Study of the ℤ3 symmetry in QCD at finite temperature and chemical potential using a worm algorithm

Traditional Monte Carlo simulations of QCD in the presence of a baryon chemical potential are plagued by the complex phase problem and new numerical approaches are necessary for studying the phase diagram of the theory. In this work we consider a ℤ3 Polyakov loop model for the deconfining phase transition in QCD and discuss how a flux representation of the model in terms of dimer and monomer variable solves the complex action problem. We present results of numerical simulations using a worm algorithm for the specific heat and two-point correlation function of Polyakov loops. Evidences of a first order deconfinement phase transition are discussed. © 2013 American Institute of Physics.

An analysis of the Hygiea asteroid family orbital region

(10) Hygiea is the fourth largest asteroid of the main belt, by volume and mass, and it is the largest member of its family, that is made mostly by low-albedo, C-type asteroids, typical of the outer main belt. Like many other large families, it is associated with a 'halo' of objects, that extends far beyond the boundary of the core family, as detected by traditional hierarchical clustering methods (HCM) in proper element domains. Numerical simulations of the orbital evolution of family members may help in estimating the family and halo family age, and the original ejection velocity field. But, in order to minimize the errors associated with including too many interlopers, it is important to have good estimates of family membership that include available data on local asteroid taxonomy, geometrical albedo and local dynamics. For this purpose, we obtained synthetic proper elements and frequencies of asteroids in the Hygiea orbital region, with their errors. We revised the current knowledge on asteroid taxonomy, including Sloan Digital Sky Survey-Moving Object Catalog 4th release (SDSS-MOC 4) data, and geometric albedo data from Wide-field Infrared Survey Explorer (WISE) and Near-Earth Object WISE (NEOWISE). We identified asteroid family members using HCM in the domain of proper elements (a, e, sin (i)) and in the domains of proper frequencies most appropriate to study diffusion in the local web of secular resonances, and eliminated possible interlopers based on taxonomic and geometrical albedo considerations. To identify the family halo, we devised a new hierarchical clustering method in an extended domain that includes proper elements, principal components PC1, PC2 obtained based on SDSS photometric data and, for the first time, WISE and NEOWISE geometric albedo. Data on asteroid size distribution, light curves and rotations were also revised for the Hygiea family. The Hygiea family is the largest group in its region, with two smaller families in proper element domain and 18 families in various frequencies domains identified in this work for the first time. Frequency groups tend to extend vertically in the (a, sin (i)) plane and cross not only the Hygiea family but also the near C-type families of Themis and Veritas, causing a mixture of objects all of relatively low albedo in the Hygiea family area. A few high-albedo asteroids, most likely associated with the Eos family, are also present in the region. Finally, the new multidomains hierarchical clustering method allowed us to obtain a good and robust estimate of the membership of the Hygiea family halo, quite separated from other asteroids families halo in the region, and with a very limited (about 3 per cent) presence of likely interlopers. © 2013 The Author Published by Oxford University Press on behalf of the Royal Astronomical Society.

Post-sphaleron baryogenesis and an upper limit on the neutron-antineutron oscillation time

A recently proposed scenario for baryogenesis, called post-sphaleron baryogenesis (PSB), is discussed within a class of quark-lepton unified framework based on the gauge symmetry SU(2)L×SU(2) R×SU(4)c realized in the multi-TeV scale. The baryon asymmetry of the Universe in this model is produced below the electroweak phase transition temperature after the sphalerons have decoupled from the Hubble expansion. These models embed naturally the seesaw mechanism for neutrino masses and predict color-sextet scalar particles in the TeV range which may be accessible to the LHC experiments. A necessary consequence of this scenario is the baryon-number-violating ΔB=2 process of neutron-antineutron (n-n̄) oscillations. In this paper we show that the constraints of PSB, when combined with the neutrino oscillation data and restrictions from flavor changing neutral currents mediated by the colored scalars, imply an upper limit on the n-n̄ oscillation time of 5×1010 sec regardless of the quark-lepton unification scale. If this scale is relatively low, in the (200-250) TeV range, τn-n̄ is predicted to be less than 1010 sec, which is accessible to the next generation of proposed experiments. © 2013 American Physical Society.

Regiões de estabilidade no sistema Plutão-Caronte

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Um estudo da dinâmica de captura em ressonância de corrotação

Pós-graduação em Física - FEG

Dinâmica e origem de asteroides de alta inclinação

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo semi-analítico das pertubações nos satélites irregulares de Júpiter

Pós-graduação em Física - FEG

Análise da região do anel F de Saturno

Pós-graduação em Física - FEG

Controle de dinâmica caótica com toros robustos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Dinâmica ressonante de alguns satélites artificiais terrestres no sistema Terra-Lua-Sol

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo de multirefringência na dinâmica de um feixe de luz considerando o bilhar anular

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Possíveis conseqüências na evolução de Triton em queda

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Possíveis ressonâncias nos sistemas de Marte-Phobos e Netuno-Triton-Proteus

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudo de Monte Carlo da produção de nova ressonância neutra decaindo em dois bósons vetoriais no experimento CMS

Pós-graduação em Física - IFT

A presença de Kierkegaard na Teoria do Romance do jovem Lukács

Pós-graduação em Filosofia - FFC