Technical question: vanishing of the cosmological constant in Randall Sundrum 1

In summary, the conversation discusses the RS models and the question of whether the 4D cosmological constant is zero. The value of the brane tensions in model 1 is related to the bulk cosmological constant, but it is not explicitly stated in the original papers that the 4D cosmological constant is zero. There are two contributions to the 4D cosmological constant, the brane tension and the integral over the fifth dimension, but they do not cancel out. A review is mentioned and the original papers are provided. It is mentioned that the 4D cosmological constant is automatically zero in Minkowski slices of AdS space.
  • #1
nrqed
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This is a very technical question so I don't really expect someone to have the answer unless they have actually worked with or studied the RS models.


They say that the value of the brane tensions in model 1 (which are related to the bulk cosmological constant) are such that the 4D cosmological constant (on our brane) is zero.
I can't see how this comes about.

I probably misunderstand but the way i see it, there are two contributions to the 4D cosmological constant: the brane tension itself plus the integral over the fifth dimension of the 5D cosmological constant. But when I do the integral, the two terms do not cancel out (there is a mismatch by a factor of 2). I could show my calculation but I will wait to see if anyone can help.

Thanks
 
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  • #2
  • #3
PhysiSmo said:
Could you pinpoint us the original paper? Also, check out this review,

http://arxiv.org/abs/hep-th/0209261,

it's one of the best I've found for the subject.

Yes, this is a very good introduction. Unfortunately, it is not shown that the 4D cosmological constant in the original RS model is zero.

The two original RS papers are

http://arxiv.org/abs/hep-ph/9905221

and

http://arxiv.org/abs/hep-th/9906064

If I recall, in the first one they don't say explicitly that the 4D cosmological constant is zero.
In the second paper, they do say it and seem to imply that it follows trivially from the value of the brane tension and the constant appearing in the warp factor.
 
  • #4
nrqed said:
This is a very technical question so I don't really expect someone to have the answer unless they have actually worked with or studied the RS models.


They say that the value of the brane tensions in model 1 (which are related to the bulk cosmological constant) are such that the 4D cosmological constant (on our brane) is zero.
I can't see how this comes about.

I probably misunderstand but the way i see it, there are two contributions to the 4D cosmological constant: the brane tension itself plus the integral over the fifth dimension of the 5D cosmological constant. But when I do the integral, the two terms do not cancel out (there is a mismatch by a factor of 2). I could show my calculation but I will wait to see if anyone can help.

Thanks

I think they're just looking at Minkowski slices of AdS space, so the 4d cosmological constant is automatically 0.
 

1. What is the Randall Sundrum 1 model?

The Randall Sundrum 1 model is a theoretical model proposed by physicists Lisa Randall and Raman Sundrum in 1999. It suggests that our universe is a 5-dimensional brane embedded in a higher-dimensional "bulk" space. This model aims to solve the hierarchy problem, which is the large discrepancy between the strength of gravity and the other fundamental forces.

2. What is the cosmological constant?

The cosmological constant is a term in Einstein's theory of general relativity that represents the energy density of the vacuum. It is also known as the "dark energy" and is responsible for the accelerating expansion of the universe.

3. What is the problem with the cosmological constant in the Randall Sundrum 1 model?

The problem is that the original Randall Sundrum 1 model predicted a non-zero value for the cosmological constant, which is in contradiction with observations that show a very small but non-zero value. This is known as the "cosmological constant problem."

4. How was the cosmological constant problem solved in the Randall Sundrum 1 model?

The cosmological constant problem was solved by introducing a new mechanism called the "brane-world mechanism." This mechanism allows for the vanishing of the cosmological constant on the 5-dimensional brane, which is our universe, while still allowing for a non-zero value in the bulk. This cancellation of the cosmological constant on the brane is due to the interactions between branes in the higher-dimensional space.

5. Has the vanishing of the cosmological constant in Randall Sundrum 1 model been confirmed by observations?

There is currently no direct observational evidence for the Randall Sundrum 1 model or the vanishing of the cosmological constant. However, the model is still considered a viable solution to the cosmological constant problem and is an active area of research in theoretical physics.

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