Precision boson-jet azimuthal decorrelation at hadron colliders
Yang-Ting Chien, Rudi Rahn, Ding Yu Shao, Wouter J. Waalewijn, Bin Wu
Abstract
A bstract The azimuthal angular decorrelation of a vector boson and jet is sensitive to QCD radiation, and can be used to probe the quark-gluon plasma in heavy-ion collisions. By using a recoil-free jet definition, the sensitivity to contamination from soft radiation on the measurement is reduced, and the complication of non-global logarithms is eliminated from our theoretical calculation. Specifically we will consider the $$ {p}_T^n $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>p</mml:mi> <mml:mi>T</mml:mi> <mml:mi>n</mml:mi> </mml:msubsup> </mml:math> recombination scheme, as well as the n → ∞ limit, known as the winner-take-all scheme. These jet definitions also significantly simplify the calculation for a track-based measurement, which is preferred due to its superior angular resolution. We present a detailed discussion of the factorization in Soft-Collinear Effective Theory, revealing why the transverse momentum $$ {\overrightarrow{q}}_T $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mover> <mml:mi>q</mml:mi> <mml:mo>→</mml:mo> </mml:mover> <mml:mi>T</mml:mi> </mml:msub> </mml:math> is more complicated than the azimuthal angle. We show that potential glauber contributions do not spoil our factorization formalism, at least up to and including order $$ {\alpha}_s^3 $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>α</mml:mi> <mml:mi>s</mml:mi> <mml:mn>3</mml:mn> </mml:msubsup> </mml:math> . The resummation is carried out using the renormalization group, and all necessary ingredients are collected or calculated. We conclude with a detailed phenomenological study, finding an enhanced matching correction for high jet p T due to the electroweak collinear enhancement of a boson emission off di-jets. We also compare with the P ythia event generator, finding that our observable is very robust to hadronization and the underlying event.