Physicshttps://repository.iitgn.ac.in/handle/123456789/6072018-11-17T15:43:24Z2018-11-17T15:43:24ZSpotlighting the sensitivities of Hyper-Kamiokande, DUNE and ESS?SBChakraborty, KaustavDeepthi, K. N.Goswami, Srubabatihttps://repository.iitgn.ac.in/handle/123456789/40132018-11-16T06:05:56Z2018-12-01T00:00:00ZSpotlighting the sensitivities of Hyper-Kamiokande, DUNE and ESS?SB
Chakraborty, Kaustav; Deepthi, K. N.; Goswami, Srubabati
Neutrino oscillation physics has entered the precision era and the potential forthcoming experiments Hyper-Kamiokande (T2HK / T2HKK), Deep Under-ground Neutrino Experiment (DUNE) and The European Spallation Source ?-Beam (ESS?SB ) project are expected to strengthen this endeavour in the future. In this paper we perform a comprehensive study of the octant, mass hierarchy and CP discovery sensitivities of T2HK / T2HKK, DUNE and ESS?SB project in their individual capacity. We present a comparative account of the probabilities at the respective baselines and explore in detail the physics issues which can cause the differences in the sensitivities among the various experiments. We also find out the optimal exposure required by these experiments for achieving 5? hierarchy, octant sensitivity and to discover CP violation at 5? for 60% values of , stand alone and in conjunction with the on going T2K and NO?A experiments. In addition, we study the hierarchy and CP sensitivities of DUNE and T2HK in combination with ESS?SB
2018-12-01T00:00:00ZBoundary conservation from bulk symmetryFairoos, C.Ghosh, AvirupSarkar, Sudiptahttps://repository.iitgn.ac.in/handle/123456789/40002018-11-16T06:05:55Z2018-10-01T00:00:00ZBoundary conservation from bulk symmetry
Fairoos, C.; Ghosh, Avirup; Sarkar, Sudipta
The evolution of the black-hole horizon can be effectively captured by a fictitious membrane fluid living on the stretched horizon. We show that the dynamics of this boundary matter arises from the invariance of the bulk action under local symmetries in the presence of the inner boundary. If general covariance is broken in a semi-classical treatment of a quantum field near a black-hole horizon, we argue that it can be restored by the inclusion of a quantum flux into the membrane conservation equation which is exactly equal to the Hawking flux.
2018-10-01T00:00:00ZGW170817: Measurements of neutron star radii and equation of stateSengupta, Anandhttps://repository.iitgn.ac.in/handle/123456789/40062018-11-16T06:05:55Z2018-10-01T00:00:00ZGW170817: Measurements of neutron star radii and equation of state
Sengupta, Anand
On 17 August 2017, the LIGO and Virgo observatories made the first direct detection of gravitational waves from the coalescence of a neutron star binary system. The detection of this gravitational-wave signal, GW170817, offers a novel opportunity to directly probe the properties of matter at the extreme conditions found in the interior of these stars. The initial, minimal-assumption analysis of the LIGO and Virgo data placed constraints on the tidal effects of the coalescing bodies, which were then translated to constraints on neutron star radii. Here, we expand upon previous analyses by working under the hypothesis that both bodies were neutron stars that are described by the same equation of state and have spins within the range observed in Galactic binary neutron stars. Our analysis employs two methods: the use of equation-of-state-insensitive relations between various macroscopic properties of the neutron stars and the use of an efficient parametrization of the defining function p(?) of the equation of state itself. From the LIGO and Virgo data alone and the first method, we measure the two neutron star radii as R1=10.8+2.0?1.7??km for the heavier star and R2=10.7+2.1?1.5??km for the lighter star at the 90% credible level. If we additionally require that the equation of state supports neutron stars with masses larger than 1.97??M? as required from electromagnetic observations and employ the equation-of-state parametrization, we further constrain R1=11.9+1.4?1.4??km and R2=11.9+1.4?1.4??km at the 90% credible level. Finally, we obtain constraints on p(?) at supranuclear densities, with pressure at twice nuclear saturation density measured at 3.5+2.7?1.7�1034??dyn?cm?2 at the 90% level.
2018-10-01T00:00:00ZViscous self interacting dark matter cosmology for small redshiftAtreya, AbhishekBhatt, Jitesh R.Mishra, Arvind Kumarhttps://repository.iitgn.ac.in/handle/123456789/39962018-11-16T06:05:54Z2018-10-01T00:00:00ZViscous self interacting dark matter cosmology for small redshift
Atreya, Abhishek; Bhatt, Jitesh R.; Mishra, Arvind Kumar
The viscosity of dark matter in cosmological models may cause an accelerated expansion and when this effect is sufficiently large, it can explain the dark energy. In this work, attributing the origin of viscosity to self-interaction of dark matter, we study the viscous cosmology at small redshift (0?z?2.5). Assuming the cluster scale to be virialized and by modeling a power law behavior of velocity gradients, we calculate the Hubble expansion rate, H(z) and the deceleration parameter, q(z). We then perform a ?2 analysis to estimate the best fit model parameters. By using the best fit values, we explain the cosmic chronometer and type Ia supernova data. We conclude that if the dissipative effects become prominent only at the late time of cosmic evolution and are smaller at higher redshift, we can explain the observational data without requiring any dark energy component. Our analysis is independent of any specific model of self interacting dark matter.
2018-10-01T00:00:00Z