The first measurement of the Michel parameter η in τ decays

H. Albrecht; T. Hamacher; R. P. Hofmann; T. Kirchhoff; R. Mankel; A. Nau; S. Nowak; H. Schröder; H. D. Schulz; M. Walter; R. Wurth; C. Hast; H. Kapitza; H. Kolanoski; A. Kosche; A. Lange; A. Lindner; M. Schieber; T. Siegmund; B. Spaan; H. Thurn; D. Töpfer; D. Wegener; P. Eckstein; K. R. Schubert; R. Schwierz; R. Waldi; K. Reim; H. Wegener; R. Eckmann; H. Kuipers; O. Mai; R. Mundt; T. Oest; R. Reiner; W. Schmidt-Parzefall; J. Stiewe; S. Werner; K. Ehret; W. Hofmann; A. Hüpper; K. T. Knöpfle; J. Spengler; P. Krieger; D. B. MacFarlane; J. D. Prentice; P. R.B. Saull; K. Tzamariudaki; R. G. Van de Water; T. S. Yoon; C. Frankl; D. Reßing; M. Schmidtler; M. Schneider; S. Weseler; G. Kernel; P. Križan; E. Križnič; T. Podobnik; T. Živko; V. Balagura; I. Belyaev; S. Chechelnitsky; M. Danilov; A. Droutskoy; Yu Gershtein; A. Golutvin; I. Korolko; G. Kostina; D. Litvintsev; V. Lubimov; P. Pakhlov; S. Semenov; A. Snizhko; I. Tichomirov; Yu Zaitsev

doi:10.1016/0370-2693(95)80027-U

The first measurement of the Michel parameter η in τ decays

H. Albrecht
, T. Hamacher
, R. P. Hofmann
, T. Kirchhoff
, R. Mankel
, A. Nau
, S. Nowak
, H. Schröder
, H. D. Schulz
, M. Walter
, R. Wurth
, C. Hast
, H. Kapitza
, H. Kolanoski
, A. Kosche
, A. Lange
, A. Lindner
, M. Schieber
, T. Siegmund
, B. Spaan

H. Thurn, D. Töpfer, D. Wegener, P. Eckstein, K. R. Schubert, R. Schwierz, R. Waldi, K. Reim, H. Wegener, R. Eckmann, H. Kuipers, O. Mai, R. Mundt, T. Oest, R. Reiner, W. Schmidt-Parzefall, J. Stiewe, S. Werner, K. Ehret, W. Hofmann, A. Hüpper, K. T. Knöpfle, J. Spengler, P. Krieger, D. B. MacFarlane, J. D. Prentice, P. R.B. Saull, K. Tzamariudaki, R. G. Van de Water, T. S. Yoon, C. Frankl, D. Reßing, M. Schmidtler, M. Schneider, S. Weseler, G. Kernel, P. Križan, E. Križnič, T. Podobnik, T. Živko, V. Balagura, I. Belyaev, S. Chechelnitsky, M. Danilov, A. Droutskoy, Yu Gershtein, A. Golutvin, I. Korolko, G. Kostina, D. Litvintsev, V. Lubimov, P. Pakhlov, S. Semenov, A. Snizhko, I. Tichomirov, Yu Zaitsev

Research output: Contribution to journal › Article › peer-review

Abstract

Using the ARGUS detector at the e⁺e^- storage ring DORIS II at DESY, we have studied lepton energy spectra in τ decays. We present a "pseudo-rest-frame" technique in which the second τ in the event, decaying into a heavy hadronic system, is used as reference. This method allows for the first measurement of the Michel Parameter η in τ decays. We also determine the Michel Parameter ρ in τ → ev̄v decays with a precision comparable to the present world average. The measured values of the parameters ρ=0.735±0.036±0.020 and η=0.03±0.18±0.12 are in good agreement with standard V-A coupling at the τ-ν-W vertex.

Original language	English
Pages (from-to)	441-447
Number of pages	7
Journal	Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume	341
Issue number	3-4
DOIs	https://doi.org/10.1016/0370-2693(95)80027-U
Publication status	Published - 5 Jan 1995
Externally published	Yes

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10.1016/0370-2693(95)80027-U

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Albrecht, H., Hamacher, T., Hofmann, R. P., Kirchhoff, T., Mankel, R., Nau, A., Nowak, S., Schröder, H., Schulz, H. D., Walter, M., Wurth, R., Hast, C., Kapitza, H., Kolanoski, H., Kosche, A., Lange, A., Lindner, A., Schieber, M., Siegmund, T., ... Zaitsev, Y. (1995). The first measurement of the Michel parameter η in τ decays. Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 341(3-4), 441-447. https://doi.org/10.1016/0370-2693(95)80027-U

@article{15b79b56af9c4742bf248ba7b3e05829,

title = "The first measurement of the Michel parameter η in τ decays",

abstract = "Using the ARGUS detector at the e+e- storage ring DORIS II at DESY, we have studied lepton energy spectra in τ decays. We present a {"}pseudo-rest-frame{"} technique in which the second τ in the event, decaying into a heavy hadronic system, is used as reference. This method allows for the first measurement of the Michel Parameter η in τ decays. We also determine the Michel Parameter ρ in τ → e{\=v}v decays with a precision comparable to the present world average. The measured values of the parameters ρ=0.735±0.036±0.020 and η=0.03±0.18±0.12 are in good agreement with standard V-A coupling at the τ-ν-W vertex.",

author = "H. Albrecht and T. Hamacher and Hofmann, \{R. P.\} and T. Kirchhoff and R. Mankel and A. Nau and S. Nowak and H. Schr{\"o}der and Schulz, \{H. D.\} and M. Walter and R. Wurth and C. Hast and H. Kapitza and H. Kolanoski and A. Kosche and A. Lange and A. Lindner and M. Schieber and T. Siegmund and B. Spaan and H. Thurn and D. T{\"o}pfer and D. Wegener and P. Eckstein and Schubert, \{K. R.\} and R. Schwierz and R. Waldi and K. Reim and H. Wegener and R. Eckmann and H. Kuipers and O. Mai and R. Mundt and T. Oest and R. Reiner and W. Schmidt-Parzefall and J. Stiewe and S. Werner and K. Ehret and W. Hofmann and A. H{\"u}pper and Kn{\"o}pfle, \{K. T.\} and J. Spengler and P. Krieger and MacFarlane, \{D. B.\} and Prentice, \{J. D.\} and Saull, \{P. R.B.\} and K. Tzamariudaki and \{Van de Water\}, \{R. G.\} and Yoon, \{T. S.\} and C. Frankl and D. Re{\ss}ing and M. Schmidtler and M. Schneider and S. Weseler and G. Kernel and P. Kri{\v z}an and E. Kri{\v z}ni{\v c} and T. Podobnik and T. {\v Z}ivko and V. Balagura and I. Belyaev and S. Chechelnitsky and M. Danilov and A. Droutskoy and Yu Gershtein and A. Golutvin and I. Korolko and G. Kostina and D. Litvintsev and V. Lubimov and P. Pakhlov and S. Semenov and A. Snizhko and I. Tichomirov and Yu Zaitsev",

year = "1995",

month = jan,

day = "5",

doi = "10.1016/0370-2693(95)80027-U",

language = "English",

volume = "341",

pages = "441--447",

journal = "Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics",

issn = "0370-2693",

number = "3-4",

}

Albrecht, H, Hamacher, T, Hofmann, RP, Kirchhoff, T, Mankel, R, Nau, A, Nowak, S, Schröder, H, Schulz, HD, Walter, M, Wurth, R, Hast, C, Kapitza, H, Kolanoski, H, Kosche, A, Lange, A, Lindner, A, Schieber, M, Siegmund, T, Spaan, B, Thurn, H, Töpfer, D, Wegener, D, Eckstein, P, Schubert, KR, Schwierz, R, Waldi, R, Reim, K, Wegener, H, Eckmann, R, Kuipers, H, Mai, O, Mundt, R, Oest, T, Reiner, R, Schmidt-Parzefall, W, Stiewe, J, Werner, S, Ehret, K, Hofmann, W, Hüpper, A, Knöpfle, KT, Spengler, J, Krieger, P, MacFarlane, DB, Prentice, JD, Saull, PRB, Tzamariudaki, K, Van de Water, RG, Yoon, TS, Frankl, C, Reßing, D, Schmidtler, M, Schneider, M, Weseler, S, Kernel, G, Križan, P, Križnič, E, Podobnik, T, Živko, T, Balagura, V, Belyaev, I, Chechelnitsky, S, Danilov, M, Droutskoy, A, Gershtein, Y, Golutvin, A, Korolko, I, Kostina, G, Litvintsev, D, Lubimov, V, Pakhlov, P, Semenov, S, Snizhko, A, Tichomirov, I & Zaitsev, Y 1995, 'The first measurement of the Michel parameter η in τ decays', Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, vol. 341, no. 3-4, pp. 441-447. https://doi.org/10.1016/0370-2693(95)80027-U

TY - JOUR

T1 - The first measurement of the Michel parameter η in τ decays

AU - Albrecht, H.

AU - Hamacher, T.

AU - Hofmann, R. P.

AU - Kirchhoff, T.

AU - Mankel, R.

AU - Nau, A.

AU - Nowak, S.

AU - Schröder, H.

AU - Schulz, H. D.

AU - Walter, M.

AU - Wurth, R.

AU - Hast, C.

AU - Kapitza, H.

AU - Kolanoski, H.

AU - Kosche, A.

AU - Lange, A.

AU - Lindner, A.

AU - Schieber, M.

AU - Siegmund, T.

AU - Spaan, B.

AU - Thurn, H.

AU - Töpfer, D.

AU - Wegener, D.

AU - Eckstein, P.

AU - Schubert, K. R.

AU - Schwierz, R.

AU - Waldi, R.

AU - Reim, K.

AU - Wegener, H.

AU - Eckmann, R.

AU - Kuipers, H.

AU - Mai, O.

AU - Mundt, R.

AU - Oest, T.

AU - Reiner, R.

AU - Schmidt-Parzefall, W.

AU - Stiewe, J.

AU - Werner, S.

AU - Ehret, K.

AU - Hofmann, W.

AU - Hüpper, A.

AU - Knöpfle, K. T.

AU - Spengler, J.

AU - Krieger, P.

AU - MacFarlane, D. B.

AU - Prentice, J. D.

AU - Saull, P. R.B.

AU - Tzamariudaki, K.

AU - Van de Water, R. G.

AU - Yoon, T. S.

AU - Frankl, C.

AU - Reßing, D.

AU - Schmidtler, M.

AU - Schneider, M.

AU - Weseler, S.

AU - Kernel, G.

AU - Križan, P.

AU - Križnič, E.

AU - Podobnik, T.

AU - Živko, T.

AU - Balagura, V.

AU - Belyaev, I.

AU - Chechelnitsky, S.

AU - Danilov, M.

AU - Droutskoy, A.

AU - Gershtein, Yu

AU - Golutvin, A.

AU - Korolko, I.

AU - Kostina, G.

AU - Litvintsev, D.

AU - Lubimov, V.

AU - Pakhlov, P.

AU - Semenov, S.

AU - Snizhko, A.

AU - Tichomirov, I.

AU - Zaitsev, Yu

PY - 1995/1/5

Y1 - 1995/1/5

N2 - Using the ARGUS detector at the e+e- storage ring DORIS II at DESY, we have studied lepton energy spectra in τ decays. We present a "pseudo-rest-frame" technique in which the second τ in the event, decaying into a heavy hadronic system, is used as reference. This method allows for the first measurement of the Michel Parameter η in τ decays. We also determine the Michel Parameter ρ in τ → ev̄v decays with a precision comparable to the present world average. The measured values of the parameters ρ=0.735±0.036±0.020 and η=0.03±0.18±0.12 are in good agreement with standard V-A coupling at the τ-ν-W vertex.

AB - Using the ARGUS detector at the e+e- storage ring DORIS II at DESY, we have studied lepton energy spectra in τ decays. We present a "pseudo-rest-frame" technique in which the second τ in the event, decaying into a heavy hadronic system, is used as reference. This method allows for the first measurement of the Michel Parameter η in τ decays. We also determine the Michel Parameter ρ in τ → ev̄v decays with a precision comparable to the present world average. The measured values of the parameters ρ=0.735±0.036±0.020 and η=0.03±0.18±0.12 are in good agreement with standard V-A coupling at the τ-ν-W vertex.

UR - https://www.scopus.com/pages/publications/6144249702

U2 - 10.1016/0370-2693(95)80027-U

DO - 10.1016/0370-2693(95)80027-U

M3 - Article

AN - SCOPUS:6144249702

SN - 0370-2693

VL - 341

SP - 441

EP - 447

JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

IS - 3-4

ER -

The first measurement of the Michel parameter η in τ decays

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