Related papers: New Physics at HERA: Implications for e+e- Scatter…
We study the production of scalar and vector leptoquarks in $e^-e^-$ scattering. We use the most general couplings to the known fermions which are dimensionless, baryon and lepton number conserving, and $SU(3)_c \otimes SU(2)_L \otimes…
Data from HERA, LEP and the Tevatron, as well as from low energy experiments are used to constrain the scale of possible electron-quark contact interactions. Different models are considered, including the most general one, in which all new…
We discuss the leptoquark discovery potential of $e^-\gamma$ scattering and show how polarization and angular distributions can be used to differentiate the different types of leptoquarks.
We discuss virtual photon scattering in the region dominated by BFKL exchange and report results for the cross sections at present and future e+ e- colliders.
We examine the possibility that the high-Q^2 events seen at HERA are due to the production and decay of squarks of R-parity violating supersymmetry. The relevant R-parity violating coupling(s) is identified and shown to lie between 0.03 and…
I present a concise review of the possible evidence for new physics at HERA and of the recent work towards a theoretical interpretation of the signal. It is not clear yet if the excess observed at large Q^2 is a resonance or a continuum…
A search for pair-produced leptoquarks has been performed using a sample of e+e- collision events collected by the OPAL detector at LEP at e+e- centre-of-mass energies of about 183 GeV. The data sample corresponds to an integrated…
A search, in e^+e^- collisions, for chargino, neutralino, scalar lepton and scalar quark pair-production is performed, without assuming R-parity conservation in decays, in the case that only one of the coupling constants lambda_ijk or…
We perform a model independent analysis of the production of scalar and vector leptoquarks in the $e^-\gamma$ mode of a linear collider of the next generation. Since these leptoquarks are produced singly, higher masses can be probed than in…
We calculate the high energy behavior of quark-antiquark exchange in $\gamma^* \gamma^*$ elastic scattering by summing, to all orders, the leading double logarithmic contributions of the QCD ladder diagrams. Motivation comes from the LEP…
The cross section for production of R-parity violating squarks ($\tilde{q}$) or leptoquarks ($LQ$) with masses above 200 GeV by positron-proton scattering at HERA can be substantially increased by a moderate increase of the beam energies.…
The $e^{+}p$ and $e^{-}p$ scattering data recorded at HERA during the recent years offer the possibility to study electroweak effects in $ep$ interactions apparent at high momentum transfers, $Q^{2}$, and to reveal information on the proton…
We examine the phenomenological implications of a 200 GeV leptoquark in light of the recent excess of events at HERA. Given the relative predictions of events rates in e^+p versus e^-p, we demonstrate that classes of leptoquarks may be…
The early observation at HERA of an excess of events compared to the expectation from the Standard Model in very short distance $e^+p$ deep-inelastic scattering processes has renewed the interest in the search for new physics which could…
The effects of Scalar Leptoquarks in various channels have been analysed for the HERA collider and also for an eventual new $ep$ machine running at higher energies. We emphasize the relevance of polarized beams.
I will briefly review the progress which has been made in the investigation of secondary heavy quark production at LEP. I will show why a calculation of the secondary heavy quark multiplicity, keeping the dependence on an event shape…
A contact interaction analysis is presented to search for new phenomena beyond the Standard Model in deep inelastic $e^\pm p \rightarrow e^\pm \, hadrons$ scattering. The data are collected with the H1 detector at HERA and correspond to…
The cross sections for the formation of scalar resonances, leptoquarks or squarks, in electron/positron-proton collisions at HERA are presented including next-to-leading order QCD corrections. Depending mildly on the mass of the resonances,…
Top quark pair production close to threshold at a next linear collider is discussed, with special focus on the influence of rescattering corrections. Numerical results are shown for the differential cross-section, i.e. the momentum…
The cross section for vector leptoquark pair production in $e^+e^-$ annihilation is calculated for the case of finite anomalous gauge boson couplings $\kappa_{\gamma, Z}$ and $\lambda_{\gamma, Z}$. The minimal cross section is found to…