Measurement of the {ital {tau}} Neutrino Helicity and Michel Parameters in Polarized {ital e}{sup +}{ital e}{sup -} Collisions

Journal Article · Sun Jun 01 00:00:00 EDT 1997 · Physical Review Letters

OSTI ID:628688

Steiner, R ^[1]; Benvenuti, A C ^[2]; Coller, J A; Hedges, S J; Johnson, A S; Shank, J T; Whitaker, J S ^[3]; Allen, N J; Cotton, R; Dervan, P J; Hasan, A; McKemey, A K; Watts, S J ^[4]; Caldwell, D O; Lu, A; Yellin, S J ^[5]; Cavalli-Sforza, M; Coyne, D G; Fernandez, J P; Liu, X ; Reinertsen, P L; Schalk, T; Schumm, B A; Williams, D A ^[6]; DOliveira, A; Johnson, R A; Meadows, B T; Nussbaum, M ^[7]; Dima, M; Harton, J L; Smy, M B; Wilson, R J ^[8]; Baranko, G; Fahey, S; Fan, C; Krishna, N M; Lauber, J A; Nauenberg, U; Wagner, D L ^[9]; Bazarko, A O; Bolton, T; Rowson, P C; Shaevitz, M H ^[10]; Camanzi, B; Mazzucato, E; Piemontese, L ^[11]; Calcaterra, A; De Sangro, R; Peruzzi, I; Piccolo, M ^[12]; Eisenstein, B I; Gladding, G; Karliner, I ^[13]; Shapiro, G; Steiner, H ^[14]; Bardon, O; Burrows, P N; Busza, W; Cowan, R F; Dong, D N; Fero, M J; Gonzalez, S; Kendall, H W; Lath, A; Lia, V; Osborne, L S; Quigley, J; Taylor, F E; Torrence, E; Verdier, R; Williams, D C; others, and

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1. Adelphi University, Garden City, New York 11530 (United States)
2. INFN Sezione di Bologna, I-40126 Bologna (Italy)
3. Boston University, Boston, Massachusetts 02215 (United States)
4. Brunel University, Uxbridge, Middlesex UB8 3PH (United Kingdom)
5. University of California at Santa Barbara, Santa Barbara, California 93106 (United States)
6. University of California at Santa Cruz, Santa Cruz, California 95064 (United States)
7. University of Cincinnati, Cincinnati, Ohio 45221 (United States)
8. Colorado State University, Fort Collins, Colorado 80523 (United States)
9. University of Colorado, Boulder, Colorado 80309 (United States)
10. Columbia University, New York, New York 10027 (United States)
11. INFN Sezione di Ferrara and Universita di Ferrara, I-44100 Ferrara (Italy)
12. INFN Lab.Nazionali di Frascati, I-00044 Frascati (Italy)
13. University of Illinois, Urbana, Illinois 61801 (United States)
14. Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720 (United States)

We present a new measurement of the {tau} neutrino helicity h{sub {nu}{sub {tau}}} and the {tau} Michel parameters {rho} , {eta} , {xi} , and the product {delta}{xi} . The analysis exploits the highly polarized SLC electron beam to extract these quantities directly from a measurement of the {tau} decay spectra, using the 1993{endash}1995 SLD data sample of 4328 e{sup +}e{sup -}{r_arrow}Z{sup 0}{r_arrow}{tau}{sup +}{tau}{sup -} events. From the decays {tau}{r_arrow}{pi}{nu}{sub {tau}} and {tau}{r_arrow}{rho}{nu}{sub {tau}} we obtain a combined value h{sub {nu}{sub {tau}}}=-0.93{plus_minus}0.10{plus_minus} 0.04 . The leptonic decay channels yield combined values of {rho}=0.72{plus_minus}0.09{plus_minus}0.03 , {xi}=1.05{plus_minus}0.35{plus_minus}0.04 , and {delta}{xi}=0.88{plus_minus}0.27{plus_minus}0.04 . {copyright} {ital 1997} {ital The American Physical Society}

• OSTI ID: 628688
• Journal Information: Physical Review Letters, Vol. 78, Issue 25; Other Information: PBD: Jun 1997
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
TAU NEUTRINOS
HELICITY
ELECTRON BEAMS
POLARIZED BEAMS
LEPTONIC DECAY
ENERGY
TAU PARTICLES
Z NEUTRAL BOSONS