arXiv subjects

E. I. Guendelman

Publications and source records attributed to E. I. Guendelman.

At least 55 records · Page 3Linked to original sources

arXiv2007

Child universes UV regularization?

It is argued that high energy density excitations, responsible for UV divergences in quantum field theories, including quantum gravity, are likely to be the source of child universes which carry them out of the original space time. This decoupling prevents these high UV excitations from having any influence on physical amplitudes. Child universe production could therefore be responsible for UV regularization in quantum field theories which takes into account gravitational effects. Also child universe production in the last stages of black hole evaporation, the prediction of absence of tranplanckian primordial perturbations, connection to the minimum length hypothesis and in particular connection to the maximal curvature hypothesis are discussed.

gr-qc↗

arXiv2007

Initial Singularity, Lambda-Problem and Crossing the Phantom Divide in Scale Invariant TMT Model

In the framework of the scale invariant model of the Two Measures Field Theory (TMT), we study the dilaton-gravity sector in the context of spatially flat FRW cosmology. The scale invariance is spontaneously broken due to the intrinsic features of the TMT dynamics. If no fine tuning is made, the effective $ϕ$-Lagrangian $p(ϕ,X)$ depends quadratically upon the kinetic term $X$. Hence TMT represents an explicit example of the effective k-essence resulting from first principles without any exotic term in the underlying action intended for obtaining this result. Depending of the choice of regions in the parameter space (but without fine tuning), TMT exhibits interesting outputs for cosmological dynamics, for example: a) Absence of initial singularity of the curvature while its time derivative is singular. This is a sort of "sudden" singularities studied by Barrow on purely kinematic grounds. b) Power law inflation in the subsequent stage of evolution which ends with a graceful exit into the state with zero cosmological constant (CC). c) Possibility of resolution of the old CC problem. From the point of view of TMT, it becomes clear why the old CC problem cannot be solved (without fine tuning) in conventional field theories; d) There is a wide range of the parameters such that in the late time universe: the equation-of-state w=p/ρ<-1; w asymptotically (as t\to\infty) approaches -1 from below; $ρ$ approaches a constant, the smallness of which does not require fine tuning of dimensionfull parameters.

gr-qc↗

arXiv2007

Generalized Gauge Field Approach To Lightlike Branes

We propose a general action describing the dynamics of lightlike (LL) p-branes in any odd (p+1) world-volume dimensions. Next, we consider self-consistent coupling of \textsl{LL}-membranes (p=2) to D=4 Einstein-Maxwell system plus a D=4 three-index antisymmetric tensor gauge field. The LL-brane serves as a material and charge source for gravity and electromagnetism and, furthermore, it produces a dynamical space-varying cosmological constant. We present static spherically-symmetric solutions where the space-time consists of two regions with different black-hole-type geometries and different values for dynamically generated cosmological constant, separated by the LL-brane which "straddles" their common event horizon.

hep-th↗

arXiv2006

Proceedings to the 9th Workshop 'What Comes Beyond the Standard Models', Bled, September 16. - 26., 2006, Slovenia

Contents: 1. Child Universes in the Laboratory (S. Ansoldi and E.I. Guendelman) 2. Relation between Finestructure Constants at the Planck Scale from Multiple Point Principle (D.L. Bennett, L.V. Laperashvili and H.B. Nielsen) 3. On the Origin of Families of Fermions and Their Mass Matrices -- Approximate Analyses of Properties of Four Families Within Approach Unifying Spins and Charges (M. Breskvar, D. Lukman and N.S. Mankoc Borstnik) 4. Cosmoparticle Physics: Cross-disciplinary Study of Physics Beyond the Standard Model (M.Yu. Khlopov) 5. Discussion Section on 4th Generation (M.Yu. Khlopov) 6. Involution Requirement on a Boundary Makes Massless Fermions Compactified on a Finite Flat Disk Mass Protected (N.S. Mankoc Borstnik and H.B. Nielsen) 7. How Can Group Theory be Generalized so Perhaps Providing Further Information About Our Universe? (R. Mirman) 8. FutureDependent Initial Conditions from Imaginary Part in Lagrangian (H.B. Nielsen and M. Ninomiya) 9. Coupling Self-tuning to Critical Lines From Highly Compact Extra Dimensions (K. Petrov)

hep-ph↗

arXiv2006

k-Essence, Avoidance of the Weinberg's Cosmological Constant No-Go Theorem and Other Dark Energy Effects of Two Measures Field Theory

The dilaton-gravity sector of the Two Measures Field Theory (TMT) is explored in detail in the context of cosmology. The dilaton ϕdependence of the effective Lagrangian appears only as a result of the spontaneous breakdown of the scale invariance. If no fine tuning is made, the effective ϕ-Lagrangian p(ϕ,X) depends quadratically upon the kinetic energy X. Hence TMT may represent an explicit example of the effective k-essence resulting from first principles without any exotic term in the fundamental action intended for obtaining this result. Depending of the choice of regions in the parameter space, TMT exhibits different possible outputs for cosmological dynamics: a) Possibility of resolution of the old cosmological constant (CC) problem. From the point of view of TMT, it becomes clear why the old CC problem cannot be solved (without fine tuning) in the conventional field theories (i.e theories with only the measure of integration \sqrt{-g} in the action). b) The power law inflation without any fine tuning can end with damped oscillations of ϕaround the state with zero CC. d) There is a broad range of the parameters such that: in the late time universe w=p/ρ<-1 and asymptotically (as t\to\infty) approaches -1 from below; ρapproaches a cosmological constant. The smallness of the CC may be achieved without fine tuning of dimensionfull parameters: either by a seesaw type mechanism or due to a correspondence principle between TMT and conventional field theories.

gr-qc↗

arXiv2006

On the Foundations of the Two Measures Field Theory

Two Measures Field Theory (TMT) uses both the Riemannian volume element \sqrt{-g}d^4x and a new one Φd^4x where the new measure of integration Φcan be build of four scalar fields. Arguments in favor of TMT, both from the point of view of first principles and from the TMT results are summarized. Possible origin of the TMT and symmetries that protect the structure of TMT are reviewed. It appears that four measure scalar fields treated as "physical coordinates" allow to define local observables in quantum gravity. The resolution of the old cosmological constant problem as a possible direct consequence of the TMT structure is discussed. Other applications of TMT to cosmology and particle physics are also mentioned.

hep-th↗

arXiv2006

Higgs-Inflaton Symbiosis, Cosmological Constant Problem and Superacceleration Phase of the Universe in Two Measures Field Theory with Spontaneously Broken Scale Invariance

We study the scalar sector of the Two Measures Field Theory (TMT) model in the context of cosmological dynamics. The scalar sector includes the inflaton ϕand the Higgs \upsilon fields. The model possesses gauge and scale invariance. The latter is spontaneously broken due to intrinsic features of the TMT dynamics. In the model with the inflaton ϕalone, in different regions of the parameter space the following different effects can take place without fine tuning of the parameters and initial conditions: a) Possibility of resolution of the old cosmological constant problem: this is done in a consistent way hinted by S. Weinberg in his comment concerning the question of how one can avoid his no-go theorem. b) The power law inflation without any fine tuning may end with damped oscillations of $ϕ$ around the state with zero cosmological constant. c) There are regions of the parameters where the equation-of-state w=p/ρin the late time universe is w<-1 and w asymptotically (as t\to\infty) approaches -1 from below. This effect is achieved without any exotic term in the action. In a model with both ϕand \upsilon fields, a scenario which resembles the hybrid inflation is realized but there are essential differences, for example: the Higgs field undergos transition to a gauge symmetry broken phase <\upsilon>\neq 0 soon after the end of a power law inflation; there are two oscillatory regimes of \upsilon, one around \upsilon =0 at 50 e-folding before the end of inflation, another - during transition to a gauge symmetry broken phase where the scalar dark energy density approaches zero without fine tuning; the gauge symmetry breakdown is achieved without tachyonic mass term in the action.

hep-th↗

arXiv2006

Exotic Low Density Fermion States in the Two Measures Field Theory: Neutrino Dark Energy

We study a new field theory effect in the cosmological context in the Two Measures Field Theory (TMT). TMT is an alternative gravity and matter field theory where the gravitational interaction of fermionic matter is reduced to that of General Relativity when the energy density of the fermion matter is much larger than the dark energy density. In this case also the 5-th force problem is solved automatically. In the opposite limit, where the magnitudes of fermionic energy density and scalar field dark energy density become comparable, nonrelativistic fermions can participate in the cosmological expansion in a very unusual manner. Some of the features of such states in a toy model of the late time universe filled with homogeneous scalar field and uniformly distributed nonrelativistic neutrinos: neutrino mass increases as m ~ a^{3/2}; the neutrino gas equation-of-state approaches w=-1, i.e. neutrinos behave as a sort of dark energy; the total (scalar field + neutrino) equation-of-state also approaches w=-1; the total energy density of such universe is less than it would be in the universe filled with the scalar field alone. An analytic solution is presented. A domain structure of the dark energy seems to be possible. We speculate that decays of the CLEP state neutrinos may be both an origin of cosmic rays and responsible for a late super-acceleration of the universe. In this sense the CLEP states exhibit simultaneously new physics at very low densities and for very high particle masses.

gr-qc↗

arXiv2005

Weyl-Conformally-Invariant Lightlike p-Brane Theories: New Aspects in Black Hole Physics and Kaluza-Klein Dynamics

We introduce and study in some detail the properties of a novel class of Weyl-conformally invariant p-brane theories which describe intrinsically lightlike branes for any odd world-volume dimension. Their dynamics significantly differs from that of the ordinary (conformally non-invariant) Nambu-Goto p-branes. We present explicit solutions of the Weyl-invariant lightlike brane- (WILL-brane) equations of motion in various gravitational models of physical relevance exhibiting various new phenomena. In D=4 the WILL-membrane serves as a material and charged source for gravity and electromagnetism in the coupled Einstein-Maxwell-WILL-membrane system; it automatically positions itself on (``straddles'') the common event horizon of the corresponding matching black hole solutions, thus providing an explicit dynamical realization of the membrane paradigm in black hole physics. In product spaces of interest in Kaluza-Klein theories the WILL-brane wraps non-trivially around the compact (internal)dimensions and still describes massless mode dynamics in the non-compact (space-time) dimensions. Due to nontrivial variable size of the internal compact dimensions we find new types of physically interesting solutions describing massless brane modes trapped on bounded planar circular orbits with non-trivial angular momentum, and with linear dependence between energy and angular momentum.

hep-th↗

arXiv2005

6-D model with scalar field condensation at brane and zero 4-D Cosmological Constant

In a previous publication we have shown that the gauge theory of relativistic 3-Branes can be formulated in a conformally invariant way if the embedding space is six-dimensional. The implementation of conformal invariance requires the use of a modified measure, independent of the metric in the action. We here generalize the theory to include conformal invariance breaking and a dynamical scalar field with a non-trivial potential. The non conformal invariance contribution can be interpreted as originating from a continious "non ideal brane fluid" that exists between two singular branes. The scalar field potential also breaks the conformal invariance. At singular brane locations, conformal invariance is restored and the dynamics of the scalar field is frozen at a certain fixed value of the scalar field which depends on an arbitrary integration constant. Spontaneous Symmetry breaking can take place due to such boundary condition without the need of invoking tachyonic mass terms for the scalar field. In these Brane-world scenarios, zero 4-D cosmological constant is achieved without the need of invoking a fine tuned cosmological constant in 6D. Thus, no ``old'' cosmological constant problem appears. The use of a measure independent of the metric is crucial for obtaining all of the above results.

hep-th↗

arXiv2005

Destabilization of Neutron Stars by Type I Dimension Bubbles

An inhomogeneous compactification of a higher dimensional spacetime can result in the formation of type I dimension bubbles, i.e., nontopological solitons which tend to absorb and entrap massive particle modes. We consider possible consequences of a neutron star that harbors such a soliton. The astrophysical outcome depends upon the model parameters for the dimension bubble, with a special sensitivity to the bubble's energy scale. For relatively small energy scales, the bubble tends to rapidly consume the star without forming a black hole. For larger energy scales, the bubble grows to a critical mass, then forms a black hole within the star, which subsequently causes the remaining star to collapse. It is possible that the latter scenario is associated with core collapse explosions and gamma ray bursts.

hep-ph↗

arXiv2004

Neutrino Dark Energy

There exist field theory models where the fermionic energy-momentum tensor contains a term proportional to g_{μν}\barΨΨwhich can be responsible for a dark matter to dark energy transmutation. We study some cosmological aspects of the new field theory effect where nonrelativistic neutrinos are obliged to be drawn into cosmological expansion (by means of dynamically changing their own parameters). This becomes possible as the magnitudes of the cold neutrino and vacuum energy densities are comparable. Some of the features of such Cosmo-Low Energy Physics (CLEP) state in the toy model of the late time universe filled with homogeneous scalar field and uniformly distributed nonrelativistic neutrinos: neutrino mass increases as a^{3/2} ($a=a(t)$ is the scale factor); its energy density scales as a sort of dark energy and its equation-of-state approaches w=-1 as a\to\infty; the total energy density of such universe is less than it would be in the universe free of fermionic matter at all. CLEP state can be realized in the framework of an alternative gravity and matter fields theory. The latter is reduced to canonical General Relativity when the fermionic matter built of the first two fermion families is only taken into account. In this case also the 5-th force problem is resolved automatically.

hep-th↗

arXiv2004

Dark energy, dark matter and fermion families in the two measures theory

gr-qc↗

arXiv2004

New Cosmic Low Energy States of Neutrino

A field theory is studied where the consistency condition of equations of motion dictates strong correlation between states of "primordial" fermion fields and local value of the dark energy. In regime of the fermion densities typical for normal particle physics, the primordial fermions split into three families identified with regular fermions. When fermion energy density is comparable with dark energy density, the theory allows transition to new type of states. The possibility of such Cosmo-Low Energy Physics (CLEP) states is demonstrated in a model of FRW universe filled with homogeneous scalar field and uniformly distributed nonrelativistic neutrinos. Neutrinos in CLEP state are drawn into cosmological expansion by means of dynamically changing their own parameters. One of the features of the fermions in CLEP state is that in the late time universe their masses increase as $a^{3/2}$ ($a=a(t)$ is the scale factor). The energy density of the cold dark matter consisting of neutrinos in CLEP state scales as a sort of dark energy; this cold dark matter possesses negative pressure and for the late time universe its equation of state approaches that of the cosmological constant. The total energy density of such universe is less than it would be in the universe free of fermionic matter at all.

hep-th↗

arXiv2004

Conformally Invariant Gauge Theory of 3-Branes in 6D and the Cosmological Constant

It is shown that the gauge theory of relativistic 3-Branes can be formulated in a conformally invariant way if the embedding space is six-dimensional. The implementation of conformal invariance requires the use of a modified measure, independent of the metric in the action. Brane-world scenarios without the need of a cosmological constant in 6D are constructed. Thus, no ``old'' cosmological constant problem appears at this level.

hep-th↗

arXiv2004

Is Cosmic Coincidence a Consequence of a Law of Nature?

A field theory is proposed where the regular fermionic matter and the dark fermionic matter are different states of the same "primordial" fermion fields. In regime of the fermion densities typical for normal particle physics, the primordial fermions split into three families identified with regular fermions. When fermion energy density becomes comparable with dark energy density, the theory allows new type of states. The possibility of such Cosmo-Low Energy Physics (CLEP) states is demonstrated by means of solutions of the field theory equations describing FRW universe filled by homogeneous scalar field and uniformly distributed nonrelativistic neutrinos. Neutrinos in CLEP state are drawn into cosmological expansion by means of dynamically changing their own parameters. One of the features of the fermions in CLEP state is that in the late time universe their masses increase as a^{3/2}. The energy density of the cold dark matter consisting of neutrinos in CLEP state scales as a sort of dark energy; this cold dark matter possesses negative pressure and for the late time universe its equation of state approaches that of the cosmological constant. The total energy density of such universe is less than it would be in the universe free of fermionic matter at all. The (quintessence) scalar field is coupled to dark matter but its coupling to regular fermionic matter appears to be extremely strongly suppressed. The key role in obtaining these results belongs to a fundamental constraint (which is consequence of the action principle) that plays the role of a new law of nature.

gr-qc↗

arXiv2004

New physics at low energies and dark matter-dark energy transmutation

A field theory is proposed where the regular fermionic matter and the dark fermionic matter can be different states of the same "primordial" fermion fields. In regime of the fermion densities typical for normal particle physics, the primordial fermions split into three families identified with regular fermions. When fermion energy density becomes comparable with dark energy density, the theory allows transition to new type of states. The possibility of such Cosmo-Low Energy Physics (CLEP) states is demonstrated by means of solutions of the field theory equations describing FRW universe filled with homogeneous scalar field and uniformly distributed nonrelativistic neutrinos. Neutrinos in CLEP state are drawn into cosmological expansion by means of dynamically changing their own parameters. One of the features of the fermions in CLEP state is that in the late time universe their masses increase as a^{3/2} (a=a(t) is the scale factor). The energy density of the cold dark matter consisting of neutrinos in CLEP state scales as a sort of dark energy; this cold dark matter possesses negative pressure and for the late time universe its equation of state approaches that of the cosmological constant. The total energy density of such universe is less than it would be in the universe free of fermionic matter at all.

hep-th↗

arXiv2004

Confinement in the presence of external fields and axions

For a theory with a pseudo scalar coupling $ϕF\tilde F$ and in the case that there is a constant electric or magnetic strength expectation value, we compute the interaction potential within the structure of the gauge-invariant but path-dependent variables formalism. While in the case of a constant electric field strength expectation value the static potential remains Coulombic, in the case of a constant magnetic field strength the potential energy is the sum of a Yukawa and a linear potentials, leading to the confinement of static charges.

hep-th↗