1,721,007 research outputs found
THE GENERALIZED CHIRAL SCHWINGER MODEL ON THE 2-SPHERE
No full textA family of theories which interpolate between vector and chiral Schwinger models is studied on the two-sphere S2. The conflict between the loss of gauge invariance and global geometrical properties is solved by introducing a fixed background connection. In this way the generalized Dirac-Weyl operator can be globally defined on S2. The generating functional of the Green functions is obtained by taking carefully into account the contribution of gauge fields with non-trivial topological charge and of the related zero-modes of the Dirac determinant. In the decompactification limit, the Green functions of the flat case are recovered; in particular the fermionic condensate in the vacuum vanishes, at variance with its behaviour in the vector Schwinger model
ANOMALOUS DIMENSIONS AND GHOST DECOUPLING IN A PERTURBATIVE APPROACH TO THE GENERALIZED CHIRAL SCHWINGER MODEL
No full textGhost decoupling in the 't Hooft spectrum for mesons
No full textWe show that the replacement of the ''instantaneous'' 't Hooft potential with the causal form suggested by equal time canonical quantization in the light-cone gauge, which entails the occurrence of negative probability states, does not change the bound state spectrum when the difference is treated as a single insertion in the kernel
CHIRAL ANOMALIES FOR VORTEX POTENTIALS IN 2 DIMENSIONS AND A DECOMPACTIFICATION LIMIT
No full textA complete set of eigenfunctions on a two-dimensional sphere is obtained for the Dirac operator corresponding to a vortexlike Abelian potential. Then a decompactification limit is studied from the sphere to R2, in which the potential leads to a constant field configuration. The chiral anomaly is studied by using first-order perturbation theory and the crucial role played by zero modes in this context is carefully discussed
Wilson loops in the adjoint representation and multiple vacua in two-dimensional Yang-Mills theory
No full textQCD(2) with fermions in the adjoint representation is invariant under SU(N)/Z(N) and thereby is endowed with a nontrivial vacuum structure (k-sectors). The static potential between adjoint charges, in the limit of infinite mass, can be therefore obtained by computing Wilson loops in the pure Yang-Mills theory with the same nontrivial structure. When the (Euclidean) space-time is compacted on a sphere S-2, Wilson loops can be exactly expressed in terms of an infinite series of topological excitations (instantons). The presence of ic-sectors modifies the energy spectrum of the theory and its instanton content. For the exact solution, in the limit in which the sphere is decompacted, a k-sector can be mimicked by the presence of k-fundamental charges at infinity, according to Witten's suggestion. However, this property does not hold before decompaction or for the genuine perturbative solution which corresponds to the zero-instanton contribution on S-2
2-DIMENSIONAL EUCLIDEAN ANOMALOUS EFFECTIVE ACTIONS IN EXACTLY SOLVABLE ABELIAN MODELS
No full textWe study two-dimensional Euclidean models involving massless Dirac spinors coupled to topologically trivial vector and axial-vector potentials in the compactifiable case as well as in the case of constant field strengths. In both cases we derive the different forms of the anomalies and, in so doing, clarify several delicate and controversial aspects involving regularization procedures, often debated in the literature
NONPERTURBATIVE SOLUTIONS AND SCALING PROPERTIES OF VECTOR AND AXIAL-VECTOR ELECTRODYNAMICS IN 1+1 DIMENSIONS
No full textWe study by nonperturbative techniques a vector and axial-vector theory characterized by a parameter which interpolates between pure vector and chiral Schwinger models. The main results are two ranges in the space of parameters which exhibit acceptable solutions. In the first range we find a free massive and a free massless bosonic excitation and interacting left-right fermions endowed with asymptotic states, which feel however a long range interaction. In the second range the massless bosonic excitation is a negative norm state which can be consistently expunged from the ''physical'' Hilbert space; fermions are confined. An intriguing feature of our model occurs in the first range where we find that fermionic correlators scale at both short and long distances, but with different critical exponents. The infrared limit in the fermonic sector is nothing but a dynamically generated massless Thirring model
Light-cone physics: Particles and strings - Proceedings of the International Workshop TRENTO 2001 Trento, Italy - 3-11 September 2001 - Foreword
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