scholarly journals CDF MULTI-MUON EVENTS AND SINGLET EXTENSIONS OF THE MSSM

2009 ◽  
Vol 24 (08) ◽  
pp. 557-566 ◽  
Author(s):  
FLORIAN DOMINGO ◽  
ULRICH ELLWANGER
Keyword(s):  
Standard Model ◽  
Cross Section ◽  
Production Cross Section ◽  
Production Cross ◽  
Supersymmetric Extension ◽  
Production Processes ◽  
The Standard Model ◽  
Additional Production ◽  
Large Production ◽  
Minimal Supersymmetric Extension

We discuss a generalization of the minimal supersymmetric extension of the Standard Model in the form of three additional singlet superfields, which would explain the essential features of the CDF multi-muon events presented recently: a large production cross section of ~ 100 pb originates from the production of a CP-odd scalar A with a mass in the 70–80 GeV range and a large value of tan β ~ 40. The CP-odd scalar A decays dominantly into CP-odd and CP-even scalars a1 and h1, which generate decay cascades h1 → 2h2 → 4a2 → 8τ, and a1 → h1 a2 with h1 decaying as above. The decay a2 → τ+τ- is slow, leading to a lifetime of [Formula: see text]. The phenomenology of the model differs from similar scenarios presented before in that one of the two cascades leads to 10 instead of 8 τ-leptons, and additional production processes like associate A production with [Formula: see text] pairs are relevant.

PROBING THE STANDARD MODEL WITH DILEPTON DECAYS OF TOP QUARK PAIRS AT CDF

2007 ◽  
Vol 22 (38) ◽  
pp. 2873-2884
Author(s):  
DANIEL WHITESON
Keyword(s):  
Standard Model ◽  
Cross Section ◽  
Top Quark ◽  
Production Cross Section ◽  
Production Cross ◽  
Fundamental Theory ◽  
Final State ◽  
Quark Pairs ◽  
The Standard Model ◽  
Selection Of

The dilepton decays of the top quark are a powerful laboratory for probing the Standard Model and searching for hints of a more fundamental theory. We present a detailed analysis of the production cross section and the kinematic qualities of top quark pair candidate events in [Formula: see text] collisions at [Formula: see text] = 1.96 TeV collected by the CDF detector which include two leptons in the final state, suggesting the decay [Formula: see text]. We describe the selection of candidate events to suppress major backgrounds and present the number of observed events over background. As a test of the top quark hypothesis, the kinematics of the events are analyzed via a measurement of M top with unprecedented precision.

MEASUREMENT OF THE W PAIR PRODUCTION CROSS SECTION AND W BRANCHING RATIOS WITH THE DELPHI DETECTOR

2001 ◽  
Vol 16 (supp01a) ◽  
pp. 348-350
Author(s):  
FABIO COSSUTTI
Keyword(s):  
Standard Model ◽  
Pair Production ◽  
Cross Section ◽  
Production Cross Section ◽  
Production Cross ◽  
Branching Ratios ◽  
Centre Of Mass ◽  
Delphi Detector ◽  
The Standard Model ◽  
Pair Production Cross Section

Data collected with the DELPHI detector at centre-of-mass energies up to the highest values explored by the LEP collider of about 206 GeV have been used to extract preliminary values of the cross-section for the process e+e- → W+W-. The branching ratios of the W decay were also measured; from them the value of |Vcs| was extracted. The results are compared with the most recent calculations in the framework of the Standard Model.

scholarly journals PRELIMINARY MEASUREMENTS OF THE QUARK-ANTIQUARK PRODUCTION CROSS-SECTION IN E+E- ANNIHILATIONS UP TO LEP2 HIGHEST ENERGIES

2001 ◽  
Vol 16 (supp01a) ◽  
pp. 342-344
Author(s):  
GIUSEPPE DELLA RICCA
Keyword(s):  
Standard Model ◽  
Pair Production ◽  
Cross Section ◽  
Cross Sections ◽  
Production Cross Section ◽  
Production Cross ◽  
Delphi Detector ◽  
The Standard Model ◽  
Model Predictions ◽  
The Cross

Data collected with the DELPHI detector at [Formula: see text] up to LEP2 highest energies (i.e. exceeding 205 GeV) have been used to extract preliminary values of the cross-sections for quark-antiquark pair-production in e + e - annihilations. The values found were used to test the Standard Model predictions and to seek for physics beyond it.

NLO QCD CORRECTIONS TO THE PRODUCTION OF HEAVY CHARGED LEPTONS BY GLUON FUSION AT THE LHC

2006 ◽  
Vol 21 (26) ◽  
pp. 1999-2008 ◽  
Author(s):  
IRINEL CAPRINI ◽  
MARINA ROTARU
Keyword(s):  
Standard Model ◽  
Production Rate ◽  
Cross Section ◽  
Production Cross Section ◽  
Production Cross ◽  
Gluon Fusion ◽  
Radiative Corrections ◽  
Leading Order ◽  
The Standard Model ◽  
Charged Leptons

The search for heavy charged leptons predicted by generalizations of the standard model is an objective of the experiments at future colliders, in particular at the LHC. We compute the Next-to-Leading Order (NLO) QCD virtual corrections to the production of pairs of heavy charged leptons by gluon fusion. The radiative corrections increase the production rate by about 30% and reduce its dependence on the renormalization and the factorization scales. The effect of a fourth family of quarks on the production cross-section is briefly discussed.

On the model dependence of fiducial cross-section measurements

2019 ◽  
Vol 34 (38) ◽  
pp. 2050065
Author(s):  
Gabriel Facini ◽  
Kyrylo Merkotan ◽  
Matthias Schott ◽  
Alexander Sydorenko
Keyword(s):  
Standard Model ◽  
Cross Section ◽  
Production Cross ◽  
Hadron Collider ◽  
New Physics ◽  
Effective Field ◽  
Model Bias ◽  
Systematic Uncertainties ◽  
Standard Model Cross Section ◽  
The Standard Model

Fiducial production cross-section measurements of Standard Model processes, in principle, provide constraints on new physics scenarios via a comparison of the predicted Standard Model cross-section and the observed cross-section. This approach received significant attention in recent years, both from direct constraints on specific models and the interpretation of measurements in the view of effective field theories. A generic problem in the reinterpretation of Standard Model measurements is the corrections application of to data to account for detector effects. These corrections inherently assume the Standard Model to be valid, thus implying a model bias of the final result. In this work, we study the size of this bias by studying several new physics models and fiducial phase–space regions. The studies are based on fast detector simulations of a generic multi-purpose detector at the Large Hadron Collider. We conclude that the model bias in the associated reinterpretations is negligible only in specific cases, however, typically on the same level as systematic uncertainties of the available measurements.

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.

TWO-BODY RADIATIVE GLUINO DECAYS

1988 ◽  
Vol 03 (16) ◽  
pp. 1561-1568 ◽  
Author(s):  
ERNEST MA ◽  
GWO-GUANG WONG
Keyword(s):  
Standard Model ◽  
Branching Fraction ◽  
Color Singlet ◽  
Supersymmetric Extension ◽  
Neutral Fermion ◽  
The Standard Model ◽  
Gluino Decays ◽  
Minimal Supersymmetric Extension

A gluino can decay into a color-singlet neutral fermion [Formula: see text] by radiating off a gluon. We study this process in a minimal supersymmetric extension of the standard model. A significant branching fraction is possible depending on how much [Formula: see text] overlaps with the Higgs fermion which couples to the t quark and the mass of the t quark itself.

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