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Smooth Crossing of wΛ=−1 Line in a Single Scalar Field ModelEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Smooth double crossing of the phantom divide line wΛ=−1 has been found possible with a single minimally coupled scalar field for the most simple form of generalized k-essence cosmological model, in the presence of background cold dark matter. Such crossing is a sufficiently late time transient phenomenon and does not have any pathological behaviour. (Source: Advances in High Energy Physics)
Source: Advances in High Energy Physics - September 14, 2009 Category: Physics Source Type: journals

Quantum Brownian Representation for the Quantum Field ModesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
When analyzing the particle-like excitations in quantum field theory it is natural to regard the field mode corresponding to the particle momentum as an open quantum system, together with the opposite momentum mode. Provided that the state of the field is stationary, homogeneous, and isotropic, this scalar two-mode system can be equivalently represented in terms of a pair of quantum Brownian oscillators under a Gaussian approximation. In other words, the two-mode system behaves as if it were interacting linearly with some effective environment. In this paper we build the details of the effective linear coupling and the eff...
Source: Advances in High Energy Physics - August 3, 2009 Category: Physics Source Type: journals

Semi-Simple Extension of the (Super) Poincaré AlgebraEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A semi-simple tensor extension of the Poincaré algebra is proposed for the arbitrary dimensions D. It is established that this extension is a direct sum of the D-dimensional Lorentz algebra so(D−1, 1) and D-dimensional anti-de Sitter (AdS) algebra so(D−1, 2). A supersymmetric also semi-simple generalization of this extension is constructed in the D=4 dimensions. It is shown that this generalization is a direct sum of the 4-dimensional Lorentz algebra so(3, 1) and orthosymplectic algebra osp(1, 4) (super-AdS algebra). (Source: Advances in High Energy Physics)
Source: Advances in High Energy Physics - June 25, 2009 Category: Physics Source Type: journals

Toy Models of a Nonassociative Quantum MechanicsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Toy models of a nonassociative quantum mechanics are presented. The Heisenberg equation of motion is modified using a nonassociative commutator. Possible physical applications of a nonassociative quantum mechanics are considered. The idea is discussed that a nonassociative algebra could be the operator language for the nonperturbative quantum theory. In such approach the nonperturbative quantum theory has observables and unobservables quantities. (Source: Advances in High Energy Physics)
Source: Advances in High Energy Physics - June 10, 2009 Category: Physics Source Type: journals

Multiparametric Quantum Algebras and the Cosmological ConstantEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
With a view towards applications for de Sitter, we construct the multiparametric q-deformation of the so(5,ℂ) algebra using the Faddeev-Reshetikhin-Takhtadzhyan (FRT) formalism. (Source: Advances in High Energy Physics)
Source: Advances in High Energy Physics - June 10, 2009 Category: Physics Source Type: journals

Astronomical Constraints on Some Long-Range Models of Modified GravityEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We use the corrections to the Newton-Einstein secular precessions of the longitudes of the perihelia of the inner planets, phenomenologically estimated E.V. Pitjeva by fitting almost one century of data with the EPM2004 ephemerides, to constrain some long-range models of modified gravity recently put forth to address the dark energy and dark matter problems. They are the four-dimensional ones obtained with the addition of inverse powers and logarithm of some curvature invariants, and the DGP multidimensional braneworld model. After working out the analytical expressions of the secular perihelion precessions induc...
Source: Advances in High Energy Physics - June 10, 2009 Category: Physics Source Type: journals

Predictions for μ→eγ in Supersymmetry from Nontrivial Quark-Lepton Complementarity and Flavor SymmetryEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We compute the effect of nondiagonal neutrino mass in li→ljγ in Supersymmetry (SUSY) theories with nontrivial quark-lepton complementarity and a flavor symmetry. The correlation matrix VM = UCKMUPMNS is such that its (1,3) entry, as preferred by the present experimental data, is zero. We do not assume that VM is bimaximal. Quark-lepton complementarity and the flavor symmetry strongly constrain the theory and we obtain a clear prediction for the contribution to μ→eγ and the τ decays τ→eγ and τ→μγ. If the Dirac neutrino Yukawa coupl...
Source: Advances in High Energy Physics - June 10, 2009 Category: Physics Source Type: journals

Can Magnetic Monopoles and Massive Photons Coexist in the Framework of the Same Classical Theory?Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
It is well known that one cannot construct a self-consistent quantum field theory describing the nonrelativistic electromagnetic interaction mediated by massive photons between a point-like electric charge and a magnetic monopole. We show that, indeed, this inconsistency arises in the classical theory itself. No semiclassic approximation or limiting procedure for ℏ→0 is used. As a result, the string attached to the monopole emerges as visible also if finite-range electromagnetic interactions are considered in classical framework. (Source: Advances in High Energy Physics)
Source: Advances in High Energy Physics - June 10, 2009 Category: Physics Source Type: journals

Fine Structure of Dark Energy and New PhysicsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Following our recent work on the cosmological constant problem, in this letter we make a specific proposal regarding the fine structure (i.e., the spectrum) of dark energy. The proposal is motivated by a deep analogy between the blackbody radiation problem, which led to the development of quantum theory, and the cosmological constant problem, for which we have recently argued calls for a conceptual extension of the quantum theory. We argue that the fine structure of dark energy is governed by a Wien distribution, indicating its dual quantum and classical nature. We discuss observational consequences of such a picture of d...
Source: Advances in High Energy Physics - June 10, 2009 Category: Physics Source Type: journals

Experiments Needed in Meson and Baryon SpectroscopyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Three (or four) straightforward experiments would contribute greatly to completing the spectroscopy of baryons and light mesons. In the baryon sector, data are needed on inelastic reactions from a polarised target with π± and K± beams up to ∼ 3 GeV/c. Similar data are needed in the light meson sector for p¯p interactions in the momentum range 0.3–2 GeV/c. In both cases, valuable information is to be obtained from longitudinal (L) and sideways (S) target polarisations as well as the conventional normal (N) polarisation. Thirdly, 3S1 and 3D1 mesons in the mass range 1–2.4 GeV could ...
Source: Advances in High Energy Physics - June 10, 2009 Category: Physics Source Type: journals

Getting Information on |Ue3|2 from Neutrinoless Double Beta DecayEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We consider the possibility to gain information on the lepton mixing matrix element |Ue3| from an improved experimental limit on the effective neutrino mass governing neutrinoless double beta decay. We show that typically a lower limit on |Ue3| as a function of the smallest neutrino mass can be set. Furthermore, we give the values of the sum of neutrino masses and |Ue3| which are allowed and forbidden by an experimental upper limit on the effective mass. Alternative explanations for neutrinoless double beta decay, Dirac neutrinos or unexplained cosmological features would be required if future measurements showed that the ...
Source: Advances in High Energy Physics - June 10, 2009 Category: Physics Source Type: journals

The Economical SU(3)C⊗SU(3)L⊗U(1)X ModelEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The SU(3)C⊗SU(3)L⊗U(1)X gauge model with minimal scalar sector, two Higgs triplets, is presented in detail. One of the vacuum expectation values u is a source of lepton-number violations and a reason for mixing among charged gauge bosons—the standard model W± and the bilepton gauge bosons Y±, as well as among the neutral non-Hermitian bilepton X0 and neutral gauge bosons—the Z and the new Z′. An exact diagonalization of the neutral gauge boson sector is derived, and bilepton mass splitting is also given. Because of these mixings, the lepton-number violating interactions exist...
Source: Advances in High Energy Physics - June 10, 2009 Category: Physics Source Type: journals

IR-Improved DGLAP-CS TheoryEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We show that it is possible to improve the infrared aspects of the standard treatment of the DGLAP-CS evolution theory to take into account a large class of higher-order corrections that significantly improve the precision of the theory for any given level of fixed-order calculation of its respective kernels. We illustrate the size of the effects we resum using the moments of the parton distributions. (Source: Advances in High Energy Physics)
Source: Advances in High Energy Physics - June 10, 2009 Category: Physics Source Type: journals

Intermediate Inflation or Late Time Acceleration?Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The expansion rate of “intermediate inflation” lies between the exponential and power law expansion but corresponding accelerated expansion does not start at the onset of cosmological evolution. Present study of “intermediate inflation” reveals that it admits scaling solution and has got a natural exit form it at a later epoch of cosmic evolution, leading to late time acceleration. The corresponding scalar field responsible for such feature is also found to behave as a tracker field for gravity with canonical kinetic term. (Source: Advances in High Energy Physics)
Source: Advances in High Energy Physics - June 10, 2009 Category: Physics Source Type: journals

On the Superstrings-Induced Four-Dimensional Gravity and Its Applications to CosmologyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We review the status of the fourth-order (quartic in the spacetime curvature) terms induced by superstrings/M-theory (compactified on a warped torus) in the leading order with respect to the Regge slope parameter, and study their (nonperturbative) impact on the evolution of the Hubble scale in the context of the four-dimensional FRW cosmology. After taking into account the quantum ambiguities in the definition of the off-shell superstring effective action, we propose the generalized Friedmann equations, find the existence of their (de Sitter) exact inflationary solutions without a spacetime singularity, and constrain the a...
Source: Advances in High Energy Physics - June 10, 2009 Category: Physics Source Type: journals

Hybrid Charmonium and the ρ−π PuzzleEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Using the method of QCD sum rules, we estimate the energy of the lowest hybrid charmonium state, and find it to be at the energy of the Ψ′(2S) state, about 600 MeV above the J/Ψ(1S) state. Since our solution is not consistent with a pure hybrid at this energy, we conclude that the Ψ′(2S) state is probably an admixed cc¯ and hybrid cc¯g state. From this conjecture, we find a possible explanation of the famous ρ−π puzzle. (Source: Advances in High Energy Physics)
Source: Advances in High Energy Physics - June 10, 2009 Category: Physics Source Type: journals

Black Hole Interior from Loop Quantum GravityEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We calculate modifications to the Schwarzschild solution by using a semiclassical analysis of loop quantum black hole. We obtain a metric inside the event horizon that coincides with the Schwarzschild solution near the horizon but that is substantially different at the Planck scale. In particular, we obtain a bounce of the S2 sphere for a minimum value of the radius and that it is possible to have another event horizon close to the r=0 point. (Source: Advances in High Energy Physics)
Source: Advances in High Energy Physics - June 10, 2009 Category: Physics Source Type: journals

Thermodynamics in Loop Quantum CosmologyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Loop quantum cosmology (LQC) is very powerful to deal with the behavior of early universe. Moreover, the effective loop quantum cosmology gives a successful description of the universe in the semiclassical region. We consider the apparent horizon of the Friedmann-Robertson-Walker universe as a thermodynamical system and investigate the thermodynamics of LQC in the semiclassical region. The effective density and effective pressure in the modified Friedmann equation from LQC not only determine the evolution of the universe in LQC scenario but also are actually found to be the thermodynamic quantities. This result comes from ...
Source: Advances in High Energy Physics - June 10, 2009 Category: Physics Source Type: journals

The Density-Dependent Correlations among Observables in Nuclear Matter and Hyperon-Rich Neutron StarsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The conserving σ-ω-ρ mean-field approximation with nonlinear interactions of hadrons has been applied to examine properties of nuclear matter and hyperonic neutron stars. The nonlinear interactions that will produce density-dependent effective masses and coupling constants of hadrons are included in order to examine density correlations among properties of nuclear matter and neutron stars such as binding energy, incompressibility, K, symmetry energy, a4, hyperon-onset density, and maximum masses of neutron stars. The conditions of conserving approximations in order to maintain thermodynamic consistency...
Source: Advances in High Energy Physics - June 10, 2009 Category: Physics Source Type: journals

Thermodynamics in Loop Quantum CosmologyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Loop quantum cosmology (LQC) is very powerful to deal with the behavior of early universe. Moreover, the effective loop quantum cosmology gives a successful description of the universe in the semiclassical region. We consider the apparent horizon of the Friedmann-Robertson-Walker universe as a thermodynamical system and investigate the thermodynamics of LQC in the semiclassical region. The effective density and effective pressure in the modified Friedmann equation from LQC not only determine the evolution of the universe in LQC scenario but also are actually found to be the thermodynamic quantities. This result comes from ...
Source: Advances in High Energy Physics - April 16, 2009 Category: Physics Source Type: journals

Black Hole Interior from Loop Quantum GravityEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We calculate modifications to the Schwarzschild solution by using a semiclassical analysis of loop quantum black hole. We obtain a metric inside the event horizon that coincides with the Schwarzschild solution near the horizon but that is substantially different at the Planck scale. In particular, we obtain a bounce of the S2 sphere for a minimum value of the radius and that it is possible to have another event horizon close to the r=0 point. (Source: Advances in High Energy Physics)
Source: Advances in High Energy Physics - March 23, 2009 Category: Physics Source Type: journals

Hybrid Charmonium and the ρ−π PuzzleEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Using the method of QCD sum rules, we estimate the energy of the lowest hybrid charmonium state, and find it to be at the energy of the Ψ′(2S) state, about 600 MeV above the J/Ψ(1S) state. Since our solution is not consistent with a pure hybrid at this energy, we conclude that the Ψ′(2S) state is probably an admixed cc¯ and hybrid cc¯g state. From this conjecture, we find a possible explanation of the famous ρ−π puzzle. (Source: Advances in High Energy Physics)
Source: Advances in High Energy Physics - February 3, 2009 Category: Physics Source Type: journals

On the Superstrings-Induced Four-Dimensional Gravity and Its Applications to CosmologyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We review the status of the fourth-order (quartic in the spacetime curvature) terms induced by superstrings/M-theory (compactified on a warped torus) in the leading order with respect to the Regge slope parameter, and study their (nonperturbative) impact on the evolution of the Hubble scale in the context of the four-dimensional FRW cosmology. After taking into account the quantum ambiguities in the definition of the off-shell superstring effective action, we propose the generalized Friedmann equations, find the existence of their (de Sitter) exact inflationary solutions without a spacetime singularity, and constrain the a...
Source: Advances in High Energy Physics - January 22, 2009 Category: Physics Source Type: journals

Intermediate Inflation or Late Time Acceleration?Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The expansion rate of “intermediate inflation” lies between the exponential and power law expansion but corresponding accelerated expansion does not start at the onset of cosmological evolution. Present study of “intermediate inflation” reveals that it admits scaling solution and has got a natural exit form it at a later epoch of cosmic evolution, leading to late time acceleration. The corresponding scalar field responsible for such feature is also found to behave as a tracker field for gravity with canonical kinetic term. (Source: Advances in High Energy Physics)
Source: Advances in High Energy Physics - October 29, 2008 Category: Physics Source Type: journals

The Economical SU(3)C⊗SU(3)L⊗U(1)X ModelEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The SU(3)C⊗SU(3)L⊗U(1)X gauge model with minimal scalar sector, two Higgs triplets, is presented in detail. One of the vacuum expectation values u is a source of lepton-number violations and a reason for mixing among charged gauge bosons—the standard model W± and the bilepton gauge bosons Y±, as well as among the neutral non-Hermitian bilepton X0 and neutral gauge bosons—the Z and the new Z′. An exact diagonalization of the neutral gauge boson sector is derived, and bilepton mass splitting is also given. Because of these mixings, the lepton-number violating interactions exist...
Source: Advances in High Energy Physics - August 13, 2008 Category: Physics Source Type: journals

IR-Improved DGLAP-CS TheoryEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We show that it is possible to improve the infrared aspects of the standard treatment of the DGLAP-CS evolution theory to take into account a large class of higher-order corrections that significantly improve the precision of the theory for any given level of fixed-order calculation of its respective kernels. We illustrate the size of the effects we resum using the moments of the parton distributions. (Source: Advances in High Energy Physics)
Source: Advances in High Energy Physics - August 13, 2008 Category: Physics Source Type: journals

Toy Models of a Nonassociative Quantum MechanicsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Toy models of a nonassociative quantum mechanics are presented. The Heisenberg equation of motion is modified using a nonassociative commutator. Possible physical applications of a nonassociative quantum mechanics are considered. The idea is discussed that a nonassociative algebra could be the operator language for the nonperturbative quantum theory. In such approach the nonperturbative quantum theory has observables and unobservables quantities. (Source: Advances in High Energy Physics)
Source: Advances in High Energy Physics - July 14, 2008 Category: Physics Source Type: journals

Multiparametric Quantum Algebras and the Cosmological ConstantEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
With a view towards applications for de Sitter, we construct the multiparametric q-deformation of the so(5,ℂ) algebra using the Faddeev-Reshetikhin-Takhtadzhyan (FRT) formalism. (Source: Advances in High Energy Physics)
Source: Advances in High Energy Physics - July 14, 2008 Category: Physics Source Type: journals

Astronomical Constraints on Some Long-Range Models of Modified GravityEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We use the corrections to the Newton-Einstein secular precessions of the longitudes of the perihelia of the inner planets, phenomenologically estimated E.V. Pitjeva by fitting almost one century of data with the EPM2004 ephemerides, to constrain some long-range models of modified gravity recently put forth to address the dark energy and dark matter problems. They are the four-dimensional ones obtained with the addition of inverse powers and logarithm of some curvature invariants, and the DGP multidimensional braneworld model. After working out the analytical expressions of the secular perihelion precessions induc...
Source: Advances in High Energy Physics - July 14, 2008 Category: Physics Source Type: journals

Predictions for μ→eγ in Supersymmetry from Nontrivial Quark-Lepton Complementarity and Flavor SymmetryEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We compute the effect of nondiagonal neutrino mass in li→ljγ in Supersymmetry (SUSY) theories with nontrivial quark-lepton complementarity and a flavor symmetry. The correlation matrix VM = UCKMUPMNS is such that its (1,3) entry, as preferred by the present experimental data, is zero. We do not assume that VM is bimaximal. Quark-lepton complementarity and the flavor symmetry strongly constrain the theory and we obtain a clear prediction for the contribution to μ→eγ and the τ decays τ→eγ and τ→μγ. If the Dirac neutrino Yukawa coupl...
Source: Advances in High Energy Physics - July 14, 2008 Category: Physics Source Type: journals

Can Magnetic Monopoles and Massive Photons Coexist in the Framework of the Same Classical Theory?Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
It is well known that one cannot construct a self-consistent quantum field theory describing the nonrelativistic electromagnetic interaction mediated by massive photons between a point-like electric charge and a magnetic monopole. We show that, indeed, this inconsistency arises in the classical theory itself. No semiclassic approximation or limiting procedure for ℏ→0 is used. As a result, the string attached to the monopole emerges as visible also if finite-range electromagnetic interactions are considered in classical framework. (Source: Advances in High Energy Physics)
Source: Advances in High Energy Physics - July 14, 2008 Category: Physics Source Type: journals

Fine Structure of Dark Energy and New PhysicsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Following our recent work on the cosmological constant problem, in this letter we make a specific proposal regarding the fine structure (i.e., the spectrum) of dark energy. The proposal is motivated by a deep analogy between the blackbody radiation problem, which led to the development of quantum theory, and the cosmological constant problem, for which we have recently argued calls for a conceptual extension of the quantum theory. We argue that the fine structure of dark energy is governed by a Wien distribution, indicating its dual quantum and classical nature. We discuss observational consequences of such a picture of d...
Source: Advances in High Energy Physics - July 14, 2008 Category: Physics Source Type: journals

Experiments Needed in Meson and Baryon SpectroscopyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Three (or four) straightforward experiments would contribute greatly to completing the spectroscopy of baryons and light mesons. In the baryon sector, data are needed on inelastic reactions from a polarised target with π± and K± beams up to ∼ 3 GeV/c. Similar data are needed in the light meson sector for p¯p interactions in the momentum range 0.3–2 GeV/c. In both cases, valuable information is to be obtained from longitudinal (L) and sideways (S) target polarisations as well as the conventional normal (N) polarisation. Thirdly, 3S1 and 3D1 mesons in the mass range 1–2.4 GeV could ...
Source: Advances in High Energy Physics - July 14, 2008 Category: Physics Source Type: journals

Getting Information on |Ue3|2 from Neutrinoless Double Beta DecayEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We consider the possibility to gain information on the lepton mixing matrix element |Ue3| from an improved experimental limit on the effective neutrino mass governing neutrinoless double beta decay. We show that typically a lower limit on |Ue3| as a function of the smallest neutrino mass can be set. Furthermore, we give the values of the sum of neutrino masses and |Ue3| which are allowed and forbidden by an experimental upper limit on the effective mass. Alternative explanations for neutrinoless double beta decay, Dirac neutrinos or unexplained cosmological features would be required if future measurements showed that the ...
Source: Advances in High Energy Physics - July 14, 2008 Category: Physics Source Type: journals