Amitabha Mukherjee

Bounce solutions and the transition to thermal hopping in phi**4 theory with a phi**3 term

The nature of the transition from quantum tunneling at low temperatures to thermal hopping at high temperatures is investigated in a scalar field theory with cubic symmetry breaking. The bounce solution which interpolates between the zero-temperature and high-temperature solutions is obtained numerically, using a multigrid method. It is found that, for a small value of the symmetry-breaking coupling f, the transition is first-order. For higher values of f, the transition continues to be first-order, though weakly so.

Transition redshift: new constraints from parametric and nonparametric methods

In this paper, we use the Cosmokinematics approach to study the accelerated expansion of the Universe. This is a model independent approach and depends only on the assumption that the Universe is homogeneous and isotropic and is described by the FRW metric. We parametrize the deceleration parameter,

Constraining cosmic curvature by using age of galaxies and gravitational lenses

q(z)

NUCLEOSYNTHESIS IN A UNIVERSE WITH A LINEARLY EVOLVING SCALE FACTOR

, to constrain the transition redshift (

Probing the cosmic distance duality relation using time delay lenses

z_t

Revisiting the distance duality relation using a non-parametric regression method

) at which the expansion of the Universe goes from a decelerating to an accelerating phase. We use three different parametrizations of

Dynamics of a scalar field, with a double exponential potential, interacting with dark matter

q(z)

Analytical approach to the transition to thermal hopping in the thin wall and thick wall approximations

namely,

String dynamics near a Kaluza-Klein black hole

q_\I(z)=q_{\textnormal{\tiny\textsc{1}}}+q_{\textnormal{\tiny\textsc{2}}}z

COSMOLOGICAL COMPACTIFICATION OF SUPERSTRINGS WITH DYNAMICAL DILATON FIELD IN FOUR DIMENSIONS

,