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Azimuthal correlation among jets produced in association with a bottom or top quark pair at the LHC

  • Kaoru Hagiwara
  • Satyanarayan Mukhopadhyay
Article

Abstract

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 \( t\overline{t} \) or \( b\overline{b} \), in terms of the gg\( t\overline{t} \) or \( b\overline{b} \) 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 \( b\overline{b} \) + 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 \( b\overline{b} \) pair. For \( t\overline{t} \) + 2 jets we find that the angular correlations are similar to that of a CP-odd scalar+2 jets near the threshold \( {M_{{t\overline{t}}}}\sim 2{m_t} \), while in the relativistic limit they resemble the distribution for \( b\overline{b} \) + 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.

Keywords

QCD Phenomenology Hadronic Colliders 

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Copyright information

© SISSA, Trieste, Italy 2013

Authors and Affiliations

  1. 1.KEK Theory Center and SokendaiTsukubaJapan
  2. 2.Kavli IPMU (WPI), University of TokyoKashiwaJapan

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