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The recent observation of the cosmic microwave background anisotropy by the WMAP confirmed that the lower multipoles are considerably suppressed. From the standpoint of the cosmic variance, it is nothing but a statistical accident.…

High Energy Physics - Phenomenology · Physics 2009-11-10 Masahiro Kawasaki , Fuminobu Takahashi

The early stages of the universe evolution are discussed according to the hot big bang model and the grand unified theories. The shortcomings of big bang are summarized and their resolution by inflationary cosmology is sketched.…

High Energy Physics - Phenomenology · Physics 2008-11-26 George Lazarides

Since inflationary perturbations must generically couple to all degrees of freedom present in the early Universe, it is more realistic to view these fluctuations as an open quantum system interacting with an environment. Then, on very…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-10 Jerome Martin , Vincent Vennin

Observations of anisotropies in the cosmic microwave background by the Wilkinson Microwave Anisotropy Probe suggest the possibility of oscillations in the primordial density perturbation. Such deviations from the usually assumed scale-free…

Astrophysics · Physics 2011-02-16 Paul Hunt , Subir Sarkar

In this paper, inflationary cosmology is reviewed, paying particular attention to its observational signatures associated with large-scale density perturbations generated from quantum fluctuations. In the most general scalar-tensor theories…

Cosmology and Nongalactic Astrophysics · Physics 2014-06-13 Shinji Tsujikawa

We study the asymmetric primordial fluctuations in a model of inflation in which translational invariance is broken by a domain wall. We calculate the corrections to the power spectrum of curvature perturbations; they are anisotropic and…

Cosmology and Nongalactic Astrophysics · Physics 2014-12-02 Sadra Jazayeri , Yashar Akrami , Hassan Firouzjahi , Adam R. Solomon , Yi Wang

We asses the contribution to the observed large scale anisotropy of the cosmic microwave background radiation, arising from both gravity waves as well as adiabatic density perturbations, generated by a common inflationary mechanism in the…

High Energy Physics - Phenomenology · Physics 2009-10-22 Tarun Souradeep , Varun Sahni

Following a new quantum cosmological model proposed by Dvali and Gomez, we quantitatively investigate possible modifications to the Hubble parameter and following corrections to the cosmic microwave background spectrum. In this model,…

General Relativity and Quantum Cosmology · Physics 2015-09-16 Roberto Casadio , Florian Kuhnel , Alessio Orlandi

We revisit the physics of transitions from a general equation of state parameter to the final stage of slow-roll inflation. We show that it is unlikely for the modes comprising the cosmic microwave background to contain imprints from a…

Cosmology and Nongalactic Astrophysics · Physics 2016-06-22 Aditya Aravind , Dustin Lorshbough , Sonia Paban

While the standard, six-parameter, spatially flat $\Lambda$CDM model has been highly successful, certain anomalies in the cosmic microwave background bring out a tension between this model and observations. The statistical significance of…

General Relativity and Quantum Cosmology · Physics 2021-09-21 Abhay Ashtekar , Brajesh Gupt , V. Sreenath

The observability of the multiverse is at the very root of its physical significance as a scientific proposal. In this conference we present, within the third quantization formalism, an interacting scheme between the wave functions of…

General Relativity and Quantum Cosmology · Physics 2017-05-30 Salvador J. Robles-Perez

We consider an inflationary universe model in which the phase of accelerated expansion was preceded by a non-singular bounce and a period of contraction which involves a phase of deceleration. We follow fluctuations which exit the Hubble…

High Energy Physics - Theory · Physics 2009-03-15 Robert Brandenberger , Xinmin Zhang

The theory of inflation provides a mechanism to explain the structures we observe today in the Universe, starting from quantum-mechanically generated fluctuations. However, this leaves the question of: how did the quantum-to-classical…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-16 Jessie de Kruijf , Nicola Bartolo

Recent Planck data confirm that the cosmic microwave background displays the quadru-pole power suppression together with large scale anomalies. Progressing from previous results, that focused on the quadrupole anomaly, we strengthen the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 Paolo Cea

Observational tests during the next decade may determine if the evolution of the Universe can be understood from fundamental physical principles, or if special initial conditions, coincidences, and new, untestable physical laws must be…

Astrophysics · Physics 2016-08-30 Paul J. Steinhardt

We investigate the observational signatures of quantum cosmology in the Cosmic Microwave Background data provided by Planck collaboration. We apply the warm inflationary paradigm with a tachyon scalar field to the loop quantum cosmology. In…

General Relativity and Quantum Cosmology · Physics 2018-04-25 Vahid Kamali , Spyros Basilakos , Ahmad Mehrabi , Meysam Motaharfar , Erfan Massaeli

We present cosmological constraints from Planck 2015 data for a universe that is kinetically dominated at very early times. We perform a Markov chain Monte Carlo analysis to estimate parameters and use nested sampling to determine the…

Cosmology and Nongalactic Astrophysics · Physics 2019-07-10 L. T. Hergt , W. J. Handley , M. P. Hobson , A. N. Lasenby

By incorporating quantum aspects of gravity, Loop Quantum Cosmology (LQC) provides a self-consistent extension of the inflationary scenario, allowing for modifications in the primordial inflationary power spectrum with respect to the…

Cosmology and Nongalactic Astrophysics · Physics 2019-11-01 Micol Benetti , Leila Graef , Rudnei O. Ramos

The evolutions of the flat FLRW universe and its linear perturbations are studied systematically in the dressed metric approach of LQC. When it is dominated by the kinetic energy of the inflaton at the quantum bounce, the evolution of the…

General Relativity and Quantum Cosmology · Physics 2017-10-25 Tao Zhu , Anzhong Wang , Gerald Cleaver , Klaus Kirsten , Qin Sheng

Recent cosmic microwave background data in temperature and polarization have reached high precision in estimating all the parameters that describe the current so-called standard cosmological model. Recent results about the integrated…