A new quantity for studies of dijet azimuthal decorrelations

Abstract

We introduce a new measurable quantity, $R_{\Delta \phi}$, for studies of the rapidity and transverse momentum dependence of dijet azimuthal decorrelations in hadron-hadron collisions. In pQCD, $R_{\Delta \phi}$ is computed as a ratio of three-jet and dijet cross sections in which the parton distribution functions cancel to a large extent. At the leading order, $R_{\Delta \phi}$ is proportional to $\alpha_s$, and the transverse momentum dependence of can therefore be exploited to determine $\alpha_s$. We compute the NLO pQCD theory predictions and non-perturbative corrections for $R_{\Delta \phi}$ at the LHC and the Tevatron and investigate the corresponding uncertainties. From this, we estimate the theory uncertainties for $\alpha_s$ determinations based on $R_{\Delta \phi}$ at both colliders. The potential of $R_{\Delta \phi}$ measurements for tuning Monte Carlo event generators is also demonstrated.Comment: 20 pages, 11 figures, 1 table, submitted to JHE

Dijet azimuthal decorrelations for Δϕ dijet < 2π/3 in perturbative QCD

“…Since in this ∆φ dijet region the quantity P is proportional to α 2 s , future measurements with higher statistical precision can also be used for novel α s determinations. This recommendation also applies to measurements of dijet azimuthal decorrelations based on the quantity R ∆φ [17,18] when this is measured for ∆φ max ≤ 2π/3.…”

Measurements of dijet azimuthal decorrelations and extraction of alpha_S at ATLAS

“…An additional observable R ∆φ has been proposed in Ref. [5]. The quantity R ∆φ is defined as the fraction of all inclusive dijet events in which ∆φ dijet is less than a specified value ∆φ max .…”

High Energy Physics Research at Louisiana Tech

“…With this approach we extract α s up to the largest p T accessible at the Tevatron and the LHC. We have study different quantities, some of which we have invented for this purpose [6]. The quantities studied are R 3/2 (the ratio of inclusive three-jet and dijet cross sections), R ∆R (the average number of neighboring jets by which jets are accompanied) R ∆φ (the fraction of dijets with a given azimuthal decorrelation), and a set of nine event shape variables.…”

“…In a recent publication, the LA Tech group has proposed the new quantity, R ∆φ , for studying the rapidity dependence of dijet azimuthal decorrelations at hadron colliders [6]. The measurement of R ∆φ using DØ data was Chakravarthula's doctoral dissertation topic, supervised by Wobisch.…”

“…Lett. B [6]. At the same time, the R ∆φ measurement is also performed using ATLAS data at √ s = 8 TeV by Tamsett, Sawyer, Wobisch, in collaboration with M. Begel (BNL) as part of Wobisch's EPSCoR grant.…”