Decaying cosmological constant

In summary, the conversation discusses a research paper that proposes a physical mechanism for neutralizing the currently observed positive effective cosmological constant. The paper argues that the existence of a large positive cosmological constant is required for the mutual consistency of particle physics and general relativity. However, the non-zero vacuum expectation value for the Higgs field results in a negative vacuum energy density, which must be cancelled out by a fundamental positive cosmological constant. The paper suggests that the observed acceleration of the universe is a result of the sum of these two cosmological constants. The person involved in the conversation is intrigued by this concept but has questions about how the negative value of the vacuum energy for the Higgs field is determined.
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deneve
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The following is from a research paper:

doi:10.1088/0034-4885/68/4/R04
The structure of the world from pure numbers
F J Tipler
Department of Mathematics and Department of Physics, Tulane University, New Orleans,
LA 70118, USA
Received 21 September 2004
Published 15 March 2005
Online at stacks.iop.org/RoPP/68/897

I quote from page 959 of the paper





"What I shall now do is describe the physical mechanism that will eventually neutralize the observed currently
positive effective cosmological constant. (See Peebles and Ratta 2003 for a recent review
of the observations suggesting that the Dark Energy is in fact an uncancelled cosmological
constant.)
It is well known that the mutual consistency of the particle physics SM and general
relativity requires the existence of a very large positive cosmological constant. The reason is
simple: the non-zero vacuum expectation value for the Higgs field yields a vacuum energy
density of ∼−1.0 × 1026 gm cm−3 (mH/246) GeV, where mH is the Higgs boson mass,
which is 114.4 GeV < mH < 251 GeV at the 95% confidence level (Abazov et al 2004).
Since this is a negative vacuum energy, it is accompanied by a positive pressure of equal
magnitude, and both the pressure and energy yield a negative cosmological constant. Since
the closure density is 1.88 × 10 to power−29 omega total x h to power 2 gm cm−3, and observations (Spergel et al 2003)
indicate that omega total = 1.02 ± 0.02 and h = 0.71 ± 0.04, there must be a fundamental positive
cosmological constant to cancel out the negative cosmological constant coming from the Higgs
field. What we observe accelerating the universe today is the sum of the fundamental positive
cosmological constant, and the negative Higgs field cosmological constant; this sum is the
‘effective’ cosmological constant."


I am intrigued by this and wonder if anyone can help me understand it. First and foremost He seems to be saying that the vacuum energy density is NEGATIVE. Classically I presume he is saying that the mexican hat potential for the higgs field potential has its maximum at zero and its minima at some less than zero value. How do we know this has a negative value? Would this not mean that the Dominant Energy condition of Hawking and Ellis is violated by the Higgs field since this condition requires energy density to be greater than or equal to zero? However, he certainly thiks it is negative , otherwise you would not get a positive pressure for it from the equation of state. I am puzzled but intrigued at the possibility of a quintessence like decaying Cosmological constant but I don't know how to see that the vacuum energy for the higgs field is negative. My particle physics knowledge is very poor so any help with this one would be gratefully accepted
 
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1. What is a decaying cosmological constant?

A decaying cosmological constant, also known as a time-varying cosmological constant, is a hypothetical property of the universe that describes the rate at which space is expanding. It is represented by the Greek letter Lambda (Λ) and is a key component in the cosmological constant model, which is used to explain the accelerating expansion of the universe.

2. What evidence supports the existence of a decaying cosmological constant?

The evidence for a decaying cosmological constant comes from observations of distant supernovae, which have shown that the expansion of the universe is accelerating. This is inconsistent with the predictions of a constant cosmological constant and has led scientists to consider a decaying cosmological constant as a possible explanation.

3. How does a decaying cosmological constant affect the evolution of the universe?

A decaying cosmological constant has a significant impact on the evolution of the universe. As the value of Lambda decreases over time, the rate of expansion of the universe increases. This leads to a faster and more rapid expansion, which has implications for the ultimate fate of the universe.

4. What are some theories about the origin of a decaying cosmological constant?

There are several theories about the origin of a decaying cosmological constant. Some scientists propose that it is a fundamental property of space and time, while others suggest that it may be caused by a form of energy that permeates the universe. Other theories propose that it may be a result of quantum fluctuations or the interactions of multiple universes.

5. How does the concept of a decaying cosmological constant impact current models of the universe?

The idea of a decaying cosmological constant has challenged traditional models of the universe, such as the Big Bang theory. It has also led to the development of new models, such as the Lambda-CDM model, which incorporates a decaying cosmological constant and other components, such as dark matter and dark energy, to better explain the structure and evolution of the universe.

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