Suratna Das

Lee-Wick radiation induced bouncing universe models

The present article discusses about the effect of a Lee-Wick partner infested radiation phase of the early universe. As Lee-Wick partners can contribute negative energy density so it is always possible that at some early phase of the universe when the Lee-Wick partners were thermalized the total energy density of the universe became very small making the effective Hubble radius very big. This possibility gives rise to the probability of a bouncing universe. As will be shown in the article that a simple Lee-Wick radiation is not enough to produce a bounce. There can be two possibilities which can produce a bounce in the Lee-Wick radiation phase. One requires a cold dark matter candidate to trigger the bounce and the other possibility requires the bouncing temperature to be fine tuned such as all the Lee-Wick partners of the standard fields are not thermalized at the bounce temperature. Both the possibilities give rise to blue-tilted power spectrum of metric perturbations. Moreover the bouncing universe model can predict the lower limit of the masses of the Lee-Wick partners of chiral fermions and massless gauge bosons. The mass limit intrinsically depends upon the bounce temperature.

Classicalization of inflationary perturbations by collapse models in the light of BICEP2

Inflationary and hence quantum origin of primordial perturbations is on a firmer ground than ever post the BICEP2 observations of primordial gravitational waves. One crucial ingredient of success of this paradigm rests on explaining the observed classicality of cosmological inhomogeinities despite their quantum origin. Although decoherence provides a partial understanding of this issue, the question of single outcome motivates the analysis of quantum collapse models in cosmological context which generically modify the dynamics of primordial perturbations and hence can leave their imprints on observables. We revisit one such recently proposed working model of classicalization by spontaneous collapse \cite{Das:2013qwa} in the light of BICEP2 observations to look for possible modifications to tensor power spectra and their implications. We show that it can potentially change the consistency relation of single-field models and a precise measurement of

Test of unparticle long range forces from perihelion precession of Mercury

n_T

Higgs vacuum stability and inflationary dynamics after BICEP2 and PLANCK dust polarisation data

and its running could serve as a test of such dynamics in the early universe.

Non-slow-roll dynamics in α-attractors

Unparticle exchange gives rise to long range forces which deviate from the inverse square law due to the noncanonical dimension of unparticles. It is well known that a potential of the form r{sup -n} where n is not equal to 1 gives rise to a precession in the perihelion of planetary orbits. We calculate the constraints on unparticle couplings with baryons and leptons from the observations of perihelion advance of Mercurys orbit.

Dilaton assisted two-field inflation from no-scale supergravity

If the recent detection of

Thermodynamics of the Lee-Wick partners: An alternative approach

B-

VERY SPECIAL RELATIVITY IS INCOMPATIBLE WITH THOMAS PRECESSION

mode polarization of the Cosmic Microwave Background by BICEP2 observations, withstand the test of time after the release of recent PLANCK dust polarisation data, then it would surprisingly put the inflationary scale near Grand Unification scale if one considers single-field inflationary models. On the other hand, Large Hadron Collider has observed the elusive Higgs particle whose presently observed mass can lead to electroweak vacuum instability at high scale

Toy model based analysis on the effect of the Lee-Wick partners in the evolution of the early universe

(\sim{\mathcal O}(10^{10})

Signature of short distance physics on inflation power spectrum and CMB anisotropy

GeV). In this article, we seek for a simple particle physics model which can simultaneously keep the vacuum of the theory stable and yield high-scale inflation successfully. To serve our purpose, we extend the Standard Model of particle physics with a