The Experts below are selected from a list of 4215 Experts worldwide ranked by ideXlab platform
Dirk H Rischke - One of the best experts on this subject based on the ideXlab platform.
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o 2 model in polar coordinates at Nonzero Temperature
Physical Review D, 2013Co-Authors: Mara Grahl, Francesco Giacosa, Dirk H Rischke, Elina SeelAbstract:We study the restoration of spontaneously broken symmetry at Nonzero Temperature in the framework of the O(2) model using polar coordinates. We apply the CJT formalism to calculate the masses and the condensate in the double-bubble approximation, both with and without a term that explicitly breaks the O(2) symmetry. We find that, in the case with explicitly broken symmetry, the mass of the angular degree of freedom becomes tachyonic above a Temperature of about 300 MeV. Taking the term that explicitly breaks the symmetry to be infinitesimally small, we find that the Goldstone theorem is respected below the critical Temperature. However, this limit cannot be performed for Temperatures above the phase transition. We find that, no matter whether we break the symmetry explicitly or not, there is no region of Temperature in which the radial and the angular degree of freedom become degenerate in mass. These results hold also when the mass of the radial mode is sent to infinity.
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quark spectral function and deconfinement at Nonzero Temperature
Physical Review D, 2013Co-Authors: Dirk H RischkeAbstract:The maximum entropy method is used to compute the quark spectral function at Nonzero Temperature. We solve the gap equation of quantum chromodynamics (QCD) self-consistently, employing a rainbow kernel which phenomenologically models results from Dyson-Schwinger equations (DSE) and lattice QCD. We use the criterion of positivity restoration of the spectral function as a signal for deconfinement. Our calculation indicates that the critical Temperature of deconfinement $T_d$ is slightly smaller than the one of chiral symmetry restoration $T_c$: $T_d\sim 94% T_c$ in the chiral limit, and $T_d\sim 96% T_c$ with physical light quark masses. Since these deviations are within the systematic error of our approach, it is reasonable to conclude that chiral symmetry restoration and deconfinement coincide at zero chemical potential.
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light tetraquark state at Nonzero Temperature
arXiv: High Energy Physics - Phenomenology, 2010Co-Authors: Achim Heinz, Stefan Struber, Francesco Giacosa, Dirk H RischkeAbstract:We study the implications of a light tetraquark on the chiral phase transition at Nonzero Temperature $T$: The behavior of the chiral and four-quark condensates and the meson masses are studied in the scenario in which the resonance $f_{0}(600)$ is described as a predominantly tetraquark state. It is shown that the critical Temperature is lowered and the transition softened. Interesting mixing effects between tetraquark, and quarkonium configurations take place.
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qcd like theories at Nonzero Temperature and density
Journal of High Energy Physics, 2010Co-Authors: Tian Zhang, Dirk H Rischke, Tomays BraunerAbstract:We investigate the properties of hot and/or dense matter in QCD-like theories with quarks in a (pseudo)real representation of the gauge group using the Nambu-Jona-Lasinio model. The gauge dynamics is modeled using a simple lattice spin model with nearest-neighbor interactions. We first keep our discussion as general as possible, and only later focus on theories with adjoint quarks of two or three colors. Calculating the phase diagram in the plane of Temperature and quark chemical potential, it is qualitatively confirmed that the critical Temperature of the chiral phase transition is much higher than the deconfinement transition Temperature. At a chemical potential equal to half of the diquark mass in the vacuum, a diquark Bose-Einstein condensation (BEC) phase transition occurs. In the two-color case, a Ginzburg-Landau expansion is used to study the tetracritical behavior around the intersection point of the deconfinement and BEC transition lines, which are both of second order. We obtain a compact expression for the expectation value of the Polyakov loop in an arbitrary representation of the gauge group (for any number of colors), which allows us to study Casimir scaling at both Nonzero Temperature and chemical potential.
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chiral symmetry restoration at Nonzero Temperature in the su 3 r su 3 l linear sigma model
Physical Review D, 2000Co-Authors: Jonathan T Lenaghan, Dirk H Rischke, J SchaffnerbielichAbstract:We study patterns of chiral symmetry breaking at zero Temperature and its subsequent restoration at Nonzero Temperature within the $\mathrm{SU}{(3)}_{r}\ifmmode\times\else\texttimes\fi{}\mathrm{SU}{(3)}_{l}$ linear sigma model. Gap equations for the masses of the scalar and pseudoscalar mesons and the non-strange and strange quark condensates are systematically derived in the Hartree approximation via the Cornwall-Jackiw-Tomboulis formalism. In the chiral limit, the chiral symmetry restoring transition is found to be first order, as predicted by universality arguments. Taking the experimental values for the meson masses, however, the transition is crossover. The absence of the $\mathrm{U}{(1)}_{A}$ anomaly is found to drive this transition closer to being first order. At large Temperatures, the mixing angles between octet and singlet states approach ideal flavor mixing.
S. D. Odintsov - One of the best experts on this subject based on the ideXlab platform.
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string theory at Nonzero Temperature and two dimensional gravity
Rivista Del Nuovo Cimento, 1992Co-Authors: S. D. OdintsovAbstract:3 Part I. Bosonic string. 3 1. Free energy of ideal gas. 7 2. Free energy for the bosonic string. 10 3. The functional integral for free energy. 11 4. Free energy for interacting strings. 13 5. One-torus compactification. 15 6. r-torus compactification. 17 7. Modular invarianee. 20 8. The modular invariance of closed bosonic string one-loop free energy. 22 9. Modular invariance of closed bosonic string (multi-loop consideration). 23 10. E-duality. 25 11. Hagedorn Temperature.
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Strings at Nonzero Temperature
Soviet Physics Journal, 1991Co-Authors: S. D. Odintsov, I. M. LikhttsierAbstract:String theory at Nonzero Temperature is reviewed. A bosonic string at Nonzero Temperature is studied and the calculation of its free energy in both the one-loop approximation and the case of arbitrary genus (multiloop analysis) is discussed. A string at Nonzero Temperature is compared with a string compacted on a one-dimensional torus. The properties of modular invariance and dual symmetry are discussed at both the one-loop and multiloop levels. The thermodynamics of superstrings, including also superstrings compactified on a torus, is also studied. Possible cosmological applications are briefly considered. It is shown that many features of string thermodynamics (in particular, the existence of the Hagedorn Temperature and dual symmetry) also occur in the theory of noncritical strings.
G R Jafari - One of the best experts on this subject based on the ideXlab platform.
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mean field solution of structural balance dynamics in Nonzero Temperature
Physical Review E, 2019Co-Authors: F Rabbani, A H Shirazi, G R JafariAbstract:: In signed networks with simultaneous friendly and hostile interactions, there is a general tendency to a global structural balance, based on the dynamical model of links status. Although the structural balance represents a state of the network with a lack of contentious situations, there are always tensions in real networks. To study such networks, we generalize the balance dynamics in Nonzero Temperatures. The presented model uses elements from Boltzmann-Gibbs statistical physics to assign an energy to each type of triad, and it introduces the Temperature as a measure of tension tolerance of the network. Based on the mean-field solution of the model, we find out that the model undergoes a first-order phase transition from an imbalanced random state to structural balance with a critical Temperature T_{c}, where in the case of T>T_{c} there is no chance to reach the balanced state. A main feature of the first-order phase transition is the occurrence of a hysteresis loop crossing the balanced and imbalanced regimes.
Steven G Johnson - One of the best experts on this subject based on the ideXlab platform.
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calculation of Nonzero Temperature casimir forces in the time domain
Physical Review A, 2011Co-Authors: Alexander P Mccauley, Alejandro W Rodriguez, M Homer T Reid, J White, Steven G JohnsonAbstract:We show how to compute Casimir forces at Nonzero Temperatures with time-domain electromagnetic simulations, for example, using a finite-difference time-domain (FDTD) method. Compared to our previous zero-Temperature time-domain method, only a small modification is required, but we explain that some care is required to properly capture the zero-frequency contribution. We validate the method against analytical and numerical frequency-domain calculations, and show a surprising high-Temperature disappearance of a nonmonotonic behavior previously demonstrated in a pistonlike geometry.
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calculation of Nonzero Temperature casimir forces in the time domain
APS, 2011Co-Authors: Alexander P Mccauley, Alejandro W Rodriguez, J White, Marvin Reid, Steven G JohnsonAbstract:Kai Pan,1,2 Alexander P. McCauley,1 Alejandro W. Rodriguez,1 M. T. Homer Reid,1,2 Jacob K. White,2,3 and Steven G. Johnson2,4 1Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA 2Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA 3Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA 4Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA (Received 22 November 2010; revised manuscript received 25 March 2011; published 29 April 2011)
Jonathan T Lenaghan - One of the best experts on this subject based on the ideXlab platform.
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chiral symmetry restoration at Nonzero Temperature in the su 3 r su 3 l linear sigma model
Physical Review D, 2000Co-Authors: Jonathan T Lenaghan, Dirk H Rischke, J SchaffnerbielichAbstract:We study patterns of chiral symmetry breaking at zero Temperature and its subsequent restoration at Nonzero Temperature within the $\mathrm{SU}{(3)}_{r}\ifmmode\times\else\texttimes\fi{}\mathrm{SU}{(3)}_{l}$ linear sigma model. Gap equations for the masses of the scalar and pseudoscalar mesons and the non-strange and strange quark condensates are systematically derived in the Hartree approximation via the Cornwall-Jackiw-Tomboulis formalism. In the chiral limit, the chiral symmetry restoring transition is found to be first order, as predicted by universality arguments. Taking the experimental values for the meson masses, however, the transition is crossover. The absence of the $\mathrm{U}{(1)}_{A}$ anomaly is found to drive this transition closer to being first order. At large Temperatures, the mixing angles between octet and singlet states approach ideal flavor mixing.
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Chiral symmetry restoration at Nonzero Temperature in the SU(3)(r) x SU(3)(l) linear sigma model
Physical Review D, 2000Co-Authors: Jonathan T Lenaghan, Dirk H Rischke, Jürgen Schaffner-bielichAbstract:We study patterns of chiral symmetry breaking at zero Temperature and its subsequent restoration at Nonzero Temperature within the SU(3){sub r}xSU(3){sub l} linear sigma model. Gap equations for the masses of the scalar and pseudoscalar mesons and the non-strange and strange quark condensates are systematically derived in the Hartree approximation via the Cornwall-Jackiw-Tomboulis formalism. In the chiral limit, the chiral symmetry restoring transition is found to be first order, as predicted by universality arguments. Taking the experimental values for the meson masses, however, the transition is crossover. The absence of the U(1){sub A} anomaly is found to drive this transition closer to being first order. At large Temperatures, the mixing angles between octet and singlet states approach ideal flavor mixing.
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the o n model at Nonzero Temperature renormalization of the gap equations in hartree and large n approximations
Journal of Physics G, 2000Co-Authors: Jonathan T Lenaghan, Dirk H RischkeAbstract:The Temperature dependence of the sigma meson and pion masses is studied in the framework of the O(N ) model. The Cornwall-Jackiw-Tomboulis formalism is applied to derive gap equations for the masses in the Hartree and large-N approximations. Renormalization of the gap equations is carried out within the cut-off and counter-term renormalization schemes. A consistent renormalization of the gap equations within the cut-off scheme is found to be possible only in the large-N approximation and for a finite value of the cut-off. On the other hand, the counter-term scheme allows for a consistent renormalization of both the large-N and Hartree approximations. In these approximations, the meson masses at a given Nonzero Temperature depend in general on the choice of the cut-off or renormalization scale. As an application, we also discuss the in-medium on-shell decay widths for sigma mesons and pions at rest.
