Avinash Sharma

Masses of charmed andb-quark hadrons in quasinuclear coloured quark model

Employing non-relativistic quasinuclear coloured quark model, which provides a unified description of mesons and baryons, masses of charmed andb-quark hadrons are studied. Various mass splittings are estimated, and mass relations among them are obtained.

W-exchange dominance and Sigma + to p gamma asymmetry

Assuming the dominance of W-exchange diagrams, the authors evaluate Sigma + to p gamma decay asymmetry in a SU(6) broken quark-diquark model. The asymmetry obtained is negative and large. Other decay rates are also found to be consistent with the available data.

Compatibility of GA/GV, rp and μ p in the quark models

The authors examine the question of a simultaneous fit to GA/GV, rp and mu p in the context of the usual quark models. Neither the non-relativistic harmonic quark model nor the MIT bag model (and its variations) is able to reconcile these three quantities. On the other hand, it is found that a model employing a potential of the form (1+ gamma 0) (1/2Kr2+V0) is able to give an excellent fit to these well known low-energy parameters.

Spin-interaction-affected interquark distances: Effect on V→pγ decays

SummaryRadiative decays of vector mesons are studied by considering spin-spin interaction effects on the spatial structure of the overlap integral. This leads to an additional correction term involving physical masses. An improved fit for the decay widths is obtained.

Baryon magnetic moments in a quark model

The magnetic moments of uncharmed and charmed baryons are considered to arise through single-quark and two-quark transitions in a quark model. The magnetic moment operator is taken to transform as:Tβα ˜aT11, +bT22 +cT33 +dT44, whereTβα are members of SU(4)20′-plet. The assumption, that the magnetic moment operator obtains contribution from the single and two-quark transitions, yields good results for the magnetic moment values of uncharmed baryons. Magnetic moments of charmed baryons can be expressed in terms of one parameter.

Electromagnetic Mass Differences of

The phenomenology of a quantum-chromodynamics-based constituent-quark model is employed to estimate the electromagnetic mass differences of the b-quark hadrons. The sign of D/sup -//sub b/-D/sup 0//sub b/ is found to be negative.