2013/02/28 by Kaoru Hagiwara, Satyanarayan Mukhopadhyay · 1 citation
Computer Science · Physics and Astronomy · #Amplitude #Computational Physics and Python Applications #Gluon #Helicity #High-Energy Particle Collisions Research #Invariant mass #Large Hadron Collider #Pair production #Particle physics theoretical and experimental studies #Quark #Scalar (mathematics) #Top quark #hep-ex #hep-ph
paper · pdf · doi:10.1007/jhep05(2013)019
published as JHEP05(2013)019 · 15 pages, 5 figures; v2: minor additions to text, references added, version as published in JHEP
openalex publication_date 2013/05/01 · arxiv created 2013/05/07 · arxiv updated 2013/05/08 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Angular correlation of jets produced in association with a massive scalar, vector or tensor boson is crucial in the determination of their spin and CP properties. We study jet angular correlations in events with a high mass bottom quark pair or a top quark pair and two jets at the LHC, whose cross-section is dominated by the virtual gluon fusion sub-processes when appropriate kinematic selection cuts (vector-boson fusion cuts) are applied. We evaluate helicity amplitudes for sub-processes initiated by qq, qg and gg collisions in the limit where the intermediate gluons are collinear to the initial partons. We first obtain a general expression for the azimuthal angle correlations among the dijets and t t-bar or b b-bar, in terms of the gg to t t-bar or b b-bar helicity amplitudes in the real gluon approximation of the full matrix elements, and find simple analytic expressions in the two kinematic limits, the production of a heavy quark pair near the threshold, and in the relativistic limit where the invariant mass of the heavy quark pair is much larger than the quark mass. For b b-bar + 2 jets we find strong azimuthal angle correlations which are distinct from those expected for events with a CP-even or odd scalar boson which may decay into a b b-bar pair. For t t-bar + 2 jets we find that the angular correlations are similar to that of a CP-odd scalar+2 jets near the threshold M_(t t-bar) ~ 2 mt, while in the relativistic limit they resemble the distribution for b b-bar + 2 jets. These correlations in the standard QCD processes will help establish the experimental technique to measure the spin and CP properties of new particles produced via gluon fusion at the LHC.