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TY - THES AU - Brancaccio, Colomba TI - Top-quark fragmentation into a Higgs boson in the context of top-Higgs associated production PB - RWTH Aachen University VL - Dissertation CY - Aachen M1 - RWTH-2023-11639 SP - 1 Online-Ressource : Illustrationen PY - 2023 N1 - Veröffentlicht auf dem Publikationsserver der RWTH Aachen University 2024 N1 - Dissertation, RWTH Aachen University, 2023 AB - This thesis analyzes the application of the fragmentation formalism to the Higgs boson associated production with a top quark pair. In this formalism, when the Higgs transverse momentum p<sub>T,H</sub> is much bigger than the top and the Higgs mass, the t ―t H cross section can be factorized into the infrared-safe hard-scattering production and the fragmentation function into a Higgs boson, which can be computed in perturbation theory. The relevant fragmentation functions for the Higgs-top associated production at next-to-leading order are the top-to-Higgs and the gluon-to-Higgs fragmentation functions. Using a diagrammatic approach and employing multi-loop techniques, these fragmentations are analytically computed up to <i>O</i>(α<sub>s</sub> y<sub>t</sub><sup>2</sup>) with complete mass dependence. Moreover, the e<sup>−</sup> e<sup>+</sup> → γ→ t ―t H fixed-order p<sub>T,H</sub> spectrum is calculated at next-to-leading order by performing the convolution of the top-to-Higgs fragmentation function with the hard-scattering production by using the <tt>STRIPPER</tt> library. Comparing the approximation to the exact prediction, the factorization formula accurately reproduces the true p<sub>T,H</sub> spectrum up to the expected power correction of the order m<sup>2</sup>/p<sub>T,H</sub><sup>2</sup>, where m is the Higgs or the top mass according to the approximation used. This test is theoretically valuable as it gives insight into the fragmentation framework applied to Higgs boson associated production and provides a check for the top-to-Higgs fragmentation function. The first steps towards potential phenomenological hadron collider applications have been made by examining the process p p → t ―t H at leading order. The formalism developed in this thesis can be employed in the future for resumming large logarithms of the type ln(p<sub>T,H</sub>/m), which may spoil the convergence of the perturbative series at future colliders. Additionally, it opens up new prospects for further fragmentation formalism applications, for instance, to processes like t―tW or t―tZ. LB - PUB:(DE-HGF)11 DO - DOI:10.18154/RWTH-2023-11639 UR - https://publications.rwth-aachen.de/record/974804 ER -