Measurement of the production cross section for W + γ in the electron channel in √s = 1.8 TeV $\bar{p}$p collisions

Abstract

The production cross section times decay branching ratio for W{sub +{gamma}} in the electron decay channel in {radical}s = 1.8 TeV {bar p}-p collisions has been measured using W {yields} e{gamma} data sample obtained from the CDF 1988--1989 Tevatron collider run. For photons in the central region ({vert_bar}{eta}{sub {gamma}}{vert_bar} 0.7, eight electron W{sub {gamma}} candidates were observed. From these events, the production cross section times decay branching ratio for the electron sample was measured to be a {sigma} {center_dot} B(W{sub {gamma}}){sub exp} = 17.0{sub {minus}13.4}{sup +13.6}(stat. + syst.)pb. The W{sub {gamma}} cross section is sensitive to the anomalous couplings of the W boson. Using the W{sub {gamma}} cross section measurement, the absence of an excess of large E{sub T} photons accompanying the production of a W boson enables one to obtain direct limits on anomalous WW{sub {gamma}} couplings. The experimental limits on the anomalous couplings was measured to be {minus}7.2 < {Delta}{kappa} < +7.7 ({lambda} = 0) and {minus}3.5 < {lambda} < +3.4 ({Delta}{kappa} = 0) at 95% CL. These experimental limits impose contraints on possible internal structure ofmore » the W boson with compositeness scale sensitivity {Lambda}{sub W} {ge} 1 TeV for saturation of unitarity, corresponding to probing a distance scale of order L{sub W} {le} 2.0 {times} 10{sup {minus}4} fm. The experimental limits on anomalous WW{sub {gamma}} couplings place bounds on the higher-order electromagnetic moments of the W boson -- the magnetic dipole and electric quadrupole moments and the W boson mean-squared charge radius. The experimental results presented in this thesis are in good agreement with Standard Model expectations.« less