118850311
Phase Structure of Thermal QCD/QED:A Gauge Invariant Solution of the HTL Resummed Improved Ladder Dyson-Schwinger Equation
Based on the hard-thermal-loop resummed improved ladder Dyson-Schwinger quation for the fermion mass function, we propose a procedure how we can get the gauge invariant solution in the sense it satisfies the Ward-Takahashi identity. Results of the numerical analysis are shown and properties of the ``gauge-invariant'' solutions are discussed.
15470225
Analysis of the phase structure of thermal QED/QCD through the HTL improved ladder Dyson-Schwinger equation: On the gauge dependence of the solution
We solved with a numerical procedure the HTL improved ladder DS equation for the retarded fermion self-energy function $\Sigma_R$ to study the spontaneous generation of fermion mass in thermal QCD/QED, and studied the gauge-dependence of the solution within a general covariant gauge where the gauge parameter $\xi$ is any constant number. 
With the numerical solutions thus obtained, we found the followings; i) The fermion wave function renormalization function $A(P)$ always deviates largely from unity even at the momentum where the mass is defined, thus the corresponding solutions explicitly contradict with the Ward-Takahashi identity. ii) As a result, the obtained solutions strongly depend on the choice of gauge parameters: the critical temperatures and the critical coupling constants significantly change gauge by gauge. In all gauges we studied in the present analysis, we could not find any solution, having a possibility to be consistent with the Ward-Takahashi identity. Thus we are forced to investigate the procedure to find a gauge which enables us to get a solution being consistent with the Ward-Takahashi identity, otherwise we can not obtain any physically sensible conclusions through the analysis of the point-vertex ladder DS equation no matter how the gauge propagator gets improved.
2677382
Phase Structure of Compact QED from the Sine-Gordon/Massive Thirring Duality
We discuss a phase structure of compact QED in four dimensions by considering the theory as a perturbed topological model. In this scenario we use the singular configuration with an appropriate regularization, and so obtain the results similar to the lattice gauge theory due to the effect of topological objects. In this paper we calculate the thermal pressure of the topological model by the use of a one-dimensional Coulomb gas approximation, which leads to a phase structure of full compact QED. Furthermore the critical-line equation is explicitly evaluated. We also discuss relations between the monopole condensation in compact QED in four dimensions and the chiral symmetry restoration in the massive Thirring model in two dimensions.
123656946
Fermionic functional integration and the temporal gauge of QCD
SummaryIn this paper we compute the Feynman transition amplitude which describes the finite-time propagation of fermionic fields and use this result to extend to QCD the functional formulation of the temporal gauge (Ao=0), already known for pure Yang-Mills theories.RiassuntoIn questo lavoro si calcola l'ampiezza di transizione di Feynman che descrive la propagazione in tempo finito di campi fermionici: questo risultato è usato per estendere alla QCD la formulazione funzionale del «gauge» temporale (Ao=0), già nota per teorie di Yang-Mills.РезюмеВ этой статье мы вычисляем амплитуду перехода Фейнмана, которая описывает распределение фермионных полей в случае конечного времени. Полученный результат испоьзуется для обобщения на случай квантовой хромодинамики функциональной формулировки временной калибровки (A0=0), уже известной для чистых теорий Янга-Миллса.
10603102
Phase structure of a compact U(1) gauge theory from the viewpoint of a sine-Gordon model
We discuss the phase structure of the four-dimensional compact U(1) gauge theory at finite temperature using a deformation of the topological model. Its phase structure can be determined by the behavior of the Coulomb gas (CG) system on the cylinder. We utilize the relation between the CG system and the sine-Gordon (SG) model, and investigate the phase structure of the gauge theory in terms of the SG model. Especially, the critical-line equation of the gauge theory in the strong-coupling and high-temperature region is obtained by calculating the one-loop effective potential of the SG model.
121806959
Measurements of interaction cross sections for light neutron-rich nuclei at relativistic energies and determination of effective matter radii
Abstract We measured the interaction cross sections ( σ I ) of 10,11B, 12–20C, 14–23N, 16–24O and 18–26F on carbon targets at energies of around 950 A MeV. We then deduced the effective matter radii of the nuclei by a Glauber-model analysis. Based on the assumption of a core plus a valence neutron structure, we applied a Glauber-model analysis for a few-body system adapted for nuclei with an odd neutron number. We also deduced the effective nucleus-matter densities as well as some spectroscopic information for selected nuclei. Evidence for a one-neutron halo structure was found for 22N, 23O and 24F, as well as 19C.
85443520
Hybrid classical integrability in squashed sigma models
Abstract We show that SU ( 2 ) L Yangian and q -deformed SU ( 2 ) R symmetries are realized in a two-dimensional sigma model defined on a three-dimensional squashed sphere. These symmetries enable us to develop the two descriptions to describe its classical dynamics, 1) rational and 2) trigonometric descriptions. The former 1) is based on the SU ( 2 ) L symmetry and the latter 2) comes from the broken SU ( 2 ) R symmetry. Each of the Lax pairs constructed in both ways leads to the same equations of motion. The two descriptions are related to one another through a non-local map.