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Scale dependence of open cc¯ and bb¯ production in the low x region.

Oliveira, E. G. de and Martin, A. D. and Ryskin, M. G. (2017) 'Scale dependence of open cc¯ and bb¯ production in the low x region.', European physical journal C., 77 (3). p. 182.


The ‘optimal’ factorization scale μ0μ0 is calculated for open heavy quark production. We find that the optimal value is μF=μ0≃0.85p2T+m2Q−−−−−−−√μF=μ0≃0.85pT2+mQ2 ; a choice which allows us to resum the double-logarithmic, (αslnμ2Fln(1/x))n(αsln⁡μF2ln⁡(1/x))n corrections (enhanced at LHC energies by large values of ln(1/x)ln⁡(1/x) ) and to move them into the incoming parton distributions, PDF (x,μ20)(x,μ02) . Besides this result for the single inclusive cross section (corresponding to an observed heavy quark of transverse momentum pTpT ), we also determined the scale for processes where the acoplanarity can be measured; that is, events where the azimuthal angle between the quark and the antiquark may be determined experimentally. Moreover, we discuss the important role played by the 2→22→2 subprocesses, gg→QQ¯gg→QQ¯ at NLO and higher orders. In summary, we achieve a better stability of the QCD calculations, so that the data on cc¯cc¯ and bb¯bb¯ production can be used to further constrain the gluons in the small x, relatively low scale, domain, where the uncertainties of the global analyses are large at present.

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Publisher statement:© The Author(s) 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Funded by SCOAP3.
Date accepted:09 March 2017
Date deposited:31 May 2017
Date of first online publication:22 March 2017
Date first made open access:31 May 2017

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