HAL : in2p3-00001114, version 1
 Zeitschrift für Physik C 75 (1997) 581-592
 A study of the reaction $e^+ e^- \rightarrow \mu^+\mu^-\gamma_{ISR}$ at LEP and search for new physics at annihilation energies near 80 GeV
 DELPHI Collaboration(s)
 (1997)
 A study of the channel $e^{+}e^{-}~\rightarrow~\mu^{+}\mu^{-}\gamma_{\ sc ISR}$, where $\gamma_{\sc ISR}$ is an initial state radiation photon, is presented using data collected by the DELPHI experiment from 1991 to 1994. The total cross-section at effective annihilation energies ($\sqrt{s'}$) below the $Z^0$ peak is obtained by using the events with relatively hard initial state radiative photon(s) ($E_{\gamma}~ ~$~1~GeV). The differential cross-section as a function of the muon polar production angle is also determined in order to extract t s alhe forward-backward asymmetries for the reaction $e^+ e^- \rightarrow \mu^+ \mu^-$ at energies $\sqrt{s'}$ between 20 and 87~GeV. The ratio of the helicity cross-sections $\frac{\sigma_{LL}+\sigma_{RR}}{\sigma_{RL}+\sigma_{LR}}$, where the two subscripts stand for the helicities of the incoming $e^-$ and outgoing $\mu^-$ respectively, is extracted from the differential cross-sections in order to test the Standard Model and to look for new physics near 80 GeV. No deviations from the Standard Model were found.
 Thème(s) : Physique/Physique des Hautes Energies - Expérience
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 in2p3-00001114, version 1 http://hal.in2p3.fr/in2p3-00001114 oai:hal.in2p3.fr:in2p3-00001114 Contributeur : Sylvie Florès <> Soumis le : Jeudi 5 Novembre 1998, 11:47:37 Dernière modification le : Mardi 12 Septembre 2006, 11:39:38