arXiv subjects

Dominik Kara

Publications and source records attributed to Dominik Kara.

4 recordsLinked to original sources

arXiv2019

Higher-Order Corrections to Higgs Boson Amplitudes with Full Quark Mass Dependence in Quantum Chromodynamics

In this thesis, higher-order corrections to the perturbative expansions of scattering amplitudes involving the Higgs boson in the framework of Quantum Chromodynamics are evaluated, where we focus on processes that are mediated through heavy-quark loops. First, we derive the third-order corrections to the form factor describing the Yukawa coupling of a Higgs boson to a pair of bottom quarks. Furthermore, we compute the two-loop corrections to the $H\to Z\,γ$ decay width by retaining the full dependence on the internal quark mass. Finally, we describe the calculation of the planar Master Integrals relevant to the two-loop amplitude for Higgs-plus-jet production with full quark mass dependence. We accomplish this by establishing a method to derive series expansions from differential equations, since the set of Master Integrals involves elliptic structures.

hep-ph↗

arXiv2015

Corrections of Order $αα_s$ to W Boson Decays

We present the calculation of the mixed two-loop QCD/electroweak corrections to hadronic W boson decays within the Standard Model. The optical theorem is applied to the W boson two-point function. The multi-scale integrals are computed with the help of asymptotic expansions, which factorize the three-loop diagrams into one- and two-loop vacuum and propagator-type integrals.

hep-ph↗

arXiv2015

The rare decay $H\to Zγ$ in perturbative QCD

The rare Higgs boson decay $H\to Zγ$ is forbidden at tree-level. In the Standard Model, it is loop-mediated through a $W$ boson or a heavy quark. We analytically compute the QCD correction to the heavy quark loop, confirming earlier purely numerical results, that were obtained for on-shell renormalization. The small quark mass expansion of the decay matrix element contains only single-logarithmic contributions at each perturbative order, which is in contrast to the double logarithms observed in $H\to γγ$. We investigate the numerical interplay of bottom and top quark contributions, and the dependence of the result on the renormalization scheme.

hep-ph↗

arXiv2014

The $Hb\bar{b}$ form factor to three loops in QCD

We compute the three-loop QCD corrections to the vertex function for the Yukawa coupling of a Higgs boson to a pair of bottom quarks in the limit of vanishing quark masses. This QCD form factor is a crucial ingredient to third-order QCD corrections for the production of Higgs bosons in bottom quark fusion, and for the fully differential decay rate of Higgs bosons to bottom quarks. The infrared pole structure of the form factors agrees with the prediction from infrared factorization in QCD.

hep-ph↗