87 research outputs found
Parton correlations in double parton scattering
Double parton scattering events are directly sensitive to the correlations
between two partons inside a proton and can answer fundamental questions on the
connections between the proton constituents. In this chapter, the different
types of possible correlations, our present knowledge of them, and the
processes where they are likely to be important, are introduced and explained.
The increasing integrated luminosity at the LHC and the refinements of the
theory of double parton scattering, lead to interesting prospects for
measuring, or severely constraining, two-parton correlations in the near
future.Comment: Prepared for: Multiple Parton Interactions at the LHC, Eds. P.
Bartalini and J. R. Gaunt, World Scientific, Singapore; v2: references adde
Studying the neutron orbital structure by coherent hard exclusive processes off 3He
Hard exclusive processes, such as Deeply Virtual Compton Scattering (DVCS),
allow to access generalized parton distributions (GPDs). By means of an Impulse
Approximation (IA) calculation, it is shown here how, in the low momentum
transfer region, the sum of the GPDs H and E is dominated by the neutron
contribution. Thanks to this property, 3He could open a new way to access the
neutron structure information. In this work, a simple and efficient extraction
procedure of the neutron GPDs, able to take into account the nuclear effects
included in IA analysis, is proposed.Comment: 4 pages, 3 figures; talk presented by Matteo Rinaldi at 3rd Workshop
On The QCD Structure Of The Nucleon (QCD-N'12), 22-26 Oct 2012, Bilbao, Spai
Generalized parton distributions in constituent quark models
An approach is proposed to calculate Generalized Parton Distributions (GPDs)
in a Constituent Quark Model (CQM) scenario. These off-diagonal distributions
are obtained from momentum space wave functions to be evaluated in a given non
relativistic or relativized CQM. The general relations linking the twist-two
GPDs to the form factors and to the leading twist quark densities are
consistently recovered from our expressions. Results for the leading twist,
unpolarized GPD, H, in a simple harmonic oscillator model, as well as in the
Isgur and Karl model, are shown to have the general behavior found in previous
estimates. NLO evolution of the obtained distributions, from the low momentum
scale of the model up to the experimental one, is also shown. Further natural
applications of the proposed formalism are addressed.Comment: 19 pages, 8 figures, discussion of the Isgur and Karl model added,
NLO QCD evolution evaluated, references and figures adde
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