Z +? Cross-section Measurement,?*BR(Z +?), in the Electron Channel for P{bar P} Collisions at √s

Z +? Cross-section Measurement,?*BR(Z +?), in the Electron Channel for P{bar P} Collisions at √s
Author:
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Total Pages: 109
Release: 1994
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The Z +? cross-section x branching ratio in the electron channel has been measured using the inclusive Z data sample from the CDF 1988--1989 collider run, for which the total integrated luminosity was 4.05 ± 0.28 pb−1. Two Z? candidates are observed from central photon events with?R/{sub?}> 0.7 and E{sub t}{sup?}> 5.0 GeV. From these events the? * BR(Z +?) is measured and compared with SM predictions:? * BR(Z +?){sub e} = 6.8{sub -5.7}{sup +5.7}(stat + syst)pb? * BR(Z + {gamma})SM = 4.7{sub -4.7}{sup +0.7}(stat + syst)pb. From this ZZ{sub {gamma}} cross section measurement limits on the Z{sub {gamma}{gamma}} and couplings for three different choices of compositeness scale?{sub Z} are obtained. The experimental sensitivity to the h30{sup Z, {gamma}}/h10{sup Z, {gamma}} couplings is in the range of?{sub Z} - 450--500 GeV and for the h40{sup Z{gamma}}/h20{sup Z, {gamma}} couplings?{sub Z} - 300 GeV.

Measurement of the W and Z Cross Sections in the Electron Channel for P Anti-p Collisions at S**(1/2)

Measurement of the W and Z Cross Sections in the Electron Channel for P Anti-p Collisions at S**(1/2)
Author: John Michael Gardner
Publisher:
Total Pages: 234
Release: 2005
Genre:
ISBN:

This dissertation presents measurements of the inclusive production cross sections for W and Z gauge bosons decaying through the electron channel with p{bar p} collisions at a center-of-mass energy of 1.96 TeV. The ratio of these cross sections is then used to extract the W total width. The Standard Model (SM) of electroweak and strong interactions is a collection of theories which together encompass what is currently known about the elementary particles that make up matter and the forces through which they interact. Experimentalists are constantly searching for violations of the Standard Model by making precision measurements of predicted interactions. The decay of the W boson is one such interaction. The rate of its decay is reflected in its width which is predicted to high precision using Standard Model-based calculations. Therefore, a high precision experimental width measurement would be very sensitive to any such violation. In principle the W and Z boson production cross sections could also be good Standard Model tests. However, a precise knowledge of integrated luminosity is required which is unfortunately difficult to obtain at the Tevatron. In fact, the W and Z cross section results can be used to obtain a more precise luminosity measurement. The data set consists of a total integrated luminosity of 177 pb{sup -1} collected from September 2002 to September 2003 using the D0 detector at Fermilab.

Measurement of Z Gamma Production in Pbar{p} Collisions at Sqrt{s}

Measurement of Z Gamma Production in Pbar{p} Collisions at Sqrt{s}
Author:
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Total Pages: 8
Release: 2010
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The production rate and kinematics of photons produced in association with Z bosons are studied using 2 fb−1 of p{bar p} collision data collected at the Collider Detector at Fermilab. The cross section for p{bar p} → ll−? + X (where the leptons l are either muons or electrons with dilepton mass M{sub l{ell}}> 40 GeV/c2, and where the photon has transverse energy E{sub T}{sup?}> 7 GeV and is well separated from the leptons) is 4.6 ± 0.2 (stat) ± 0.3 (syst) ± 0.3 (lum) pb, which is consistent with standard model expectations. We use the photon ET distribution from Z{gamma} events where the Z has decayed to?+?−, e+e−, or?{bar {nu}} to set limits on anomalous (non-standard-model) trilinear couplings between photons and Z bosons.

Measurement of the W and Z Cross Sections in the Electron Channel for P{u00AF}p Collisions at {u221A}s

Measurement of the W and Z Cross Sections in the Electron Channel for P{u00AF}p Collisions at {u221A}s
Author:
Publisher:
Total Pages: 234
Release: 2005
Genre:
ISBN:

This dissertation presents measurements of the inclusive production cross sections for W and Z gauge bosons decaying through the electron channel with p¯p collisions at a center-of-mass energy of 1.96 TeV. The ratio of these cross sections is then used to extract the W total width. The Standard Model (SM) of electroweak and strong interactions is a collection of theories which together encompass what is currently known about the elementary particles that make up matter and the forces through which they interact. Experimentalists are constantly searching for violations of the Standard Model by making precision measurements of predicted interactions. The decay of the W boson is one such interaction. The rate of its decay is reflected in its width which is predicted to high precision using Standard Model-based calculations. Therefore, a high precision experimental width measurement would be very sensitive to any such violation. In principle the W and Z boson production cross sections could also be good Standard Model tests. However, a precise knowledge of integrated luminosity is required which is unfortunately difficult to obtain at the Tevatron. In fact, the W and Z cross section results can be used to obtain a more precise luminosity measurement. The data set consists of a total integrated luminosity of 177 pb-1 collected from September 2002 to September 2003 using the DØ detector at Fermilab.

Measurement of W and Z Production Cross-sections in P[bar P] Collisions at [radical]

Measurement of W and Z Production Cross-sections in P[bar P] Collisions at [radical]
Author:
Publisher:
Total Pages:
Release: 2005
Genre:
ISBN:

The cross sections for W and Z production in p[bar p] collisions at [radical]s = 1.8 TeV are measured using the D0 detector at the Fermilab Tevatron collider. The detected final states are W [yields] ev[sub e], Z [yields] e[sup +]e[sup [minus]], W [yields] [mu]v[sub [mu]], and Z [yields] [mu][sup +][mu][sup [minus]]. In the ratio of these measurements, many common sources of systematic error cancel and we measure R = [sigma], (p[bar p] [yields] W) [center-dot] Br(W [yields] lv)/ [sigma], (p[bar p] [yields] Z) [center-dot] Br(Z [yields] l[sup +]l[sup [minus]]). Assuming standard model couplings, this result is used to determine the width of the W bosom and to set a limit on the decay W[sup +] [yields] t[bar b].

Measurement of $Z/\gamma^* + B$-jet Production Cross Section in $p\bar{p}$ Collisions at $\sqrt{s}

Measurement of $Z/\gamma^* + B$-jet Production Cross Section in $p\bar{p}$ Collisions at $\sqrt{s}
Author:
Publisher:
Total Pages: 151
Release: 2012
Genre:
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Processes at hadron colliders, such as the production of jets, are described by the Quantum Chromodynamics theory (QCD). Precise descriptions of processes involving jets in association with a vector boson have nowadays large relevance as they represent irreducible background to other Standard Model (SM) processes and searches for new physics. The experimental study and understanding of the b-jet production in association with a Z boson are crucial for many reasons. For one side, it is the most important background for a light Higgs boson decaying into a bottom-antibottom quark pair and produced in the ZH mode. This is one of the most promising channels for the Higgs search at Tevatron in particular since the latest results have excluded the high mass region (MH> 127 GeV/c2). For another side the signature of b-jets and a Z boson is also background to new physics searches, such as supersymmetry, where a large coupling of the Higgs boson to bottom quarks is allowed. The produ ction cross section measurement of b-jets in events with a Z boson has already been performed at hadron colliders, at the Tevatron by CDF and D0 experiments and are now pursued at the LHC by ATLAS and CMS. In particular the CDF measurement was performed with only 2 fb-1 and was limited by the statistical uncertainty. This PhD thesis presents a new measurement of the $Z/\gamma^* + b$-jet production cross section using the complete dataset collected by CDF during the Run II. $Z/\gamma^*$ bosons are selected in the electron and muon decay modes and are required to have 66