%0 Journal Article %1 Easther2004 %A Easther, Richard %A Kinney, William H %A Peiris, Hiranya %D 2004 %K transplanckian %T Observing Trans-Planckian Signatures in the Cosmic Microwave Background %U http://arxiv.org/abs/astro-ph/0412613 %X We examine the constraints cosmological observations can place on any trans-Planckian corrections to the primordial spectrum of perturbations underlying the anisotropies in the Cosmic Microwave Background. We focus on models of trans-Planckian physics which lead to a modulated primordial spectrum. Rather than looking at a generic modulated spectrum, our calculations are based on a specific model, and are intended as a case study for the sort of constraints one could hope to apply on a well-motivated model of trans-Planckian physics. We present results for three different approaches -- a grid search in a subset of the overall parameter space, a Fisher matrix estimate of the likely error ellipses, and a Monte Carlo Markov Chain fit to a simulated CMB sky. As was seen in previous analyses, the likelihood space has multiple peaks, and we show that their distribution can be reproduced via a simple semi-analytic argument. All three methods lead to broadly similar results. We vary 10 cosmological parameters (including two related to the trans-Planckian terms) and show that the amplitude of the tensor perturbations is directly correlated with the detectability of any trans-Planckian modulation. We argue that this is likely to be true for any trans-Planckian modulation in the paradigm of slow-roll inflation. For the specific case we consider, we conclude that if the tensor to scalar ratio, $r 0.15$, the ratio between the inflationary Hubble scale $H$, and the scale of new physics $M$ has to be on the order of 0.004 if the modulation is detectable at the 2$\sigma$ level. For a lower value of $r$, the bound on $H/M$ becomes looser.

@article{Easther2004, abstract = { We examine the constraints cosmological observations can place on any trans-Planckian corrections to the primordial spectrum of perturbations underlying the anisotropies in the Cosmic Microwave Background. We focus on models of trans-Planckian physics which lead to a modulated primordial spectrum. Rather than looking at a generic modulated spectrum, our calculations are based on a specific model, and are intended as a case study for the sort of constraints one could hope to apply on a well-motivated model of trans-Planckian physics. We present results for three different approaches -- a grid search in a subset of the overall parameter space, a Fisher matrix estimate of the likely error ellipses, and a Monte Carlo Markov Chain fit to a simulated CMB sky. As was seen in previous analyses, the likelihood space has multiple peaks, and we show that their distribution can be reproduced via a simple semi-analytic argument. All three methods lead to broadly similar results. We vary 10 cosmological parameters (including two related to the trans-Planckian terms) and show that the amplitude of the tensor perturbations is directly correlated with the detectability of any trans-Planckian modulation. We argue that this is likely to be true for any trans-Planckian modulation in the paradigm of slow-roll inflation. For the specific case we consider, we conclude that if the tensor to scalar ratio, $r \sim 0.15$, the ratio between the inflationary Hubble scale $H$, and the scale of new physics $M$ has to be on the order of 0.004 if the modulation is detectable at the 2$\sigma$ level. For a lower value of $r$, the bound on $H/M$ becomes looser. }, added-at = {2010-09-07T12:04:39.000+0200}, author = {Easther, Richard and Kinney, William H and Peiris, Hiranya}, biburl = {https://www.bibsonomy.org/bibtex/24b1e915199b45309a95910fcae44c649/jpschaar}, description = {Observing Trans-Planckian Signatures in the Cosmic Microwave Background}, interhash = {7e0199ffcc4e96a9845a1dfb7ffdd4bc}, intrahash = {4b1e915199b45309a95910fcae44c649}, keywords = {transplanckian}, note = {cite arxiv:astro-ph/0412613 Comment: Reference aded, typos corrected (eq 8 and 12)}, timestamp = {2010-09-07T12:04:39.000+0200}, title = {Observing Trans-Planckian Signatures in the Cosmic Microwave Background}, url = {http://arxiv.org/abs/astro-ph/0412613}, year = 2004 }