30 September 2019 to 4 October 2019
Europe/London timezone

On the ambiguities of the BLM/PMC procedure for hadron collider processes

1 Oct 2019, 17:45
12m

Speaker

Herschel Chawdhry (University of Cambridge)

Description

In any calculation in perturbative Quantum Chromodynamics (QCD) a choice needs to be made for the unphysical renormalisation scale, $\mu_R$. The Brodsky-Lepage-Mackenzie/Principle of Maximum Conformality (BLM/PMC) scale-setting procedure is one proposed method for selecting this scale and has previously been applied to a number of processes, including Higgs production. In this work we identify three ambiguities in the BLM/PMC procedure itself. Their numerical impact is studied using the example of the total cross-section for $t\bar{t}$ production through Next-to-Next-to-Leading Order in QCD. One ambiguity is the arbitrary choice of the value of the highest-order PMC scale. The numerical impact of this choice on the BLM/PMC prediction for the cross-section is found to be comparable to the impact of the choice of $\mu_R$ in the conventional scale-setting approach. Another ambiguity relates to the definitions of the other PMC scales and is similarly found to have a large impact on the cross-section.

Primary author

Herschel Chawdhry (University of Cambridge)

Co-author

Alexander Mitov (University of Cambridge (GB))

Presentation materials