Measurement of the axial-vector τ spectral functions and determination of α<inf>s</inf>(M<sup>2</sup><inf>τ</inf>) from hadronic τ decays

R. Barate, D. Buskulic, D. Decamp, P. Ghez, C. Goy, J. P. Lees, A. Lucotte, E. Merle, M. N. Minard, J. Y. Nief, B. Pietrzyk, R. Alemany, G. Boix, M. P. Casado, M. Chmeissani, J. M. Crespo, M. Delfino, E. Fernandez, M. Fernandez-Bosman, L. GarridoE. Graugès, A. Juste, M. Martinez, G. Merino, R. Miquel, L. M. Mir, I. C. Park, A. Pascual, J. A. Perlas, I. Riu, F. Sanchez, A. Colaleo, D. Creanza, M. de Palma, G. Gelao, G. Iaselli, G. Maggi, M. Maggi, S. Nuzzo, A. Ranieri, G. Raso, F. Ruggieri, G. Selvaggi, L. Silvestris, P. Tempesta, A. Tricomi, G. Zito, X. Huang, J. Lin, Q. Ouyang, T. Wang, Y. Xie, R. Xu, S. Xue, J. Zhang, L. Zhang, W. Zhao, D. Abbaneo, U. Becker, P. Bright-Thomas, D. Casper, M. Cattaneo, V. Ciulli, G. Dissertori, H. Drevermann, R. W. Forty, M. Frank, R. Hagelberg, J. B. Hansen, J. Harvey, P. Janot, B. Jost, I. Lehraus, P. Mato, A. Minten, L. Moneta, A. Pacheco, J. F. Pusztaszeri, F. Ranjard, L. Rolandi, D. Rousseau, D. Schlatter, W. Tejessy, F. Teubert, I. R. Tomalin, H. Wachsmuth, A. Wagner, Z. Ajaltouni, F. Badaud, G. Chazelle, O. Deschamps, A. Falvard, C. Ferdi, P. Gay, C. Guicheney, P. Henrard, J. Jousset, B. Michel, S. Monteil, J. C. Montret

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310 Citations (Scopus)


An analysis based on 124 000 selected τ pairs recorded by the ALEPH detector at LEP provides the vector (V) and axial-vector (A) spectral functions of hadronic τ decays together with their total widths. This allows the evaluation of finite energy chiral sum rules that are weighted integrals over the (V - A) spectral functions. In addition, a precise measurement of αs, along with a determination of non-perturbative contributions at the τ mass scale is performed. The experimentally and theoretically most robust determination of αs(Mτ2) is obtained from the (V + A) fit that yields αs (Mτ2) = 0.334 ±0.022 giving αs (MZ2) = 0.1202 ± 0.0027 after the extrapolation to the mass of the Z boson. The approach of the Operator Product Expansion (OPE) is tested experimentally studying the evolution of the τ hadronic widths to masses smaller than the τ mass.
Original languageEnglish
Pages (from-to)409-431
JournalEuropean Physical Journal C
Issue number3
Publication statusPublished - 1 Jan 1998


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