Total and differential cross sections for the process e(+)e(-) --> gamma gamma(gamma), and the total cross section for the process e(+)e(-) --> gamma gamma gamma, are measured at energies around 91 GeV using the data collected with the L3 detector from 1991 to 1993. We set lower limits, at 95% CL, on a contact interaction energy scale parameter Lambda > 602 GeV, on the mass of an excited electron m(c)* > 146 GeV and on the QED cut-off parameters Lambda(+) > 149 GeV and Lambda(-) > 143 GeV. Upper limits are also set on the branching fractions of Z decaying into gamma gamma, pi degrees gamma and eta gamma of 5.2 x 10(-5), 5.2 x 10(-5) and 7.6 x 10(-5) respectively. The reactions e(+)e(-) --> rho(+)rho(-)n gamma (rho = e, mu, tau) are studied using the data collected from 1990 to 1994. The data are consistent with the QED expectations.
Tests Qed At Lep Energies Using E(+)e(-)-]gamma-gamma(gamma) and E(+)e(-)-]l(+)l(-)gamma-gamma
SANTOCCHIA, Attilio;FIANDRINI, Emanuele;
1995
Abstract
Total and differential cross sections for the process e(+)e(-) --> gamma gamma(gamma), and the total cross section for the process e(+)e(-) --> gamma gamma gamma, are measured at energies around 91 GeV using the data collected with the L3 detector from 1991 to 1993. We set lower limits, at 95% CL, on a contact interaction energy scale parameter Lambda > 602 GeV, on the mass of an excited electron m(c)* > 146 GeV and on the QED cut-off parameters Lambda(+) > 149 GeV and Lambda(-) > 143 GeV. Upper limits are also set on the branching fractions of Z decaying into gamma gamma, pi degrees gamma and eta gamma of 5.2 x 10(-5), 5.2 x 10(-5) and 7.6 x 10(-5) respectively. The reactions e(+)e(-) --> rho(+)rho(-)n gamma (rho = e, mu, tau) are studied using the data collected from 1990 to 1994. The data are consistent with the QED expectations.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
