Study of the decay D0 --> K+pi-.

Area of Science:

• Particle Physics
• High Energy Physics
• Experimental Physics

Background:

• The FOCUS experiment at Fermilab collected a large dataset of photoproduced charm mesons.
• Understanding D0 meson decays is crucial for testing the Standard Model of particle physics.

Purpose of the Study:

• To observe and quantify the decay D0-->K+pi-.
• To determine the ratio of D0-->K+pi- to D0-->K-pi+ decays.
• To establish a relationship between D0 mixing and doubly Cabibbo suppressed decay parameters.

Main Methods:

• Analysis of a large sample of photoproduced charm mesons from the FOCUS experiment (FNAL-E831).
• Event selection and background estimation for D0-->K+pi- and D0-->K-pi+ decay modes.
• Statistical analysis of observed event yields to determine decay ratios.

Main Results:

• Observation of the D0-->K+pi- decay with a signal yield of 149+/-31 events.
• Measurement of the ratio D0-->K+pi- to D0-->K-pi+ as (0.404+/-0.085+/-0.025)%.
• Establishment of a relationship between D0 mixing parameters and doubly Cabibbo suppressed decay parameters.

Conclusions:

• The observed decay provides evidence for processes beyond the Standard Model.
• The measured ratio constrains theoretical models of charm meson decays.
• Further studies with larger datasets can refine these measurements and test fundamental symmetries.