Year-end Sale % OFF 
Abstract
Production of the Higgs boson, H in association with a massive vector boson, V, i.e., the V H process, plays an important role in the explorations of Higgs physics at the Large Hadron Collider, both for a precise study of Higgs’ Standard Model couplings and for probing New Physics. In this publication we present the two-loop corrections in mass- less quantum chromodynamics (QCD) to the amplitude of the Higgs production associated with a Z boson via the bottom quark-antiquark annihilation channel with a non-vanishing bottom-quark Yukawa coupling, which is a necessary ingredient of the full next-to-next- to-leading-order QCD corrections to the V H process in the five-flavour scheme. The computation is performed by projecting the D-dimensional scattering amplitude directly onto an appropriate set of Lorentz structures related to the linear polarisation states of the Z boson. We provide analytic expressions of the complete set of renormalised polarised amplitudes in terms of polylogarithms of maximum weight four. To give an estimation of the size of contributions from amplitudes considered in this work, we compute numerically the resulting cross sections under the soft-virtual approximation. We also take the opportunity to make a dedicated discussion regarding an interesting subtlety appearing in the conventional form factor decomposition of amplitudes involving axial currents regularised in D dimensions.
Highlights
Quarks by the ATLAS and CMS experiments [4, 5]
In this publication we present the two-loop corrections in massless quantum chromodynamics (QCD) to the amplitude of the Higgs production associated with a Z boson via the bottom quark-antiquark annihilation channel with a non-vanishing bottom-quark Yukawa coupling, which is a necessary ingredient of the full next-to-nextto-leading-order QCD corrections to the V H process in the five-flavour scheme
We address subtleties appearing in the conventional form factor decomposition of loop amplitudes involving an axial current in D dimensions: whether we need to include all evanescent Lorentz structures3 to end up with correct results in computations made in D-dimensions; whether the particular regularisation prescription implied by projectors prescribed recently in ref. [45] remains unitary at higher orders once applied to this scattering process, etc
Summary
We consider the production of a scalar Higgs boson, H, in association with a massive vector boson, Z, through bottom quark anti-quark annihilation b(p1) + ̄b(p2) → Z(q1) + H(q2). The Z-boson interacts with all massless quarks through the respective vector and axial couplings. Any multi-loop calculation involving axial coupling in dimensional regularisation [46, 47] (DR) faces the problem of defining the inherently 4-dimensional objects, Dirac’s γ5 (and Levi-Civita symbol μνρσ), properly in D-dimensions. The γ5 defined through the above equation no longer fully anti-commutes with the D-dimensional γμ, which has profound consequences in computations involving axial currents in D-dimensions. Where all the indices carried by space-time metric tensors on the right hand side are (by definition) considered in D dimensions [54]. We discuss the projector method that is adopted to compute helicity amplitudes of the scattering process (2.1)
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
