Related papers: Comments on the high-$Q^2$ HERA anomaly
We introduce a novel mechanism for the leptoquark pair production at LHC that is of a $t$-channel topology and is quark-quark initiated. This mechanism operates under fairly general conditions. One of them is that the two leptoquarks in…
We discuss the possibility of explaining the excess in the cross section at high-Q^2 recently found at HERA in terms of four-fermion effective interactions. To avoid the constraints from low-energy data, we select three special cases in…
In this paper we pursue a consistent leptoquark interpretation for HERA anomalies in the framework of Technicolor. We find that: (a) one F=0 scalar Technicolor leptoquark $P_3^{'}$ with a mass of 200 GeV can provide the required…
A search for leptoquarks at HERA was performed in H1 using 1994 $e^+ p$ data corresponding to an integrated luminosity of about $3 \pb^{-1}$. Single leptoquarks were searched for in direct positron-quark fusion processes taking into account…
The cross section for production at the 7 TeV LHC has been measured. For the first time it therefore becomes possible to measure Z couplings to top quarks. Interpreting the notorious LEP1 anomaly on Z couplings to b quarks in terms of an…
We summarize two sets of signals at HERA in supersymmetric models with explicitly broken R-parity. (1) The resonant production of single squarks through an operator $L_1Q_i{ \bar D}_j$. (2) The MSSM production of a squark and a slepton…
Recent results on searches for new particles at the electron-proton collider HERA are reported. Based on roughly 40pb-1 of e^+p data taken in the years 1994-1997, the H1 and ZEUS collaborations have derived new exclusion limits for the…
In this talk I summarize the capability of future lepton colliders to discover leptoquarks and to determine their electroweak quantum numbers. This analysis is an updated discussion based on the results presented in the Snowmass 1996 New…
High Q^2 NC and CC cross-sections as measured at HERA can give information on two distinct areas of current interest. Firstly, supposing that all the electroweak parameters are well known, these cross-sections may be used to give…
Data from HERA, LEP and the Tevatron, as well as from low energy experiments are used to constrain the Yukawa couplings for scalar and vector leptoquarks in the Buchmuller-Ruckl-Wyler effective model. In the limit of very high leptoquark…
The significant excess of events recently found by the H1 and ZEUS Collaborations at HERA in the deep-inelastic e^+ p scattering for high momentum-transfers squared Q^2>15000 GeV^2 over the expectation of the standard model can be explained…
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 summarise possible explanations of the HERA large-Q^2 data, in the framework of R-parity violating supersymmetry. Experimental limits indicate that the most likely production channels are e^+ d --> scharm_L, e^+ d --> stop and e^+ s -->…
The production of neutral strange hadrons is investigated using deep-inelastic scattering events measured with the H1 detector at HERA. The measurements are made in the phase space defined by the negative four-momentum transfer squared of…
We calculate contributions to the oblique parameters $S$ and $T$ for leptoquarks and bileptons, and find phenomenological constraints on their allowed masses. Leptoquarks suggested by the neutral and charged current anomalies at HERA can…
In reference to the recently observed high Q^2, large x events in deep-inelastic positron-proton scattering at HERA, various leptoquark and supersymmetric scenarios are discussed. We study the impact of virtual leptoquark or R-parity…
We explore the possibility that the excess neutral and charged current events seen by the H1 and ZEUS Collaborations at HERA at large x and Q^2 could arise from a hard charm component of the nucleon. While the symmetric intrinsic charm…
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 phenomenology and prospects for a discovery of R-parity violating Supersymmetry at HERA are analysed. Emphasis is put on the direct resonant production of squarks by electron-quark fusion and all possible subsequent decay modes of the…
The favoured R-parity violating SUSY scenarios for the anomalous HERA events correspond to top and charm squark production via the $\lambda'_{131}$ and $\lambda'_{121}$ couplings. In both cases the corresponding electronic branching…