Observation of the radiative decay D0-->phigamma

Area of Science:

• Particle Physics
• High Energy Physics
• Experimental Physics

Background:

• Charmed mesons are crucial for understanding fundamental particle interactions.
• Flavor-changing radiative decays provide unique insights into New Physics beyond the Standard Model.
• Previous searches for D0-->phigamma decay had not yielded conclusive results.

Purpose of the Study:

• To report the first observation of the flavor-changing radiative decay D0-->phigamma.
• To report the first observation of the Cabibbo- and color-suppressed decays D0-->phipi(0) and D0-->phieta.
• To measure the branching fractions of these newly observed decays.

Main Methods:

• Analysis of 78.1 fb(-1) of data collected by the Belle experiment at the KEKB e+e- collider.
• Statistical analysis to establish the significance of observed decay signals.
• Precise measurement of branching fractions for the identified decay modes.

Main Results:

• Observation of D0-->phigamma decay with a statistical significance of 5.4 sigma.
• First observation of D0-->phipi(0) and D0-->phieta decays.
• Measured branching fractions: B(D0-->phigamma)=[2.60(+0.70)(-0.61)(stat)+0.15-0.17(syst)] x 10(-5), B(D0-->phipi(0))=[8.01+/-0.26(stat)+/-0.47(syst)] x 10(-4), and B(D0-->phieta)=[1.48+/-0.47(stat)+/-0.09(syst)] x 10(-4).

Conclusions:

• The first observation of a flavor-changing radiative decay of a charmed meson (D0-->phigamma) has been achieved.
• The study provides the first experimental evidence for D0-->phipi(0) and D0-->phieta decays.
• These measurements offer valuable data for theoretical models of particle physics and searches for new physics phenomena.