COSMOS- \(e'\) -soft Higgsotic attractors

The European Physical Journal C, Jul 2017

In this work, we have developed an elegant algorithm to study the cosmological consequences from a huge class of quantum field theories (i.e. superstring theory, supergravity, extra dimensional theory, modified gravity, etc.), which are equivalently described by soft attractors in the effective field theory framework. In this description we have restricted our analysis for two scalar fields – dilaton and Higgsotic fields minimally coupled with Einstein gravity, which can be generalized for any arbitrary number of scalar field contents with generalized non-canonical and non-minimal interactions. We have explicitly used \(R^2\) gravity, from which we have studied the attractor and non-attractor phases by exactly computing two point, three point and four point correlation functions from scalar fluctuations using the In-In (Schwinger–Keldysh) and the \(\delta \mathcal{N}\) formalisms. We have also presented theoretical bounds on the amplitude, tilt and running of the primordial power spectrum, various shapes (equilateral, squeezed, folded kite or counter-collinear) of the amplitude as obtained from three and four point scalar functions, which are consistent with observed data. Also the results from two point tensor fluctuations and the field excursion formula are explicitly presented for the attractor and non-attractor phase. Further, reheating constraints, scale dependent behavior of the couplings and the dynamical solution for the dilaton and Higgsotic fields are also presented. New sets of consistency relations between two, three and four point observables are also presented, which shows significant deviation from canonical slow-roll models. Additionally, three possible theoretical proposals have presented to overcome the tachyonic instability at the time of late time acceleration. Finally, we have also provided the bulk interpretation from the three and four point scalar correlation functions for completeness.

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COSMOS- \(e'\) -soft Higgsotic attractors

Eur. Phys. J. C COSMOS-e -soft Higgsotic attractors Sayantan Choudhury 0 0 Department of Theoretical Physics, Tata Institute of Fundamental Research , Colaba, Mumbai 400005 , India In this work, we have developed an elegant algorithm to study the cosmological consequences from a huge class of quantum field theories (i.e. superstring theory, supergravity, extra dimensional theory, modified gravity, etc.), which are equivalently described by soft attractors in the effective field theory framework. In this description we have restricted our analysis for two scalar fields - dilaton and Higgsotic fields minimally coupled with Einstein gravity, which can be generalized for any arbitrary number of scalar field contents with generalized non-canonical and non-minimal interactions. We have explicitly used R2 gravity, from which we have studied the attractor and non-attractor phases by exactly computing two point, three point and four point correlation functions from scalar fluctuations using the InIn (Schwinger-Keldysh) and the δN formalisms. We have also presented theoretical bounds on the amplitude, tilt and running of the primordial power spectrum, various shapes (equilateral, squeezed, folded kite or counter-collinear) of the amplitude as obtained from three and four point scalar functions, which are consistent with observed data. Also the results from two point tensor fluctuations and the field excursion formula are explicitly presented for the attractor and non-attractor phase. Further, reheating constraints, scale dependent behavior of the couplings and the dynamical solution for the dilaton and Higgsotic fields are also presented. New sets of consistency relations between two, three and four point observables are also presented, which shows significant deviation from canonical slow-roll models. Additionally, three possible theoretical proposals have presented to overcome the tachyonic instability at the time of late time acceleration. Finally, we have also provided the bulk interpretation from the three and four point scalar correlation functions for completeness. - S. Choudhury: Presently working as a Visiting (Post-Doctoral) fellow at DTP, TIFR, Mumbai. Contents 10.2 Dynamical dilaton at late times . . . . . . . . . 10.3 Details of the δN formalism . . . . . . . . . . 10.3.1 Useful field derivatives of N . . . . . . 10.3.2 Second-order perturbative solution with various source . . . . . . . . . . . . . . 10.3.3 Expressions for perturbative solutions in final hypersurface . . . . . . . . . . . 10.3.4 Shift in the inflaton field due to δN . . . 10.3.5 Various useful constants for δN . . . . . 10.4 Momentum dependent functions in four point function . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . 1 Introduction The inflationary paradigm is a theoretical proposal which attempts to solve various long-standing issues with standard Big Bang cosmology and has been studied earlier in various works [ 1–12 ]. But apart from the success of this theoretical framework it is important to note that no single model exists till now using which one can explain the complete evolution history of the universe and also one is unable to break the degeneracy between various cosmological parameters computed from various models of inflation [ 13–33 ]. It is important to note that we have the vacuum energy contribution generated by the trapped Higgs field in a metastable vacuum state which mimics the role of an effective cosmological constant in effective theory. At the later stages of the universe such a vacuum contribution dominates over other contents and correspondingly the universe expands in an exponential fashion. But using such metastable vacuum state it is not possible to explain the tunneling phenomenon and also impossible to explain the end of inflation. To serve both of the purposes the effective potential for inflation should have a flat structure. Due to such a specific structure the effective potential for inflation satisfies the flatness or slow-roll condition using which one can easily determine the field value corresponding to the end of inflation. There are various classes of models in existence in the cosmological literature where one has derived such a specific structure of inflation [ 14,34– 39 ]. For example, the Coleman–Weinberg effective potential serves this purpose [ 40,41 ]. Now if we consider the finite temperature contributions in the effective potential [ 42,43 ] then such thermal effects need to localize the inflaton field to small expectation values at the beginning of inflation. The flat structure of the effective potential for inflation is such that the scalar inflaton field slowly rolls down in the valley of potential during which the scale factor varies exponentially and then inflation ends when the scalar inflaton field goes to the non-slow-rolling region by violating the flatness condition. At this epoch inflaton field evolve (...truncated)


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Sayantan Choudhury. COSMOS- \(e'\) -soft Higgsotic attractors, The European Physical Journal C, 2017, pp. 469, Volume 77, Issue 7, DOI: 10.1140/epjc/s10052-017-5001-8