A Measurement of the Z Gamma Cross Section and Limits on Anomalous Triple Gauge Couplings at Square Root of S


Book Description

A study of the properties of the Z$\gamma$ diboson system is presented using 5.0 fb$^{-1}$ of proton-proton collision data from the LHC using the CMS detector. The pp $\rightarrow Z(\rightarrow\mu \mu) \gamma$ and pp $\rightarrow Z(\rightarrow e e) \gamma$ production cross sections are measured within the fiducial volume of CMS with a combined measurement of $\sigma_{\ell\ell\gamma} = 5.33 \pm 0.08 ~\text{(stat.)} \pm 0.25 ~\text{(syst.)} \pm 0.12 ~\text{(lumi.)}$ pb that is in good agreement with Standard Model predictions. Upper limits on the neutral anomalous triple gauge couplings set are the most stringent limits on these couplings to date, with allowed regions: $-0.010




A Measurement of Z(vv̄)[photon] Cross Section and Limits on Anomalous Triple Gauge Couplings at [square Root Of]


Book Description

In this thesis, the first measurement of Z(vv̄)[photon] cross section in pp collisions at [square root of]s = 7 TeV has been done using data collected by the CMS detector. The measured cross section is 21.3 ± 4.2 (stat.) ± 4.3 (syst.) ± 0.5 (lumi.) fb. This measurement is based on the observations of events with missing transverse energy in excess of 130 GeV and photon in the rapidity range [eta]







Measurements of the $\mathrm{ Pp \to W \gamma\gamma }$ and $\mathrm{ Pp \to Z \gamma\gamma }$ Cross Sections and Limits on Anomalous Quartic Gauge Couplings at $\sqrt{s}


Book Description

Measurements are presented of $ \mathrm{ W \gamma\gamma } $ and $ \mathrm{ Z \gamma\gamma } $ production in proton-proton collisions. Fiducial cross sections are reported based on a data sample corresponding to an integrated luminosity of 19.4 fb$^{-1}$ collected with the CMS detector at a center-of-mass energy of 8 TeV. Signal is identified through the $\mathrm{ W } \to \ell\nu$ and $\mathrm{ Z }\to\ell\ell$ decay modes, where $\ell$ is a muon or an electron. The production of $ \mathrm{ W \gamma\gamma } $ and $ \mathrm{ Z \gamma\gamma } $, measured with significances of 2.6 and 5.9 standard deviations, respectively, is consistent with standard model predictions. In addition, limits on anomalous quartic gauge couplings in $ \mathrm{ W \gamma\gamma } $ production are determined in the context of a dimension-8 effective field theory.




Measurement of the Z Gamma ---] Nu Anti-nu Gamma Cross Section and Limits on Anomalous Z Z Gamma and Z Gamma Gamma Couplings in P Anti-p Collisions at S**1/2


Book Description

We present the first observation of the Z[gamma] →[nu]{bar [nu]}[gamma] process at the Tevatron at 5.1 standard deviations significance, based on 3.6 fb−1 of integrated luminosity collected with the D0 detector at the Fermilab Tevatron p{bar p} Collider at √s = 1.96 TeV. The measured Z[gamma] cross section multiplied by the branching fraction of Z → {nu}{bar {nu}} is 32 ± 9(stat. + syst.) ± 2(lumi.) fb for the photon E{sub T} > 90 GeV. It is in agreement with the standard model prediction of 39 ± 4 fb. We set the most restrictive limits on anomalous trilinear Z[gamma][gamma] and ZZ[gamma] gauge boson couplings at a hadron collider to date, with three constraints being the world's strongest.










Measurement of the $WZ$ Cross Section and Triple Gauge Couplings in $p \bar P$ Collisions at $\sqrt{s}


Book Description

This Letter describes the current most precise measurement of the WZ production cross section as well as limits on anomalous WWZ couplings at a center-of-mass energy of 1.96 TeV in proton-antiproton collisions. The WZ candidates are reconstructed from decays containing three charged leptons and missing energy from a neutrino, where the charged leptons are either electrons or muons. Using data collected by the CDF II detector (7.1 fb−1 of integrated luminosity), 64 candidate events are observed with the expected background contributing 8 ± 1 events. The measured total cross section?(p{bar p} → WZ) = 3.93{sub -0.53}{sup +0.60}(stat){sub -0.46}{sup +0.59}(syst) pb is in good agreement with the standard model prediction of 3.50 ± 0.21. The same sample is used to set limits on anomalous WWZ couplings.




Measurement of the Z? Production Cross Section in Pp Collisions at 8 TeV and Search for Anomalous Triple Gauge Boson Couplings


Book Description

The cross section for the production of Z? in proton-proton collisions at 8 TeV is measured based on data collected by the CMS experiment at the LHC corresponding to an integrated luminosity of 19.5 fb-1. Events with an oppositely-charged pair of muons or electrons together with an isolated photon are selected. Furthermore, the differential cross section as a function of the photon transverse momentum is measured inclusively and exclusively, where the exclusive selection applies a veto on central jets. These observed cross sections are compatible with the expectations of next-to-next-to-leading-order quantum chromodynamics. As a result, limits on anomalous triple gauge couplings of ZZ? and Z?? are set that improve on previous experimental results obtained with the charged lepton decay modes of the Z boson.