218 articles – 619 Notices  [english version]
 HAL : in2p3-00025986, version 1
 arXiv : hep-ex/0604038
 European Physical Journal C 47 (2006) 273-294
 Evidence for an excess of soft photons in hadronic decays of Z$^0$
 DELPHI Collaboration(s)
 (2006)
 Soft photons inside hadronic jets converted in front of the DELPHI main tracker (TPC) in events of qqbar disintegrations of the Z^0 were studied in the kinematic range 0.2 < E_gamma < 1 GeV and transverse momentum with respect to the closest jet direction p_T < 80 MeV/c. A clear excess of photons in the experimental data as compared to the Monte Carlo predictions is observed. This excess (uncorrected for the photon detection efficiency) is (1.17 +/- 0.06 +/- 0.27) x 10^{-3} gamma/jet in the specified kinematic region, while the expected level of the inner hadronic bremsstrahlung (which is not included in the Monte Carlo) is (0.340 +/- 0.001 +/- 0.038) x 10^{-3} gamma/jet. The ratio of the excess to the predicted bremsstrahlung rate is then (3.4 +/- 0.2 +/- 0.8), which is similar in strength to the anomalous soft photon signal observed in fixed target experiments with hadronic beams.
 Thème(s) : Physique/Physique des Hautes Energies - Expérience
 Lien vers le texte intégral : http://fr.arXiv.org/abs/hep-ex/0604038
 in2p3-00025986, version 1 http://hal.in2p3.fr/in2p3-00025986 oai:hal.in2p3.fr:in2p3-00025986 Contributeur : Sylvie Florès <> Soumis le : Mardi 25 Avril 2006, 12:40:43 Dernière modification le : Lundi 21 Août 2006, 10:27:52