A study of the channel e(+)e(-) --> mu(+)mu(-)gamma ISR, where gamma 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 (root 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 eo extract the forward-backward asymmetries for the reaction e(+)e(-) --> mu(+)mu(-) at energies root s' between 20 and 87 GeV. The ratio of the helicity cross-sections 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.
A study of the reaction e(+)e(-)->mu(+)mu(-)gamma(ISR) at LEP and search for new physics at annihilation energies near 80 GeV
DE LOTTO, Barbara;SCURI, Fabrizio;
1997-01-01
Abstract
A study of the channel e(+)e(-) --> mu(+)mu(-)gamma ISR, where gamma 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 (root 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 eo extract the forward-backward asymmetries for the reaction e(+)e(-) --> mu(+)mu(-) at energies root s' between 20 and 87 GeV. The ratio of the helicity cross-sections 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
