A. Rahaman

CHIRAL QED IN TERMS OF CHIRAL BOSON WITH A GENERALIZED FADDEEVIAN REGULARIZATION

Chiral QED with a generalized Faddeevian regularization is considered. Imposing a chiral constraint a gauged version of Floreanini–Jackiw Lagrangian is constructed. The imposition of the chiral constraint has spoiled the manifestly Lorentz covariance structure of the theory. The phase space structure for this theory has been determined in the present situation. It is found that spectrum changes drastically but it remains Lorentz invariant in its constrained (physical) subspace. Chiral fermion disappears from the spectra and the photon acquire mass as well. Poincare algebra has been calculated to show physical Lorentz invariance explicitly.

NONPERTURBATIVE SOLUTION OF THE NONCONFINING SCHWINGER MODEL WITH A GENERALIZED REGULARIZATION

The nonconfining Schwinger model4 is studied with a one-parameter class of kinetic energy-like regularization. It may be thought of as a generalization over the regularization considered in Ref. 4. The phase space structure has been determined in this new situation. The mass of the gauge boson acquires a generalized expression with the bare coupling constant and the parameters involved in the regularization. The confinement and deconfinement scenario has been studied at the quark–antiquark potential level.

To Restore the Broken Symmetry in the Nonconfining Schwinger Model

A new generalization of the vector Schwinger model is considered where gauge symmetry is broken at the quantum mechanical level. By proper extension of the phase space this broken symmetry has been restored in two different ways. One of these two leads to a BRST-invariant effective action. An equivalent gauge-invariant theory is reformulated even in the usual phase space also.

Gauged Floreanini-Jackiw type chiral boson and its BRST quantization

Abstract The gauged model of Siegel type chiral boson is considered. It has been shown that the action of gauged model of Floreanini–Jackiw (FJ) type chiral boson is contained in it in an interesting manner. A BRST invariant action corresponding to the action of gauged FJ type chiral boson has been formulated using Batalin, Fradkin and Vilkovisky based improved Fujiwara, Igarishi and Kubo (FIK) formalism. An alternative quantization of the gauge symmetric action has been made with a Lorentz gauge and an attempt has been made to establish the equivalence between the gauge symmetric version of the extended phase space and original gauge non-invariant version of the usual phase space.

On the BRST and finite field-dependent BRST of a model where vector and axial vector interactions get mixed up with different weights

The generalized version of a lower dimensional model where vector and axial vector interactions get mixed up with different weights is considered. The bosonized version of which does not possess the local gauge symmetry. An attempt has been made here to construct the BRST invariant reformulation of this model using Batalin–Fradlin and Vilkovisky formalism. It is found that the extra field needed to make it gauge invariant turns into Wess–Zumino scalar with appropriate choice of gauge fixing. An application of finite field-dependent BRST and anti-BRST transformation is also made here in order to show the transmutation between the BRST symmetric and the usual nonsymmetric version of the model.

Coulomb breakup of neutron-rich Na-29,Na-30 isotopes near the island of inversion

First results are reported on the ground state configurations of the neutron-rich Na-29,Na-30 isotopes, obtained via Coulomb dissociation (CD) measurements. The invariant mass spectra of these nuclei have been obtained through measurement of the four-momenta of all decay products after Coulomb excitation of those nuclei on a Pb-208 target at energies of 400-430 MeV/nucleon using the FRS-ALADIN-LAND setup at GSI, Darmstadt. Integrated inclusive CD cross-sections (CD) of 89 (7) mb and 167 (13) mb for one neutron removal from Na-29 and Na-30, respectively, have been extracted up to an excitation energy of 10 MeV. The major part of one neutron removal, CD cross-sections of those nuclei populate the core, in its ground state. A comparison with the direct breakup model, suggests the predominant occupation of the valence neutron in the ground state of Na-29 (3/2(+)) and Na-30 (2(+)) is the d-orbital with a small contribution from the s-orbital, which are coupled with the ground state of the core. One of the major components of the ground state configurations of these nuclei are Na-28(gs)(1(+)) circle times v(s,d) and Na-29(gs)(3/2(+)) circle times v(s,d), respectively. The ground state spin and parity of these nuclei obtained from this experiment are in agreement with earlier reported values. The spectroscopic factors for the valence neutron occupying the s and d orbitals for these nuclei in the ground state have been extracted and reported for the first time. A comparison of the experimental findings with shell model calculation using the MCSM suggests a lower limit of around 4.3 MeV of the sd-pf shell gap in Na-30.