Asymmetry and cross-section in e sup + e sup minus yields. tau. sup +. tau. sup minus from radical s = 52 to 57 GeV

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:5665043

Malchow, R L

The reaction e{sup {plus}}e{sup {minus}} {yields} {tau}{sup {plus}}{tau}- was studied at center-of-mass energies of 52, 55, 56, and 57 GeV in the AMY detector, located on the TRISTAN storage ring at KEK, Japan. Creation of {tau}-lepton pairs in e{sup {plus}}e{sup {minus}} collisions is an excellent test of the Standard Model. The forward-backward asymmetry is a particularly sensitive test, since the measurement depends not only on the number of events, but also on the distribution of these events. Measurements of the total production cross-section, {sigma}{sub {tau}{tau}}, and the differential cross-section, d{sigma}{sub {tau}}/d{Omega}, were made using data contained in a total integrated luminosity of 17.65 pb{sup {minus}1}. Total measured cross sections at each energy were in agreement with predictions from the Standard Model. The forward-backward asymmetry in the polar production angle, A{sub fb}, was obtained from the differential cross-section. At the average energy of {radical}s {equals} 55.16 GeV, it was determined that A{sub fb} {equals} {minus}0.33 {plus minus} 0.09. This is in good agreement with the Standard Model prediction of A{sub fb (Std. Mod.)} {equals} {minus}0.30 at this energy. Values of the weak coupling constants, g{sub V}{sup {tau}}g{sub V}{sup e} and g{sub A}{sup {tau}}g{sub A}{sup e}, were extracted from the measured asymmetry with the results g{sub V}{sup {tau}}g{sub V}{sup e} {equals} {minus}0.12 {plus minus} 0.08 and g{sub A}{sup {tau}}g{sub A}{sup e} {equals} 0.28 {plus minus} 0.08, in agreement with the Standard Model values of g{sub V}{sup {tau}}g{sub V}{sup e} (Std. Mod.) {equals} 0.0016 and g{sub A}{sup {tau}}g{sub A}{sup e} (Std. Mod.) 0.25. Lower limits on the QED cutoff parameters, {Lambda}{plus minus}, were obtained from the measured cross-section.

• Research Organization: California Univ., Davis, CA (United States)
• OSTI ID: 5665043
• Country of Publication: United States
• Language: English

Related Subjects

645101* -- High Energy Physics-- Particle Interactions & Properties-Experimental-- Electromagnetic Interactions & Properties
645102 -- High Energy Physics-- Particle Interactions & Properties-Experimental-- Weak Interactions & Properties
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ASYMMETRY
COMPARATIVE EVALUATIONS
COUPLING CONSTANTS
CROSS SECTIONS
DIFFERENTIAL CROSS SECTIONS
ELECTRON-POSITRON INTERACTIONS
ELEMENTARY PARTICLES
ENERGY RANGE
FERMIONS
GEV RANGE
GEV RANGE 10-100
HEAVY LEPTONS
INTERACTIONS
LEPTON-LEPTON INTERACTIONS
LEPTONS
MATHEMATICAL MODELS
PAIR PRODUCTION
PARTICLE INTERACTIONS
PARTICLE MODELS
PARTICLE PRODUCTION
PARTICLE STRUCTURE
POSTULATED PARTICLES
STANDARD MODEL
STORAGE RINGS
TAU PARTICLES
TOTAL CROSS SECTIONS
TRISTAN STORAGE RINGS
UNIFIED GAUGE MODELS