Searcharxiv⌕ Search

arXiv subjects

R. Cowsik

Publications and source records attributed to R. Cowsik.

24 records · Page 2Linked to original sources
arXiv2000

Early observations of the Afterglow of GRB000301c

We report multiband observations of the Optical Transient (OT) associated with GRB000301c carried out between 2--4 March 2000 using the 2.34-m Vainu Bappu Telescope (VBT) at Kavalur, India. When combined with other reported data, the initial decline in the R-band magnitude with log ($t-t_0$), the time since the burst is fit with a slope $α_{1}$ = -0.70 $\pm$ 0.07 which steepens after about 6.0 days to a slope of $α_{2}$ = -2.44 $\pm$ 0.29. This change in slope does not occur smoothly but there is an indication for a bimodal distribution. The available measurements of the evolution of (B--R) color do not show any discernible evolution in the first 12 days.

astro-ph↗
arXiv1999

Radio Ranging Techniques to test Relativistic Gravitation

It is suggested that modern techniques of radio ranging when applied to study the motion of the Moon, can improve the accuracy of tests of relativistic gravitation obtained with currently operating laser ranging techniques. Other auxillary information relevant to the Solar system would also emerge from such a study.

astro-ph↗
arXiv1998

A Bound on Violations of Lorentz Invariance

Recently Coleman and Glashow [1] have developed a model which allows the introduction of a small violation of Lorentz invariance. Observational signatures arise because this interaction also violates flavor conservation and allows the radiative decay of the muon, $μ\to e + γ$, whose branching ratio increases as b $γ^4$ where $γ$ is the Lorentz factor of the muon with respect to the reference frame in which the dipole anisotropy of the universal microwave radiation vanishes. In this paper we place a bound of b$< 10^{-25}$ based on observations of horizontal air showers with $n_e \geq 5 \times 10^6$. With such small values of b the proposed radiative decay of the muon will not affect the functioning of the muon collider.(THIS IS A PRELIMINARY VERSION)

hep-ph↗
arXiv1996

Reply to Comment on ``Dispersion Velocity of Galactic Dark Matter Particles'' by Evans (astro-ph/9606155)

In a recent Comment on our Letter (Phys. Rev. Lett, Vol 76, p 3886 (1996); astro-ph/9605001) Evans (astro-ph/9606155) has raised some issues concerning the specific choice of the distribution function used in our calculation. He has also raised questions concerning the numerical validity of our results. We clarify these issues and show that Evans's criticisms are unfounded and that our results are robust and remain unaffected.

astro-ph↗
arXiv1996

The Dispersion Velocity of Galactic Dark Matter Particles

The self-consistent spatial distribution of particles of Galactic dark matter is derived including their own gravitational potential, as also that of the visible matter of the Galaxy. In order to reproduce the observed rotation curve of the Galaxy the value of the dispersion velocity of the dark matter particles, $\rmsveldm$, should be $\sim 600\kmps$ or larger.

astro-ph↗