相关论文: Hard Photoproduction by Colour Singlet Exchange at…
The search for events containing isolated leptons (electrons or muons) and missing transverse momentum produced in e^{\pm}p collisions is performed individually and in a common phase space with the H1 and ZEUS detectors at HERA in the…
Charged particles ($h^\pm$) and \kz mesons have been studied in photoproduced events containing at least one jet of $E_T > 8$ GeV in a pseudorapidity interval (--0.5, 0.5) in the ZEUS laboratory frame. Distributions are presented in terms…
Many important QCD tests with jets and prompt photons have been performed with the experiments H1 and ZEUS at the HERA ep collider. This contribution focuses on results from jet and prompt photon photoproduction. In particular, the concept…
The latest results from the H1 and ZEUS collaborations are presented on leptoquark production and rare Standard Model processes. The data were taken in the period 1994-2005, at a centre of mass energy of up to 319 GeV. Intriguing events…
A first measurement is presented of exclusive photoproduction of $\rho^0$ mesons associated with leading neutrons at HERA. The data were taken with the H1 detector in the years 2006 and 2007 at a centre-of-mass energy of 319 GeV and…
The exclusive photoproduction reactions $\gamma p \to J/\psi(1S) p$ and $\gamma p \to \psi(2S) p$ have been measured at an $ep$ centre-of-mass energy of 318 GeV with the ZEUS detector at HERA using an integrated luminosity of 373 pb$^{-1}$.…
Interactions of the type ep -> eXY are studied, where the component X of the hadronic final state contains two jets and is well separated in rapidity from a leading baryonic system Y. Analyses are performed of both resolved and direct…
The reaction $\gamma p \rightarrow \omega p$ $(\omega \rightarrow \pi^+\pi^-\pi^0$ and $\pi^0\rightarrow\gamma\gamma)$ has been studied in $ep$ interactions using the ZEUS detector at photon-proton centre-of-mass energies between $70$ and…
The production of neutrons carrying at least 20% of the proton beam energy ($\xl > 0.2$) in $e^+p$ collisions has been studied with the ZEUS detector at HERA for a wide range of $Q^2$, the photon virtuality, from photoproduction to deep…
We calculate the cross-section for events at HERA where the proton loses only a minute fraction of its initial energy, all of which goes into producing a single pair of transverse jets.
We have studied events with a high-x_F antiproton and two central jets with E_T>7 GeV in CDF, in p+p_bar collisions at sqrt(s) = 1800 GeV. From the di-jet kinematics we derive the diffractive structure function of the antiproton. We also…
The precision of new HERA data on jet photoproduction opens up the possibility to discriminate between different models of the photon structure. This requires equally precise theoretical predictions from perturbative QCD calculations. In…
We review the theoretical framework of jet photoproduction at HERA discussing the conceptual ideas, phenomenological models, and higher order perturbative calculations. Numerically, we study the physically interesting distribution 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…
Recent results, obtained by the H1 and ZEUS collaborations, are presented on differential cross sections, for inclusive prompt photon production in DIS and for photoproduction of prompt photons accompanied by a hadronic jet. Also presented…
Three-jet production in deep inelastic ep scattering and photoproduction was investigated with the ZEUS detector at HERA using an integrated luminosity of 127 pb-1. Measurements of differential cross sections are presented as functions of…
Preliminary results are presented from a study of dijet photoproduction in ep collisions with both virtual and quasi-real photons at the ZEUS detector. Samples of events with photons of virtuality $P^2$ in the ranges $0.1 < P^2 < 0.55$…
Events with isolated leptons and missing transverse momentum are searched for in electron- or positron-proton collisions at HERA by the H1 and ZEUS experiments. Such events may be explained within the Standard Model by W boson production,…
Recent results on jet cross sections and heavy-flavor production in photoproduction and neutral current deep inelastic ep scattering from the H1 and ZEUS Collaborations are presented. The jet measurements are used to perform stringent tests…
Exclusive electroproduction of $\phi$ mesons has been studied in $e^\pm p$ collisions at $\sqrt{s}=318 \gev$ with the ZEUS detector at HERA using an integrated luminosity of 65.1 pb$^{-1}$. The $\gamma^*p$ cross section is presented in the…