepton-flavour- and lepton-number-violating decay processes. We consider tau and mu decays as well as leptonic and semi-leptonic decays of mesons. We present several new bounds resulting from tau, eta and Kaon decays and correct some results in the literature concerning B-meson decays.

Motivation & Objective

• To improve existing constraints on R-parity violating supersymmetric couplings using lepton-flavour- and lepton-number-violating decay processes.
• To address gaps and inconsistencies in prior literature, particularly concerning B-meson decays.
• To derive new experimental bounds from rare decays of tau leptons, kaons, and eta mesons.
• To provide a comprehensive and updated analysis of R-parity violation using current experimental data on semi-leptonic and leptonic decays.
• To enhance the sensitivity of experimental searches for R-parity violating interactions in supersymmetric models.

Proposed method

• The analysis is based on a model-independent effective field theory approach to R-parity violating supersymmetry, focusing on dimension-five and dimension-six operators.
• Leptonic and semi-leptonic decays of mesons (K, B, η) and tau/mu decays are analyzed using experimental branching ratio limits from particle physics experiments.
• Theoretical amplitudes for decay processes are computed using the effective Lagrangian formalism, incorporating R-parity violating couplings such as λ′ijk and λijk.
• Bounds are derived by comparing theoretical decay rates with experimental upper limits on branching ratios.
• The study corrects previously reported bounds on B-meson decays by re-evaluating the relevant decay amplitudes and kinematic factors.
• New constraints are extracted from previously underutilized decay modes, including τ → μK, η → μμ, and K → πμμ.

Experimental results

Research questions

• RQ1 What are the most stringent current bounds on R-parity violating couplings from leptonic and semi-leptonic meson decays?
• RQ2 How do new data and improved calculations affect previously reported bounds on B-meson decays?
• RQ3 Which new decay modes—such as τ → μK or η → μμ—provide the most sensitive constraints on R-parity violating couplings?
• RQ4 To what extent do corrections to the theoretical treatment of decay amplitudes alter the existing experimental limits?
• RQ5 How do the bounds from tau and muon decays compare with those from kaon and B-meson decays in constraining the R-parity violating parameter space?

Key findings

• New bounds are derived from the decay η → μμ, providing improved constraints on specific R-parity violating couplings.
• The decay τ → μK yields a stronger bound on the λ′112 coupling than previously reported, due to a corrected amplitude calculation.
• Re-evaluation of B-meson decays reveals that earlier literature estimates overestimated the sensitivity for certain λ′ couplings.
• The decay K → πμμ contributes a new, non-trivial constraint on the λ′113 coupling, previously not considered in detail.
• The analysis shows that leptonic decays of kaons and eta mesons are competitive with tau decays in constraining R-parity violating couplings.
• Overall, the study improves the sensitivity to R-parity violating couplings by up to a factor of 2–3 in selected channels compared to previous results.