Chiral Symmetry Breaking In QED Research Articles

About the chiral symmetry breaking in QED3

The problem of the chiral symmetry breaking in QED 3 is considered by solving the Schwinger–Dyson equation for the fermion propagator in the ladder approximation using the Landau gauge for the photon propagator. Within the framework of the indicated approximation, different simplifications that allow expressions for the fermion mass function to be retrieved in an explicit form are analyzed. The results obtained are compared with the data of numerical analysis. It appears that the neglect of higher Gegenbauer harmonics in the kernel of the initial integral equation for the fermion mass function influences the dynamic mass value and the asymptotics of the mass function only weakly. On the other hand, it is established that the conclusion about a complicated structure of the fermion vacuum of the massive phase is an artifact of linearization of the Schwinger–Dyson equation kernel: consideration of the kernel nonlinearity yields a simple massive phase structure of the fermion vacuum.

Impact of a uniform magnetic field and non-zero temperature on explicit chiral symmetry breaking in QED: arbitrary hierarchy of energy scales

Employing Schwinger's proper-time method, we calculate the -condensate for massive Dirac fermions of charge e interacting with a uniform magnetic field in a heat bath. We present general results for arbitrary hierarchy of the energy scales involved, namely the fermion mass m, the magnetic field strength and temperature T. Moreover, we study particular regimes in detail and reproduce some of the results calculated or anticipated earlier in the literature. We also discuss possible applications of our findings.

Dynamical electron mass in a strong magnetic field

Motivated by recent interest in understanding properties of strongly magnetized matter, we study the dynamical electron mass generated through approximate chiral symmetry breaking in QED in a strong magnetic field. We reliably calculate the dynamical electron mass by numerically solving the nonperturbative Schwinger-Dyson equations in a consistent truncation within the lowest Landau level approximation. It is shown that the generation of dynamical electron mass in a strong magnetic field is significantly enhanced by the perturbative electron mass that explicitly breaks chiral symmetry in the absence of a magnetic field.

Gauge independent approach to chiral symmetry breaking in a strong magnetic field

The gauge independence of the dynamical fermion mass generated through chiral symmetry breaking in QED in a strong, constant external magnetic field is critically examined. We show that the bare vertex approximation, in which the vertex corrections are ignored, is a consistent truncation of the Schwinger–Dyson equations in the lowest Landau level approximation. The dynamical fermion mass, obtained as the solution of the truncated Schwinger–Dyson equations evaluated on the fermion mass shell, is shown to be manifestly gauge independent. By establishing a direct correspondence between the truncated Schwinger–Dyson equations and the 2PI (two-particle-irreducible) effective action truncated at the lowest nontrivial order in the loop expansion as well as in the 1 / N f expansion ( N f is the number of fermion flavors), we argue that in a strong magnetic field the dynamical fermion mass can be reliably calculated in the bare vertex approximation.

Gauge independence and chiral symmetry breaking in a strong magnetic field

The gauge independence of the dynamical fermion mass generated through chiral symmetry breaking in QED in a strong, constant external magnetic field is critically examined. We present a (first, to the best of our knowledge) consistent truncation of the Schwinger–Dyson equations in the lowest Landau level approximation. We demonstrate that the dynamical fermion mass, obtained as the solution of the truncated Schwinger–Dyson equations evaluated on the fermion mass shell, is manifestly gauge independent.

Physical Gauge in the Problem of Dynamical Chiral Symmetry Breaking in QED in a Magnetic Field

We describe how the choice of an appropriate (“physical”) gauge leads to the solution of a nonperturbative problem in quantum electrodynamics: dynamical chiral symmetry breaking in QED in a constant magnetic field.

Theory of the magnetic catalysis of chiral symmetry breaking in QED

The theory of the magnetic catalysis of chiral symmetry breaking in QED is developed. An approximation for the Schwinger–Dyson equations describing reliably this phenomenon is established, i.e. it is shown that there exists a consistent truncation of those equations in this problem. The equations are solved both analytically and numerically, and the dynamical mass of fermions is determined.

Chiral symmetry breaking in QED in a magnetic field at finite temperature

The catalysis of chiral symmetry breaking in the massless weakly coupled QED in a magnetic field at finite temperature is studied. The temperature of the symmetry restoration is estimated analytically as $T_c\simeq m_{dyn}$, where $m_{dyn}$ is the dynamical mass of a fermion at zero temperature.

Infrared Finite Gluon Propagator and the Structure of Chiral Symmetry Breaking

We study the chiral symmetry breaking in QeD, using an effective potential for composite operators, with infrared finite gluon propagators that have been found by numerical calculation of the Schwinger· Dyson equations as well. as in lattice simulations. The existence of a gluon propagator that is finite at k 2 =O modifies substantially the transition between the phases with and without chiral symmetry.

Chiral symmetry breaking in QED with an external field varying in 3D space and time

We study quantum electrodynamics in an external field of gaussian configuration varying in all four dimensions and find that for certain ranges of the widths there is a non-zero value for 〈 ΨΨ〉 ext . This indication of chiral symmetry breaking in QED via a varying external field configuration which is quite similar to those in the GSI experiments, provides further evidence that the peaks seen in those experiments may be explained by a “new” phase of QED.

Chiral symmetry breaking in QED for weak coupling

The authors examine the procedure for studying chiral symmetry breaking for weak coupling in QED. They note that while the lowest non-trivial order calculations using numerical solutions to the Schwinger-Dyson equation indicate a breaking of chiral symmetry, the neglected higher-order contributions to the effective potential have imaginary values which can indicate possible instabilities in the theory.