Related papers: Bounds on QCD Instantons from HERA
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…
The influence of nonperturbative fields on instantons in quantum chromodynamics is studied. Effective action for instanton is derived in bilocal approximation and it is demonstrated that stochastic background gluon fields are responsible…
Multiplicities in semi-inclusive deep-inelastic scattering are presented for each charge state of \pi^\pm and K^\pm mesons. The data were collected by the HERMES experiment at the HERA storage ring using 27.6 GeV electron and positron beams…
We pursue the intriguing possibility that larger-size instantons build up diffractive scattering, with the marked instanton-size scale $<\rho> \approx 0.5$ fm being reflected in the conspicuous ``geometrization'' of soft QCD. As an explicit…
Multiplicity moments of charged particles in deep inelastic E+P scattering have been measured with the ZEUS detector at HERA using an integrated luminosity of 38.4 pb^{-1}$. The moments for Q^2 > 1000 GeV^2 were studied in the current…
Characteristics of the hadronic final state of diffractive deep inelastic scattering events, ep -> eXp, were studied in the kinematic range 4 < M_X < 35 GeV, 4 < Q^2 < 150 GeV^2, 70 < W < 250 GeV and 0.0003 < x_pom < 0.03 with the ZEUS…
These notes are a summary of our predictions for the new THERA project, related to deep inelastic scattering in the region of ultra low $x$ ($x \to 10^{-7}$). We collect here predictions that satisfy two criteria (i) they do not depend on…
I address the question of how much of QCD in the chiral limit is reproduced by instantons. After reconstructing the instanton content of smoothed Monte Carlo lattice configurations, I compare hadron spectroscopy on this instanton ensemble…
We summarize our current understanding of instantons in the large N_c limit of QCD. We also present some recent results from simulations of the instanton liquid in QCD for N_c>3.
Deep--inelastic scattering events with a leading baryon have been detected by the H1 experiment at HERA using a forward proton spectrometer and a forward neutron calorimeter. Semi--inclusive cross sections have been measured in the…
Charged particle production in deep-inelastic ep scattering is measured with the H1 detector at HERA. The kinematic range of the analysis covers low photon virtualities, 5 < Q^2 < 100 GeV^2, and small values of Bjorken-x, 10^{-4} < x <…
The structure of the hadronic final state in deep inelastic scattering at HERA is studied on the level of the Monte Carlo event generator. Special emphasis is given to the colour coherence phenomenon in the current fragmentation region. It…
It has been proposed that at small Bjorken $x$, or equivalently at high energy, hadrons represent maximally entangled states of quarks and gluons. This conjecture is in accord with experimental data from the electron-proton collider HERA at…
The diffractive process ep \rightarrow eXY, where Y denotes a proton or its low mass excitation with MY < 1.6 GeV, is studied with the H1 experiment at HERA. The analysis is restricted to the phase space region of the photon virtuality 3…
The latest results from the H1 and ZEUS collaborations which challenge the QCD description of high energy $ep$ collisions are presented. Data from HERA continue to provide precision measurements and are compared to the latest theoretical…
We briefly report on the contribution of QCD-instantons to the phenomenon of saturation in deep-inelastic scattering (DIS) at small Bjorken-x. The explicitly known instanton gauge field serves as a concrete realization of an underlying…
A search for physics beyond the Standard Model in neutral current deep inelastic scattering at high negative four-momentum transfer squared Q^2 is performed in e^{\pm}p collisions at HERA. The differential cross section ds/dQ^2, measured…
The cross section for the diffractive deep-inelastic scattering process ep -> e X p is measured, with the leading final state proton detected in the H1 Forward Proton Spectrometer. The data sample covers the range x_pom<0.1 in fractional…
A precise measurement of the inclusive deep-inelastic e^+p scattering cross section is reported in the kinematic range 1.5<= Q^2 <=150 GeV^2 and 3*10^(-5)<= x <=0.2. The data were recorded with the H1 detector at HERA in 1996 and 1997, and…
The QCD instanton can be observed at relatively low energies at Nica collider by studying the spin-spin correlations between the incoming proton and the produced hyperons .