Measurement of ttbar production differential cross section at \sqrt{s}=8 TeV at ATLAS


Autoria(s): Fabbri, Federica
Contribuinte(s)

Semprini Cesari, Nicola

Data(s)

24/10/2014

Resumo

Top quark studies play an important role in the physics program of the Large Hadron Collider (LHC). The energy and luminosity reached allow the acquisition of a large amount of data especially in kinematic regions never studied before. In this thesis is presented the measurement of the ttbar production differential cross section on data collected by ATLAS in 2012 in proton proton collisions at \sqrt{s} = 8 TeV, corresponding to an integrated luminosity of 20.3 fb^{−1}. The measurement is performed for ttbar events in the semileptonic channel where the hadronically decaying top quark has a transverse momentum above 300 GeV. The hadronic top quark decay is reconstructed as a single large radius jet and identified using jet substructure properties. The final differential cross section result has been compared with several theoretical distributions obtaining a discrepancy of about the 25% between data and predictions, depending on the MC generator. Furthermore the kinematic distributions of the ttbar production process are very sensitive to the choice of the parton distribution function (PDF) set used in the simulations and could provide constraints on gluons PDF. In particular in this thesis is performed a systematic study on the PDF of the protons, varying several PDF sets and checking which one better describes the experimental distributions. The boosted techniques applied in this measurement will be fundamental in the next data taking at \sqrt{s}=13 TeV when will be produced a large amount of heavy particles with high momentum.

Formato

application/pdf

Identificador

http://amslaurea.unibo.it/7599/1/Fabbri_Federica_tesi.pdf

Fabbri, Federica (2014) Measurement of ttbar production differential cross section at \sqrt{s}=8 TeV at ATLAS. [Laurea magistrale], Università di Bologna, Corso di Studio in Fisica [LM-DM270] <http://amslaurea.unibo.it/view/cds/CDS8025/>

Relação

http://amslaurea.unibo.it/7599/

Direitos

info:eu-repo/semantics/openAccess

Palavras-Chave #ttbar differential cross section boosted 8 TeV #scuola :: 843899 :: Scienze #cds :: 8025 :: Fisica [LM-DM270] #indirizzo :: 788 :: Curriculum B: Fisica nucleare e subnucleare #sessione :: seconda
Tipo

PeerReviewed