Unintegrated parton distributions of pions and nucleons from the CCFM equations in the single loop approximation
May, 2003Citations per year
Abstract:
The unintegrated quark and gluon distributions in the pion and nucleon are analysed using the CCFM equations in the single-loop approximation. We utilise the transverse-coordinate (or impact-parameter) representation which diagonalises the equations and study in detail the dependence on the transverse coordinate induced by the CCFM evolution. We find considerable broadening of the transverse-momentum distributions with an increasing magnitude of the hard scale, Q. For instance, at the Bjorken x=0.1 the root mean squared transverse momentum of the gluons is enhanced by about 1 GeV when evolved from the the initial low scale to Q^2=10 GeV^2, and by about 2 GeV when evolved up to Q^2=100 GeV^2. The broadening effect is enhanced with decreasing Bjorken x, and is stronger for the gluons than for the quarks. Analytic solution for the average transverse momentum corresponding to the x-moments of the distributions is obtained. The parton luminosities are also discussed.- 13.60.Hb
- 12.38.Bx
- 12.38.Cy
- pi: structure function
- nucleon: structure function
- momentum spectrum: parton
- transverse momentum: spectrum
- gluon
- integral equations: approximation
- model: impact parameter
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