Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Improved Measurement of the K+ to pi+ nu nubar Branching Ratio

E949 Collaboration, A. V. Artamonov

Abstract

An additional event near the upper kinematic limit for K+ to pi+ nu nubar has been observed by Experiment E949 at Brookhaven National Laboratory. Combining previously reported and new data, the branching ratio is B(K+ to pi+ nu nubar)= 1.47 (+1.30, - 0.89) x 10-10 based on three events observed in the pion momentum region 211<P<229 MeV/c. At the measured central value of the branching ratio, the additional event had a signal-to-background ratio of 0.9.

Improved Measurement of the K+ to pi+ nu nubar Branching Ratio

Abstract

An additional event near the upper kinematic limit for K+ to pi+ nu nubar has been observed by Experiment E949 at Brookhaven National Laboratory. Combining previously reported and new data, the branching ratio is B(K+ to pi+ nu nubar)= 1.47 (+1.30, - 0.89) x 10-10 based on three events observed in the pion momentum region 211<P<229 MeV/c. At the measured central value of the branching ratio, the additional event had a signal-to-background ratio of 0.9.

Paper Structure

This paper contains 1 figure, 2 tables.

Figures (1)

  • Figure 1: Range (R) vs. energy (E) distribution of events passing all other cuts of the final sample. The circles represent E787 data and the triangles E949 data. The group of events around $E=108$ MeV was due to the $K_{\pi 2}$ background. The simulated distribution of events from $K^+ \! \rightarrow \! \pi^+ \nu\overline{\nu}$ decay is indicated by dots. The solid-line (dashed-line) box represents the signal region for E949 (E787).