First observation of the decay. pi. /sup +/. -->. e/sup +/e/sup -/e/sup +/. nu. and a determination of the form factors F/sub V/, F/sub A/ and R

Conference · Mon Sep 01 00:00:00 EDT 1986

OSTI ID:5083417

Grab, C

The radiative pion decay ..pi../sup +/ ..-->.. e/sup +/e/sup -/e/sup +/..nu.. has been observed for the first time with a branching ratio of (3.4 +- 0.5) x 10/sup -9/. From the kinematical distribution of 79 events information on the form factors was extracted. The vector form factor F/sub V/ was found to have the same sign as the pion decay constant f/sub ..pi../. For the axial-vector form factors the following values have been measured: ..gamma.. = F/sub A//F/sub V/ = 0.7 +- 0.5 and xi = R/F/sub V/ = 2.3 +- 0.6. This value of ..gamma.. agrees well with the small positive value of (0.53 +- 0.06) and excludes the large negative value obtained in ..pi../sup +/ ..-->.. e/sup +/..nu gamma.. experiments. 8 refs. 8 refs.

• Research Organization: Stanford Linear Accelerator Center, Menlo Park, CA (USA)
• DOE Contract Number: AC03-76SF00515
• OSTI ID: 5083417
• Report Number(s): SLAC-PUB-4080; CONF-860701-22; ON: DE87000196
• Resource Relation: Conference: 23. international conference on high-energy physics, Berkeley, CA, USA, 16 Jul 1986
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
PIONS PLUS
RADIATIVE DECAY
AXIAL-VECTOR CURRENTS
BRANCHING RATIO
ENERGY SPECTRA
EXPERIMENTAL DATA
FORM FACTORS
ALGEBRAIC CURRENTS
BOSONS
CURRENTS
DATA
ELEMENTARY PARTICLES
HADRONS
INFORMATION
MESONS
NUMERICAL DATA
PARTICLE PROPERTIES
PIONS
PSEUDOSCALAR MESONS
SPECTRA
645101* - High Energy Physics- Particle Interactions & Properties-Experimental- Electromagnetic Interactions & Properties