Sudden gravitational transition

Caldwell, Robert R.; Komp, William; Parker, Leonard; Vanzella, Daniel A. T.

doi:10.1103/physrevd.73.023513

Cited by 108 publications

(82 citation statements)

References 50 publications

(54 reference statements)

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“…The answer is yes: one of the earliest dark energy models, vacuum metamorphosis [23][24][25] lives in just this part of phase space. This model has a sound physical foundation, taking into account quantum loop corrections to gravity in the presence of a massive scalar field.…”

Section: A Backgroundmentioning

confidence: 99%

“…However, there is a model considered in the early days of dark energy investigations that possesses just these phenomenological properties, from a sound theoretical foundation: the vacuum metamorphosis (VM) model of [23][24][25], which has a phase transition in the nature of the vacuum. In this article, we explore the observational viability of VM in fitting the data simultaneously and removing the tension in H 0 values.…”

Section: Introductionmentioning

confidence: 99%

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Vacuum phase transition solves the H0 tension

2018

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Taking the Planck cosmic microwave background data and the more direct Hubble constant measurement data as unaffected by systematic offsets, the values of the Hubble constant H 0 interpreted within the ΛCDM cosmological constant and cold dark matter cosmological model are in ∼3.3σ tension. We show that the Parker vacuum metamorphosis (VM) model, physically motivated by quantum gravitational effects and with the same number of parameters as ΛCDM, can remove the H 0 tension and can give an improved fit to data (up to a mean Δχ 2 ¼ −7.5). It also ameliorates tensions with weak lensing data and the high redshift Lyman alpha forest data. Considering Bayesian evidence, we found in the case of the Planck data set alone positive evidence for a VM model against a cosmological constant both in the six-and nine-parameter framework. When the R16 data set is also considered, we found a strong evidence for the VM model against a cosmological constant in nine-parameter space. We separately consider a scale-dependent scaling of the gravitational lensing amplitude, such as provided by modified gravity, neutrino mass, or cold dark energy, motivated by the somewhat different cosmological parameter estimates for low and high CMB multipoles. We find that no such scale dependence is preferred.

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Section: A Backgroundmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Vacuum phase transition solves the H0 tension

2018

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“…This violation gives a reverse gravitational effect. Due to this effect, the Universe gets a jerk and the transition from the earlier deceleration phase to the recent acceleration phase take place (Caldwell et al 2006). The cause of this sudden transition and the source of accelerated expansion is still unknown.…”

Section: Introductionmentioning

confidence: 99%

Some anisotropic dark energy models in Bianchi type-V space-time

Yadav

2011

Astrophys Space Sci

102

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The paper deals with Bianchi type V Universe, which has dynamical energy density. We consider Bianchi type V space-time, introducing three different skewness parameters along spatial directions to quantify the deviation of pressure from isotropy. To study the anisotropic nature of the dynamical dark energy, we assume that the skewness parameters are time dependent. It is found that the Universe achieves flatness in quintessence model. The physical behavior of the Universe has been discussed in detail.

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“…While doing so quintessence produces an effective, time-dependent, cosmic energy density accompanied by a sufficiently negative pressure, i.e., an effective cosmological constant. As far as identifying quintessence is concerned several possibilities have been considered (see e.g., [21,22,23,24,25,26,27,28]); in particular, those motivated by string theory include the dilaton and time-varying moduli fields [29]. In addition to analyzing for new signals at the LHC, this Dissertation is aimed at investigating a number of topics that exploit the recent astrophysical observations mentioned above.…”

Section: On a Separate Track The Remarkable Accuracy Of The Wilkinsomentioning

confidence: 99%

Manifestations of string theory in astrophysical data and at the LHC

Nawata

2009

Fortschritte der Physik

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With the advent of the LHC and the continuing influx of cosmological data, phenomenological aspects of string theory have received renewed attention in recent years and many problems have been properly incorporated in this framework. For instance, recent theoretical considerations in string theory have applied a statistical approach to the enormous landscape of metastable vacua. The large number of vacua may shed some light on the cosmological constant problem. In addition, in string theory, attempts have been made to address the hierarchy problem within the context of the existence of large or warped internal dimensions transverse to a braneworld where we are confined, which lowers the effective scale of gravity to the TeV region. If this were the case, unseen dimensions of the space-time can be at the border of the energy domain within reach of the next generation of particle accelerators.iii Although the picture of the landscape may be the key to the cosmological constant problem, it is well-known that the compactification of a string background to a four dimensional solution undergoing accelerating expansion is difficult, which is described by the no-go theorem of Maldacena-Nuñez. In the first part of this Dissertation, we investigate the cosmological content of the Salam-Sezgin supergravity which circumvents one of the hypotheses of the no-go theorem of Maldacena-Nuñez and consequently can support a de Sitter phase when lifted to string theory. We find a solution to the field equations in qualitative agreement with the observed dark energy density. The carrier of the acceleration in the present de Sitter epoch is a quintessence field slowly rolling down its exponential potential.Intrinsic to this model, there is a second modulus, which is automatically stabilized and acts as a source of cold dark matter with a mass proportional to an exponential function of the quintessence field.In the second part, we explore a "new physics" signal at LHC, in the processes pp → γ + jet, pp → γγ, and pp → dijet. In D-brane quivers, there are one or more additional U (1) gauge symmetries, beyond the U (1) Y of the standard model, which follows from the property that the gauge group for open strings terminating on a stack of N identical D-branes is U (N ) rather than SU (N ) for N > 2. Because of this, the photon will participate with the SU (N ) gauge boson in string tree level scattering processes which in the standard model occur only at one-loop level. In order to evaluate this stringy correction, we considered the processes gg → gγ and gg → γγ, and found that cross section measurements of the process pp → γ + jet at the LHC will attain 5σ discovery reach on low scale string models for M string as large as 4 TeV. We have also considered the processes gg → gg, gg → qq, qq → gg, qg → gq andqg →qg, and found that, for the pp → dijet channel, the LHC discovery reach will extend up to M string ∼ 6.8 TeV. Luis Anchordoqui Date iv

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Sudden gravitational transition

Cited by 108 publications

References 50 publications

Vacuum phase transition solves the H0 tension

Vacuum phase transition solves the H0 tension

Some anisotropic dark energy models in Bianchi type-V space-time

Manifestations of string theory in astrophysical data and at the LHC

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