MEASUREMENT OF THE CROSS SECTION RATIOS AND FORWARD-BACKWARD ASYMMETRIES OF FLAVOUR TAGGED EVENTS WITH THE DELPHI DETECTOR AT LEP 2

2001 ◽  
Vol 16 (supp01a) ◽  
pp. 333-335
Author(s):  
WOLFGANG LIEBIG
Keyword(s):  
Standard Model ◽  
Cross Section ◽  
High Purity ◽  
Secondary Vertex ◽  
Final States ◽  
Cross Section Ratio ◽  
Preliminary Results ◽  
Delphi Detector ◽  
The Standard Model ◽  
The Cross

In this paper preliminary results of the cross-section ratio [Formula: see text] and the forward-backward asymmetry [Formula: see text] are presented for [Formula: see text] final states produced in the reaction [Formula: see text]. They are measured with the DELPHI detector at LEP collision energies ranging from 183 up to a maximum of 209 GeV. Lifetime and secondary vertex information provided by DELPHI's 3-layer microvertex detector are the main ingredients of a tagging variable which is used to separate the quark flavours. High purity selections are made from which Rf and [Formula: see text] are measured. The compatibility of the results with the Standard Model expectations is evaluated.

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.

ASSOCIATED PRODUCTION OF LIGHT PSEUDOSCALAR BOSON η WITH TOP QUARK PAIRS IN THE SLH MODEL AT THE ILC

2011 ◽  
Vol 26 (21) ◽  
pp. 1577-1586 ◽  
Author(s):  
JINZHONG HAN ◽  
DAPENG YANG ◽  
XUELEI WANG
Keyword(s):  
Standard Model ◽  
Cross Section ◽  
Cross Sections ◽  
Top Quark ◽  
Linear Collider ◽  
International Linear Collider ◽  
Quark Pairs ◽  
Associated Production ◽  
The Standard Model ◽  
The Cross

The light pseudoscalar boson η is the typical particle predicted by the Simplest Little Higgs (SLH) model. In this paper, we investigate some processes of the associated production of a light pseudoscalar boson η with a pair of top quarks in the SLH model at the International Linear Collider (ILC), i.e. [Formula: see text] and [Formula: see text]. We find that the cross-sections of these two processes could reach [Formula: see text] fb in the favorite parameter space in the SLH model, which is consistent with the results of the cross-section of [Formula: see text] in the standard model and the cross-section of [Formula: see text] in the minimal supersymmetric standard model. It should be clear that hundreds to thousands of η can be produced at the ILC per year, these processes of [Formula: see text] are really interesting in testing the standard model and searching the signs of the SLH model.

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 LABORATORY FRAME ANALYSIS OF e+e-→μ+μ- SCATTERING IN THE NONCOMMUTATIVE STANDARD MODEL AT LINEAR COLLIDER

2012 ◽  
Vol 27 (24) ◽  
pp. 1250141 ◽  
Author(s):  
PRASANTA KUMAR DAS ◽  
ABHISHODH PRAKASH
Keyword(s):  
Standard Model ◽  
Cross Section ◽  
Linear Collider ◽  
Strong Dependence ◽  
Laboratory Frame ◽  
Angular Distributions ◽  
Muon Pair ◽  
The Standard Model ◽  
The Cross ◽  
Muon Pair Production

We study the muon pair production e+e-→μ+μ- in the framework of the nonminimal noncommutative standard model (NCSM) to the second-order of the noncommutative (NC) parameter Θμν at linear collider. The [Formula: see text] momentum-dependent NC interaction significantly modifies the cross-section and angular distributions which are different from the standard model. After including the effects of earth's rotation we analyze the time-averaged and time-dependent observables in detail. The time-averaged azimuthal distribution of the cross-section shows significant departure from the standard model which can be tested at the upcoming linear collider. We find strong dependence of total cross-section (time-averaged) and their distributions on the orientation and the magnitude of the NC electric vector (ΘE). Assuming that the future linear collider data will differ from the standard model result by 5%, we obtain Λ≥615 GeV and Λ≥946 GeV corresponding to the machine energy E com = 1000 GeV and 1500 GeV.

LATEST RESULTS FROM THE UA2 EXPERIMENT

1987 ◽  
Vol 02 (04) ◽  
pp. 899-910
Author(s):  
H. PLOTHOW-BESCH
Keyword(s):  
Standard Model ◽  
Cross Section ◽  
Hadronic Decay ◽  
Model Parameters ◽  
Cross Section Ratio ◽  
Upper Limit ◽  
Z Decays ◽  
The Standard Model ◽  
Electroweak Model ◽  
Hadronic Decay Mode

The decays W → e ν, Z → e + e - have been studied using the UA2 detector at the CERN [Formula: see text] Collider. Measurements of the Standard Model parameters from a sample of 251 W decays and 39 Z decays are compared with expectations of the Standard Electroweak Model. An upper limit on the number of light neutrino species is deduced from the cross — section ratio σ( W → e ν)/σ( Z → e + e -). A signal of the hadronic decay mode, [Formula: see text], is observed above the background of QCD produced di-jets.

Search for Compositeness in Dilepton Final States at DØ

2005 ◽  
Vol 20 (15) ◽  
pp. 3284-3286
Author(s):  
◽  
Subhendu Chakrabarti
Keyword(s):  
Standard Model ◽  
Invariant Mass ◽  
Contact Interaction ◽  
Confidence Level ◽  
Composite Structure ◽  
Final States ◽  
Preliminary Results ◽  
The Standard Model ◽  
Lower Limits ◽  
Compositeness Scale

We report preliminary results of a search for substructure in quarks and leptons assuming a four-fermion contact interaction for dielectron pairs of large invariant mass. The search is based on dielectron data collected by the DØ detector in [Formula: see text] collisions at [Formula: see text]. The results agree well with predictions of the standard model and we obtain model-dependent lower limits at 95% confidence level on the compositeness scale of 3.6 to 9.1 TeV for different chiral models of the composite structure of quarks and electrons.

scholarly journals HEAVY BOSON PRODUCTION THROUGH THE COLLISION OF AN ULTRAHIGH-ENERGY NEUTRINO ON A TARGET NUCLEON

2005 ◽  
Vol 20 (19) ◽  
pp. 1465-1482
Author(s):  
R. M. GARCÍA-HIDALGO ◽  
A. ROSADO
Keyword(s):  
Standard Model ◽  
Cross Section ◽  
Destructive Interference ◽  
Ultrahigh Energy ◽  
Abelian Gauge ◽  
Target Nucleon ◽  
Photon Exchange ◽  
The Standard Model ◽  
The Cross ◽  
Heavy Boson

We discuss W and Z production through the deep inelastic [Formula: see text]-scattering in the context of the standard model SU (3)C× SU (2)L× U (1) of the strong and electroweak interactions. We find the cross-section rates for the process [Formula: see text] for the case of ultrahigh-energy neutrinos (1014 eV ≤Eν≤1017 eV ) colliding on a target nucleon [Formula: see text]. We also calculate [Formula: see text] in order to compare it with [Formula: see text]. We show that the cross-section rates for the process [Formula: see text] did not become so large as one could expect, due to the strong destructive interference between the two different mechanisms which contribute at the lowest order in α (keeping only photon exchange diagrams). This destructive interference mechanism is inherent to the standard model as a non-Abelian gauge theory.

scholarly journals K → μ+μ− as a clean probe of short-distance physics

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Avital Dery ◽  
Mitrajyoti Ghosh ◽  
Yuval Grossman ◽  
Stefan Schacht
Keyword(s):  
Matrix Element ◽  
Standard Model ◽  
Short Distance ◽  
Time Dependent ◽  
Final States ◽  
Interference Effects ◽  
Fundamental Theory ◽  
Long Distance ◽  
Ckm Matrix ◽  
The Standard Model

Abstract The K → μ+μ− decay is often considered to be uninformative of fundamental theory parameters since the decay is polluted by long-distance hadronic effects. We demonstrate that, using very mild assumptions and utilizing time-dependent interference effects, ℬ(KS → μ+μ−)ℓ=0 can be experimentally determined without the need to separate the ℓ = 0 and ℓ = 1 final states. This quantity is very clean theoretically and can be used to test the Standard Model. In particular, it can be used to extract the CKM matrix element combination $$ \mid {V}_{ts}{V}_{td}\sin \left(\beta +{\beta}_s\right)\mid \approx \mid {A}^2{\lambda}^5\overline{\eta}\mid $$ ∣ V ts V td sin β + β s ∣ ≈ ∣ A 2 λ 5 η ¯ ∣ with hadronic uncertainties below 1%.

NOTE ON THE MEASUREMENT OF y-DEPENDENCE IN NEUTRINO-ELECTRON SCATTERING: A SENSITIVE TEST OF THE STANDARD MODEL

1993 ◽  
Vol 02 (04) ◽  
pp. 915-921 ◽  
Author(s):  
C. RANGACHARYULU ◽  
A. RICHTER
Keyword(s):  
Standard Model ◽  
Differential Cross Section ◽  
Cross Section ◽  
Electron Scattering ◽  
Differential Cross ◽  
Sensitive Test ◽  
Testing Ground ◽  
The Standard Model ◽  
Sensitive Testing

It is pointed out that the y-dependence of the differential cross-section for various types of neutrinos on the electron promises to be a sensitive testing ground of the electroweak Standard Model at KAON in Vancouver. Estimates of the flux requirements are given and the feasibility of such experiments is discussed.

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