New, high statistics measurement of the K+ -> pi0 e+ nu (Ke3) branching ratio

A. Sher; R. Appel; G. S. Atoyan; B. Bassalleck; D. R. Bergman; N. Cheung; S. Dhawan; H. Do; J. Egger; S. Eilerts; H. Fischer; W. Herold; V. V. Issakov; H. Kaspar; D. E. Kraus; D. M. Lazarus; P. Lichard; J. Lowe; J. Lozano; H. Ma; W. Majid; S. Pislak; A. A. Poblaguev; P. Rehak; Aleksey Sher; J. A. Thompson; P. Truol; M. E. Zeller

doi:10.1103/PhysRevLett.91.261802

paper

New, high statistics measurement of the K+ -> pi0 e+ nu (Ke3) branching ratio

arXiv:hep-ex/0305042 · doi:10.1103/PhysRevLett.91.261802

Abstract

E865 at the Brookhaven National Laboratory AGS collected about 70,000 K+(e3) events with the purpose of measuring the relative K+(e3) branching ratio. The pi0 in all the decays was detected using the e+e- pair from pi0 -> e+e-gamma decay and no photons were required. Using the Particle Data Group branching ratios for the normalization decays we obtain BR(K+(e3(gamma))=(5.13+/-0.02(stat)+/-0.09(sys)+/-0.04(norm))%, where $K + (e 3 (g amma)) in c l u d es t h ee f f ec t o f v i r t u a l an d r e a l p h o t o n s . T hi sr es u l t i s 2.3 s i g mahi g h er t han t h ec u r r e n tP a r t i c l eD a t a G r o u p v a l u e . T h e im pl i c a t i o n so f t hi sr es u l t f or t h e$ V_{us}$ element of the CKM matrix, and the matrix's unitarity are discussed.

4 pages, 5 figures; final version accepted by PRL