Heavy Quarkonium Potential Model and the 1P1{}^1P_1 State of Charmonium

A theoretical explanation of the observed splittings among the P~states of charmonium is given with the use of a nonsingular potential model for heavy quarkonia. We also show that the recently observed mass difference between the center of gravity of the ${}^3P_J$ states and the ${}^1P_1$ state of $c\bar{c}$ does not provide a direct test of the color hyperfine interaction in heavy quarkonia. Our theoretical value for the mass of the ${}^1P_1$ state is in agreement with the experimental result, and its E1 transition width is 341.8~keV. The mass of the $\eta_c'$ state is predicted to be 3622.3~MeV.Comment: 15 page REVTEX documen

Pulsar Scintillation and the Local Bubble

We present here the results from an extensive scintillation study of twenty pulsars in the dispersion measure (DM) range 3 - 35 pc cm^-3 caried out using the Ooty Radio Telescope (ORT) at 327 MHz, to investigate the distribution of ionized material in the local interstellar medium. Observations were made during the period January 1993 to August 1995, in which the dynamic scintillation spectra of these pulsars were regularly monitored over 10 - 90 epochs spanning 100 days. Reliable and accurate estimates of strengths of scattering have been deduced from the scintillation parameters averaged out for their long-term fluctuations arising from refractive scintillation (RISS) effects. Our analysis reveals several anomalies in the scattering strength, which suggest tht the distribution of scattering material in the Solar neighborhood is not uniform. We have modelled these anomalous scattering effects in terms of inhomogeneities in the distribution of electron dnsity fluctuations in the local interstellar medium (LISM). Our model suggests the presence of a low density bubble surrounded by a shell of much higher density fluctuations. We are able to put constraints on geometrical and scattering properties of such a structure, and find it to be morphologically similar to the Local Bubble known from other studies.Comment: 35 pages, 12 figure

Long-Term Scintillation Studies of Pulsars: III. Testing Theoretical Models of Refractive Scintillation

Refractive interstellar scintillation (RISS) is thought to be the cause behind a variety of phenomena seen at radio wavelengths in pulsars and compact radio sources. Though there is substantial observational data to support several consequences of it, the quantitative predictions from theories have not been thoroughly tested. In this paper, data from our long-term scintillation study of 18 pulsars are used to test the predictions. The fluctuations of decorrelation bandwidth ($\nu_d$), scintillation time scale ($\tau_d$) and flux density (F) are examined for their cross-correlations and compared with the predictions. The theory predicts a strong correlation between $\nu_d$ and $\tau_d$, and strong anti-correlations between $\nu_d$ and F, and $\tau_d$ and F. For 5 pulsars, we see a reasonable agreement. There is considerable difficulty in reconciling the results for the rest of the pulsars. Our analysis shows the underlying noise sources can sometimes reduce the correlation, but cannot cause an absence of correlation. It is also unlikely that the poor flux correlations arise from a hitherto unrecognized intrinsic flux variations. For PSR B0834+06, which shows anomalous behaviour of persistent drift slopes, positive correlation is found between $\tau_d$ and the drift-corrected $\nu_d$. Many pulsars show an anti-correlation between $\nu_d$ and the drift slope, and this is in accordance with the simple models of RISS. The detections of correlated variations of observables and a reasonable agreement between the predicted and measured correlations for some pulsars confirm RISS as the primary cause of the observed fluctuations. However, the complexity seen with the detailed results suggests the necessity of more comprehensive theoretical treatments for describing refractive fluctuations and their correlations.Comment: 27 pages, 6 Figures, 6 Tables. Accepted for publication in The Astrophysical Journa

Surface-slip equations for multicomponent nonequilibrium air flow

Equations are presented for the surface-slip (or jump) values of species concentration, pressure, velocity, and temperature in the low-Reynolds number, high-altitude flight regime of a space vehicle. The equations are obtained from closed form solutions of the mass, momentum, and energy flux equations using the Chapman-Enskog velocity distribution function. This function represents a solution of the Boltzmann equation in the Navier-Stokes approximation. The analysis, obtained for nonequilibrium multicomponent air flow, includes the finite-rate surface catalytic recombination and changes in the internal energy during reflection from the surface. Expressions for the various slip quantities were obtained in a form which can be employed in flowfield computations. A consistent set of equations is provided for multicomponent, binary, and single species mixtures. Expression is also provided for the finite-rate, species-concentration boundary condition for a multicomponent mixture in absence of slip

A new microscopic nucleon-nucleon interaction derived from relativistic mean field theory

A new microscopic nucleon-nucleon (NN) interaction has been derived for the first time from the popular relativistic mean field theory (RMFT) Lagrangian. The NN interaction so obtained remarkably relate to the inbuilt fundamental parameters of RMFT. Furthermore, by folding it with the RMFT-densities of cluster and daughter nuclei to obtain the optical potential, it's application is also examined to study the exotic cluster radioactive decays, and results obtained found comparable with the successfully used M3Y phenomenological effective NN interactions. The presently derived NN-interaction can also be used to calculate a number of other nuclear observables.Comment: 4 Pages 2 Figure

Surface-slip equations for multicomponent, nonequilibrium air flow

Equations are presented for the surface slip (or jump) values of species concentration, pressure, velocity, and temperature in the low-Reynolds-number, high-altitude flight regime of a space vehicle. These are obtained from closed-form solutions of the mass, momentum, and energy flux equations using the Chapman-Enskog velocity distribution function. This function represents a solution of the Boltzmann equation in the Navier-Stokes approximation. The analysis, obtained for nonequilibrium multicomponent air flow, includes the finite-rate surface catalytic recombination and changes in the internal energy during reflection from the surface. Expressions for the various slip quantities have been obtained in a form which can readily be employed in flow-field computations. A consistent set of equations is provided for multicomponent, binary, and single species mixtures. Expression is also provided for the finite-rate species-concentration boundary condition for a multicomponent mixture in absence of slip