Título: | SEARCH FOR CP VIOLATION IN THE D+ → Π−Π+K+ PHASE SPACE IN THE LHCB EXPERIMENT | ||||||||||||
Autor: |
VICTORIA RAMOS DE OLIVEIRA |
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Colaborador(es): |
CARLA GOBEL BURLAMAQUI DE MELLO - Orientador |
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Catalogação: | 22/NOV/2023 | Língua(s): | ENGLISH - UNITED STATES |
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Tipo: | TEXT | Subtipo: | THESIS | ||||||||||
Notas: |
[pt] Todos os dados constantes dos documentos são de inteira responsabilidade de seus autores. Os dados utilizados nas descrições dos documentos estão em conformidade com os sistemas da administração da PUC-Rio. [en] All data contained in the documents are the sole responsibility of the authors. The data used in the descriptions of the documents are in conformity with the systems of the administration of PUC-Rio. |
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Referência(s): |
[pt] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=65049&idi=1 [en] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=65049&idi=2 |
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DOI: | https://doi.org/10.17771/PUCRio.acad.65049 | ||||||||||||
Resumo: | |||||||||||||
The Standard Model (SM) of particle physics is currently the best theory
to describe the interactions between elementary particles and their properties.
The observation of CP violation in a variety of weak processes in the quark
sector — allowing an absolute distinction of particles and antiparticles —
is well explained by the SM (through so-called Cabibbo-Kobayashi-Maskawa
ansatz). CP violation is one of the necessary conditions for baryogenesis and
might be the key to explain the matter-antimatter asymmetry in the universe.
This dissertation presents the search for CP violation in the doubly
Cabibbo suppressed (DCS) D+ → π−π+K+ decay, using data collected by
LHCb from 2016-2018 of pp collisions with a centre of mass energy of 13
TeV, corresponding to an integrated luminosity of 5.6 fb1. The goal of this
analysis is the implementation of a model-independent technique to perform
a statistical comparison between the phase space, called Dalitz Plot (DP),
of particle and antiparticle decay channel, searching for local differences in
the distribution of events between the two DPs. First, a selection process was
executed to remove background contributions from other charm decays, as
well as a multivariate analysis using machine learning algorithms to reduce
combinatorial background levels. After the selection, a final sample of ¨6M
signal candidates was obtained, which is nowadays the largest sample ever
obtained for a DCS D+ decay channel, allowing an outstanding sensitivity
for CPV search. This is the first CPV search in the studied decay channel.
This analysis is performed blinded, meaning that there is no actual result for
the signal region at this first stage and in order to guarantee that there are
no nuisance asymmetries, from production and detection effects, tests were
performed using the background region, the control channel D+ → K−π+π+
and the Monte Carlo simulated sample.
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