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Implications of a new effective chiral meson Lagrangian

Osipov, Alexander A.; Sampaio, Marcos; Hiller, Brigitte
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
ENG
Relevância na Pesquisa
36.4%
Based on a recently derived effective chiral meson Lagrangian from the extended SU(2)[circle times operator]SU(2) Nambu-Jona-Lasinio (ENJL) model, in the linear realization of chiral symmetry, we extract to leading order in the 1/Nc expansion all associated relevant three-point functions [rho]-->[pi][pi], [sigma]-->[pi][pi], a1-->[rho][pi], a1-->[sigma][pi], as well as the amplitude for [pi][pi] scattering. We discuss the formal differences of these amplitudes as compared with those derived in the literature and calculate the associated decay widths and scattering parameters. The differences have two origins:; http://www.sciencedirect.com/science/article/B6TVB-44N03J5-1/1/2f1adbabb4cb846149810efe015d2ced

A nuvem mesônica e os fatores de forma estranhos do próton; The meson cloud and the strange form factors of the proton

Leite, Daniela Morales Tolentino
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 25/08/2008 PT
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O objetivo deste trabalho foi incluir o méson escalar $\kappa$ na núvem de mésons estranhos do próton e verificar se, desta forma, a contribuição de estranheza para as suas propriedades eletromagnéticas poderia ser explicada pelo modelo da núvem mesônica. Os observáveis que quantificam tal contribuição são os fatores de forma estranhos elétrico ($G_E^s$) e magnético ($G_M^s$), que têm sido objeto de grande interesse experimental nos últimos 10 anos. Usando a versão da nuvem que inclui o méson $\kappa$, nós calculamos $G_E^s$ e $G_M^s$ em função do momento transferido dentro do intervalo 0 $\leq Q^2 \leq$ 1,2 GeV$^2$, de modo a abranger toda a gama de dados disponíveis no momento. Comparamos nossos resultados com os dados existentes para $G_E^s$ e $G_M^s$ e encontramos um ótimo acordo entre experimento e modelo, demonstrando que a inclusão do $\kappa$ na núvem de mésons do próton é fundamental para que o seu conteúdo de estranheza possa ser compreendido.; The goal of this work was to include the scalar $\kappa$ meson on the meson cloud of the proton, and then to verify if the strangeness contribution to the electromagnetic properties of the proton could be explained by the meson cloud model. The observables that quantify such a contribution are the electric ($G_E^s$) and magnetic ($G_M^s$) strange form factors...

Quark-meson coupling model with constituent quarks: Exchange and pionic effects

Bracco, M. E.; Krein, G.; Nielsen, M.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 258-265
ENG
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The binding energy of nuclear matter including exchange and pionic effects is calculated in a quark-meson coupling model with massive constituent quarks. As in the case with elementary nucleons in QHD, exchange effects are repulsive. However, the coupling of the mesons directly to the quarks in the nucleons introduces a new effect on the exchange energies that provides an extra repulsive contribution to the binding energy. Pionic effects are not small. Implications of such effects on observables are discussed. © 1998 Published by Elsevier Science B.V. All rights reserved.

Droplet formation in cold asymmetric nuclear matter in the quark-meson-coupling model

Krein, G.; Menezes, D. P.; Nielsen, M.; Providência, C.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 125-140
ENG
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The quark-meson-coupling model is used to study droplet formation from the liquid-gas phase transition in cold asymmetric nuclear matter. The critical density and proton fraction for the phase transition are determined in the mean field approximation. Droplet properties are calculated in the Thomas-Fermi approximation. The electromagnetic field is explicitly included and its effects on droplet properties are studied. The results are compared with the ones obtained with the NL1 parametrization of the non-linear Walecka model. © 2000 Elsevier Science B.V.

Heavy-light mesons scattering from nucleons: Quark-gluon and meson exchanges

Fontoura, C. E.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 318-321
ENG
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We investigate the scattering of heavy-light K and D mesons by nucleons at low energies. The short-distance part of the interaction is described by quark-gluon interchange and the longdistance part is described by a one-meson-exchange model that includes the contributions of vector (ρ, ω) and scalar (σ) mesons. The microscopic quark model incorporates a confining Coulomb potential extracted from lattice QCD simulations and a transverse hyperfine interaction consistent with a finite gluon propagator in the infrared. The derived effective meson-nucleon potential is used in a Lippmann-Schwinger equation to obtain s-wave phase shifts. Our final aim is to set up a theoretical framework that can be extended to finite temperatures and baryon densities. © 2010 American Institute of Physics.

DN interaction from the Jülich meson-exchange model

Tolos, L.; Haidenbauer, J.; Krein, G.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 350-352
ENG
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36.4%
The DN interaction is studied in close analogy to the meson-exchange K̄N potential of the Jülich group using SU(4) symmetry constraints. The model generates the Λ c(2595) resonance dynamically as a DN quasi-bound state. Results for DN scattering lengths and cross sections are presented and compared with predictions based on the Weinberg-Tomozawa term. Some features of the Λ c(2595) resonance are also discussed emphasizing the role of the near-by πΣ c threshold. © 2012 American Institute of Physics.

Studies of nucleon resonance structure in exclusive meson electroproduction

Aznauryan, I. G.; Bashir, A.; Braun, V. M.; Brodsky, S. J.; Burkert, V. D.; Chang, L.; Chen, Ch; El-Bennich, B.; Cloët, I. C.; Cole, P. L.; Edwards, R. G.; Fedotov, G. V.; Giannini, M. M.; Gothe, R. W.; Gross, F.; Lin, Huey-Wen; Kroll, P.; Lee, T. S H; M
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.51%
Studies of the structure of excited baryons are key factors to the N* program at Jefferson Lab (JLab). Within the first year of data taking with the Hall B CLAS12 detector following the 12 GeV upgrade, a dedicated experiment will aim to extract the N* electrocouplings at high photon virtualities Q 2. This experiment will allow exploration of the structure of N* resonances at the highest photon virtualities ever achieved, with a kinematic reach up to Q2 = 12 GeV2. This high-Q 2 reach will make it possible to probe the excited nucleon structures at distance scales ranging from where effective degrees of freedom, such as constituent quarks, are dominant through the transition to where nearly massless bare-quark degrees of freedom are relevant. In this document, we present a detailed description of the physics that can be addressed through N* structure studies in exclusive meson electroproduction. The discussion includes recent advances in reaction theory for extracting N* electrocouplings from meson electroproduction off protons, along with Quantum Chromodynamics (QCD)-based approaches to the theoretical interpretation of these fundamental quantities. This program will afford access to the dynamics of the nonperturbative strong interaction responsible for resonance formation...

Limite de acoplamento forte da QCD e a interação méson-méson

Morales, Patrícia Soares
Fonte: Universidade Estadual Paulista (UNESP) Publicador: Universidade Estadual Paulista (UNESP)
Tipo: Dissertação de Mestrado Formato: 83 f.
POR
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Pós-graduação em Física - IFT; O mecanismo de rearranjo de tubos de fluxo predito no limite de acoplamento forte da formulação Hamiltoniana da QCD na rede foi implementado num modelo de quarks constituintes e suas consequências investigadas para o espalhamento méson-méson. O rearranjo de tubos de fluxo leva a efeitos similares aos tradicionais efeitos de troca de quarks com troca de um glúon em interações hádron-hádron. Contudo, enquanto o primeiro está relacionado ao regime de confinamento da QCD, o último está relacionado ao regime de liberdade assintótica desta teoria. Mostra-se aqui que ambos mecanismos levam a resultados qualitativamente similares quando o potencial de rearranjo pode ser escrito como a soma de interações locais quark-quark, antiquark-antiquark e quark-antiquark. Para interações gerais, não locais e de longo alcance, o rearranjo de tubos de fluxo leva a resultados qualitativa e quantitativamente diferentes dos resultados de troca de quarks com troca de um glúon. As consequências disso para a fenomenologia das interações hádron-hádron são discutidas.; The mechanism of link rearrangement predicted in the strong coupling limit of Hamiltonian lattice QCD is implemented in a constituent quark model and its consequences for meson-meson scattering are investigated. Link rearrangement leads to effects similar to the traditional quark exchange with one gluon exchange in hadron-hadron interactions. However while the first is related to the confinement regime of QCD...

Leptonic decays of the B charged meson and B → Xsγ in the Two Higgs Doublet Model type III

Idárraga,J. P.; Martinez,R.; Rodríguez,J-Alexis; Poveda T.,N.
Fonte: Sociedade Brasileira de Física Publicador: Sociedade Brasileira de Física
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2008 EN
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We consider the Two Higgs Doublet Model (2HDM) of type III which leads to Flavour Changing Neutral Currents (FCNC) at tree level. In the framework of this model we calculate the NLO contribution for b → sγ and the branchings for the meson decays B+ → l+ν. We examine the limits on the new parameters λbb and M H±. We take into account the relationship between λtt and λbb coming from the validness of perturbation theory.

Applications of the octet baryon quark-meson coupling model to hybrid stars.

Carroll, Jonathan David
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2010
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The study of matter at extreme densities has been a major focus in theoretical physics in the last half-century. The wide spectrum of information that the field produces provides an invaluable contribution to our knowledge of the world in which we live. Most fascinatingly, the insight into the world around us is provided from knowledge of the intangible, at both the smallest and largest scales in existence. Through the study of nuclear physics we are able to investigate the fundamental construction of individual particles forming nuclei, and with further physics we can extrapolate to neutron stars. The models and concepts put forward by the study of nuclear matter help to solve the mystery of the most powerful interaction in the universe; the strong force. In this study we have investigated a particular state-of-the-art model which is currently used to refine our knowledge of the workings of the strong interaction and the way that it is manifested in both neutron stars and heavy nuclei, although we have placed emphasis on the former for reasons of personal interest. The main body of this work has surrounded an effective field theory known as Quantum Hadrodynamics (QHD) and its variations, as well as an extension to this known as the Quark-Meson Coupling (QMC) model...

Quantum Field Theory Approaches to Meson Structure; Quantenfeldtheoretische Modelle für die Beschreibung von Mesonstruktur

Branz, Tanja
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
EN
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Meson spectroscopy became one of the most interesting topics in particle physics in the last ten years. In particular, the discovery of new unexpected states in the charmonium spectrum which cannot be simply explained by the constituent quark model attracted the interest of many theoretical efforts. In the present thesis we discuss different meson structures ranging from light and heavy quark-antiquark states to bound states of hadrons-hadronic molecules. Here we consider the light scalar mesons f0(980) and a0(980) and the charmonium-like Y(3940), Y(4140) and Z(4430) states. In the discussion of the meson properties like mass spectrum, total and partial decay widths and production rates we introduce three different theoretical methods for the treatment and description of hadronic structure. For the study of bound states of mesons we apply a coupled channel approach which allows for the dynamical generation of meson-meson resonances. The decay properties of meson molecules are further on studied within a second model based on effective Lagrangians describing the interaction of the bound state and its constituents. Besides hadronic molecules the effective Lagrangian approach is also used to study the radiative and strong decay properties of ordinary quark-antiquark states. The AdS/QCD model forms the completion of the three theoretical methods introduced in the present thesis. This holographic model provides a completely different ansatz and is based on extra dimensions and string theory. Within this framework we calculate the mass spectrum of light and heavy mesons and their decay constants.; Meson-Spektroskopie ist eines der interessantesten Themen in der Teilchenphysik. Vor allem durch die Entdeckung von zahlreichen neuen Zuständen im Charmonium Spektrum mit Eigenschaften...

Vector meson mixing and charge symmetry violation.

O'Connell, H.; Williams, A.; Bracco, M.; Krein, G.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
Publicado em //1996 EN
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We discuss the consistency of the traditional vector meson dominance (VMD) model for photons coupling to matter, with the vanishing of vector meson-meson and meson-photon mixing self-energies at q2 = 0. This vanishing of vector mixing has been demonstrated in the context of rho-omega mixing for a large class of effective theories. As a further constraint on such models, we here apply them to a study of photon-meson mixing and VMD. As an example we compare the predicted momentum dependence of one such model with a momentum-dependent version of VMD discussed by Sakurai in the 1960's. We find that it produces a result which is consistent with the traditional VMD phenomenology. We conclude that comparison with VMD phenomenology can provide a useful constraint on such models.; H.B. O’Connell, A.G. Williams, M. Bracco, G. Krein

Vector meson mixing and charge symmetry violation

O'Connell, H. B.; Williams, A. G.; Bracco, M.; Krein, G.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 12-16
ENG
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We discuss the consistency of the traditional vector meson dominance (VMD) model for photons coupling to matter, with the vanishing of vector meson-meson and meson-photon mixing self-energies at q2 = 0. This vanishing of vector mixing has been demonstrated in the context of rho-omega mixing for a large class of effective theories. As a further constraint on such models, we here apply them to a study of photon-meson mixing and VMD. As an example we compare the predicted momentum dependence of one such model with a momentum-dependent version of VMD discussed by Sakurai in the 1960's. We find that it produces a result which is consistent with the traditional VMD phenomenology. We conclude that comparison with VMD phenomenology can provide a useful constraint on such models.

[Vía Vehicular: El mesón]

Universidad de la Sabana; Jordan Gómez, Lizette
Fonte: Universidade La Sabana Publicador: Universidade La Sabana
Tipo: Imagem
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Se muestra un plano panorámico del sendero peatonal desde edificio H hacia El Mesón, a lo largo de la vía, algunos árboles que no fueron talados.

[Sendero peatonal: El mesón]

Universidad de la Sabana; Jordan Gómez, Lizette
Fonte: Universidade La Sabana Publicador: Universidade La Sabana
Tipo: Imagem
Relevância na Pesquisa
36.4%
Se muestra un plano panorámico del sendero peatonal desde edificio H hacia El Mesón, algunos funcionarios de la universidad caminan a lo largo del sendero. A la derecha, algunos árboles recién plantados.

[Residuos del proceso de tala en El Mesón]

Universidad de la Sabana; Jordan Gómez, Lizette
Fonte: Universidade La Sabana Publicador: Universidade La Sabana
Tipo: Imagem
Relevância na Pesquisa
36.4%
Se muestra una vista panorámica de algunos residuos formados por ramas y trozos de tronco en la zona verde de El Mesón, en el centro de la foto, el tocón del árbol talado.

[El Mesón: plano general después de la tala]

Universidad de la Sabana; Jordan Gómez, Lizette
Fonte: Universidade La Sabana Publicador: Universidade La Sabana
Tipo: Imagem
Relevância na Pesquisa
36.4%
Se muestra el Mesón después de la tala en donde se aprecia varias pilas de residuos del proceso de tala y algunos árboles jóvenes recién plantados.

[Residuos de desrame en el Mesón]

Universidad de la Sabana; Jordan Gómez, Lizette
Fonte: Universidade La Sabana Publicador: Universidade La Sabana
Tipo: Imagem
Relevância na Pesquisa
36.4%
Se muestra un plano general de una pila de ramas en la zona verde de El Mesón, se aprecia también algunos árboles jóvenes recién plantados.

New insights on the origin of the Mesón Alto deposit, Yeso Valley, central Chile: A composite deposit of glacial and landslide processes?; Nuevas observaciones sobre el origen del Depósito Mesón Alto, Valle del Yeso, Chile central: un depósito compuesto de procesos glaciares y de remoción en masa?.

Pinto, Luisa; Pinochet, Katherine; Moreiras, Stella M.; Sepúlveda, Sergio A.; Deckart, Katja
Fonte: Servicio Nacional de Geología y Minería Publicador: Servicio Nacional de Geología y Minería
Tipo: Artículo de revista
EN
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Artículo de publicación SciELO; The Mesón Alto chaotic deposit, located in the Main Cordillera at about 33°40’S, is an important landform with a volume of ca. 4.5 km3 unconsolidated material deposited downstream of the Yeso Dam in the Yeso Valley, Río Maipo drainage basin. Historical work related this large deposit to a glacial origin whereas later on, it was assigned to a megalandslide that originated in the Cerro Mesón Alto Massif. First results of integrated fieldwork along with petrographic and geochemical laboratory work on granitoid blocks from five different portions of the deposit, compared with the major outcropping intrusive units in the neighbourhood (La Gloria Pluton, Cerro Mesón Alto Massif and Cerro Aparejo Intrusion) point to a landslide origin of the surface blocks. The results suggest that granitoid fragments of the deposit most likely belong to the Cerro Mesón Alto Massif, the proposed source of the rock avalanche. However, morphometric parameters and field observations support the idea of a rock avalanche deposited on top of glacial material. Therefore, the Mesón Alto deposit should be assigned to a composite origin. Confirmation of a post-glacial, large volume rock avalanche in a strategic area for existent infrastructure for Santiago water supply and ongoing energy projects is fundamental for a correct hazard and risk assessment of the region.; Field work was supported by the Department of Geology at the Universidad de Chile through its Engineering Geology and Natural Hazards Program and by a professor interchange grant of the Cuyo National University to S. Moreiras. The authors would like to thank J. Martínez...

Dynamically generated open and hidden charm meson systems

Gamermann, Daniel; Oset, Eulogi; Strottman, Dan; Vicente Vacas, Manuel J.
Fonte: American Physical Society Publicador: American Physical Society
Tipo: Artículo Formato: 2373 bytes; text/plain
ENG
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17 pages, 13 figures.-- PACS nr.: 12.39.Hg.-- ISI Article Identifier: 000250621200047.-- ArXiv pre-print available at: http://arxiv.org/abs/hep-ph/0612179; We will study open and hidden charm scalar meson resonances within two different models. The first one is a direct application of a chiral Lagrangian already used to study flavor symmetry breaking in Skyrme models. In another approach to the problem a SU(4) symmetric Lagrangian is built and the symmetry is broken down to SU(3) by identifying currents where heavy mesons are exchanged and suppressing those. Unitarization in coupled channels leads to dynamical generation of resonances in both models, in particular, a new hidden charm resonance with mass 3.7 GeV is predicted. The small differences between these models and with previous works is discussed. We also perform an error analysis of the results, checking their stability and determining the uncertainties in masses and couplings of the heavy resonances.; This work is partly supported by DGICYT Contract No. BFM2003-00856 and the Generalitat Valenciana. This research is part of the EU Integrated Infrastructure Initiative Hadron Physics Project under Contract No. RII3-CT-2004-506078.; Peer reviewed