Related papers: Anomalous gamma gamma interaction
Data from the Large Electron Positron collider (LEP) at CERN on hadron production in gamma-gamma interactions exceed the predictions of the standard model by an order of magnitude at the highest observed transverse momenta in three…
We propose some channels for the possible observation of anomalous interactions of the fourth standard model generation quarks at the Large Hadron Collider based ep and gamma-p colliders. Namely, u_4 (d_4) -> q gamma and u_4 (d_4) -> q Z ->…
The potential of LC+HERA based gamma-p collider to probe WW-gamma vertex is presented through the discussion of sensitivity to anomalous couplings and p_{T} distribution of the final quark. The limits of -0.16<(kappa-1)<0.14,…
We consider possible production of heavy leptons via anomalous interactions at future $ep$ colliders (THERA and LHeC), $e^+e^-$ colliders (ILC and CLIC) and $pp$ collider CERN LHC. The production, backgrounds and signatures of heavy leptons…
The exchange of gluons between heavy quarks produced in $e^+e^-$ interactions results in an enhancement of their production near threshold. We study QCD threshold effects in $\gamma\gamma$ collisions. The results are relevant to heavy quark…
We investigate the potential of a high-energy $\gamma\gamma$ collider to detect an anomalous $\bar t q \gamma$ coupling from observation of the reaction $\gamma \gamma \to t\bar q$, $\bar t q$, where $q=c$ or $u$. We find that with…
A contact four-fermion interaction between light quarks and electrons has been evoked as a possible explanation for the excess of events observed by HERA at high-$Q^2$. We explore the 1-loop effects of such interaction in $\Gamma(Z^0 \to…
New results on inclusive heavy quark production in gamma gamma collisions are presented. Charm and bottom production are investigated at LEP II energies by the experiments ALEPH, DELPHI, L3, and OPAL. The total and differential cross…
Exclusive photoproduction of dileptons, gamma p ->l+ l- p, will be measured in ultraperipheral collisions at LHC. The mechanism where the lepton pair comes from a heavy timelike photon radiated from a quark interferes with the pure QED…
Inclusive charged hadron production, e+e- -> e+e- h+- X, is studied using 414 pb-1 of data collected at LEP with the L3 detector at centre-of-mass energies between 189 and 202 GeV. Single particle inclusive differential cross sections are…
The top quark could provide very important information for the Standard Model extentions due to its large mass close to the electroweak symmetry breaking scale. In this work, anomalous single top production is studied by using gamma…
The cross--section for two--photon events with (at least) two independent partonic scatters is estimated, for LEP energies as well as a 500 GeV ``photon collider". This results in events with (at least) four central (mini--)jets. Such…
The single production of top quark due to flavor changing neutral current (FCNC) interaction and its decay to bW are studied at CLIC+LHC based gamma-p colliders. We consider both t-c-gamma and t-u-gamma anomalous couplings. The anomalous…
The potential of LC+HERAp based Gamma-p collider to probe WW-Gamma vertex is presented through the discussion of sensitivity to anomalous couplings and P_T distribution of the final quark. The limits of -0.04<\Delta\kappa<0.04 and…
The production of c and b quarks in gamma-gamma collisions is studied with the L3 detector at LEP with 410 pb^-1 of data, collected at centre-of-mass energies from 189 GeV to 202 GeV. Hadronic final states containing c and b quarks are…
We investigate the effect of anomalous gamma-W-W couplings in e-gamma --> nu W through the angular and energy spectrum of the secondary leptons. Within the narrow-width approximation, a semi-analytical study of the secondary lepton…
The production of charged hadrons and jets is measured in collisions of quasi-real photons. The data were taken with the OPAL detector at LEP at e+e- centre-of-mass energies of 161 and 172 GeV. The measured cross-sections are compared to…
Strange baryon pair production in two-photon collisions is studied with the L3 detector at LEP. The analysis is based on data collected at e+e- centre-of-mass energies from 91 GeV to 208 GeV, corresponding to an integrated luminosity of 844…
A sizeable difference in the differential production cross section of top and antitop quarks, respectively, is predicted for hadronically produced heavy quarks. It is of order $\alpha_s$ and arises from the interference between charge odd…
The total and differential cross sections of the process e+e- -> n gamma with n >= 2 are measured using data collected by the L3 experiment at centre-of-mass energies of \sqrt{s}=183 and 189 GeV. The results are in agreement with the…