LambdaCDM inflation model dependancies

In summary, this paper looks at ways to tackle pre-inflationary dynamics by using techniques from loop quantum gravity. It finds that for a large class of initial conditions, the inflationary paradigm still holds up. However, for a narrow window of initial conditions, there are some new effects that need to be explained.
  • #1
Mordred
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I've been haqving a tough time tracking down which particular inflationary models form the basis of [itex]\Lambda[/itex]CDM.

the model I have discounted already is false vacuum A.Guth. some articles seem to suggest concepts from slow roll inflation. Others deal specifically with the inflaton field in the early universe inflation so I'm thinking eternal inflation is still used. I'm still looking for data on Roulette inflation just heard about it today lol.

Part of the problem with my search is that there is lots of misleading data on the search. Also the [itex]\Lambda[/itex]CDM model may derive from multiple inflationary models.

Any direction would be helpful, its more a curiosity on my part.

needless to say their is numerous inflationary models, I've been compiling a list of the variations
 
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  • #2
So far my list of related include:

tunneling models:
(i) double-field inflation (Adams and Freese)
(ii) extended inflation (Steinhardt)
(iii) Chain inflation (Freese and Spolyar))

2) Rolling Models:
new inflation,
chaotic inflation,
hybrid inflation
Natural inflation (Freese,
Frieman, Olinto)

edit:: if my understanding of the group separation between otunneling models and rolling models, fundamentally it can be separated into degrees of freedom.

Still not clear on how to place slow roll. In terms of the above categories
 
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  • #3
Mordred said:
I've been haqving a tough time tracking down which particular inflationary models form the basis of [itex]\Lambda[/itex]CDM.
...

The tough time does not seem so surprising to me because AFAIK there is no particular inflation that is basis for LCDM.

LCDM starts expansion with certain conditions, e.g. near flatness, near isotropy, a fluctuation spectrum appropriate for seeding structure.

People are free to imagine various scenarios calculated to produce these conditions. I don't think anyone has proven logically that ONLY SOME INFLATION scenario is capable of yielding these initial conditions.

I would say that so far there is NO one unique inflation scenario that "forms the basis" for LCDM.

People would do well to watch this talk by Paul Steinhardt, a world-class cosmologist who was one of the principle inventors of inflation. He seems to have now rejected it as a front-end prep for LCDM and is working on an alternative front-end scenario for LCDM.
http://pirsa.org/13030079/

Here's what Perimeter says about Steinhardt:
http://www.perimeterinstitute.ca/people/paul-steinhardt
"Currently the Albert Einstein Professor in Science, and on the Faculty of both the Department of Physics and the Department of Astrophysical Sciences at Princeton University, Dr. Steinhardt is one of the leading theorists responsible for inflationary theory. He constructed the first workable model of inflation and the theory of how inflation could produce seeds for galaxy formation. Among his awards is the 2002 Paul Dirac Medal of the International Centre for Theoretical Physics"

After being one of the principal inventors of inflation, he is now busy showing that LCDM does not require inflation.

Basically LCDM is a classic model of expansion cosmology once it got started.

People have speculations scenarios and opinions about how it got started (and these include various inflations and bounces) but they are not part of LCDM proper.
 
  • #4
To balance the mention of Steinhardt with another major figure, consider Abhay Ashtekar.

The Springer press publishes a line of scientific Handbooks, and they are now bringing out a
Handbook of Spacetime, with Ashtekar as editor. From the looks of it this is going to be a massive project. Many top experts have been recruited to write chapters. the aim is to represent the state of the art in our understanding of spacetime geometry, gravity, cosmology.

Well, this his current take on a front end for the LCDM. He accepts a version of slow-roll inflation but then because THAT ITSELF NEEDS EXPLAINING he puts a pre-inflation stage in front of that to create the necessary conditions for a satisfactory inflation episode. And he is concerned with observational tests of this. Go figure :biggrin:

http://arxiv.org/abs/1302.0254
The pre-inflationary dynamics of loop quantum cosmology: Confronting quantum gravity with observations
Ivan Agullo, Abhay Ashtekar, William Nelson
(Submitted on 1 Feb 2013)
Using techniques from loop quantum gravity, the standard theory of cosmological perturbations was recently generalized to encompass the Planck era. We now apply this framework to explore pre-inflationary dynamics. The framework enables us to isolate and resolve the true trans-Planckian difficulties, with interesting lessons both for theory and observations. Specifically, for a large class of initial conditions at the bounce, we are led to a self consistent extension of the inflationary paradigm over the 11 orders of magnitude in density and curvature, from the big bounce to the onset of slow roll. In addition, for a narrow window of initial conditions, there are departures from the standard paradigm, with novel effects ---such as a modification of the consistency relation between the ratio of the tensor to scalar power spectrum and the tensor spectral index, as well as a new source for non-Gaussianities--- which could extend the reach of cosmological observations to the deep Planck regime of the early universe.
64 pages, 15 figures. Published version
 
  • #5
There are hundreds of inflationary models, and you can read the latest Planck papers to see which are still consistent with the data. To start, this paper (http://arxiv.org/abs/1303.3787) compiles an encyclopaedia of solely single field inflation models, and splits them into different classes.
 
  • #6
cristo said:
There are hundreds of inflationary models, and you can read the latest Planck papers to see which are still consistent with the data. To start, this paper (http://arxiv.org/abs/1303.3787) compiles an encyclopaedia of solely single field inflation models, and splits them into different classes.

Thanks for the link. The method you described is how I had generated the above list. I've been pouring over LCDM to inflationaty paradigm reviews. The above models are still considered good fits to observational data. Whether in part or overall.

Thanks for the above info on Steinhard Marcus. LQC I will eventually study if you happen to have a good step by step from the LQC original derivitaves to current development training articles. That will make my future LQC studies easier.

As you can see I enjoy studying the history of development. As if its done properly fills in the missing blanks in how this
formula or that derived.

Thus far the list above narrows down which of the multitude of inflation model alternatives to further study
 
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Related to LambdaCDM inflation model dependancies

1. What is the LambdaCDM inflation model and why is it important in cosmology?

The LambdaCDM inflation model, also known as the Lambda Cold Dark Matter model, is a cosmological model that describes the evolution of the universe from its earliest stages to its current state. It is based on the Big Bang theory and includes the effects of both dark energy (represented by the Greek letter lambda) and cold dark matter. This model is important because it provides a framework for understanding the large-scale structure and behavior of the universe.

2. What are the main assumptions and components of the LambdaCDM inflation model?

The main assumptions of the LambdaCDM inflation model include the presence of dark energy and cold dark matter, as well as the idea that the universe is homogeneous and isotropic on a large scale. The main components of the model include the Friedmann-Lemaitre-Robertson-Walker (FLRW) metric, which describes the expansion of the universe, and the energy density parameters for matter, radiation, and dark energy.

3. How does the LambdaCDM inflation model explain the early expansion and later acceleration of the universe?

The LambdaCDM inflation model proposes that in the very early stages of the universe, a period of rapid expansion called inflation occurred due to a hypothetical particle called the inflaton. This inflationary period helped to smooth out the universe and explain the observed uniformity of the cosmic microwave background radiation. Later on, as the universe continued to expand, the effects of dark energy became dominant and caused the expansion to accelerate.

4. What are some of the current challenges and open questions in the LambdaCDM inflation model?

While the LambdaCDM inflation model has been successful in describing many aspects of the universe, there are still some challenges and open questions that remain. For example, the nature of dark energy and dark matter is still not fully understood, and there are discrepancies between the observed expansion of the universe and the predicted expansion rate based on the model. Additionally, the inflationary period is still not well understood and there are different theories about how it occurred.

5. How do scientists test and validate the predictions of the LambdaCDM inflation model?

Scientists use a variety of methods to test and validate the predictions of the LambdaCDM inflation model. This includes observations of the cosmic microwave background radiation, measurements of the large-scale structure of the universe, and studies of the distribution and behavior of galaxies and other celestial objects. Additionally, scientists continue to refine and develop the model to better match observations and make new predictions that can be tested through future observations and experiments.

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