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Modified loop cosmology and the non-viability of cyclic evolution

Dec 15
Group Seminar
4:00 pm o'clock to 5:30 pm o'clock
Prof. Parampreet Singh (Louisiana State University)

In this talk we will discuss a modification of standard loop quantum cosmology using Thiemann regularization of the Hamiltonian constraint. This regularization treats Euclidean and Lorentzian terms of the Hamiltonian constraint independently in the quantization procedure and results in a de Sitter phase
in the pre-bounce regime. While studies so far have shown various similarities and subtle differences of the physics between this and standard LQC, we show that in presence of a negative cosmological constant or a negative potential as motivated in cyclic scenarios, striking phenomenological differences appear. In particular, the Thiemann regularized loop cosmology though non-singular makes a cyclic evolution practically unviable. On one hand, this study suggests that if any evidence was found for a cyclic evolution in the history of the universe it will rule out this particular loop cosmology and on the other hand it suggests that Thiemann regularized loop cosmology favors an inflationary explanation for the early universe than its cyclic alternatives. This study provides an example that different regularization of the Hamiltonian constraint might lead to very striking differences in phenomenological predictions.