Buonocore, Luca (2020) Ultimate precision for the Drell-Yan process: mixed QCDxQED(EW) corrections, final state radiation and power suppressed contributions. [Tesi di dottorato]


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Item Type: Tesi di dottorato
Resource language: English
Title: Ultimate precision for the Drell-Yan process: mixed QCDxQED(EW) corrections, final state radiation and power suppressed contributions
Buonocore, Lucalbuono@na.infn.it
Date: 13 February 2020
Number of Pages: 168
Institution: Università degli Studi di Napoli Federico II
Department: Fisica
Dottorato: Fisica
Ciclo di dottorato: 32
Coordinatore del Corso di dottorato:
Capozziello, Salvatoresalvatore.capozziello@unina.it
Francesco, TramontanoUNSPECIFIED
Massimiliano, GrazziniUNSPECIFIED
Date: 13 February 2020
Number of Pages: 168
Keywords: Drell-Yan, mixed QCD-EW radiative corrections, power corrections
Settori scientifico-disciplinari del MIUR: Area 02 - Scienze fisiche > FIS/02 - Fisica teorica, modelli e metodi matematici
Date Deposited: 31 Mar 2020 16:12
Last Modified: 08 Nov 2021 12:10
URI: http://www.fedoa.unina.it/id/eprint/13156

Collection description

The discovery of the Higgs Boson at the Large Hadron Collider in 2012 represented a breakthrough in particle physics, providing a strong confirmation of the mechanism of Electro-Weak-Symmetry-Breaking, which is in turn responsible for the generation of elementary-particle masses. The Higgs discovery, however, was not followed by any evidence of physics Beyond the Standard Model, and it is difficult to reconcile our current description of the fundamental particles and their interactions with long-standing problems like neutrino masses, matter-anti matter asymmetry, the existence of dark matter and dark energy and the hierarchy problem. The lack of new-physics signals has stimulated a new precision collider programme, which was made possible by the advances on both the experimental and theoretical sides. Indeed, the precision target accuracy expected by the end of the planned LHC data taking in 2038 is at the (sub)percent level. For a meaningful comparison with experimental data, we need theoretical predictions which have a similar level of accuracy. This translates into the necessity of computing higher order terms in perturbation theory, known as radiative corrections in the language of Quantum Field Theory. At an hadronic collider as the LHC the effects due to the strong interaction (described by Quantum CromoDynamics (QCD)) dominate. In the last decades a big effort has been profused to compute QCD radiative corrections and nowadays Next-to-Next-to Leading Order (NNLO) computations represent the state of the art for many $2\to2$ processes. The production of a dilepton pair via the Drell-Yan mechanism has a special place in the precision phenomenology program at LHC for its importance in experimental calibrations and for the precise determination of important electro-weak (EW) parameters such as the W mass. From the theoretical side, Drell-Yan is one of the most studied processes. QCD corrections are known up to NNLO and in part at N$^3$LO, while EW corrections are known at NLO. At this level of accuracy, it becomes relevant to assess the relative importance of the mixed QCD-EW corrections. In this thesis, we set up a subtraction framework to compute the full set of mixed QCD-EW(QED) corrections to the the Drell-Yan process at the differential level. We rely on the transverse momentum resummation formalism to handle the genuine NNLO-type infrared divergences associated to both initial and final state radiation in the small transverse momentum limit, exploiting the corresponding results for heavy-quark pair production. In particular, we have to deal with massive leptons in the final state as the their mass acts as a regulator for final-state collinear divergences. This may challenge the numerical stability since the physical lepton masses are very small. We extensively study the radiation pattern of massive emitters, building a dedicated momentum mapping which smoothly approaches the massless limit. Furthermore, we study, for the first time, the leading power suppressed contributions appearing at small transverse momenta, and we show that they are driven by final-state soft radiation. As a validation of our construction, we show results both for the inclusive and the relevant differential distribution for the mixed QCD-QED corrections to the production of an on-shell Z boson.


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