scholarly journals Search for Heavy Particles Decaying into Electron-Positron Pairs in $p{\bar p}$ Collisions

2001 ◽  
Vol 16 (supp01b) ◽  
pp. 866-868
Author(s):  
◽  
Chyi-Chang Miao
Keyword(s):  
Cross Section ◽  
Production Cross Section ◽  
Z Boson ◽  
Production Cross ◽  
Model Parameters ◽  
Heavy Particles ◽  
Preliminary Results ◽  
Electron Positron ◽  
Upper Limits

We present preliminary results of searches for technibadrons (ρT,ωT), and Z′ particles, using their decay into e+e-. The search is based on 124.8 pb -1 of data collected by the DØ detector at the Tevatron during 1992-1996. In the absence of a signal we set 95% CL upper limits on the production cross section and decay into e+e- as a function of the mass of the decaying particle. For certain model parameters, we exclude the existence of degenerate ρT and ωT states with masses below 207 GeV/c2. We exclude a Z′ with mass below 670 GeV/c2, assuming that the Z′ has the same couplings as the Z boson.

scholarly journals Cross Section Prediction for Inclusive Production of Z Boson in pp Collisions at s=14 TeV: A Study of Systematic Uncertainty due to Scale Dependence

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Hasan Ogul ◽  
Kamuran Dilsiz
Keyword(s):  
Cross Section ◽  
Production Cross Section ◽  
Z Boson ◽  
Production Cross ◽  
Branching Ratio ◽  
Leading Order ◽  
Proton Proton ◽  
Proton Collisions ◽  
Central Values ◽  
Proton Proton Collisions

Prediction of Z→l+l- production cross section (where l±=e±,μ±) in proton-proton collisions at s=14 TeV is estimated up to next-to-next-to-leading order (NNLO) in perturbative QCD including next-to-leading order (NLO) electroweak (EW) corrections. The total inclusive Z boson production cross section times leptonic branching ratio, within the invariant mass window 66<mll<116 GeV, is predicted using NNLO HERAPDF2.0 at NNLO QCD and NLO EW as σZTot=2111.69-26.92+26.31 (PDF) ±11 (αs) ±17 (scale) -30.98+57.41 (parameterization and model). Theoretical prediction of the fiducial cross section is further computed with the latest modern PDF models (CT14, MMHT2014, NNPDF3.0, HERAPDF2.0, and ABM12) at NNLO for QCD and NLO for EW. The central values of the predictions are based on DYNNLO 1.5 program and the uncertainties are extracted using FEWZ 3.1 program. In addition, the cross section is also calculated as functions of μR and μF scales. The choice of μR and μF for scale variation uncertainty is further discussed in detail.

scholarly journals STUDY OF ZZ PRODUCTION AT LEP AT $\sqrt{s} =183 -209\, {\rm GeV}$

2001 ◽  
Vol 16 (supp01a) ◽  
pp. 311-314
Author(s):  
GABRIELLA PÁSZTOR
Keyword(s):  
Quantum Gravity ◽  
Pair Production ◽  
Cross Section ◽  
Production Cross Section ◽  
Z Boson ◽  
Production Cross ◽  
Opal Detector ◽  
Boson Pair ◽  
Boson Pair Production ◽  
Spatial Dimensions

A study of Z boson pair production in e + e - annihilation using the OPAL detector at LEP is reported . The ZZ production cross-section is measured, limits on anomalous ZZ γ and ZZZ couplings are derived, and constraints on models of low scale quantum gravity in extra spatial dimensions are set.

Searches for Technicolor Particles at DØ

2005 ◽  
Vol 20 (15) ◽  
pp. 3302-3304
Author(s):  
LORENZO FELIGIONI
Keyword(s):  
Standard Model ◽  
Cross Section ◽  
Production Cross Section ◽  
Production Cross ◽  
Model Parameters ◽  
Decay Channels ◽  
Upper Limit ◽  
200 Gev ◽  
Quark Jets ◽  
B Quark

We present preliminary results of searches for technirho (ρT) and techniomega (ωT) particles, using the decay channels (ρT), ωT → e+e- and [Formula: see text], where [Formula: see text], [Formula: see text]. These searches are based respectively on 200 pb-1 and 238 pb-1 of data collected in Run II of the Fermilab Tevatron. We select events with b–quark jets by identifying secondary vertices in the jets. We interpret our findings in terms of limits on the production of particles predicted by extended technicolor models. For the WπT analysis, in the absence of an excess over standard model background, we compute a 95% C.L. upper limit on the techniparticle production cross section for the mass combination m(ρT) = 200 GeV and m(πT) = 105 GeV of 6.4 pb. In the e+e- channel, for certain model parameters, we exclude the existence of degenerate ρT and ωT states with masses below 367 GeV; the most restrictive constraints on dilepton technicolor decays to date.

ϒ MEASUREMENT IN STAR

2007 ◽  
Vol 16 (07n08) ◽  
pp. 2110-2115
Author(s):  
◽  
MAURO R. COSENTINO
Keyword(s):  
Cross Section ◽  
Production Cross Section ◽  
Decay Channel ◽  
Production Cross ◽  
Preliminary Results ◽  
Analysis Methods ◽  
Central Rapidity ◽  
Star Experiment

We present preliminary results of ϒ production in p + p collisions at [Formula: see text] at central rapidity. This measurement was performed at the STAR experiment through the ϒ → e+ e− decay channel. In this manuscript we describe the experimental details, from the development of a specially designed trigger setup to the analysis methods used to discriminate electrons from hadrons. The production cross-section obtained [Formula: see text] pb is compatible with our expectations based on pQCD calculations.

SEARCH FOR SUPER-NARROW DIBARYON RESONANCES BY THE pd → pdX AND pd → ppX REACTIONS

2003 ◽  
Vol 18 (02n06) ◽  
pp. 410-413
Author(s):  
A. TAMII ◽  
M. HATANO ◽  
H. KATO ◽  
Y. MAEDA ◽  
T. SAITO ◽  
...  
Keyword(s):  
Decay Width ◽  
Cross Section ◽  
Production Cross Section ◽  
Nuclear Physics ◽  
Production Cross ◽  
Mass Region ◽  
Magnetic Spectrometer ◽  
Research Center ◽  
Free Condition ◽  
Upper Limits

Dibaryons which have a very narrow decay width, called super-narrow dibaryons, are searched for by the p+d scattering at Ep = 295 MeV . The experiment was carried out at the Research Center for Nuclear Physics employing a two-arm magnetic spectrometer. A good mass resolution of 0.95 MeV and background free condition have been achieved. No resonance has been observed in the mass region of 1896–1914 MeV. The upper limits of the dibaryon production cross section have been determined.

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