[Paper Review] Measurements of the absolute branching fractions for D ->(K)over-bar-pi e(+)nu(e), D ->(K)over-bar*e+nu(e) and determination of Gamma(D+->(K)over-bar*(0)e+nu(e))/Gamma(D+->(K)over-bar(0)e+nu(e))

Bes Callaboration|arXiv (Cornell University)|May 1, 2006

Particle physics theoretical and experimental studies5 citations

TL;DR

This study measures the absolute branching fractions for semileptonic D meson decays D+ → K̄⁻π⁺e⁺νₑ, D⁰ → K̄⁰π⁻e⁺νₑ, D+ → K̄*⁰e⁺νₑ, and D⁰ → K̄*⁻e⁺νₑ using 33 pb⁻¹ of data collected at √s ≈ 3.773 GeV with the BES-II detector. The key result is a precise determination of the ratio of vector to pseudoscalar decay rates, Γ(D+ → K̄*⁰e⁺νₑ)/Γ(D+ → K̄⁰e⁺νₑ) = 0.57 ± 0.17 ± 0.02.

ABSTRACT

Using the data of about 33 pb(-1) collected at and around 3.773 GeV with the BES-II detector at the BEPC collider, we have studied the exclusive semileptonic decays D+ -> K-pi(+)e(+)nu(e), D-0 -> (K) over bar (0)pi(-)e(+)nu(e), D+ -> (K) over bar (*0)e(+)nu(e) and D-0 -> K(*-)e(+)nu(e). The absolute branching fractions for the decays are measured to be BF(D+ -> K-pi(+)e(+)v(e)) = (3.50 +/- 0.75 +/- 0.27)%, BF(D-0 -> (K) over bar (0)pi(-)e(+)v(e)) = (2.61 +/- 1.04 +/- 0.28)%, BF(D+ -> (K) over bar (*0)pi(+)e(+)nu(e)) = (5.06 +/- 1.21 +/- 0.40)% and BF(D-0 -> (K) over bar (0)pi(-)e(+)nu(e)) = (2.87 +/- 1.48 +/- 0.39)%. The ratio of the vector to pseudoscalar semileptonic decay rates Gamma(D+ -> (K) over bar (*0)e+nu(e))/Gamma(D+ -> (K) over bar (0)e+nu(e)) is determined to be 0.57 +/- 0.17 +/- 0.02.

Motivation & Objective

• To measure the absolute branching fractions of exclusive semileptonic D+ and D⁰ decays into K̄π and K̄* final states.
• To determine the ratio of decay rates for vector (K̄*⁰) and pseudoscalar (K̄⁰) final states in D+ decays.
• To improve the precision of semileptonic D meson decay parameters relevant for testing the Standard Model and extracting CKM matrix elements.
• To provide updated experimental inputs for theoretical models of charm meson decays.

Proposed method

• Data were collected at center-of-mass energy √s ≈ 3.773 GeV using the BES-II detector at the BEPC collider.
• Decay events were reconstructed by identifying final-state particles: K̄, π, e⁺, and νₑ via missing energy and momentum.
• Kinematic fitting was applied to reconstruct the D meson mass and improve signal purity.
• Branching fractions were extracted using signal yields, detection efficiencies, and branching fraction normalization.
• Systematic uncertainties were evaluated by varying selection criteria and modeling assumptions.
• The ratio of decay rates was determined from the relative yields of K̄*⁰ and K̄⁰ final states in D+ decays.

Experimental results

Research questions

• RQ1 What is the absolute branching fraction for D+ → K̄⁻π⁺e⁺νₑ decay?
• RQ2 What is the absolute branching fraction for D⁰ → K̄⁰π⁻e⁺νₑ decay?
• RQ3 What is the absolute branching fraction for D+ → K̄*⁰e⁺νₑ decay?
• RQ4 What is the absolute branching fraction for D⁰ → K̄*⁻e⁺νₑ decay?
• RQ5 What is the ratio of the vector to pseudoscalar decay rates in D+ → K̄*⁰e⁺νₑ and D+ → K̄⁰e⁺νₑ decays?

Key findings

• The absolute branching fraction for D+ → K̄⁻π⁺e⁺νₑ is measured to be (3.50 ± 0.75 ± 0.27)%.
• The absolute branching fraction for D⁰ → K̄⁰π⁻e⁺νₑ is measured to be (2.61 ± 1.04 ± 0.28)%.
• The absolute branching fraction for D+ → K̄*⁰e⁺νₑ is measured to be (5.06 ± 1.21 ± 0.40)%.
• The absolute branching fraction for D⁰ → K̄*⁻e⁺νₑ is measured to be (2.87 ± 1.48 ± 0.39)%.
• The ratio of decay rates Γ(D+ → K̄*⁰e⁺νₑ)/Γ(D+ → K̄⁰e⁺νₑ) is determined to be 0.57 ± 0.17 ± 0.02.