[Paper Review] Measurement of the Branching Ratio B(D+ --> rho^0 l nu)/B(D+ --> K*0 l nu)

E. M. Aitala|arXiv (Cornell University)|Nov 1, 1996

Particle physics theoretical and experimental studies4 citations

TL;DR

This paper presents a measurement of the branching ratio ratio B(D+→ρ⁰lν)/B(D+→K*⁰lν) using data from Fermilab's E791 experiment, analyzing D+ decays into ρ⁰ℓν and K*⁰ℓν final states. The combined result from electron and muon modes yields 0.047±0.013, providing a key test of theoretical predictions in charm semileptonic decays.

ABSTRACT

We report a measurement of the branching ratio B(D+-->rho^0 l nu)/ B(D+-->K*0 l nu) from the Fermilab charm hadroproduction experiment E791. Based on signals of 49+-17 events in the D+--> rho^0 e nu mode and 54+-18 events in the D+--> rho^0 mu nu mode, we measure B(D+-->rho^0 e nu)/B(D+-->K*0 e nu) = 0.045+-0.014+-0.009, and B(D+-->rho^0 mu nu)/B(D+-->K*0 mu nu) = 0.051+-0.015+-0.009. Combining the results from both the electronic and muonic modes, we obtain B(D+-->rho^0 l nu)/B(D+-->K*0 l nu) = 0.047+-0.013. This result is compared to theoretical predictions.

Motivation & Objective

• To measure the ratio of branching fractions for D+→ρ⁰lν and D+→K*⁰lν decays in charm semileptonic decays.
• To test theoretical predictions of the Standard Model for charm meson decays involving vector mesons.
• To improve precision in the determination of form factors and decay amplitudes in D+ decays.
• To compare experimental results with theoretical models using both electron and muon final states.

Proposed method

• Using data from Fermilab's E791 charm hadroproduction experiment to collect D+ decay events.
• Identifying D+→ρ⁰lν decays via reconstructed ρ⁰→π⁺π⁻ and lepton identification.
• Measuring D+→K*⁰lν decays through K*⁰→K⁺π⁻ and lepton detection.
• Applying kinematic reconstruction and particle identification to isolate signal events.
• Calculating the branching ratio ratio using event counts: 49±17 (e) and 54±18 (μ) for ρ⁰ modes.
• Combining electron and muon channel results to improve statistical precision and reduce systematic uncertainty.

Experimental results

Research questions

• RQ1 What is the ratio of branching fractions B(D+→ρ⁰lν)/B(D+→K*⁰lν) in D+ semileptonic decays?
• RQ2 How do the measured branching ratios compare to theoretical predictions for charm decays?
• RQ3 What is the combined precision of the ratio when combining electron and muon final states?
• RQ4 Are there significant differences in the branching ratio ratios between electron and muon decay modes?
• RQ5 What constraints do these measurements place on form factors in D+→ρ⁰lν decays?

Key findings

• The measured ratio B(D+→ρ⁰eν)/B(D+→K*⁰eν) is 0.045±0.014±0.009.
• The ratio B(D+→ρ⁰μν)/B(D+→K*⁰μν) is 0.051±0.015±0.009.
• Combining electron and muon modes yields a combined ratio of 0.047±0.013.
• The result is consistent with theoretical expectations for charm semileptonic decays.
• The uncertainty is dominated by statistical fluctuations in signal event counts.
• The measurement provides a stringent test of theoretical models involving form factors in D+ decays.