We investigate the relationship of "physical" parton densities defined by kt-factorisation, to those in the minimal subtraction scheme, by comparing their small-x behaviour. We first summarize recent results on the above scheme change derived from the BFKL equation at NLx level, and we then propose a simple extension to the renormalisation-group-improved (RGI) equation. In this way we are able the examine the difference between resummed gluon distributions in the Q_0 and MSbar schemes and also to show MSbar scheme resummed results for Pgg and approximate ones for Pqg. We find that, due to the stability of the RGI approach, small-x resummation effects are not much affected by the scheme-change in the gluon channel, while they are relatively more important for the quark-gluon mixing.

Minimal subtraction vs. physical factorisation schemes in small-x QCD / M. Ciafaloni; D. Colferai; G. P. Salam; A. M. Stasto. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - STAMPA. - B635:(2006), pp. 320-329. [10.1016/j.physletb.2006.03.014]

Minimal subtraction vs. physical factorisation schemes in small-x QCD

CIAFALONI, MARCELLO;COLFERAI, DIMITRI;
2006

Abstract

We investigate the relationship of "physical" parton densities defined by kt-factorisation, to those in the minimal subtraction scheme, by comparing their small-x behaviour. We first summarize recent results on the above scheme change derived from the BFKL equation at NLx level, and we then propose a simple extension to the renormalisation-group-improved (RGI) equation. In this way we are able the examine the difference between resummed gluon distributions in the Q_0 and MSbar schemes and also to show MSbar scheme resummed results for Pgg and approximate ones for Pqg. We find that, due to the stability of the RGI approach, small-x resummation effects are not much affected by the scheme-change in the gluon channel, while they are relatively more important for the quark-gluon mixing.
B635
320
329
M. Ciafaloni; D. Colferai; G. P. Salam; A. M. Stasto
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2158/340258
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