Revisiting constraints on (pseudo)conformal Universe with Planck data

We revisit constraints on the (pseudo)conformal Universe from the non-observation of statistical anisotropy in the Planck data. The quadratic maximal likelihood estimator is applied to the Planck temperature maps at frequencies 143 GHz and 217 GHz as well as their cross-correlation. The strongest constraint is obtained in the scenario of the (pseudo)conformal Universe with a long intermediate evolution after conformal symmetry breaking. In terms of the relevant parameter (coupling constant), the limit is h^2 <0.0013 at 95% C.L. (using the cross-estimator). The analogous limit is much weaker in the scenario without the intermediate stage (h^2 \ln \frac{H_0}{\Lambda}<0.52) allowing the coupling constant to be of order one. In the latter case, the non-Gaussianity in the 4-point function appears to be a more promising signature.Comment: 13 pages, 2 figures. Appendix with detailed computation of the Fisher matrix adde

Algebraic properties of Manin matrices II: q-analogues and integrable systems

We study a natural q-analogue of a class of matrices with noncommutative entries, which were first considered by Yu. I. Manin in 1988 in relation with quantum group theory, (called Manin Matrices in [5]) . These matrices we shall call q-Manin matrices(qMMs). They are defined, in the 2x2 case, by the relations M_21 M_12 = q M_12 M_21; M_22 M_12 = q M_12 M_22; [M_11;M_22] = 1/q M_21 M_12 - q M_12 M_21: They were already considered in the literature, especially in connection with the q-Mac Mahon master theorem [16], and the q-Sylvester identities [25]. The main aim of the present paper is to give a full list and detailed proofs of algebraic properties of qMMs known up to the moment and, in particular, to show that most of the basic theorems of linear algebras (e.g., Jacobi ratio theorems, Schhur complement, the Cayley-Hamilton theorem and so on and so forth) have a straightforward counterpart for q-Manin matrices. We also show how this classs of matrices ?ts within the theory of quasi-determninants of Gel'fand-Retakh and collaborators (see, e.g., [17]). In the last sections of the paper, we frame our definitions within the tensorial approach to non-commutative matrices of the Leningrad school, and we show how the notion of q-Manin matrix is related to theory of Quantum Integrable Systems.Comment: 62 pages, v.2 cosmetic changes, typos fixe

Statistical anisotropy of CMB as a probe of conformal rolling scenario

Search for the statistical anisotropy in the CMB data is a powerful tool for constraining models of the early Universe. In this paper we focus on the recently proposed cosmological scenario with conformal rolling. We consider two sub-scenarios, one of which involves a long intermediate stage between conformal rolling and conventional hot epoch. Primordial scalar perturbations generated within these sub-scenarios have different direction-dependent power spectra, both characterized by a single parameter h^2. We search for the signatures of this anisotropy in the seven-year WMAP data using quadratic maximum likelihood method, first applied for similar purposes by Hanson and Lewis. We confirm the large quadrupole anisotropy detected in V and W bands, which has been argued to originate from systematic effects rather than from cosmology. We construct an estimator for the parameter h^2. In the case of the sub-scenario with the intermediate stage we set an upper limit h^2 < 0.045 at the 95% confidence level. The constraint on h^2 is much weaker in the case of another sub-scenario, where the intermediate stage is absent.Comment: 27 pages, 4 figures. Stronger constraint in case of sub-scenario A obtained. Version accepted for publication in JCA