=================================================================== =================================================================== == == == README for H1 2007 DPDF Fit Jets Parameterization == == == =================================================================== =================================================================== Version 1.0, 04/06/2009 H1 Collaboration Contact persons: Matthias Mozer - mmozer@vub.ac.be Karel Cerny - kcerny@ipnp.troja.mff.cuni.cz === www source === https://www-h1.desy.de/h1/www/publications/htmlsplit/DESY-07-115.long.html These files provide a fortran parameterisation of the results of the NLO DGLAP QCD fits labelled 'H1 2007 DPDF Fit Jets' from the paper below. Please reference this paper when using this parametrisation. H1 Collaboration, A. Aktas et al., "Dijet Cross Sections and Parton Densities in Diffractive DIS at HERA", DESY-07-115, Aug 2007. 33pp. Published in JHEP 0710:042,2007. e-Print: arXiv:0708.3217 [hep-ex] === Details of the fit === The DPDFs are parameterised at a starting scale = 2.5 GeV^2 available for : 1.960 <= Q2 <= 2000.0 GeV^2 and : 0.001 <= x <= 0.932603 for x outside limits, the closest limit is assumed f (x > xmax, q2) = f (xmax, q2) f (x < xmin, q2) = f (xmin, q2) for q2 outside limits, the closest limit is assumed f (x, q2 > q2max) = f (x, q2max) f (x, q2 < q2min) = f (x, q2min) === Files provided === readme_h12007.txt This readme file h12007jetsdpdf_prcoeff.f Pomeron and Reggeon fluxes h12007jetsdpdf_singlet.f Quark singlet pdf paramterisation h12007jetsdpdf_gluon.f Gluon pdf paramterisation h12007jetsdpdf_charm.f F2 charm parameterisatoin h12007jetsdpdf_singlet.data Grid data for singlet pdf h12007jetsdpdf_gluon.data Grid data for gluon pdf h12007jetsdpdf_charm.data Grid data for F2 charm h12007jetsdpdf_pdflib_interface.f pdflib adaptor function === Usage === For details on the arguments of the available routines, please also look at the comments provided in the .f files. References are used to the above publication. a) Flux factor -------------- f_{IP/p}(xpom) or f_{IR, p}(xpom) ... see pages 13, 14 of the paper Subroutine h12007jetsdpdf_prcoeff(int type ,real xpom) provides the Pomeron or Reggeon flux factor for a given xpom, i.e.: type = 1 => Pomeron type = 2 => Reggeon The fluxes are integrated over the following 't' range (GeV^2): tmin = -1 tmax = -(mp*xpom)**2 / (1 - xpom) where mp is the proton rest mass. b) Parton distributions ----------------------- The Pomeron parton distributions in the form of pdf_IP = z * f_{i/IP}(z,Q^2), i ... singlet, gluon, charm are provided by the functions: h12007jetsdpdf_singlet(xin,q2in,icycle), h12007jetsdpdf_gluon (xin,q2in,icycle), h12007jetsdpdf_charm (xin,q2in,icycle), where: 'xin' is the parton four-momentum fraction (often called beta or zpomeron) 'q2in' is the factorization scale squared 'icycle' MUST BE SET TO ZERO by default. Only the flux for the Reggeon component is provided here, the parton densities must be provided separately. The fit used Owens set 1 - PDFLIB-Owens(2,1,1). c) Final instructions --------------------- Eventually, in order to obtain proton diffractive PDFs, the Pomeron/Reggeon parton distributions have to be multiplied by the Pomeron/Reggeon flux factor. If a cross section integrated over xpomeron is calculated, then also the flux * pdf should multiplied by the xpomeron-bin-width, DPDF_diff = (flux_IP * pdf_IP * xpom_width) + (flux_IR * pdf_IR * xpom_width) where all terms are provided by the H1 2007 Fit Jets, except for the pdf_IR which needs to be provided separately. An example is given in section d) below. d) A minimal example of PDFLIB use of the fit. ---------------------------------------------- Although not supported anymore an example how to use the fit by means of use of PDFLIB is given in: h12007jetsdpdf_pdflib_interface.F