A measurement of the Michel parameter {rho} in muon decay

Technical Report · Fri Jul 01 04:00:00 EDT 1994

DOI:https://doi.org/10.2172/10162471· OSTI ID:10162471

Mischke, R E; Amann, J F; Bolton, R D ^[1]

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1. and others

An improved measurement of the Michel parameter {rho} in normal muon decay has been made using the MEGA positron spectrometer. Muons were stopped in the center of a large solenoid (1.5 T nominal field) and the momenta of positrons with energies over about 35 MeV were measured with a precision of about 0.6 MeV/c FWHM. There over 15 million events in each spectrum taken for three operating configurations. The previous result has a precision of {delta}{rho}/{rho} = 0.003 based on a sample of about 1 million events in the positron energy spectrum. The present experiment expects to improve the precision by a factor of three to six, depending on the level of systematic uncertainties. The improved result is a precise test of the standard model of electroweak interactions for a purely leptonic process. It also provides a better constraint on the mixing angle in a left-right symmetric extension to the standard model.

• Research Organization: Los Alamos National Lab., NM (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 10162471
• Report Number(s): LA-UR--94-2201; CONF-940722--5; ON: DE94014423
• Country of Publication: United States
• Language: English

Related Subjects

662370
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
DECAYS OF LEPTONS
ENERGY DEPENDENCE
EXPERIMENTAL DATA
LEPTONIC DECAY
MONTE CARLO METHOD
MUONS
WEINBERG-SALAM GAUGE MODEL