The azimuthal decorrelation of jets widely separated in rapidity as a test of the BFKL kernel

TL;DR

The paper tackles azimuthal decorrelations of Mueller–Navelet jets at hadron colliders within the BFKL framework, incorporating NLO and collinearly improved corrections for all conformal spins. It develops an RG-improved collinear resummation and analyzes the angular decomposition through the C_n coefficients to study energy dependence and convergence. The findings show that higher-spin intercepts are stable under resummation, while the zero-spin sector requires resummation to stabilize predictions, yielding improved but not perfect agreement with Tevatron data. The authors advocate measurements at the LHC with large rapidity gaps to maximally probe BFKL dynamics and guide future theoretical and Monte Carlo work.

Abstract

We study the decorrelation in azimuthal angle of Mueller-Navelet jets at hadron colliders within the BFKL formalism. We introduce NLO terms in the evolution kernel and present a collinearly-improved version of it for all conformal spins. We show how this further resummation has good convergence properties and is closer to the Tevatron data than a simple LO treatment. However, we are still far from a good fit. We offer estimates of these decorrelations for larger rapidity differences which should favor the onset of BFKL effects and encourage experimental studies of this observable at the LHC.

Figures (10)

• Figure 1: Representation of Mueller--Navelet jets at a hadron collider.
• Figure 2: Eigenvalues of the scale invariant sector of the BFKL kernel as a function of $\gamma$ for different values of the conformal spin.
• Figure 3: Eigenvalues of the scale invariant sector of the BFKL kernel as a function of $\nu$ for different values of the conformal spin.
• Figure 4: Eigenvalues of the scale invariant sector of the BFKL kernel as a function of the coupling constant for different values of the conformal spin.
• Figure 5: $\left<\cos\phi\right> = {\cal C}_1/{\cal C}_0$ and $\left<\cos 2\phi\right> = {\cal C}_2/{\cal C}_0$ at a $p\bar{p}$ collider with $\sqrt{s}$ = 1.8 TeV for BFKL at LO (solid) and NLO (dashed). The results from the resummation presented in the text are shown as well (dash--dotted). Tevatron data points are taken from Ref. Kim:1996dg.