Neutral D→KK^{*} Decays as Discovery Channels for Charm CP Violation

Area of Science:

• High Energy Physics
• Particle Physics
• Standard Model Physics

Background:

• CP violation is a fundamental concept in particle physics.
• Charm CP violation in the Standard Model is not yet definitively observed.
• Previous studies focused on different decay channels or required flavor tagging.

Purpose of the Study:

• To identify potential discovery channels for charm CP violation within the Standard Model.
• To propose efficient experimental strategies for measuring CP asymmetries in D0 decays.
• To highlight the advantages of using untagged measurements.

Main Methods:

• Analysis of CP asymmetries in the decays D0→KSK*0 and D0→KSK̄*0.
• Theoretical investigation of CP asymmetry generation through exchange diagrams.
• Evaluation of experimental efficiency considering the K*0→K+π− decay.

Main Results:

• The decays D0→KSK*0 and D0→KSK̄*0 are identified as potential discovery channels for charm CP violation.
• Untagged CP asymmetry measurements are shown to be essentially equal to tagged ones, offering a statistical gain.
• |aCPdir,untag| can reach up to 0.003 depending on the strong phase.
• CP asymmetry is primarily generated by exchange diagrams, not requiring non-vanishing penguin amplitudes.

Conclusions:

• Untagged measurements of D0→KSK*0 decays provide an efficient method for discovering charm CP violation.
• The proposed channels offer a significant statistical advantage over previous methods.
• Further analysis in the Dalitz plot near the K*0 peak may reveal favorable strong phases.