Hard probes in heavy-ion collisions at the LHC: Photon physics in heavy ion collisions at the LHC

title: Dynamical correlations in the Dual Parton Model
abstract: The effect of multiple ‘chain’ contributions to particle production, which appears in the Dual Parton Model at collider energies, is investigated in an exploratory model, in which other sources of correlations are largely neglected. Attention is given to the question of KNO scaling for the multiplicities observed in restricted or unrestricted rapidity ranges. The rapidity distribution associated with a fixed number of particles within a suitably chosen interval, is found to be sensitive to details of the mechanism of multiple chain production.

title: Hadron production at supercolliders in the two component dual parton model and the smallx behaviour of the structure functions
abstract: Models which contain a semihard component sensitively depend on the smallx region of the structure functions. Within the framework of a two component dual parton model the effect of recently proposed steeper structure functions is investigated. Drastic changes which appear in the bare scattering amplitudes get significantly reduced by unitarization. For presently available energies the semihard component seems still too small to allow for clear cut conclusions about the correctness of the various proposed structure functions. However, the predictions for SSC or LHC energies depend on the choice of the structure function quite decisively, resulting in a substantial uncertainty in the extrapolations. The uncertainty is reduced to a less worrisome level if the consideration is restricted to the strongly shadowed parton distribution.

title: Charge and baryon transfers in the dual unitary model
abstract: This paper deals with the application of the dual unitary model to highly inelastic reactions. In particular the predictions of the model are consistent with the data on charge transfer correlation functions and leading pionic charge spectra. A test regarding the role of the baryon exchanges, which are assumed to boost the meson trajectories, is proposed and found to be in qualitative agreement with the data.

title: d-Au and p-p collisions at RHIC and the multichain Monte Carlo Dpmjet-III
abstract: In this paper we compare systematically the two-component Dual Parton Model (DPM) event generator Dpmjet-III to d-Au and p-p data from RHIC. In this process we are able to improve the model. The need for fusion of chains and a recalibration of the model to obtain collision scaling in h-A and d-A collisions was found already in previous comparisons. Here, comparing to transverse momentum distributions of identified charged hadrons we find also the need to modify the transverse momentum distributions in the decay of hadronic strings, the basic building blocks of the model on soft hadronic collisions.

title: Spinless bosons in electron-positron annihilation
abstract: AbstractThe contributions to the processes
$$e^ + e^ - \to \mu ^ + \mu ^ - ,q\bar q,\gamma \gamma ,e^ + e^ - $$
, mediated by scalar and/or pseudoscalar bosons are calculated. The constraints on their coupling constants and their masses are investigated as they arise from the radiative decayZ0→+e− γ and from the experimental data for the annihilation processes into lepton, photon and quark pairs. Data one+e−→μ+ μ−, γγ ande+e− seriously reduce the domain of coupling constants to leptons and photons still allowed by the probable value of the width ofZ0→e+e−γ. Experimentse+e−→μ+ μ−, γγ,e+e− at 45 GeV c.m.s. energy with a sensitivity of 10% will decide about the existence of a heavy spinless boson with the presumed phenomenological couplings to leptons and photons. Assuming universality of the coupling to leptons and quarks a conservative bound on the contribution toR arising from spinless boson exchange is already in conflict with the presumed radiative width ofZ0→e+e−γ.

title: SYMMETRY PROPERTIES OF EIGHT COMPONENT SPINOR FIELDS IN THE LATTICE SPACE.

title: Particles and Antiparticles According to Covariant Schrödinger Equations
abstract: We introduce manifestly covariant Schrödinger equations. This has the advantage that the energies of particles are always positive. Charges of particles and antiparticles have opposite signs. The physical vacuum equals the formal one. - All that occurs because manifestly covariant Schrödinger equations yield pairs of operators which differ only in some signs of eigenvalues: (i) The number of particles and the charge, (ii) the space-time wave vector and the space time momenta, (iii) the kinematical and the dynamical angular momenta.

title: Spinor field ground state and global excitations
abstract: Rather exact energies for the ground state (vacuum) and for global excitation states of a Heisenberg type spinor field theory in a lattice space are obtained by the inverse perturbation method.

title: Representation of bosons by fermions
abstract: Starting from the proposition that all quantum processes can be understood as a cooperation of a set of elementary processes (dichotomic processes), we prove how Bose processes can be represented by an enumerable set of Fermi operators.РезюмеИсходя из предположения, согласно которому каждый квантовый процесс может быть представлен как совокупность элементарных процессов (разветвляющихся процессов), рассмотрена возможность представления процессов, подчиняющихся статистике Бозе, с помощью счетного множества операторов Ферми.