First Measurement of the Form Factors in D_{s}^{+}→K^{0}e^{+}ν_{e} and D_{s}^{+}→K^{*0}e^{+}ν_{e} Decays

Area of Science:

• High Energy Physics
• Particle Physics
• Quantum Chromodynamics

Background:

• Semileptonic decays of heavy quarks offer crucial insights into fundamental interactions.
• Cabibbo-suppressed decays of the D_{s}^{+} meson are sensitive probes of the Standard Model.
• Precise measurements are needed to test theoretical predictions and search for new physics.

Purpose of the Study:

• To report new, precise measurements of Cabibbo-suppressed semileptonic D_{s}^{+} decays.
• To determine branching fractions and hadronic form-factor parameters for D_{s}^{+}→K^{0}e^{+}ν_{e} and D_{s}^{+}→K^{*0}e^{+}ν_{e}.
• To provide improved data for theoretical calculations and comparisons.

Main Methods:

• Analysis of 3.19 fb^{-1} of e^{+}e^{-} annihilation data at 4.178 GeV.
• Utilized the BESIII detector at the BEPCII collider.
• Performed measurements of branching fractions and hadronic form-factor parameters.

Main Results:

• Achieved significantly improved branching fractions: B(D_{s}^{+}→K^{0}e^{+}ν_{e})=[3.25±0.38(stat)±0.16(syst)]×10^{-3} and B(D_{s}^{+}→K^{*0}e^{+}ν_{e})=[2.37±0.26(stat)±0.20(syst)]×10^{-3}.
• Reported the first measurements of hadronic form-factor parameters for these decays.
• Obtained f_{+}(0)=0.720±0.084(stat)±0.013(syst) for D_{s}^{+}→K^{0}e^{+}ν_{e}.
• Determined form-factor ratios r_{V}=1.67±0.34(stat)±0.16(syst) and r_{2}=0.77±0.28(stat)±0.07(syst) for D_{s}^{+}→K^{*0}e^{+}ν_{e}.

Conclusions:

• The new measurements offer substantial improvements over previous results.
• These findings provide crucial data for testing theoretical models of heavy meson decays.
• The first measurements of form-factor parameters open new avenues for precision studies in particle physics.