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Precise measurement of tau lifetime in ALEPH experiment at the LEP; Mesure precise de la duree de vie du tau dans l`experience ALEPH au LEP

Abstract

A new method is presented for the measurement of the tau lifetime using tau decays to hadrons. Precise measurements ({sigma} {approx} 20{mu}m) of impact parameters (d{sub o} and z{sub o}) of charged tracks using full vertex detector informations allow the reconstruction of the 3-dimensional point of minimum approach of the track to the beam axis. On the other hand, it is shown that an axis perpendicular to the tau axis can be precisely determined ({sigma} {approx} 10 mrad) in the hadronic-hadronic {tau}{sup +}{tau}{sup -} decay events using kinematics and the back-to-back nature of tau pairs in e{sup +}e{sup -} colliders. Combination of both quantities yields a generalized IPS relation in 3D space which is not affected by the beam size nor by the tau direction uncertainty. The experimental resolution can be fitted together with lifetime due to the small smearing. The method allows, therefore, a self-consistent and self-calibrating analysis of tau lifetime. The method has good stability against systematical uncertainties like tracking resolution, non-gaussian tails, etc...The method has been applied to the data collected by the ALEPH detector at LEP in 1992. From 2840 {tau}{sup +} + {sup {tau}-} {yields} hadron + hadron (1-1) decay events and 794 hadron +  More>>
Authors:
Publication Date:
Feb 01, 1995
Product Type:
Thesis/Dissertation
Report Number:
LAL-95-03
Reference Number:
SCA: 662430; 663420; 440104; PA: AIX-27:020738; EDB-96:049336; NTS-96:016136; SN: 96001551389
Resource Relation:
Other Information: TH: These (D. es Sc.).; PBD: Feb 1995
Subject:
66 PHYSICS; 44 INSTRUMENTATION, INCLUDING NUCLEAR AND PARTICLE DETECTORS; TAU PARTICLES; LEPTONIC DECAY; LIFETIME; WEAK HADRONIC DECAY; BEAM POSITION; BRANCHING RATIO; COMPUTERIZED SIMULATION; DATA-FLOW PROCESSING; ELECTRON-MUON-TAU UNIVERSALITY; ELECTRON-POSITRON COLLISIONS; IMPACT PARAMETER; LEP STORAGE RINGS; LEPTON-LEPTON INTERACTIONS; MASS; MAXIMUM-LIKELIHOOD FIT; MONTE CARLO METHOD; SHOWER COUNTERS; STANDARD MODEL; TIME PROJECTION CHAMBERS
OSTI ID:
189701
Research Organizations:
Paris-11 Univ., 91 - Orsay (France). Lab. de l`Accelerateur Lineaire
Country of Origin:
France
Language:
French
Other Identifying Numbers:
Other: ON: DE96616443; TRN: FR9504416020738
Availability:
INIS; OSTI as DE96616443
Submitting Site:
FRN
Size:
171 p.
Announcement Date:

Citation Formats

Park, I. Precise measurement of tau lifetime in ALEPH experiment at the LEP; Mesure precise de la duree de vie du tau dans l`experience ALEPH au LEP. France: N. p., 1995. Web.
Park, I. Precise measurement of tau lifetime in ALEPH experiment at the LEP; Mesure precise de la duree de vie du tau dans l`experience ALEPH au LEP. France.
Park, I. 1995. "Precise measurement of tau lifetime in ALEPH experiment at the LEP; Mesure precise de la duree de vie du tau dans l`experience ALEPH au LEP." France.
@misc{etde_189701,
title = {Precise measurement of tau lifetime in ALEPH experiment at the LEP; Mesure precise de la duree de vie du tau dans l`experience ALEPH au LEP}
author = {Park, I}
abstractNote = {A new method is presented for the measurement of the tau lifetime using tau decays to hadrons. Precise measurements ({sigma} {approx} 20{mu}m) of impact parameters (d{sub o} and z{sub o}) of charged tracks using full vertex detector informations allow the reconstruction of the 3-dimensional point of minimum approach of the track to the beam axis. On the other hand, it is shown that an axis perpendicular to the tau axis can be precisely determined ({sigma} {approx} 10 mrad) in the hadronic-hadronic {tau}{sup +}{tau}{sup -} decay events using kinematics and the back-to-back nature of tau pairs in e{sup +}e{sup -} colliders. Combination of both quantities yields a generalized IPS relation in 3D space which is not affected by the beam size nor by the tau direction uncertainty. The experimental resolution can be fitted together with lifetime due to the small smearing. The method allows, therefore, a self-consistent and self-calibrating analysis of tau lifetime. The method has good stability against systematical uncertainties like tracking resolution, non-gaussian tails, etc...The method has been applied to the data collected by the ALEPH detector at LEP in 1992. From 2840 {tau}{sup +} + {sup {tau}-} {yields} hadron + hadron (1-1) decay events and 794 hadron + 3 hadrons (1-3) decay events, the tau lifetimes of 292.9 {+-} 5.9 {+-} 2.7fs and 284.6 {+-} 11.9 {+-} 5.1fs are obtained respectively. The combined {tau} lifetimes is 290.8 {+-} 5.3 {+-} 2.7fs. Statistical uncertainty corresponds to 1.1/{radical}N{sub {tau}}{tau}. This result has low statistical correlation with other precision methods. (author). 70 refs., 80 figs., 21 tabs., 7 ann.}
place = {France}
year = {1995}
month = {Feb}
}