Double parton distributions incorporating perturbative QCD evolution and momentum and quark number sum rules

By J. Gaunt, W. James Stirling. 2009

170 citations recorded by the source corpus.

It is anticipated that hard double parton scatterings will occur frequently in the collisions of the LHC, producing interesting signals and significant backgrounds to certain single scattering processes. For double scattering processes in which the same hard scale t = ln(Q2) is involved in both collisions, we require the double parton distributions (dPDFs) $ D_h^{{j_1}{j_2}}\left( {{x_1},{x_2};t} \right) $ in order to make theoretical predictions of their rates and properties. We describe the development of a new set of leading order dPDFs that represents an improvement on approaches used previously. First, we derive momentum and number sum rules that the dPDFs must satisfy. The fact that these must be obeyed at any scale is used to construct improved dPDFs at the input scale Q0, for a particular choice of input scale (Q02 = 1GeV2) and corresponding single PDFs (the MSTW2008LO set). We then describe a novel program which uses a direct x−space method to numerically integrate theLO DGLAP equation for the dPDFs, and which may be used to evolve the input dPDFs to any other scale. This program has been used along with the improved input dPDFs to produce a set of publicly available dPDF grids covering the ranges 10−6 < x1 < 1, 10−6 < x2 < 1, and 1 < Q2 < 109 GeV2.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/75e9a3c05e6752e7382c5dc89876d956a43b70e3

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In Nuclear and High Energy Physics

Citations in the corpus

Elements of a theory for multiparton interactions in QCD (2011, background): “95) has long been known in the literature, see [145–147] and the recent detailed study [148].”
On the characterisation of the underlying event (2009, background): “[14]), or because they can have a common origin from an initial-state collinear splitting, as in figure 1b.”
General-purpose event generators for LHC physics (2011, background): “[120] and references therein), and, as discussed previously, how the showers are regulated at low p⊥ (or low x).”
String formation beyond leading colour (2015, background): “Although correlations in double-parton densities has been the topic of several recent developments [101–109], the field is still not at a stage at which it would be straightforward”
New observables in inclusive production of quarkonia (2019, background): “where Di j(x1, x2) is the double-parton distribution functions (dPDF) [388].”