Tests to completely measure the photon and Z sup 0 -boson couplings of the. tau. lepton

Journal Article · Thu Oct 31 23:00:00 EST 1991 · Physical Review, D (Particles Fields); (United States)

DOI:https://doi.org/10.1103/PhysRevD.44.2818· OSTI ID:6103501

Goozovat, S; Nelson, C A ^[1]

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1. Department of Physics, State University of New York, Binghamton, New York (USA)

Ongoing experiments with unpolarized {ital e}{sup {minus}}{ital e+} collisions contain many events for the production-decay sequence {ital e}{sup {minus}}{ital e+}{r arrow}{ital Z}{sup 0},{gamma}{sup *}{r arrow}{tau}{sub 1}{sup {minus}}{tau}{sub 2}{sup +}{r arrow}({ital h}{sub 1}{sup {minus}}{nu}) ({ital h}{sub 2}{sup +}{bar {nu}}), where {ital h}={pi},{rho}. In principle, from the beam-referenced spin-correlation function for this sequence the photon and {ital Z}{sup 0}-boson couplings of the {tau} lepton can be completely measured. From 10{sup 7} {ital Z}{sup 0} events the moduli of the {ital Z}{sup 0}{r arrow}{tau}{sup {minus}}{tau}{sup +} helicity-conserving neutral-current amplitudes {vert bar}{ital T}({minus}+){vert bar} and {vert bar}{ital T}(+{minus}){vert bar} can be measured to the 1% level (ideal statistical error), and their relative phase {beta}{sub +{minus}} to the 3{degree} level. Unless experimental surprises occur, the helicity-changing neutral-current amplitudes {ital T}(++) and {ital T}({minus}{minus}) will not be measured by this technique ({Delta}{vert bar}{ital T}({minus}{minus}){vert bar}/{vert bar}{ital T}({minus}{minus}){vert bar}=6). From 10{sup 7}{tau}{sup {minus}}{tau}{sup +} events at {radical}{ital s} =10 GeV, the modulus {vert bar}{ital t}({minus}+){vert bar}={vert bar}{ital t}(+{minus}){vert bar} for {gamma}{sup *}{r arrow}{tau}{sup {minus}}{tau}{sup +} can be measured to the 0.5% level and their relative phase {beta}{sub +{minus}} to 0.5{degree}, the modulus {vert bar}{ital t}(++){vert bar}={vert bar}{ital t}({minus}{minus}){vert bar} to 1% and their relative phase {beta}{sub ++} to 4{degree}, and the remaining relative phase {beta}{sub 0} to 1{degree}. Similar {gamma}{sup *}{r arrow}{tau}{sup {minus}}{tau}{sup +} ideal statistical error levels are found for a {tau}-charm factory ({radical}{ital s} {similar to}4 GeV).

• DOE Contract Number: FG02-86ER40291
• OSTI ID: 6103501
• Journal Information: Physical Review, D (Particles Fields); (United States), Journal Name: Physical Review, D (Particles Fields); (United States) Vol. 44:9; ISSN PRVDA; ISSN 0556-2821
• Country of Publication: United States
• Language: English

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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANGULAR MOMENTUM
BOSONS
CORRELATION FUNCTIONS
COUPLING CONSTANTS
CP INVARIANCE
ELECTRON-POSITRON INTERACTIONS
ELEMENTARY PARTICLES
FERMIONS
FUNCTIONS
HEAVY LEPTONS
HELICITY
INTERACTIONS
INTERMEDIATE BOSONS
INTERMEDIATE VECTOR BOSONS
INVARIANCE PRINCIPLES
LEP STORAGE RINGS
LEPTON-LEPTON INTERACTIONS
LEPTONS
MASSLESS PARTICLES
MECHANICS
NEUTRAL-CURRENT INTERACTIONS
PAIR PRODUCTION
PARTICLE INTERACTIONS
PARTICLE PRODUCTION
PARTICLE PROPERTIES
PHOTONS
POSTULATED PARTICLES
SPIN
STATISTICAL MECHANICS
STORAGE RINGS
TAU PARTICLES
TESTING
Z NEUTRAL BOSONS