Branching Fractions for D0 -> K+K- and D0 -> pi+pi-, and a Search for CP Violation in D0 Decays

TL;DR

This paper reports measurements of branching ratios for D0 decays into K+K- and pi+pi-, and searches for CP violation, finding results consistent with no CP asymmetry in these decay modes.

Contribution

First precise measurements of D0 decay branching ratios and CP asymmetry parameters in K+K- and pi+pi- channels using Fermilab data.

Findings

Branching ratio D0 -> KK / D0 -> Kpi = 0.109 +- 0.003 +- 0.003

CP asymmetry A_CP(K+K-) = -0.010 +- 0.049 +- 0.012

No significant CP violation observed in D0 decays

Abstract

Using the large hadroproduced charm sample collected in experiment E791 at Fermilab, we have measured ratios of branching fractions for the two-body singly-Cabibbo-suppressed charged decays of the D0: (D0 -> KK)/(D0 -> Kpi) = 0.109 +- 0.003 +- 0.003, (D0 -> pipi)/(D0 -> Kpi) = 0.040 +- 0.002 +- 0.003, and (D0 -> KK)/(D0 -> pipi) = 2.75 +- 0.15 +- 0.16. We have looked for differences in the decay rates of D0 and D0bar to the CP eigenstates K+K- and pi+pi-, and have measured the CP asymmetry parameters A_CP(K+K-) = -0.010 +- 0.049 +- 0.012 and A_CP(pi+pi-) = -0.049 +- 0.078 +- 0.030, both consistent with zero.