Related papers: Wave Function Properties in a High Energy Process
High energy scattering processes of charged particles are accompanied by radiation of hard photons. Emission collinear to the incident particles, which leads to a reduction of the effective beam energy, and the possibility to directly…
We underline the general features of the constituent quark model and its success in the description of the spectrum and transitions of hadrons made up of light or heavy quarks, briefly compared to first principles of QCD. To show the…
We present a method to compute, by numerical simulations of lattice QCD, the light-cone wave functions which enter exclusive processes at large momentum transfer, such as electromagnetic elastic scatterings, or exclusive semi-leptonic…
The study of light hadrons is central to the understanding of confinement--a unique property of QCD. The quark model describs mesons as bound states of quarks and antiquarks. LQCD and QCD-motivated models for hadrons, however, predict a…
Perturbative QCD in the high-energy limit describes the evolution of scattering amplitudes with increasing energy towards and into the so-called saturation regime. Comparisons of the predictions with experimental data for a number of…
The hadronic quark structure is investigated in the frame of high energy electron proton scattering. A phenomenological model based on the Born approximation is used to calculate the transition matrix element for the quark system forming…
In diffractive jet production, two high energy hadrons A and B collide and produce high transverse momentum jets, while hadron A is diffractively scattered. Ingelman and Schlein predicted this phenomenon. In their model, part of the…
Measurements of structure functions and of the hadronic final state in deep inelastic scattering at HERA are presented. The results comprise the extraction of parton densities, measurements of the strong coupling, and the search for novel…
If studies of electroweak gauge boson final states at the Large Hadron Collider, for Standard Model physics and beyond, are sensitive to effects of the initial state's transverse momentum distribution, appropriate generalizations of QCD…
We present results for the photoproduction of inclusive prompt photons and for prompt photons accompanied by jets, measured with the ZEUS detector at HERA. Cross sections as a function of pseudorapidity and transverse energy are presented…
We demonstrate that perturbative QCD allows one to calculate the absolute cross section of diffractive exclusive production of photons at large $Q^2$ at HERA, while the aligned jet model allows one to estimate the cross section for…
Measurements of transverse energy flow are presented for neutral current deep-inelastic scattering events produced in positron-proton collisions at HERA. The kinematic range covers squared momentum transfers Q^2 from 3.2 to 2,200 GeV^2, the…
We consider the propagation of heavy quarks through a dense, hydrodynamically flowing QCD medium, representative of the quark-gluon plasma formed in ultrarelativistic heavy-ion collisions. Working in the high-energy limit, we identify two…
We have studied in perturbative QCD all independent helicity amplitudes describing the photoproduction of light vector mesons at large $t$. We found a new hard production mechanism which is related to the possibility for a real photon to…
We use the vacuum expectation value of a Wegner-Wilson loop representing a fast moving quark-antiquark pair to derive the light cone Hamiltonian for a $q\bar q$ meson. We solve the corresponding Schr\"odinger equation for various trial wave…
The meson-cloud model of the nucleon consisting of a system of three valence quarks surrounded by a meson cloud is applied to study the electroweak structure of the proton and neutron. Light-cone wavefunctions are derived for the dressed…
Hadronic resonances are sensitive to the properties of a hot and dense medium created in a heavy ion collisions. During the hadronic phase, after hadronization of quark and gluons into hadrons, resonances are useful to determine the…
An investigation of the hadronic final state in diffractive and non--diffractive deep--inelastic electron--proton scattering at HERA is presented, where diffractive data are selected experimentally by demanding a large gap in pseudo…
Recent results from the HERA ep collider are reviewed in these proceedings. The results are from measurements that probe QCD at high-energy scales, as defined by $Q^2$, the four-momentum-transfer squared of the collisions. These…
A measurement of the beauty production cross section in ep collisions at a centre-of-mass energy of 319 GeV is presented. The data were collected with the H1 detector at the HERA collider in the years 1999-2000. Events are selected by…