Abstract
Jet production at hadron colliders is a benchmark process to probe the dynamics of the strong interaction and the structure of the colliding hadrons. One of the most basic jet production observables is the single jet inclusive cross section, which is obtained by summing all jets that are observed in an event. Our recent computation of next-to-next-to-leading order (NNLO) QCD contributions to single jet inclusive observables uncovered large corrections in certain kinematical regions, which also resulted in a sizeable ambiguity on the appropriate choice of renormalization and factorization scales. We now perform a detailed investigation of the infrared sensitivity of the different ingredients to the single jet inclusive cross section. We show that the contribution from the second jet, ordered in transverse momentum pT, in the event is particularly sensitive to higher order effects due to implicit restrictions on its kinematics. By investigating the second-jet transverse momentum distribution, we identify large-scale cancellations between different kinematical event configurations, which are aggravated by certain types of scale choice. Taking perturbative convergence and stability as selection criteria enables us to single out the total partonic transverse energy ĤT and twice the individual jet transverse momentum 2 pT (with which ĤT coincides in Born kinematics) as the most appropriate scales in the perturbative description of single jet inclusive production.
Highlights
Summing over all jets in the event
One of the most basic jet production observables is the single jet inclusive cross section, which is obtained by summing all jets that are observed in an event
By investigating the second-jet transverse momentum distribution, we identify large-scale cancellations between different kinematical event configurations, which are aggravated by certain types of scale choice
Summary
The renormalization group equation describing the running of αs as a function of the renormalization scale μR reads: μ2R dαs(μR) dμ2R. Where CA = 3, CF = 4/3, TR = 1/2 and NF is the number of light quark flavours. Using the solution of this equation, the coupling at a fixed scale μR0 can be truncated in terms of the coupling at μR by introducing. The perturbative expansion of the single jet inclusive cross section starts at order αs. In evaluating the expansion coefficients σ(n) = σ(n)(μR0), the renormalization scale is fixed to a value μR0 (which can be dynamically evaluated event-by-event). Rescalings can be made for a fixed ratio μR/μR0 for all events; e.g. if μR0 = pT,, we can rescale to μR = 2 pT, or μR = pT,1/2, but not to μR = MZ or μR = HT )
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