Related papers: Four quark processes at LEP 200
We compute the leading mass corrections to the high-energy behavior of the massive quark vector form factor to three loops in QCD in the double-logarithmic approximation.
Neutral-current four-fermion production, e+e- -> ffff is studied in 0.7/fb of data collected with the L3 detector at LEP at centre-of-mass energies root(s)=183-209GeV. Four final states are considered: qqvv, qqll, llll and llvv, where l…
In this talk we summarize the top physics setup in the event generator WHIZARD with a main focus on lepton colliders. This includes full six-, eight- and ten-fermion processes, factorized processes and spin correlations. For lepton…
We discuss issues of QCD at the LHC including parton distributions, Monte Carlo event generators, the available next-to-leading order calculations, resummation, photon production, small x physics, double parton scattering, and backgrounds…
The study of QCD processes at the LHC will serve two main goals. First the predictions of QCD will be tested and precision measurements will be performed. Second QCD processes represent a major part of the background to other Standard Model…
A precise calculation of the top quark pair production associated with a hard photon is essential for testing the electroweak property of the top quark in the Standard Model (SM). We investigate the one-loop QCD corrections to the process…
The current status of theoretical work and experimental analyses on power corrections in QCD for e+e- annihilation will be reviewed. Measurements of the number of active quark flavours n_f and the QCD colour factors C_A and C_F derived from…
Analytic formulae are derived for the complete photon energy spectrum due to QED corrections to fermion pair production in case of a limited angular acceptance for the final state fermions. After a numerical integration over the energy of…
We study the single production of fourth-family $t'$ quarks via the process $ep\to t'\nu$ at Large Hadron electron Collider (LHeC). We calculate the background and signal cross sections for the mass range 300-800 GeV. It is shown that the…
We study the hadronic production of four-quark states with double heavy quarks and double light antiquarks at LHC. The production mechanism is that a color anti-triplet diquark cluster consisting of double heavy quarks is formed first from…
We argue that recent results from two-photon processes at LEP are better explained by quarks possessing integer electric charges.
Four top quark production is a rare standard model process that has been observed for the first time in proton-proton collisions at \sqrts at the CERN LHC by both the ATLAS and CMS Collaborations. Both observations were made in the…
We investigate the production of fourth family up-type quarks using effective lagrangian approach at future lepton-hadron colliders and study the kinematical characteristics of the signal with an optimal set of cuts. We obtain the upper…
If a leptoquark is produced at HERA as a narrow resonance, various effects tend to broaden the measurable mass distribution considerably. These effects are discussed here, with special emphasis on initial- and final-state QCD radiation. A…
We analyze the impact of using $b$-tagged samples in studying non-Abelian effects due to QCD in $e^+e^-\ar 4$jet events at $\sqrt s=M_{Z^0}$, using angular variable analyses and comparisons with $e^+e^-\ar 3 \mbox{jet}\gamma$ events. We…
Measurements of heavy quark production at a possible future $ep$ facility, THERA, would provide valuable information on the structure of the photon. QCD cross-section predictions are made at LO for both charm and beauty production and their…
Recent developments in the treatment of a system of heavy quarks close to their production threshold are discussed. Particular emphasis is put on the next-to-next-to-next-to-leading order (N$^3$LO) corrections to the energy levels and the…
The production of photon pairs in $e^+e^-\rightarrow f \bar f \gamma\gamma$ processes is studied using exact helicity amplitudes at tree level. Total cross sections, including initial state radiation effects, are given. They are presented…
In this talk we discuss top-quark pair production in association with an additional jet. We present numerical results based on a next-to-leading order QCD calculation.
We discuss QCD studies that will be possible at LEP2. We examine both experimental and theoretical aspects of jets, fragmentation functions, multiplicities and particle spectra.