Browsing by Author "R. Nag"

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An explanation for negative strange sea polarization using an extended Fock space wavefunction
(1994) R. Nag; S. Sanyal
An extended Fock space wavefunction has been used to explain the origin of the negative strange sea polarization in the proton. This explanation is based primarily on the Clebsch-Gordan coefficients appearing in the wavefunction and is independent of the potential and other parameters of the system. The space part of the wavefunction is handled using hyperspherical harmonics and the effect of antisymmetrization is taken into account. A rough estimate of Delta s is also given.
Connection between low- and high-momentum transfer-spin observables
(1998) R. Nag
The Fock space of the nucleon is extended to include states with three quarks and a gluon together with states of the type three quarks and a quark-antiquark pair. The probabilities of various states are determined using the experimental results of deep inelastic scattering. It is found that the resulting wavefunction is able to correlate spin observables measured at low-momentum transfer (F, D and GA/GV) with those measured in high-momentum transfer using a single multiplicative constant, apart from the usual QCD correction factor. This constant is determined by comparison with experimental values.
Criterion for a unique non-relativistic quark model
(1989) R. Nag; S.N. Mukherjee; S. Sanyal
We have calculated the mean square charge radii of the neutron and proton, and compared them with the experimental values, to construct a unique non-relativistic quark potential model. It is shown for the first time that, contrary to general belief, it is possible to reproduce simultaneously the baryon mass spectrum and the electromagnetic sizes of neutron and proton using a single potential model. It was found necessary to add admixtures of excited states of the nucleon in the unperturbed ground state wavefunctions. © 1989, Indian Academy of Sciences. All rights reserved.
Electromagnetic structure of the proton and baryon spectrum in the nonrelativistic quark model
(1987) R. Nag; S. Sanyal; S.N. Mukherjee
The properties of the positive-parity ground-state baryons are analyzed in the nonrelativistic quark model using the hyperspherical harmonic expansion method to handle the dynamics of the three-quark system bound by a confinement potential. The usual contact term is made more flexible with an adjustable parameter to account for terms missing from the standard Fermi-Breit potential. The root-mean-square radius and charge form factor of the free proton are obtained and compared with experimental values. The reliability of the model is ascertained for the rms radius and charge form factor of the proton and the masses of the ground-state baryons. We also calculate the masses of the N*(1470), N*(1710), and *(1690) resonances. © 1987 The American Physical Society.
Energy levels of a muonic hydrogen atom with the use of a quark model
(1991) R. Nag; S.N. Mukherjee; S. Sanyal
The energy levels of the muonic hydrogen atom are calculated using proton charge distribution due to the nonrelativistic quark model. The charge form factor of the proton calculated in the model is in reasonable agreement with electron-scattering measurements. The effect of two orders of vacuum polarization and the finite size of the proton is included. We find good agreement with the results of earlier works, especially where the experimental charge distribution of the proton was employed. This calculation provides a useful test of nonrelativistic quark models. © 1991 The American Physical Society.
Integrated spin structure function of the nucleon using extended Fock space approach
(Springer Verlag, 1997) R. Nag; S. Sanyal
We study the effect of sea quarks on the integrated spin structure functions, the F/D ratio and the total quark polarization, Σ, of the nucleon. The extended Fock space approach is used to incorporate the sea quarks and its wavefunction is properly antisymmetrized. These configurations give significant contributions to the integrated spin structure functions. In particular, antisymmetrization is found to play an important role in the case of the integrated spin structure function of the neutron and the F/D ratio. We find good agreement with experimental values for all four spin polarization observables. © Springer-Verlag 1996.
Quark potential approach to baryons and mesons
(1993) S.N. Mukherjee; R. Nag; S. Sanyal; T. Morii; J. Morishita; M. Tsuge
Applicability of quark potential models for nucleons, qqq, and heavy mesons like quarkonia QQ̄ and atomlike mesons Qq̄ is reviewed. Information regarding interquark potentials contained therein is used in predicting mass levels of these hadrons, and charge from factors and charge radii of nucleons. Related subjects such as quark cluster effects, heavy flavored baryons and heavy hybrid mesons, non-local potentials in baryons and possible superheavy toponium are reviewed for future development. Theoretical problems connected to the quark potential approach are spelled out. © 1993.
μp/μn using an extended Fock space wavefunction
(1996) S. Sanyal; R. Nag
The ratio of the magnetic moment of the proton to that of the neutron is explained using the extended Fock space wavefunction for the nucleon. In addition, we also show that the same wavefunction is capable of explaining the negative integrated spin structure function of the neutron. © 1996 IOP Publishing Ltd.