Physicshttp://repository.iitgn.ac.in/handle/123456789/6072017-12-07T10:04:50Z2017-12-07T10:04:50ZGW170608: Observation of a 19-solar-mass binary Black Hole coalescenceSengupta, Anandhttp://repository.iitgn.ac.in/handle/123456789/33422017-12-06T05:29:09Z2017-11-01T00:00:00ZGW170608: Observation of a 19-solar-mass binary Black Hole coalescence
Sengupta, Anand
On June 8, 2017 at 02:01:16.49 UTC, a gravitational-wave signal from the merger of two stellar-mass black holes was observed by the two Advanced LIGO detectors with a network signal-to-noise ratio of 13. This system is the lightest black hole binary so far observed, with component masses 12+7?2M? and 7+2?2M? (90% credible intervals). These lie in the range of measured black hole masses in low-mass X-ray binaries, thus allowing us to compare black holes detected through gravitational waves with electromagnetic observations. The source's luminosity distance is 340+140?140 Mpc, corresponding to redshift 0.07+0.03?0.03. We verify that the signal waveform is consistent with the predictions of general relativity.
2017-11-01T00:00:00ZHeavy quark complex potential in a strongly magnetized hot QGP mediumSingh, BalbeerThakur, LataMishra, Hiranmayahttp://repository.iitgn.ac.in/handle/123456789/33312017-12-06T05:29:07Z2017-11-01T00:00:00ZHeavy quark complex potential in a strongly magnetized hot QGP medium
Singh, Balbeer; Thakur, Lata; Mishra, Hiranmaya
We study the effect of strong constant magnetic field, generated in relativistic heavy ion collisions, on the heavy quark complex potential. We work in the strong magnetic field limit with lowest Landau level approximation. We find that the screening of the real part of the potential increases with the increase in the magnetic field. Therefore, we expect less binding of QQ� pair in the presence of strong magnetic field. The imaginary part of the potential increases in magnitude with the increase in magnetic field, leading to a increase of the width of the quarkonium state with the magnetic field. All of these effects results in the early dissociation of QQ� states in a magnetized hot quark-gluon plasma medium.
2017-11-01T00:00:00ZSub-MeV self interacting dark matterChauhan, Bhaveshhttp://repository.iitgn.ac.in/handle/123456789/33302017-12-06T05:29:07Z2017-11-01T00:00:00ZSub-MeV self interacting dark matter
Chauhan, Bhavesh
In this paper, we present a model for sub-MeV dark matter with strong self interactions which can solve some of the small scale crisis of the ?CDM. The dark matter is a Majorana fermion with only off-diagonal interactions with a hidden U(1)D gauge boson. The relic density is obtained by freeze-out of Boltzmann suppressed annihilations to a light fermionic species. The self interaction is a one loop process and constrained to be between 0.1 to 1 cm2/g. Severe constraints from the BBN on Neff require that the dark and visible sector are not in thermal equilibrium during freeze-out. The effect of this temperature asymmetry is studied.
2017-11-01T00:00:00ZTransport coefficients of a hot QCD medium and their relative significance in heavy-ion collisionsMitra, SukanyaChandra, Vinodhttp://repository.iitgn.ac.in/handle/123456789/33152017-12-06T05:29:06Z2017-11-01T00:00:00ZTransport coefficients of a hot QCD medium and their relative significance in heavy-ion collisions
Mitra, Sukanya; Chandra, Vinod
The main focus of this article is to obtain various transport coefficients for a hot QCD medium that is likely to be produced while colliding two heavy nuclei ultra-relativistically. The technical approach adopted here is the semiclassical transport theory. The away-from-equilibrium linearized transport equation has been set up by employing the Chapman-Enskog technique from the kinetic theory of a many-particle system with a collision term that includes the binary collisions of quarks/antiquarks and gluons. In order to include the effects of a strongly interacting, thermal medium, a quasi-particle description of a realistic hot QCD equation of state has been employed through the equilibrium modeling of the momentum distributions of gluons and quarks with nontrivial dispersion relations while extending the model for finite but small quark chemical potential. The effective coupling for strong interaction has been redefined following the charge renormalization under the scheme of the quasi-particle model. The consolidated effects on transport coefficients are seen to have a significant impact on their temperature dependence. Finally, the relative significances of momentum and heat transfer, as well as the charge diffusion processes in hot QCD, have been investigated by studying the ratios of the respective transport coefficients indicating different physical laws.
2017-11-01T00:00:00Z