New measurement of the rare decay K+ --> pi(+)&mgr;(+)&mgr;(-)

H Ma; R Appel; GS Atoyan; B Bassalleck; DR Bergman; N Cheung; S Dhawan; H Do; J Egger; S Eilerts; H Fischer; W Herold; VV Issakov; H Kaspar; DE Kraus; DM Lazarus; P Lichard; J Lowe; J Lozano; W Majid; W Menzel; S Pislak; AA Poblaguev; P Rehak; A Sher; JA Thompson

doi:10.1103/PhysRevLett.84.2580

New measurement of the rare decay K+ --> pi(+)&mgr;(+)&mgr;(-)

Phys Rev Lett. 2000 Mar 20;84(12):2580-3. doi: 10.1103/PhysRevLett.84.2580.

Authors

Affiliation

¹ Brookhaven National Laboratory, Upton, New York 11973, USA.

PMID: 11017274
DOI: 10.1103/PhysRevLett.84.2580

Abstract

More than 400 K+-->pi(+)&mgr;(+)&mgr;(-) events were observed in a rare K+ decay experiment at the Brookhaven Alternating Gradient Synchrotron. Normalized to the K+-->pi(+)pi(+)pi(-) decay, the branching ratio is determined to be [9.22+/-0.60(stat)+/-0. 49(syst)]x10(-8). This branching ratio and the &mgr;&mgr; mass spectrum is in very good agreement with the measurement of the K+-->pi(+)e(+)e(-) decay, but deviates significantly from the previous measurement.