https://doi.org/10.1140/epjc/s10052-017-4750-8
Regular Article - Theoretical Physics
Scale dependence of open 
and 
production in the low x region
1
Departamento de Física, CFM, Universidade Federal de Santa Catarina, C.P. 476, Florianópolis, SC, CEP 88.040-900, Brazil
2
Institute for Particle Physics Phenomenology, University of Durham, Durham, DH1 3LE, UK
3
Petersburg Nuclear Physics Institute, NRC Kurchatov Institute, Gatchina, St. Petersburg, 188300, Russia
* e-mail: a.d.martin@durham.ac.uk
Received:
21
October
2016
Accepted:
9
March
2017
Published online:
22
March
2017
The ‘optimal’ factorization scale 
is calculated for open heavy quark production. We find that the optimal value is 
; a choice which allows us to resum the double-logarithmic, 
corrections (enhanced at LHC energies by large values of 
) and to move them into the incoming parton distributions, PDF
. Besides this result for the single inclusive cross section (corresponding to an observed heavy quark of transverse momentum 
), 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 
subprocesses, 
at NLO and higher orders. In summary, we achieve a better stability of the QCD calculations, so that the data on and 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.
© The Author(s), 2017
