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Master's Dissertation
DOI
10.11606/D.43.2009.tde-15042009-154205
Document
Author
Full name
Raphael Moreira de Albuquerque
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2009
Supervisor
Committee
Nielsen, Marina (President)
Chiapparini, Marcelo
Frederico, Tobias
Title in Portuguese
Estudo da estrutura dos novos mésons
Keywords in Portuguese
Cromodinâmica Quântica
Detecção de Partículas
Física de Partículas
Física Experimental
Física Nuclear
Abstract in Portuguese
Nós utilizamos as Regras de Soma da QCD para estudar a natureza dos mésons observados recentemente Y (4260), Y (4360) e Y (4660), e que são candidatos a estados exóticos de tetraquark (c¯cq¯q) ou (c¯cs¯s) com números quânticos JPC = 1. Nós trabalhamos com o termo dominante em s, com as contribuições dos condensados de dimensão mais alta e com termos lineares da massa do quark estranho ms. Nós obtivemos uma massa mY = (4.65 ± 0.11) GeV para o estado (c¯cs¯s) que é compatível com o valor experimental do Y (4660), enquanto que para o estado (c¯cq¯q) n´os obtivemos uma massa mY = (4.49 ± 0.11) GeV, que também é consistente com o valor experimental do Y (4360). Com a estrutura de tetraquark não foi possível explicar o Y (4260). Nós também consideramos os estados moleculares Ds0 ¯D s e D0 ¯D . Para a molécula Ds0 ¯D s nós obtivemos uma massa mDs0 ¯D s = (4.42 ±0.10) GeV que é consistente, considerando a incerteza, com a massa do méson Y (4360) e para a molécula D0 ¯D obtivemos mD0 ¯D = (4.27±0.10) GeV em excelente acordo com a massa do m´eson Y (4260).
Title in English
Study of the structure of new mesons
Keywords in English
Detection of Particles
Experimental Physics
Nuclear Physics
Particle Physics
Quantum Chromodynamics
Abstract in English
We use QCD sum rules to test the nature of the recently observed mesons Y (4260), Y (4360) and Y (4660), assumed to be exotic four-quark (c¯cq¯q) or (c¯cs¯s) states with JPC = 1. We work at leading order in s, consider the contributions of higher dimension condensates and keep terms which are linear in the strange quark mass ms. We find for the (c¯cs¯s) state a mass mY = (4.65 ± 0.10) GeV which is compatible with the experimental candidate Y (4660), while for the (c¯cq¯q) state we find a mass mY = (4.49 ± 0.11) GeV, which is still consistent with the mass of the experimental candidate Y (4360). With the tetraquark structure we are working we can not explain the Y (4260) as a tetraquark state. We also consider molecular Ds0 ¯D s and D0 ¯D states. For the Ds0 ¯D s molecular state we get mDs0 ¯D s = (4.42 ± 0.10) GeV which is consistent, considering the errors, with the mass of the meson Y (4360) and for the D0 ¯D molecular state we get mD0 ¯D = (4.27±0.10) GeV in excelent agreement with the mass of the meson Y (4260).
 
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Publishing Date
2009-04-16
 
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