Using Z gamma candidate events collected by the CDF detector at the Tevatron Collider, we search for potential anomalous (non-standard-model) couplings between the Z boson and the photon. Z gamma couplings vanish at tree level and are heavily suppressed at higher orders; hence any evidence of couplings indicates new physics. Measurements are performed using data corresponding to an integrated luminosity of 4.9 fb(-1) in the Z -> nu(nu) over bar decay channel and 5.1 fb(-1) in the Z -> l(+)l(-) (l=mu, e) decay channels. The combination of these measurements provides the most stringent limits to date on Z gamma trilinear gauge couplings. Using an energy scale of Lambda = 1.5 TeV to allow for a direct comparison with previous measurements, we find limits on the CP-conserving parameters that describe Z gamma couplings to be |h(3)(gamma,Z)| < 0.022 and |h(4)(gamma,Z)| < 0.0009. These results are consistent with standard model predictions.
Limits on Anomalous Trilinear Gauge Couplings in Z gamma Events from p(p)over-bar Collisions at root s=1.96 TeV
CIOCCI, MARIA AGNESE;DONATI, SIMONE;
2011-01-01
Abstract
Using Z gamma candidate events collected by the CDF detector at the Tevatron Collider, we search for potential anomalous (non-standard-model) couplings between the Z boson and the photon. Z gamma couplings vanish at tree level and are heavily suppressed at higher orders; hence any evidence of couplings indicates new physics. Measurements are performed using data corresponding to an integrated luminosity of 4.9 fb(-1) in the Z -> nu(nu) over bar decay channel and 5.1 fb(-1) in the Z -> l(+)l(-) (l=mu, e) decay channels. The combination of these measurements provides the most stringent limits to date on Z gamma trilinear gauge couplings. Using an energy scale of Lambda = 1.5 TeV to allow for a direct comparison with previous measurements, we find limits on the CP-conserving parameters that describe Z gamma couplings to be |h(3)(gamma,Z)| < 0.022 and |h(4)(gamma,Z)| < 0.0009. These results are consistent with standard model predictions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.