Related papers: Probing Positron Gravitation at HERA
We present preliminary measurements of electron and positron spectra in d+Au and p+p collisions at $\sqrt{s_{NN}}=200$ GeV for $1.5 < p_{T} < 7.0$ GeV/c. These measurements were carried out using the STAR Time Projection Chamber (TPC) and…
In a paper by Villata (2011), the possibility of a repulsive gravitational interaction between antimatter and ordinary matter was discussed. The author argued that this anti-gravity can be regarded as a prediction of general relativity,…
The distribution of the azimuthal angle for the charged hadrons has been studied in the hadronic centre-of-mass system for neutral current deep inelastic positron-proton scattering at HERA. Measurements of the dependence of the moments of…
Recent results on spectroscopy with special focus on searches for pentaquarks are presented from the H1 and ZEUS collaborations. Cross sections of observed states and upper limits on the production cross section of unobserved states are…
We are looking at a Dirac electron in the electromagnetic field of a plane monochrome polarized X-ray. It will be attempted to link the terms of a certain (joint) asymptotic expansion of the Heisenberg propagations of momentum- and…
We have substantially extended our analysis of the partonic content of the pomeron. Ambiguities in the normalization of the pomeron flux and the possiblity of a direct coupling of the pomeron to single quarks are discussed, yielding two…
Experimental results obtained with the HERA collider and recent progress in their theoretical interpretation are reviewed. After a short introduction to HERA physics, deep inelastic scattering and photoproduction are discussed as (virtual)…
At HERA, the large flux of almost real photons accompanying the electron beam leads to the copious photoproduction of jets. Regions of small momentum fractions $x$ of the incoming particles are explored, where the density of partons is…
A possible way of producing gravitons in the laboratory is investigated. We evaluate the cross section electron + photon $\rightarrow$ electron + graviton in the framework of linearized gravitation, and analyse this reaction considering the…
The measurement of the polarized gluon distribution function Delta G(x) from photon-gluon fusion processes in electron-proton deep inelastic scattering producing two jets has been investigated. The study is based on the MEPJET and PEPSI…
The Lagrangian formulation of Gravitoelectromagnetism (GEM) theory is considered. GEM is a gravitational theory constructed based on the similarities between gravity and electromagnetism. In this framework, we investigate gravitational…
Two-particle azimuthal correlations have been measured in neutral current deep $\mbox{inelastic}$ $\textit{ep}$ scattering with virtuality $Q^2 > 5$ GeV$^2$ at a centre-of-mass energy $\sqrt{s}=318$ GeV recorded with the ZEUS detector at…
The cross sections for charged and neutral current deep inelastic scattering in e^+p collisions with a longitudinally polarised positron beam have been measured using the ZEUS detector at HERA. The results, based on data corresponding to an…
Among the dipole models of deep inelastic scattering at small values of the Bjorken variable $x$, one has been recently proposed which relates the virtual photon-proton cross section to the dipole-proton forward scattering amplitude in…
Interactions between photons and electrons are ubiquitous in astrophysics. Photons can be down scattered (Compton scattering) or up scattered (inverse Compton scattering) by moving electrons. Inverse Compton scattering, in particular, is an…
The distribution of the azimuthal angle of charged and neutral hadrons relative to the lepton plane has been studied for neutral current deep inelastic $ep$ scattering using an integrated luminosity of 45 pb-1 taken with the ZEUS detector…
A first measurement is presented of the charge asymmetry in the hadronic final state from the hard interaction in deep-inelastic ep neutral current scattering at HERA. The measurement is performed in the range of negative squared four…
In matrix theory the effective action for graviton-graviton scattering is a double expansion in the relative velocity and inverse separation. We discuss the systematics of this expansion and subject matrix theory to a new test. Low energy…
Low-energy neutral-current couplings arising in the Standard Model of electroweak interactions can be constrained in lepton scattering off hydrogen or a nuclear fixed target. Recent polarized electron scattering experiments at Jefferson Lab…
Certain modern theories of gravity predict that antimatter will fall differently than matter in the Earth's gravitational field. However, no experimental tests of gravity on antimatter exist and all conclusions drawn from experiments on…