22567437
Induced fermionic charge in background gauge theories in odd space-time dimensions.
123590008
Currents and the anomalies in chiral gauge theories: Dynamical approach in higher dimensions
Abstract An integral representation for the fermion effective action for chiral gauge theories in d = 2 n space-time dimensions is given which is able to reproduce the mismatch, as suggested by differential geometric methods, between the covariant current and the consistent current. Both types of anomalies (i.e. covariant as well as consistent) can also be calculated without having to evaluate Feynman diagrams or to introduce any local counterterms.
14549875
Fermion decoupling and the axial anomaly on the lattice
Abstract In the axial Ward identity of lattice QED we show that in the limit of infinite fermion mass m the pseudoscalar density term exactly cancels the Adler-Bell-Jackiw (ABJ) anomaly. Using this result we calculate the U(1) axial anomaly in a non-abelian gauge theory.
122998425
DYNAMICAL APPROACH TO HIGHER SYMMETRIES.
122763022
Infrared and high energy fixed angle domains of scattering and the role of eikonal approximation
Abstract We examine the infrared structure and fixed angle behaviour of generalised ladder diagrams in spinor electrodynamics. The external line rules for infrared divergence is proved within the framework of parametric representation of the amplitudes. We derive a set of rules for computing the precise form of the leading infrared behaviour of any generalised ladder diagram. The same set of rules is shown to yield the leading term in the high energy fixed angle limit. Our analysis shows that both in the infrared and in the fixed-angle high energy limits the usual propagator eikonal approximation fails even in the leading order. The deficiencies of eikonal approximation can be partially removed if one also makes the small angle approximation. Leading corrections of relative O( |t | 1 2 /s 1 2 ) to the small-angle eikonal amplitude are calculated.
122522996
Dirac fermion in Euclidean metric and theU(1) and strong CP problems
AbstractIn Euclidean metric the usual description of a Dirac fermion needs two independent Dirac fields for ψ(x) and
$$\bar \psi (x)$$
. In the instanton sector this leads to the first option for the fermion path integral which vanishes in the chiral limit due to the zero eigenvalues of the Euclidean Dirac operator. We propose here a novel representation for the conjugate field
$$\bar \psi (x)$$
 which depends on ψ(x), has the correct chiral properties, and reproduces all the fermionic Green functions of the Euclidean theory. In the alternative scenario, the chiral limit of FPI coincides with the product of only the non-zero eigenvalues of the singular Dirac operator in instanton sector, and the QCD action is invariant under global chiral rotation. The anomaly term in effective theory conforming to the alternative scenario breaks chiral symmetry spontaneously and solves theU(1)-problem. A chiral phase in quark mass, which is a possible source of CP violation in the first option, does not have any observable effect in the second. The strong CP problem is a legacy of the first option. In the alternative scenario CP invariance is ensured in QCD if Ψ=0.
26544987
Gauge independent analysis of Chern-Simons theory with matter coupling.
We show that the Chern-Simons theory coupled to complex scalars can be consistently quantized in the Hamiltonian formalism without gauge constraints. A new structure of the anyon operator displaying fractional spin and statistics follows logically from our analysis without any {ital ad} {ital hoc} assumptions.
26680973
Quantum equivalence of O(3) nonlinear sigma model and the CP1 model: A gauge-independent Hamiltonian approach.
We use Dirac's constrained analysis to quantize the O(3) nonlinear [sigma] model and the CP[sup 1] model without using gauge constraints. The equivalence of the models (at the quantum level) is established provided the identification [ital n][sup [ital a]]=[ital Z][sup *][sigma][sup [ital a]Z], [pi][sup [ital a]]=1/2([pi][sigma][sup [ital a]Z]+[ital Z][sup *][sigma][sup [ital a]][pi][sup *]) ([sigma][sup [ital a]]=Pauli matrices) is used to relate the canonical variables. While the first relation has been discussed in the literature, the second relation connecting the canonical momenta is a new observation. It plays a significant role in displaying the above stated equivalence.