Study of the Semileptonic Decay Λ_{c}^{+}→Λe^{+}ν_{e}

Area of Science:

• * Particle Physics
• * High-Energy Physics
• * Nuclear Physics

Background:

• * The Cabibbo-favored semileptonic decay of Lambda_c+ to Lambda e+ nu_e is crucial for understanding weak interactions.
• * Previous measurements have limited precision, hindering detailed comparisons with theoretical models.

Purpose of the Study:

• * To precisely measure the branching fraction of the Lambda_c+ -> Lambda e+ nu_e decay.
• * To investigate the internal dynamics of this decay process.
• * To compare experimental results with Lattice Quantum Chromodynamics (LQCD) predictions and determine the CKM matrix element |V_cs|.

Main Methods:

• * Analysis of a 4.5 fb^-1 data sample from e+e- annihilations collected at BESIII.
• * Measurements performed at center-of-mass energies between 4.600 GeV and 4.699 GeV.
• * Direct comparison of differential decay rates and form factors with LQCD calculations.

Main Results:

• * The branching fraction B(Lambda_c+ -> Lambda e+ nu_e) was measured as (3.56 ± 0.11_stat ± 0.07_syst)%, the most precise value to date.
• * First direct comparisons of differential decay rates and form factors with LQCD predictions are presented.
• * The CKM matrix element |V_cs| was determined to be 0.936 ± 0.017_B ± 0.024_LQCD ± 0.007_tau_Lambda_c.

Conclusions:

• * This study provides the most precise measurement of the Lambda_c+ -> Lambda e+ nu_e branching fraction.
• * The results offer valuable data for testing theoretical models, particularly LQCD.
• * The determination of |V_cs| contributes to refining the Standard Model parameters.