Search for unconventional tau decays and measurement of the tau production cross section in e⁺e^- annihilations at SPEAR [Thesis]

Technical Report · Thu Jan 01 04:00:00 EST 1981

DOI:https://doi.org/10.2172/5445539· OSTI ID:5445539

Hayes, Kenneth Gregory ^[1]

---

1. SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Stanford Univ., CA (United States)

We present the results of an experimental study of two properties of the tau lepton performed with the MARK II detector in the SPEAR e⁺e^- storage ring at SLAC. The tau production cross section in e/sup +/e/sup -/ annihilation between 3.85 and 6.85 Gev in the center of mass has been measured using electron-muon events, and is constent with the spin 1/2, point cross section. The branching ratio product for the electron and muon leptonic decay modes is measured to be .032 +- .002 +- .004. Searches for 12 neutrinoless decay modes of the tau which violate lepton number conservation have been made. No evidence for lepton number violation is observed, and we set upper limits (90% C.L.) on the branching ratio for each decay mode. The branching ratio limits on the radiative decays tau..-->..muon + photon and tau..-->..electron + photon are .055% and .064%, respectively. For the 3 charged lepton decays tau..-->..3 electrons, tau..-->..electron + 2 muons, tau..-->..muon + 2 electrons, and tau..-->..3muons, the branching ratio limits are .040%, .033%, .044%, and .049%, respectively. Upper limits on the branching ratios are also set for the following charged lepton + neutral hadron decays of the tau: tau ..-->..electron + rho (.037), tau..-->..muon + rho (.044%), tau..-->..electron + kzero (.13%), tau..-->..muon + kzero (.10%), tau..-->..electron + pizero (.21%), and tau..-->..muon + pizero (.082%).

• Research Organization: SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Stanford Univ., CA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC03-76SF00515
• OSTI ID: 5445539
• Report Number(s): SLAC--237; SLAC-R--237
• 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
ANNIHILATION
BASIC INTERACTIONS
BRANCHING RATIO
CONSERVATION LAWS
CROSS SECTIONS
DATA
DECAY
ELECTROMAGNETIC INTERACTIONS
ELECTRON-MUON INTERACTIONS
ELECTRON-POSITRON INTERACTIONS
ELEMENTARY PARTICLES
ENERGY RANGE
EXPERIMENTAL DATA
FERMIONS
GEV RANGE
GEV RANGE 01-10
HEAVY LEPTONS
INFORMATION
INTERACTIONS
LEPTON NUMBER
LEPTON-LEPTON INTERACTIONS
LEPTONIC DECAY
LEPTONS
NUMERICAL DATA
PARTICLE DECAY
PARTICLE INTERACTIONS
PARTICLE PRODUCTION
POSTULATED PARTICLES
SPEAR
STORAGE RINGS
TAU PARTICLES
WEAK INTERACTIONS
WEAK PARTICLE DECAY