Evidence for the Decay $D^0\to K^+ \pi^-\pi^+\pi^-$

TL;DR

This paper reports a search for the rare decay D0 -> K+ pi- pi+ pi- in electron-positron collisions, providing evidence for its occurrence with a significance of 3.9 sigma, and discusses implications for charm meson mixing and decay processes.

Contribution

First measurement of the wrong-sign decay D0 -> K+ pi- pi+ pi- with evidence at 3.9 sigma significance, advancing understanding of charm meson decay mechanisms.

Findings

Measured wrong-sign decay rate relative to right-sign decay.

Observed evidence for the decay with 3.9 sigma significance.

Quantified the decay rate with statistical and systematic uncertainties.

Abstract

We present a search for the ``wrong-sign'' decay D0 -> K+ pi- pi+ pi- using 9 fb-1 of e+e- collisions on and just below the Upsilon(4S) resonance. This decay can occur either through a doubly Cabibbo-suppressed process or through mixing to a D0bar followed by a Cabibbo-favored process. Our result for the time-integrated wrong-sign rate relative to the decay D0 -> K- pi+ pi- pi+ is (0.0041 +0.0012-0.0011(stat.) +-0.0004(syst.))x(1.07 +-0.10)(phase space), which has a statistical significance of 3.9 standard deviations.