Cronin effect and energy conservation constraints in pA collisions at LHC and RHIC

We evaluate the Cronin effect in pA collisions at the CERN LHC and at RHIC in the framework of Glauber-Eikonal model of initial state multiparton interactions. Taking carefully into account all kinematical constraints of each multi-parton interaction process we obtain a softening of the spectrum of produced partons, improving in this way the agreement of the model with the recent measurements of pi0 production in d+Au collisions at sqrt{s}=200 AGeV.Comment: Proceeding of 34th International Symposium on Multiparticle dynamics (ISMD), Sonoma California, 26th-1st Aug 2004, to be published in Acta Phisica Polonica

Incoherence and Multiple Parton Interactions

At the LHC Multiple Parton Interactions will represent an important feature of the minimum bias and of the underlying event and will give important contributions in many channels of interest for the search of new physics. Different numbers of multiple collision may contribute to the production of a given final state and one should expect important interference effects in the regime where different contributions have similar rates. We show, on the contrary, that, once multiple parton interactions are identified by their different topologies, terms with different numbers of multiple parton interactions do not interfere in the final cross section.Comment: 10 pages, 3 figure

Stripping Cross Sections in Collisions of Light Nuclei

By evaluating all the contributions of the intermediate states of the multiple scattering theory diagrams, we compute the integrated stripping cross sections of collisions among light nuclei. The resulting expressions have the simple form of a combination of total inelastic cross sections of nuclear reactions with projectile nuclei differing in the atomic mass number. We also check the accuracy of some widely used relations in heavy ion collisions.Comment: 9 pages, 4 figures, Latex fil

Multiparton scattering at the LHC

The large parton flux at high energy gives rise to events where different pairs of partons interact contemporarily with large momentum exchange. A main effect of multiple parton interactions is to generate events with many jets at relatively large transverse momenta. The large value of the heavy quarks production cross section may however give also rise a sizable rate of events with several $b$-quarks produced. We summarize the main features of multiparton interactions and make some estimate of the inclusive cross section to produce two $b{\bar b}$ pairs within the acceptance of the ALICE detector.Comment: 10 pages, 4 figures, contribution to ALICE PP

Multi-parton correlations and "exclusive" cross sections

In addition to the inclusive cross sections discussed within the QCD-parton model, in the regime of multiple parton interactions, different and more exclusive cross sections become experimentally viable and may be suitably measured. Indeed, in its study of double parton collisions, the quantity measured by CDF was an "exclusive" rather than an inclusive cross section. The non perturbative input to the "exclusive" cross sections is different with respect to the non perturbative input of the inclusive cross sections and involves correlation terms of the hadron structure already at the level of single parton collisions. The matter is discussed in details keeping explicitly into account the effects of double and of triple parton collisions.Comment: 18 pages, no figures, corrected typo

Finite formation time effects in inclusive and semi-inclusive electro-disintegration of few-body nuclei

Finite Formation Time (FFT) effects in the exclusive reaction ^4He(e,e'p)^3H at high values of Q^2 are introduced and discussed. It is shown that the minimum in the momentum distributions predicted by the Plane Wave Impulse Approximation (PWIA), which is filled by the Glauber-type Final State Interaction (FSI), is completely recovered when FFT effects are taken into account. The semi-inclusive process ^4 He(e,e'p)X is also investigated.Comment: 4 pages, 2 eps figure

Minijet transverse spectrum in high-energy hadron-nucleus collisions

Hadron-nucleus collisions at LHC energies are studied by including explicitly semi-hard parton rescatterings in the collision dynamics. Under rather general conditions, we obtain explicit formulae for the semi-hard cross-section and the inclusive minijet transverse spectrum. As an effect of the rescatterings the spectrum is lowered at small $p_t$ and is enhanced at relatively large transverse momenta, the deformation being more pronounced at increasing rapidity. Its study allows to test the proposed interaction mechanisms and represents an important baseline to examine nucleus-nucleus collisions