10,659 research outputs found
The QCD Critical End Point in the Context of the Polyakov--Nambu--Jona-Lasinio Model
We investigate the phase diagram of the so-called
Polyakov--Nambu--Jona-Lasinio model at finite temperature and nonzero chemical
potential with three quark flavors. Chiral and deconfinement phase transitions
are discussed, and the relevant order-like parameters are analyzed. A special
attention is payed to the critical end point (CEP): the influence of the
strangeness on the location of the CEP is studied; also the strength of the
flavor-mixing interaction alters the CEP location, once when it becomes weaker
the CEP moves to low temperatures and can even disappear.Comment: Prepared for Strangeness in Quark Matter 2011, Sept. 18--24, Cracow,
Polan
Exploring the role of model parameters and regularization procedures in the thermodynamics of the PNJL model
The equation of state and the critical behavior around the critical end point
are studied in the context of the Polyakov--Nambu--Jona--Lasinio model. We
prove that a convenient choice of the model parameters is crucial to get the
correct description of isentropic trajectories. The physical relevance of the
effects of the regularization procedure is insured by the agreement with
general thermodynamic requirements. The results are compared with simple
thermodynamic expectations and lattice data.Comment: Talk given at XIII International Conference on Hadron Spectroscopy
(Hadron 2009), Tallahassee, Florida, USA, 29 Nov - 4 Dec, 200
How parameters and regularization affect the PNJL model phase diagram and thermodynamic quantities
We explore the phase diagram and the critical behavior of QCD thermodynamic
quantities in the context of the so-called Polyakov--Nambu--Jona-Lasinio model.
We show that this improved field theoretical model is a successful candidate
for studying the equation of state and the critical behavior around the
critical end point. We argue that a convenient choice of the model parameters
is crucial to get the correct description of isentropic trajectories. The
effects of the regularization procedure in several thermodynamic quantities is
also analyzed. The results are compared with simple thermodynamic expectations
and lattice data.Comment: 27 pages, 7 figures, 4 tables; PRD versio
How the Polyakov loop and the regularization affect strangeness and restoration of symmetries at finite T
The effects of the Polyakov loop and of a regularization procedure that
allows the presence of high momentum quark states at finite temperature is
investigated within the Polyakov-loop extended Nambu--Jona-Lasinio model. The
characteristic temperatures, as well as the behavior of observables that signal
deconfinement and restoration of chiral and axial symmetries, are analyzed,
paying special attention to the behavior of strangeness degrees of freedom. We
observe that the cumulative effects of the Polyakov loop and of the
regularization procedure contribute to a better description of the
thermodynamics, as compared with lattice estimations. We find a faster partial
restoration of chiral symmetry and the restoration of the axial symmetry
appears as a natural consequence of the full recovering of the chiral symmetry
that was dynamically broken. These results show the relevance of the effects of
the interplay among the Polyakov loop dynamics, the high momentum quark sates
and the restoration of the chiral and axial symmetries at finite temperature.Comment: Talk given at XIII International Conference on Hadron Spectroscopy
(Hadron 2009), Tallahassee, Florida, USA, 29 Nov - 4 Dec, 200
Self-Similarity of Friction Laws
The change of the friction law from a mesoscopic level to a macroscopic level
is studied in the spring-block models introduced by Burridge-Knopoff. We find
that the Coulomb law is always scale invariant. Other proposed scaling laws are
only invariant under certain conditions.}Comment: Plain TEX. Figures not include
Comportamento de híbridos de coqueiro nos Tabuleiros Costeiros do Piauí.
Com o objetivo de avaliar o comportamento de híbridos de coqueiro nas condições de clima e solo dos Tabuleiros Costeiros do Piauí, conduziu-se um experimento no Campo Experimental da Embrapa Meio-Norte em Parnaíba-PI, no período de 2002 a 2004. Utilizou-se o delineamento experimental de blocos ao acaso, com sete tratamentos e quatro repetições. Os tratamentos foram constituídos por cinco híbridos entre coqueiro-anão e coqueiro-gigante: AAG x GBrPF, AVG x GBrPF, AVeJ x GBrRN, AAG x GOA e AVG x GOA) e os dois parentais (GBrRN e AVeJ) como testemunha. As características vegetativas, avaliadas semestralmente, foram o número de folhas vivas (NFV) emitidas (NFE), e as reprodutivas, avaliadas mensalmente, foram o número de inflorescências emitidas (NIE), número de flores femininas por inflorescência (NFFI) e número de frutos colhidos/planta (NFC). Os híbridos AAG x GBrPF; AVG x GBrP e AVG x GOA apresentam maior potencial de adaptação às condições edafoclimáticas dos Tabuleiros Costeiros do Piauí.bitstream/item/35881/1/BP61.pd
Some properties of two Nambu--Jona-Lasinio -type models with inputs from lattice QCD
We investigate the phase diagram of the so-called
Polyakov--Nambu--Jona-Lasinio (PNJL) model at finite temperature and nonzero
chemical potential. The calculations are performed in the light and strange
quark sectors (, , ), which includes the 't Hooft instanton induced
interaction term that breaks the axial symmetry, and the quarks are coupled to
the (spatially constant) temporal background gauge field. On one hand, a
special attention is payed to the critical end point (CEP). The strength of the
flavor-mixing interaction alters the CEP location, since when it becomes weaker
the CEP moves to low temperatures and can even disappear. On the other hand, we
also explore the connection between QCD, a nonlocal Nambu--Jona-Lasinio type
model and the Landau gauge gluon propagator. Possible links between the
quenched gluon propagator and low energy hadronic phenomenology are
investigated.Comment: Contribution to the International Meeting "Excited QCD", Peniche,
Portugal, 06 - 12 May 201
Comportamento de cultivares de coqueiro-anão nos Tabuleiros Costeiros do Piauí.
bitstream/CPAMN-2009-09/20331/1/BOLP60.pd
Agroenergia e as potencialidades do pinhão-manso (Jatropha curcas L.) para a produção de óleo para biodiesel na região Meio-Norte do Brasil.
Introdução; Desenvolvimento; Biodiesel: energia limpa para substituir o óleo diesel fóssil; Pinhão-manso; Espaçamento; Exigências hídricas do pinhão-manso; Biologia floral; Rendimento em óleo; Poda; Produtividade de sementes e óleo de pinhão-manso ;Colheita; Considerações finais.bitstream/item/37189/1/Doc158.pd
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