66 research outputs found
Disentangling correlations in Multiple Parton Interactions
Multiple Parton Interactions are the tool to obtain information on the
correlations between partons in the hadron structure. Partons may be correlated
in all degrees of freedom and all different correlation terms contribute to the
cross section. The contributions due to the different parton flavors can be
isolated, at least to some extent, by selecting properly the final state. In
the case of high energy proton-proton collisions, the effects of correlations
in the transverse coordinates and in fractional momenta are, on the contrary,
unavoidably mixed in the final observables. The standard way to quantify the
strength of double parton interactions is by the value of the effective cross
section and a small value of the effective cross section may be originated both
by the relatively short transverse distance between the pairs of partons
undergoing the double interaction and by a large dispersion of the distribution
in multiplicity of the multi-parton distributions. The aim of the present paper
is to show how the effects of longitudinal and transverse correlations may be
disentangled by taking into account the additional information provided by
double parton interactions in high energy proton-deuteron collisions.Comment: 23 pages, 8 figure
The N - Jet Inclusive Cross-Section in the Hard Pomeron Model
The inclusive production of several jets is studied in the framework of the
hard pomeron model. The average jet momenta are found to be strongly ordered
and growing towards the central c.m. rapidity, as expected. Strong positive
correlations are found for pairs of jets neighbouring in rapidity, both in the
forward-backward and forward-forward directions.Comment: 20 pages, latex, one figure (fig.2), an hard copy of fig.1 can be
obtained on reques
The double parton distributions in the hard pomeron model
We study the double parton interaction process in collisions between highly
virtual pairs in the BFKL regime. Explicit expressions for the
double parton distributions are obtained both in the case of direct coupling of
the BFKL pomerons to the pair and in the case of triple pomeron
interaction.Comment: 29 pages, 6 figure
Double Parton Scatterings in High-Energy Proton-Nucleus Collisions and Partonic Correlations
The joint study of Double Parton Scatterings, in high energy proton-proton
and proton-nucleus collisions, can provide a lot of information on multi-parton
correlations. The multi-parton structure is in fact probed in a different way
by DPS, in - and in - collisions. In - collisions the
interpretation of the experimental results may be however complicated by the
presence of interference terms, which are missing in -. A suitable
reaction channel, where interference terms are absent, is production. By
studying production in - collisions, we estimate that the fraction
of events due to DPS may be larger by a factor 3 or 4, as compared to -,
while the amount of the increased fraction can give a direct indication on the
importance of different correlation terms.Comment: 27 pages, 9 figure
Double parton scattering, diffraction and effective cross section
The rates of multiparton collisions in high energy hadronic interactions
provide information on the typical transverse distances between partons in the
hadron structure. The different configurations of the hadron in transverse
space are, on the other hand, at the origin of hadron diffraction. The relation
between the two phenomena is exploted in an eikonal model of hadronic
interactions.Comment: 17 pages, no figure
Double Parton Interactions in pp and pA Collisions
As a consequence of the increasingly large flux of partons at small x , Double Parton Interactions (DPI) play an increasingly important role at high energies. A detail understanding of DPI dynamics is therefore mandatory, for a reliable subtraction of the background in the search of new physics. On the other hand, DPI are an interesting topic of research by themselves, as DPI probe the hadron structure in a rather different way, as compared with the large pt processes usually considered. In this note we will make a short illustration of some of the main features characterizing DPI in pp and in pA collisions
Hard Break-Up of Two-Nucleons and QCD Dynamics of NN Interaction
We discus recent developments in theory of high energy two-body break-up of
few-nucleon systems. The characteristics of these reactions are such that the
hard two-body quasielastic subprocess can be clearly separated from the
accompanying soft subprocesses. We discuss in details the hard rescattering
model(HRM) in which hard photodisintegration develops in two stages. At first,
photon knocks-out an energetic quark which rescatters subsequently with a quark
of the other nucleon. The latter provides a mechanism of sharing the initial
high momentum of the photon between two outgoing nucleons. This final state
hard rescattering can be expressed through the hard NN scattering amplitude.
Within HRM we discuss hard break-up reactions involving D and 3He targets and
demonstrate how these reactions are sensitive to the dynamics of hard pn and pp
interaction. Another development of HRM is the prediction of new helicity
selection mechanism for hard two-body reactions, which was apparently confirmed
in the recent JLab experiment.Comment: Invited talk at 6th International Conference on Perspective in
Hadronic Physics, Trieste, Italy, 12-18 May 2008. Submitted to AIP Conf.Pro
Exploring the transverse spin structure of the nucleon
We discuss our present understanding of the transverse spin structure of the
nucleon and of related properties originating from parton transverse motion.
Starting from the transversity distribution and the ways to access it, we then
address the role played by spin and transverse momentum dependent (TMD)
distributions in azimuthal and transverse single spin asymmetries. The latest
extractions of the Sivers, Collins and transversity functions are also
presented.Comment: 8 pages, 6 ps figures, uses aipproc.cls. Invited talk at "6th
International Conference on Perspectives in Hadronic Physics (Hadron 08)",
Trieste, Italy, 12-18 May 2008. Submitted to AIP Conf.Pro
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