相关论文: Contact Interactions and high-Q2 events in e^+ p c…
In this talk, I summarize a global analysis on electron-quark contact interactions using the updated NC DIS data at HERA, Drell-yan production at the Tevatron, total hadronic cross sections at LEP, atomic parity violation measurement, low…
Theoretical interpretations of the high-Q^2 events recently observed in deep-inelastic positron-proton scattering at HERA are reviewed. We discuss leptoquarks, squarks with R-parity violating couplings, and contact interactions. Bounds from…
The analysis of events containing multiple high Pt leptons (electrons and muons) produced in ep collisions has been performed with the H1 and ZEUS detectors at HERA, using the full data sets collected by the experiments in the period…
We investigate an event excess in the reaction $e^+p \to e^+ X$ with large $x$ and high $Q^2$ observed at HERA and show that the events could naturally be interpreted as a signature of the production of the scalar top quarks (stops) in a…
The reaction e+p --> e+X is studied with the H1 detector at Hera. The data cover momentum transfers Q^2 between 200 GeV^2 and 30,000 GeV^2 and correspond to an integrated luminosity of 35.6 pb^(-1). The differential cross section…
The most severe constraints on quark-lepton four-fermion contact interactions come from the agreement of atomic parity violation measurements with the Standard Model. In this letter I note that for contact interactions which arise in…
Many explanations for the excess high-Q^2 $e^+p \to e^+X$ events from H1 and ZEUS at HERA have been proposed each with criticisms. We propose a new method to distinguish different models by looking at a new distribution which is insensitive…
The H1 and ZEUS collaborations have searched for signals of physics beyond the Standard Model in ep collisions at a center-of-mass energy of 301-319 GeV. During the HERA I phase each experiment accumulated an integrated luminosity of about…
An interpretation that the HERA excess events are due to intermediate production and decay of composite leptoquarks in the left-right symmetric preon model is given. Because of the preon-line rule, expected to be valid well, the event-ratio…
The latest measurements of the cross sections for neutral and charged current deep inelastic scattering in e+/-p collisions at HERA with longitudinally polarised lepton beams are presented. The measured cross sections are compared with the…
Multi-electron and multi-muon production at high transverse momentum is measured in $ep$ scattering at HERA. Previous published analyses are extended, combining new HERA II data taken in 2003-2004 with previous HERA I data sample. In…
The H1 and ZEUS experiments are measuring diffractive interactions in ep collisions at HERA. Performing QCD fits of these data with NLO DGLAP, diffractive parton distribution functions can be calculated. These diffractive PDFs can be used…
High-precision HERA data corresponding to a luminosity of around 1 fb$^{-1}$ have been used in the framework of $eeqq$ contact interactions (CI) to set limits on possible high-energy contributions beyond the Standard Model to electron-quark…
The four fermion contact interactions, required to explain the anomalous HERA result, could come from the exchange of new heavy (probably composite) resonances. Depending on their charges and quantum numbers, one gets different scenarios…
We obtain bounds on the mass scales characterizing four-fermion contact interactions in charged current processes. The bounds arise from the Q^2 and x distributions in the processes e p -> \nu X measured by the two HERA experiments, H1 and…
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 excess of high-Q2 events recently observed in deep-inelastic positron-proton scattering at HERA has refuelled speculations on physics beyond the standard model, in particular on low-mass leptoquark-type particles. We review the…
The kinematic reconstruction of neutral current high Q^2 events at HERA is discussed in detail using as an example the recently published events of the H1 and ZEUS collaborations at Q^2 > 15000 GeV^2 and M > 180 GeV, which are more numerous…
Processes leading to a final state with at least two high transverse momentum leptons (electrons or muons) are studied using the full ep data sample collected by the H1 experiment at HERA. The data correspond to an integrated luminosity of…
The e^+ jet invariant mass spectrum produced in the reaction e^+ p -> e^+ X has been studied at a center-of-mass energy of 300 GeV. The data were collected using the ZEUS detector operating at the HERA collider, and correspond to an…