A measurement of W boson-photon and Z boson-photon cross sections in the muon channel in 1.8 TeV proton-antiproton collisions

We have measured the production cross sections x decay branching ratios for W + γ and Z + γ in the muon channel in $\sqrt{s}$ = 1.8 TeV p-p collisions, from 3.54 $\pm$ 0.24 $pb\sp{-1}$ of muon W and Z data from the CDF 1988-89 Tevatron collider run. For photons in the central region ($\vert\eta\vert $ 5.0 GeV and lepton-photon angular separation \Delta R\sb{\ell\sbγ} > 0.7, 5 W\sb{γ} candidates and 2 Z\sb{γ} candidates were observed. From these events, the σ \cdot BR(W + γ) and σ \cdot BR(Z + γ) cross sections for the muon samples are measured, and compared with Standard Model predictions. We also determined the cross section ratios, W\sb{γ}/W, Z\sb{γ}/Z and W\sb{γ}/Z\sb{γ}, which, along with the previous CDF measurement(s) of the W/Z cross section ratio provide new insight on the Standard Model, and are sensitive to anomalous couplings of the W and Z bosons. Using the W\sb{γ} and Z\sb{γ} absolute cross section measurements, the absence of an excess of hard photons accompanying W and Z boson production enables us to obtain direct limites on anomalous WW\sb{γ}, ZZ\sb{γ} and Z\sb{γγ} couplings. For saturation of unitarity, these experimental limits impose constraints on possible internal (composite) structure for the W and Z bosons with compositeness scale sensitivity up to $\Lambda\sb{W} \sim$ 1 TeV and $\Lambda\sb{Z} \sim$ 250-500 GeV, respectively. These compositeness scale limits probe the possible internal structure of the W to ${\sim}<$2 $\times$ 10$\sp{-4}$fm and internal structure of the Z to ${\sim}<$4-7 $\times$ 10$\sp{-4}$ fm. Limits on the anomalous W\sb{γ} and Z\sb{γ} couplings also impose constraints on the higher order static and transition EM moments of the W and Z boson, respectively. The muon channel measurements were combined with those made from the electron channel to arrive at μ + e combined σ \cdot BR(W) + γ) and σ \cdot BR(Z + γ) absolute cross sections, and limits on the anomalous couplings for combined μ + e W\sb{γ} and Z\sb{γ}.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Luchini, Christopher B.

Contributors dc:contributor

• Errede, Steven M.

• Physics, Elementary Particles and High Energy

Statement dc:rights

• Copyright 1994 Luchini, Christopher B.

Language dc:language

eng

Identifier

AAI9503260
(UMI)AAI9503260

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/22948