J P Singh
Articles written in Pramana – Journal of Physics
Volume 60 Issue 2 February 2003 pp 401-404
Working group report: Quantum chromodynamics (QCD) and hadronic structure
Rahul Basu V Ravindran D Choudhury R Gavai S Gupta J P Singh Swapan K Majhi B P Mahapatra Prakash Mathews Rajarshi Ray D Chakrabarti Pijush Bhattacharjee
We discuss potential problems in hadronic physics. Recent developments are reviewed and possible future studies in some interesting areas which are underway are highlighted.
Volume 65 Issue 6 December 2005 pp 1075-1083
Parametric study of optical emission from two successive laser pulses produced chromium and magnesium plasma is presented. The line emission from chromium and magnesium plasma showed an increase by more than six times for double laser pulse excitation than for single-pulse excitation. An optimum increase in emission intensity was noted for inter-pulse delay of ∼2–3 μs for all the elements. The experimental observations were qualitatively explained on the basis of absorption of second laser pulse in the pre-formed (by first laser) coronal plasma by inverse Bremsstrahlung process, which were found responsible for the excitation of more ions and atoms in the plasma. This process starts as the plasma scale length becomes greater than the laser wavelength. This study further indicated the suitability of this technique in the field of elemental analysis
Volume 70 Issue 4 April 2008 pp 565-574 Research Articles
Perfect fluid Bianchi Type-I cosmological models with time varying 𝐺 and 𝛬
Bianchi Type-I cosmological models containing perfect fluid with time varying 𝐺 and 𝛬 have been presented. The solutions obtained represent an expansion scalar 𝜃 bearing a constant ratio to the anisotropy in the direction of space-like unit vector $\lambda^{i}$. Of the two models obtained, one has negative vacuum energy density, which decays numerically. In this model, we obtain $\Lambda \sim H^{2}$, $\Lambda \sim R_{44}/R$ and $\Lambda \sim T^{-2}$ (𝑇 is the cosmic time) which is in accordance with the main dynamical laws for the decay of 𝛬. The second model reduces to a static solution with repulsive gravity.
Volume 97, 2023
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