Quasi-particles at finite temperatures

Narnhofer, Heide; Requardt, Manfred; Thirring, Walter

doi:10.1007/bf01210849

Cited by 68 publications

(65 citation statements)

References 14 publications

(14 reference statements)

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“…Though the existence of such a formulation has not yet been excluded, the impossibility of such a bleaching at zero temperature for non-Abelian gauge theories [10] makes this rather unlikely. Furthermore, the impossibility of stable asymptotic states of elementary particles at finite temperature due to the Narnhofer-Thirring theorem [404] alleviates this question anyway [405].…”

Section: Gluons At Finite Temperaturementioning

confidence: 99%

Gauge bosons at zero and finite temperature

2013

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Gauge theories of the Yang-Mills type are the single most important building block of the standard model of particle physics and beyond. They are an integral part of the strong and weak interactions, and in their Abelian version of electromagnetism. Since Yang-Mills theories are gauge theories their elementary particles, the gauge bosons, cannot be described without fixing a gauge. Therefore, to obtain their properties a quantized and gauge-fixed setting is necessary.Beyond perturbation theory, gauge-fixing in non-Abelian gauge theories is obstructed by the Gribov-Singer ambiguity, which requires the introduction of non-local constraints. The construction and implementation of a method-independent gauge-fixing prescription to resolve this ambiguity is the single most important first step to describe gauge bosons beyond perturbation theory. Proposals for such a procedure, generalizing the perturbative Landau gauge, are described here. Their implementation are discussed for two example methods, lattice gauge theory and the quantum equations of motion.After gauge-fixing, it is possible to study gauge bosons in detail. The most direct access is provided by their correlation functions. The corresponding two-and three-point correlation functions are presented at all energy scales. These give access to the properties of the gauge bosons, like their absence from the asymptotic physical state space, particle-like properties at high energies, and the running coupling. Furthermore, auxiliary degrees of freedom are introduced during gauge-fixing, and their properties are discussed as well. These results are presented for two, three, and four dimensions, and for various gauge algebras.Finally, the modifications of the properties of gauge bosons at finite temperature are presented. Evidence is provided that these reflect the phase structure of Yang-Mills theory. However, it is found that the phase transition is not deconfining the gauge bosons, although the bulk thermodynamical behavior is of a Stefan-Boltzmann type. The resolution of this apparent contradiction is also presented. In addition, this resolution provides an explicit and constructive solution to the Linde problem.Thus, the technical and conceptual framework presented here can be taken as a basis how to determine correlation functions in Yang-Mills theory, therefore opening up the avenue to investigate theories of direct practical relevance. The status of this effort will be briefly described, alongside with connections to other approaches to Yang-Mills theory beyond perturbation theory.

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Section: Gluons At Finite Temperaturementioning

confidence: 99%

Gauge bosons at zero and finite temperature

2013

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“…At non-zero temperature the physical processes are essentially dependent on the mixtures induced by the thermal bath. For the physical picture and for building models the question is whether these phenomena can be described in terms of some effective excitations (quasi-particles [20]), which "replace" thus the fundamental particle modes, or completely new states dominate the physics above some T .…”

Section: Introductionmentioning

confidence: 99%

Meson correlators in finite temperature lattice QCD

et al. 2001

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We analyze temporal and spatial meson correlators in quenched lattice QCD at T ≥ 0. Below T c we observe little change in the meson properties as compared with T = 0. Above T c we observe new features: chiral symmetry restoration and signals of plasma formation, but also indication of persisting "mesonic" (metastable) states and different temporal and spatial "masses" in the mesonic channels. This suggests a complex picture of QGP in the region 1 − 1.5 T c .

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“…As argued above, such poles may not exist in a finite temperature system [5], and thus it is on the one hand clear that infrared divergences in finite temperature field theory are not present in the full theory but a mere artifact of perturbation theory.…”

Section: Approximations To the Boson Spectral Functionmentioning

confidence: 99%

“…This NRT theorem due to Narnhofer and Thirring states that particle-like excitations with infinite lifetime can exist in a hot system only if they do not interact [5].…”

Section: Introductionmentioning

confidence: 99%

“…For a sufficiently large coupling, they have a big effect on the propagator along the real axis, while for small coupling they are far away from the physical region. Hence, their consistent removal is mandatory for strongly interacting systems, and the only way to do so is by calculating the real part of the propagator by a dispersion integral according to (5).…”

Section: Ghost Polesmentioning

confidence: 99%

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Damping Rate of a Massive Fermion in a Hot Medium

Henning¹

2000

Condens. Matter Phys.

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In a hot system every excitation acquires a finite lifetime, manifesting itself in a non-zero spectral width. Ordinary damping as well as quantum memory effects arise from this nontrivial spectral function. This report presents a new method for the self-consistent calculation of the spectral width of a fermion coupled to massless bosons of scalar, vector and pseudoscalar type. In accordance with the known procedures of Quantum Electrodynamics, the self-consistent summation of the corresponding Fock diagram eliminates all infrared divergences although the bosons are not screened at all. The solutions for the fermion damping rate are analytical in the coupling constant g , but not analytical in the temperature parameter, i.e., γ ∝ g 2 T + O(g 4 T log(T /M )) .

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Quasi-particles at finite temperatures

Cited by 68 publications

References 14 publications

Gauge bosons at zero and finite temperature

Gauge bosons at zero and finite temperature

Meson correlators in finite temperature lattice QCD

Damping Rate of a Massive Fermion in a Hot Medium

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