July 8-18, 2008 - ICRANet Center, Pescara (Italy)
| HOME | PROGRAM | SPEAKERS | PARTICIPANTS | LIFE SCHEDULE | S.O.C. | PHOTOS |
Prof. G. 't Hooft
Title: Some Misconceptions concerning Gravitational Radiation
Speaker: G. 't Hooft
Author: G. 't HooftAbstract: Einstein's field equations allow for wavelike solutions, with two possible polarizations, just like electromagnetic waves. Fluctuations in energy, momentum density and tension are the sources of this radiation, but at the same time gravitational radiation carries energy and momentum itself. This sometimes leads to confusion and controversy, but the situation can be neatly explained. An exact solution already found by Weber and Wheeler back in 1957 can be used to illustrate what happens.
Title: Quantum mechanics, discretization and local determinism
Speaker: G. 't Hooft
Author: G. 't HooftAbstract: If mechanical laws of evolution at tiny distance scales, say the Planck scale, are given by some fundamental laws, which may well be non-quantum mechanical, these laws may well result in completely chaotic behavior at larger scales, say those of atoms, molecules, or indeed today's Standard Model. There will be subtle correlations in the fluctuations at longer distances, and these may well be described by quantum mechanics exactly as we know it today. This idea leads to a theory as to what quantum mechanics really is, and why our world of atoms, molecules and subatomic particles appears to be quantum mechanical. There is a mathematical theory showing how this might work in a simple cellular automaton, although simple cellular automata do not produce particles of the kind that we know. The model of the previous lecture might be a more suitable starting point.
Title: A locally finite model for gravity
Speaker: G. 't Hooft
Author: G. 't HooftAbstract: Matter interacting classically with gravity in 3+1 dimensions usually gives rise to a continuum of degrees of freedom, so that, in any attempt to quantize the theory, ultraviolet divergences are nearly inevitable. Here, we investigate matter of a form that only displays a finite number of degrees of freedom in compact sections of space-time. In finite domains, one has only exact, analytic solutions. This is achieved by limiting ourselves to straight pieces of string, surrounded by locally flat sections of space-time. Globally, however, the model is not finite, because solutions tend to generate infinite fractals. The model is not (yet) quantized, but could serve as an interesting setting for analytical approaches to classical general relativity, as well as a possible stepping stone for quantum models. Details of its properties are explained, but some problems remain unsolved, such as a complete description of the most violent interactions, which can become quite complex. A remarkable feature appears to be that in this model, gravity and matter appear to be unified.
Title: Black holes and elementary particle physics
Speaker: G. 't Hooft
Author: G. 't HooftAbstract: The most conspicuous features in the theory of the gravitational field is the emergence of black holes.
Trying to subject them to the laws of Quantum Mechanics may well be the best attack on the quantization problem in General Relativity. If one applies the laws of Quantum Field Theory to the environment of a black hole, one finds a kind of uncertainty on top and above the usual quantum uncertainties that one would expect. It seems as if the very foundations of Quantum Theory are being undermined by this result. Postulating the demand that "quantized" black holes ought to behave just like other quantum systems, leads to a new theory on the physical states and their dynamics at the Planck scale, and perhaps also to a fresh view on what Quantum Mechanics might actually be.Download 1:
PPT
Download 2:
Download 3:
---------------------------------------------------------------------------------------------------------------------------------------------
A.G. Aksenov
Title: Relativistic Boltzmann equations for the pair plasma in presence of proton loading
Speaker: A.G. Aksenov
Authors: A.G. Aksenov, R. Ruffini, G.V. VereshchaginAbstract: In the recent publication we analyzed the role of the direct and the inverse binary and triple interactions in reaching thermal equilibrium in homogeneous isotropic pair plasma, starting from a nonequlibrium state. In the present work we extend the analysis to the case of proton-loaded plasma. The corresponding timescales for thermalization of electrons, positrons, protons and photons are determined out from the numerical solution of the relativistic Boltzmann equations. We include all exact QED collisional integrals for binary reactions, while for the corresponding radiative variants we reduce reaction rates to the known expressions of kinetic coefficients in the thermal equilibrium.
Download:
E. Alesci
Title: Graviton Propagator in LQG: a Tool to Test Spinfoam Models
Speaker: E. Alesci
Author: E. AlesciAbstract:We briefly review the construction of the graviton propagator in the context of LQG and Spinfoam Models and we show how the Barrett-Crane vertex fails to give the correct long-distance limit. The same kind of calculation however, can give the correct propagator using an alternative vertex with a specific asymptotic behavior. It is still an open issue if the vertex amplitudes of the new models satisfy the requirements for yielding the correct two point function or more in general GR in the classical limit. We present some preliminary results that can give new insight to this problem.
Download:
L. Amati
Title: The Ep,i-Eiso correlation in GRB: recent observations, implications and cosmology
Speaker: L. Amati
Author:Abstract: The correlation between the photon energy at which the redshift corrected nufnu spectrum peaks (hence called "peak energy", Ep,i) and the isotropic equivalent radiated energy (Eiso), is one of the most intriguing and debated observational evidences in Gamma--Ray Bursts (GRB) astrophysics. I present the updated Ep,i-Eiso correlation, its main implications for the physics, geometry and origin of the GRB emission, with particular emphasis on recent Swift results, and the recently proposed use of this correlation for the estimate of cosmological parameters.
Download:
G. Amelino-Camelia
Title: Falsifiable Planck-Scale Theories of NOT Everything
Speaker: G. Amelino-Camelia
Author: G. Amelino-CameliaAbstract: Primarily as a result of the nature of the quantum-gravity problem, with its extraordinarily rich conceptual structure, and its clever resistance to our (however feeble) attempts to gain experimental insight, it is becoming customary to consider reasoning in terms of the ``anthropic principle" as a possible tool of scientific analysis. I stress that the validity of any thesis based on the anthropic principle cannot be established through reproducible experiments, and that theories elaborated on the basis of the anthropic principle gain nothing for what concerns their predictive power. The anthropic-principle temptation should therefore be left to the appetites of philosophers. I argue that for physicists the difficulties encountered in the study of the quantum-gravity problem should represent an invitation to adopt a more humble approach, which I describe as the search of "Planck-scale theories of not everything". To illustrate the concept I review some recent results on noncommutative field theories, which appear to provide the basis for some examples of falsifiable Planck-scale theories of not everything.
G. Barbiellini
Speaker: G. Barbiellini
Authors: G. BarbielliniDownload:
M.V. Battisti
Title: Time Evolution of a Generic Quantum Universe
Speaker: M.V. Battisti
Authors: M.V. Battisti, G. MontaniAbstract: The evolutionary quantization of a generic inhomogeneous Universe is analyzed. In particular, the time-evolution of the model is traced with respect to the energy density of a perfect gas and at the same level a new matter contribution is induced in the Universe dynamics. We show that such an approach is suitable to describe the time evolution of a quantum Universe since no phenomenology arises today from the new matter field.
Download:
Title: Extended Approach to the Canonincal Quantization in the Minisuperspace
Speaker: M.V. Battisti
Author: M.V. BattistiAbstract: A phenomenological framework which describes the effective Friedmann dynamics of loop and braneworlds theories is developed. More precisely, it appears as soon as a deformed Heisenberg (minisuperspace) algebra is taken into account. This way, the peculiar differences of these approaches are immediately understood from this point of view.
Download:
Title: Quantum Cosmology in the GUP Approach
Speaker: M.V. Battisti
Authors: M.V. Battisti, G. MontaniAbstract: The quantization of cosmological models by the use of a deformed algebra is described. Such an algebra reproduces a generalized uncertainty principle as appeared from studies on string theory. The FRW, Taub and Mixmaster Universes are analyzed in such a framework and the implications on the cosmological singularity, the isotropization mechanism and the chaotic proprieties are investigated.
Download:
V.A. Belinski
Title: Charged masses and repulsive gravity
Speaker: V.A. Belinski
Authors: V.A. Belinski, G. Alekseev, M. Pizzi, A. PaolinoAbstract: We discuss some exact solutions of the Einstein-Maxwell equations exhibiting repulsive gravitational forces. We show that it is possible to construct a regular material source in the form of Nambu-Goto membrane outside of which the Reissner-Nordstrom (RN) repulsive gravity effect exists. The point is that membrane are able to cut out the central naked singularity region and at the same time join the RN repelling region. The existence of such kind of sources gives a sensible physical status to the RN solution for the naked singularity case.
R. Belvedere
Title: Quantum Isotropization Mechanism for the Mixmaster Model
Speaker: R. Belvedere
Authors: R. Belvedere, M.V. Battisti, G. MontaniAbstract: An exact solution of the quantum quasi-isotropic Mixmaster model is described. In particular, the volume of the Universe is regarded as a time-coordinate for the dynamics and a probabilistic interpretation of the wave function naturally arises. Once large volume regions are investigated, the closed FRW Universe configuration is deeply privileged.
Download:
R. Benini
Title: E.C.G. Stueckelberg: a Forerunner of Modern Physics III
Speakers: R. Benini, O.M. Lecian
Authors: R. Benini, O.M. Lecian
Title: Review on the Generic Cosmological Solution Near the Singularity
Speaker: R. Benini
Authors: R. Benini, G. MontaniAbstract: In this talk I discuss the main properties characterizing the cosmological singularity associated to the homogeneous and the inhomogeneous Mixmaster model. We firstly assess the classical picture reviewing the historical works by Belinski, Lifshitz and Khalatnikov and these of Misner; particular attention is paid to the chaotic properties of the model. Finally I present the semi-classical and quantum behaviour.
Download:
M.G. Bernardini
Title: The GRB classification within the fireshell model: short, long and fake short GRBs
Speakers: M.G. Bernardini
Authors: M.G. Bernardini, C.L. Bianco, L. Caito, M.G. Dainotti, R. Guida, R. RuffiniAbstract: Within the fireshell model we define a "canonical GRB" light curve with two sharply different components: the Proper-GRB (P-GRB), emitted when the optically thick fireshell of electron-positron plasma originating the phenomenon reaches transparency, and the afterglow, emitted due to the collision between the remaining optically thin fireshell and the CircumBurst Medium (CBM). The identification of these two component is crucial in order to interpret in a new and more physical way the standard GRB classification in "short" and "long". Moreover, we trace a new class of "fake" short GRBs, whose features are affected by the peculiar astrophysical conditions in which they occur.
Download:
S. Bernuzzi
Title: Gravitational waves from neutron star oscillations: comparisons between linear and nonlinear evolutions
Speakers: S. Bernuzzi
Authors: S. Bernuzzi, A. NagarDownload:
B. Betz
Title: Plasminos - collective excitations of relativistic fermions
Speaker: B. Betz
Authors: B. BetzAbstract: QCD, the theory of strong interactions between quarks, exhibits the feature of asymptotic freedom. Thus, for systems with high temperatures and/or densities hadronic matter is supposed to undergo a phase transition to the quark-gluon plasma, while for low temperature and high densities a new ground state forms - the color superconductivity. Both regions of the phase diagram have been studied intensively during the last years, either in heavy-ion collisions or studying astrophysical situations of quark matter in compact stellar objects. In general, gaining an understanding of the structure of the matter requires to identify their quasi-particle properties. The fermionic excitation spectrum is reviewed for both normal - and superconducting systems, discussing the additionally occuring collective excitations - the plasminos.
Download:
C.L. Bianco
Title: Equations of motion of the fireshell
Speakers: C.L. Bianco
Authors: C.L. Bianco, M.G. Bernardini, L. Caito, M.G. Dainotti, R. Guida, R. Ruffini, G.V. Vereshchagin, S.S. XueAbstract: The Fireshell originating a Gamma-Ray Burst (GRB) encompasses an optically thick regime followed by an optically thin one. In the first one the fireshell self-accelerates from a Lorentz gamma factor equal to 1 all the way to 200-300. The physics of this system is based on the continuous annihilation of electron-positron pairs in an optically thick e^+e^- plasma with a small baryon loading. In the following regime, the optically thin fireshell, composed by the baryons left over after the transparency point, ballistically expands into the CircumBurst Medium (CBM). The kinematics and dynamics of the fireshell during both regimes will be analyzed, and the corresponding equations of motion will be compared with the ones of the "fireball" model, usually adopted in GRB literature. Implications for the interpretation of the observational data will be discussed.
Download:
D. Bini
Title: Extended Bodies in General Relativity: the Quadrupole Approximation
Speakers: D. Bini
Authors: D. BiniAbstract: Applications of Dixon's model for the motion of extended bodies in general relativity up to the quadrupole moment will be considered for the Schwarzschild, Kerr and gravitational plane wave spacetimes. Comparison of the Dixon and Papapetrou models will be made.
Download:
L. Caito
Title: GRB 060614, a canonical Fake Short Burst
Speakers: L. Caito
Authors: L. Caito, M.G. Bernardini, C.L. Bianco, M.G. Dainotti, R. Guida, R. RuffiniAbstract: GRB 060614 is the first clear example of a near, long burst without a bright SN Ib/c emission observed, crucial issue that undermines one of the fundamental assumptions of the standard scenario. Moreover, this source presents peculiarities both of long bursts and of short bursts, not belonging definitely neither to the first nor to the second class.
This "anomalous" situation finds a natural interpretation in our "Fireshell" scenario: GRB 060614 is a canonical fake short burst; the initial spikelike emission, followed in the 15-150 KeV energy band by a deflated but mostly energetic tail, is due to the particularly lower density of the environment. This interpretation is compatible with the merger of a binary system as progenitor of the burst.Download:
S. Capozziello
Title: Dark Energy Models toward Observational Tests and Data
Speaker: S. Capozziello
Author: S. CapozzielloAbstract: An impressive amount of different astrophysical data converges towards the picture of a spatially flat universe undergoing a recent phase of accelerated expansion. The nature of the dark energy dominating the Hubble flow is still unknown and a lot of different scenarios are viable candidates to explain such a cosmic acceleration. Methods adopted to test these cosmological models are based on distance measurements of given classes of objects (e.g. SNeIa, quasars, etc), on lookback time by cosmic clocks (e.g. galaxy clusters) and on cosmic age measurements. We critically discuss models and methods with respect to the observational data.
Download:
A. Cardinali
Title: Asymptotic Techniques and Hamiltonian Formalism in the Solution of the Electromagnetic Wave Equation in Ionized Gases
Speaker: A. Cardinali
Author: A. CardinaliAbstract: The Maxwell-Vlasov partial integro-differential equation provides a mathematical scheme to describe the propagation of an electromagnetic pulse in an ionized gas, with and without externally imposed static fields. Under opportune simplifying assumptions this equation can be reduced to a more tractable equation for both analytical and numerical investigations. In particular asymptotic methods, like WKB techniques, simplifies further the model allowing to investigate it in the frame of the Hamiltonian theory of dynamical systems. Analytical and numerical solutions are presented and some features of the non-linear Hamiltonian of non-integrable dynamical system, like the destruction of KAM tori and the emersion of the chaos are pointed out.
Download:
N. Carlevaro
Title: New Issues in Lorentz Guage Theories
Speaker: N. Carlevaro
Authors: N. Carlevaro, O.M. Lecian, G. MontaniAbstract: This talk is devoted to introduce a gauge theory of the Lorentz Group based on the ambiguity emerging in dealing with isometric diffeomorphism-induced Lorentz transformations. The behaviors under local transformations of fermion fields and spin connections (assumed to be coordinate vectors) are analyzed in flat space-time and the role of the torsion field within the generalization to curved space-time is briefly discussed. The fermion dynamics including the new gauge field is then analyzed assuming time-gauge and stationary solutions in the non-relativistic limit are founded.
Download:
Title: Gravitational Instability in Presence of Dissipative Effects
Speaker: N. Carlevaro
Authors: N. Carlevaro, G. MontaniAbstract: This talk focus on the analysis of gravitational instability in presence of dissipative effects. In particular, the standard Jeans Mechanism and the generalization in treating the Universe expansion are both analyzed when bulk viscosity affects the first order Newtonian dynamics. As results, the perturbations evolution is founded to be dumped by dissipative processes and the top-down mechanism of structure formation is suppressed. In such a scheme the Jeans mass remain unchanged also in presence of viscosity.
Download:
C. Cherubini
Title: On the energetics of the dyadotorus
Speaker: C. Cherubini
Authors: C. Cherubini, A. Geralico, J.A. Rueda H., R. RuffiniAbstract: The “dyadotorus” is defined as the region around a charged and rotating black hole where pair creation by vacuum polarization can occurr. It represents the extension of the concept of “dyadosphere” already introduced in the static case in the Reissner-Nordstrom geometry. An analysis of the energetics of the dyadotorii as well as a discussion of their topology and embedding diagrams are presented.
Download:
F. Cianfrani
Title: The Role of Time-Gauge in Quantizing Gravity
Speaker: F. Cianfrani
Authors: F. Cianfrani, G. MontaniAbstract: We present the Hamiltonian formulation of General Relativity in a generic local Lorentz frame in both a second and a first order formulation. In the former, we demonstrate the possibility to define formally a unitary operator connecting different frames. In the latter, a Gauss constraint is inferred by a proper generalization of Ashtekar-Barbero-Immirzi connections.
Download:
PS
Title: Review on Extended Approaches in the Kaluza-Klein Model
Speaker: F. Cianfrani
Authors: F. Cianfrani, G. MontaniAbstract: A review of the Kaluza-Klein formulation is provided, with a particular emphasis on the geometrization issue. The failure at reproducing quantum numbers of particles and the appearance of huge mass terms are outlined. The possibility to solve these points by an extended approach based on an averaging procedure is discussed.
Download:
C. Corda
Title: Signals and interferometric response functions in the framework of GW arising from extended theory of gravity
Speaker: C. Corda
Author: C. CordaAbstract: The talk is organized as follows. We start with a discussion on the importance of both of the weak-field approximation and the gravitational radiation into the framework of gravity theories. After this, the response functions of interferometers to gravitational waves arising from standard General Relativity will be shown. Then, the discussion will be further improved considering the important issue of the ''magnetic'' component of gravitational waves. After this, the case of massless scalar-tensor gravity will be considered and the analysis will be extended to f(R) theories of gravity. At the end of the talk, a discussion of the presented results will be performed, showing that, assuming an improvement in the sensitivity of advanced projects, the presented frequency-dependent response functions could, in principle, help to discriminate between various gravity theories, while such a potential discrimination will be impossible considering only the low-frequency approximation response functions of previous literature. The papers which founded this talk have been the world most cited in the Official Astroparticle Publication Review of ASPERA in the course of 2007 (13 citations).
Download:
M.G. Dainotti
Title: GRB 060418: flares and spectral lag
Speaker: M.G. Dainotti
Authors: M.G. Dainotti, M.G. Bernardini, L. Caito, C.L. Bianco, R. Guida, R. RuffiniAbstract: We present the features of this source within the fireshell model taking into account the parameters we need to fit this GRB. In this model the GRB is composed by the flash of the photons (P-GRB) emitted by the fireshell when it reaches the transparency and the afterglow produced by the interaction between the fireshell and the circumburst medium.We try to explain the spectral lag in correspondence to the big flares and the features of the P-GRB.
Download:
G. De Barros
Title: Is GRB050509b a genuine short GRB ?
Speaker: G. De Barros
Authors: G. De BarrosAbstract: Within our "fireshell" model we introduced a "canonical" GRB scenario which differentiates physically the "proper GRB" (P-GRB) emission when photons decouple, and the afterglow emission due to interaction of the accelerated baryons with the CircumBurst Medium (CBM). The ratio between energetics of the two components is ruled by the baryon loading of the fireshell. We here analyse the possibility that GRB050509b is the first case of a "genuine" short GRB the ones with smaller baryon loading. In such a case, the GRB050509b "prompt emission" would be dominated by the "proper GRB" and, moreover, the P-GRB total energy would be greater than the afterglow one. Our fit of the afterglow data and of the P-GRB energetics indicates that this source present the smallest baryon loading we ever encountered so far, being on the order of 10^{-4}, and we expect to have emission in order of MeV.
Download:
M.F. De Laurentis
Title: Stochastic background of gravitational waves "tuned" by f(R) gravity
Speaker: M.F. De Laurentis
Authors: M F.. De LaurentisAbstract: We show that the stochastic background of gravitational waves, produced in the early cosmological epochs, strictly depends on the assumed theory of gravity. In particular, the specific form of the function f(R), where R is the Ricci scalar, is related to the evolution and the production mechanism of gravitational waves. On the other hand, detecting the stochastic background by the forthcoming interferometric experiments (VIRGO, LIGO, LISA) could be a further tool to select the effective theory of gravity.
G. Fodor
Title: Almost periodic localized systems: oscillons and oscillatons
Speaker: G. Fodor
Authors: G. Fodor, P. Forgács, Z. Horváth, Á. LukácsAbstract: Extremely long living, localized, almost periodically oscillating configurations have been observed numerically in various nonlinear field theoretical models involving massive fields. For the scalar field case these objects were named pulsons or oscillons, and they have been demonstrated to form even in the bosonic sector of the Standard Model. We discuss their behaviour in terms of the exactly periodic but infinite energy quasi-breather solutions. We also present a small amplitude expansion, which reduces the problem to ordinary differential equations. Closely related objects in General Relativity are called boson stars in case of complex or quantized real fields, and oscillatons in case of a classical real Klein-Gordon field coupled to gravity. For osicllatons the metric also changes almost periodically in time. Although the very slow energy loss of oscillatons cannot be observed by numerical methods, considerations similar to those given by Don Page indicate that they are most likely not exactly periodic.
Download:
A. Geralico
Title: On the "electric Meissner effect" in the field of a Reissner-Nordstrom black hole
Speaker: A. Geralico
Authors: A. GeralicoAbstract: A perturbative solution describing a two-body system consisting of a Reissner-Nordstrom black hole and a charged massive particle at rest is presented. The general properties of the perturbed metric, completely reconstructed analytically, are discussed. The perturbed electromagnetic field is also analyzed by plotting the associated lines of force.
Download:
L. Izzo
Title: Detection of the CSB of GW in f(R) gravity with FASTICA
Speaker: L. Izzo
Authors: L. IzzoAbstract: We show that the stochastic background of gravitational waves, produced in the early cosmological epochs, strictly depends on the assumed theory of gravity. In particular, the specific form of the function f(R), where R is the Ricci scalar, is related tothe evolution and the production mechanism of gravitational waves. Using a neural network algorthm which only requires non-Gaussian nature and independence of the input signals we conclude that, in order to detect a CSB signal, the interferometric sensitivity of detector like VIRGO will be improved.
Download:
H. Kleinert
Title: Multivalued Fields and Third Quantization
Speaker: H. Kleinert
Authors: H. KleinertAbstract: It is shown that the extension of quantum field theory from single- to multivalued fields greatly enriches our understanding of a large variety of physical phenomena associated with electromagnetic and gravitational interactions. It also forms a bridge from elementary-particle physics to phenomena in condensed matter caused by vortex and defect lines.
V. Lacquaniti
Title: Recent Developement in Particle and Field Motion within the Kaluza-Klein Picture
Speaker: V. Lacquaniti
Authors: V. Lacquaniti, G. MontaniAbstract: The standard approach to matter dynamics in a compactified Kaluza Klein model leads to inconsistent results. After a brief review of such a framework, with some emphasis on the charge-mass problem and the huge massive modes generation, we present a revised approach based on a delocalization hypothesis about the motion along the fifth dimension, where a Papapetrou expansion is performed. We show how this approach gives a consistent dynamics and rules out the huge massive modes. At the same time in this framework is possible to deal with a complete Kaluza-Klein model with source. Some perspectives of this model are discussed.
Download:
M. Lattanzi
Title: Constraining Dark Matter Models Through 21cm Observations
Speaker: M. Lattanzi
Author: M. LattanziAbstract: Different dark matter candidates can inject energy into the intergalactic medium through their decay and/or annihilation products. This will affect the ionization and heating history of the Universe, leading to a distinct signature in the 21cm signal. Here I will discuss the observational signatures of different dark matter candidates, including supersymmetryc neutralinos, sterile neutrinos, majorons, and light dark matter, and discuss the possibility of detecting this signal in upcoming experiments.
Download:
O.M. Lecian
Title: E.C.G. Stueckelberg: a Forerunner of Modern Physics III
Speakers: O.M. Lecian, R. Benini
Authors: R. Benini, O.M. Lecian
Title: Recent Approaches to Modified-Gravity Theories
Speaker: O.M. Lecian
Authors: O.M. Lecian, G. MontaniAbstract: After reviewing the main features of f(R) gravity and the corresponding scalar-tensor description, we present some recent issues. From a cosmological point of view, we analyze the main implications of an exponential gravitational action, and particular attention will be devoted to the non-vanishing value of f(0). As far as Newtonian Physics is concerned, we investigate the weak-field limit of non-analytical f(R) gravity, impose constraints on the parameter space of the model from Solar-System data, and compare the results with other f(R) models.
Title: The Taub Universe viewed in a Polymer Quantization Approach
Speaker: O.M. Lecian
Authors: M.V. Battisti, O.M. Lecian, G. MontaniAbstract: We investigate the implications of the polymer-quantization technique on the Taub cosmological model, analyzed within the ADM reduction of its dynamics at both semiclassical and quantum levels. As a result, classical trajectories flatten with respect to the potential wall, and the dynamics of the wavepackets is characterized by an interference phenomenon, which however is not able to probabilistically remove the classical singularity.
L. Lusanna
Title: Towards Relativistic Atomic Physics and Relativistic Entanglement
Speaker:L. Lusanna
Author:L. LusannaAbstract: After reviewing the rest-frame instant form of dynamics, I will describe the isolated system of N charged positive-energy particles with Grassmann-valued electric charges and mutual Coulomb potential plus the electromagnetic field in the radiation gauge. The Grassmann regularization of the Coulomb self-energy implies the existence of a canonical transformation to a system formed by N Coulomb-dressed particles with mutual Coulomb+ Darwin potential plus a free transverse radiation field. Due to clock synchronization and to the non-covariance of the relativistic canonical center of mass, the quantization implies a "spatial non-separability" absent in the non-relativistic theory. This formulation open the path to the treatment of relativistic entanglement and to the relativistic generalization of the protocols for teleportation and the test of Bell's inequalities.
Download:
S. Mercuri
Title: From the Einstein-Cartan to the Ashketar-Barbero formulation of Gravity and a possible interpretation of the Immirzi parameter
Speaker: S. Mercuri
Author: S. MercuriDownload:
G. Montani
Title: Perspectives in Cosmology, Gravitation and Multidimensions
Speaker: G. Montani
Author: G. MontaniAbstract: Recent developments from the activity of the CGM group are discussed. Cosmological implications of fundamental approaches to quantization of gravity are presented in order to fix the main issues as well as perspectives for future investigations. Particular attention will be devoted to the classical and quantum features of the generic inhomogeneous Universe, to the role of reference frame in quantum gravity, and eventually to phenomenological features related with the Kaluza-Klein framework.
Download:
H. Mosquera-Cuesta
Title: Cosmological redshift and nonlinear electrodynamics propagation of photons from distant sources
Speaker: H. Mosquera Cuesta
A. Nagar
Title: Gravitational Waves from Binary Black Hole Coalescence: Comparison Between Numerical and Effective-One-Body analytical results
Speaker: A. Nagar
Download:
B. Patricelli
Title: On the Crust of Neutron Stars
Speaker: B. Patricelli
Authors: B. Patricelli, J.A. Rueda H., R. RuffiniAbstract: We develope a theoretical model of Neutron Stars within General Relativity, describing the system as composed by two different physical regions: the Core and the Crust. The Core has a density upper the “melting” density and is composed by a relativistic degenerate plasma of electrons, protons and neutrons; the Crust has a smaller density and is composed by White Dwarf - like material (fully ionized nuclei and free electrons). We calculate the pressure (P) and the mass density (M) of the system, showing that the Core pressure is baryonic dominated and that the transition between the Core and the Crust is characterized by a discontinuity in . We also determine the mass and the thickness of the Crust (Mcrust and R respectively), finding that the Crust is lighter and smaller for stars with more compact Cores; furthermore, with the idea that in the process of gravitational collapse of the Core the Crust is left as a remnant, we compare Mcrust with the mass of the baryonic remnant considered in the fireshell model of GRBs, finding that the values are compatible.
Download:
M. Pizzi
Title: Electric force lines and Stability in the Alekseev-Belinski solution
Speaker: M. Pizzi
Author: M. PizziAbstract: The double Reissner-Nordstrom (RN) solution without strings nor struts, recently found by Alekseev and Belinski, shows that classically-forbidden equilibria are allowed for a naked singularity near a black hole. We give a brief summary of the different configurations allowed by the solution, then we draw the electric force lines plots in three qualitatively different situations: equal-signed charges, opposite charges and the case of a naked singularity near a neutral black hole. Finally we analyze the stability of the possible equilibria. The most of the configurations result to be stable.
Download:
D. Pugliese
Title: Deformations of Space–time Metrics
Speaker: D. Pugliese
Authors: C. Storneiolo, D. Pugliese, S. CapozzielloAbstract: A definition of space-time metric deformations on an n-dimensional manifold is given. Such deformations, parameterized in terms of scalar field matrices, can be regarded as extended conformal transformations. Their features can be related also to the perturbation theory. In fact, perturbations of arbitrary exact solutions of the Einstein equations are studied as metric deformations, and the equations governing the small perturbations are derived. Moreover, deformations can be related to approximate Killing vectors (or approximate symmetries) . Therefore it is possible to parameterize by to approximate Killing vectors the deformed region of a given manifold. As another application of the metric deformation, the motion of test particles in deformed space-times are compared with the motion in the original space-time, and finally the gravitational redshift, lensing effects and geodesic deviations in a deformed space-time were considered. The perspectives and other possible physical applications of such an approach are discussed.
Download:
L.J. Rangel Lemos
Title: Threshold Energies of Pions from pp Interactions
Speaker: L.J. Rangel Lemos
Authors: L.J. Ranger Lemos, S.R. KelnerAbstract: In this work we studied the threshold energies of pions produced by pp interactions. We obtained the maximum and minimum energy possible of created pion in function of energy of incident proton. We analysed the threshold energies of the work of Blattnig 2000.
Download:
M. Rotondo
Title: On the gravitational and electrodynamical stability of nuclear matter cores
Speaker: M. Rotondo
Authors: R. Ruffini, M. Rotondo, S.S. XueAbstract: Using an explicit analytic solution of the relativistic Thomas-Fermi equation we show that a core of neutrons, protons and electrons in beta equilibrium at nuclear densities has stable configurations both in the limit of super-heavy nuclei with mass number A\approx 10^4--10 ^6 and in the limit of massive cores with A≈(m_Pl/m_n)^3 ≈ 10^57. These are globally neutral configurations which have a maximum value of the electric field E_max=0.95(alpha)^(1/2)(m_pion)^2c^3/e hbar near the core surface. This electric field, the value of which is below the critical value for muon and pion production but well above the critical value E_c=m_e^2c^3/e hbar for electron-positron pair creation, is stabilized against pair creation by the degenerate electrons present in the configuration (Pauli blocking). On the one extreme, super-heavy nuclei are bound together by the strong interactions, while on the other extreme we show that globally neutral massive cores can be gravitationally bound. The value of the charge-to-mass ratios predicted at the surface of massive cores coincides with the range of values expected in astrophysical scenarios for Kerr-Newman black holes.
Download:
J.A. Rueda H.
Title: The Extended Nuclear Matter Model with Smooth Transition Surface
Speaker: J.A. Rueda H
Authors: J.A. Rueda H, B. Patricelli, M. Rotondo, R. Ruffini, S.S. XueAbstract: The existence of electric fields close to their critical value $E_c=\frac{m_e^2 c^3}{e \hbar}$ has been proved for massive cores of $10^7$ up to $10^{57}$ nucleons using a proton distribution of constant density and a sharp step function at its boundary. We explore the modifications of this effect by considering a smoother density profile with a proton distribution fulfilling a Woods--Saxon dependence. The occurrence of a critical field has been confirmed. We discuss how the location of the maximum of the electric field as well as its magnitude is modified by the smoother distribution.
Download:
T. P. Shestakova
Title: The “extended phase space” approach to Quantum Geometrodynamics: What can it give for the development of Quantum Gravity?
Speaker: T. P. Shestakova
Author: T. P. ShestakovaAbstract: The talk is devoted to the “extended phase space” approach to Quantum Geometrodynamics. The premises that have led to the formulation of this approach are briefly reviewed, namely, non-trivial topology of the Universe which implies the absence of asymptotic states, in contrast to situations one usually deals in ordinary quantum field theory; parametrization noninvariance in the Wheeler - DeWitt theory; the problem of time and the absence of dynamical evolution. Then we discuss the main features of the approach: Hamiltonian dynamics in extended phase space, gauge-dependent Schrodinger equation for the wave function of the Universe, the description of quantum Universe from the viewpoint of observers in a wide enough class of reference frames. After all, we analyse problems arising in this approach: the structure of Hilbert space in Quantum Geometrodynamics, the relations between solutions for the wave function of the Universe corresponding to various reference frames, properties of a medium to be necessary to fix a reference frame, the transition to classical limit.
Download:
C. Sigismondi
Title: Nonlinearity in Astronomy: the case of lunar acceleration. How ancient occultations and eclipses have been used to recover this orbital parameter.
Speaker: C. Sigismondi
Author: C. SigismondiAbstract: A brief review of the data, from Ptolemy's Almagest, used in this study is presented as well as the history of the method and some examples.
Title: The Quest of Solar Variability
Speaker: C. Sigismondi
Author: C. SigismondiAbstract: The method of Baily's beads timing is presented. The limb darkening function and its influence on the magnitude of a Baily's bead event is shown, its detectability is dependent on the filter used and on the diameter of the telescope. The data on solar diameter gathered with solar astrolabes and with solar eclipses are compared.
Download:
I.A. Siutsou
Title: The space-time of the Pioneer anomaly
Speaker: I.A. Siutsou
Author: I.A. SiutsouAbstract: We obtain a general result of a red shift value for a signal that is reflected or retransmitted by a radially geodetically moving body in an arbitrary spherically-symmetric static metric. The task of metric determination by Doppler tracking data only is unsolvable, so the obtaining of a metric with free geodetic motion reproducing the Pioneer Anomaly cannot be done without considering data on circular motion of astronomical objects. On these grounds we find solution for the problem of manifest absence of anomaly acceleration in orbits of outer planets and extra-Pluto objects of Solar system. But the energy-momentum tensor of matter that can generate such a gravitational field violates energy dominance conditions that strongly suggests non-gravitational origin of the Pioneer Anomaly.
Download:
G.V. Vereshchagin
Title: Thermalization of the pair plasma with proton loading
Speaker: G.V. Vereshchagin
Authors: G.V. Vereshchagin, A.G. Aksenov, R. RuffiniAbstract: We show that hot and dense pair plasma, created in the source, relaxes to thermal equilibrium configuration with zero chemical potentials well before it starts to expand driven by the radiative pressure. The relaxation process follows the sequence: pairs, photons, protons, thus the first particles reaching the same temperature are electrons and positrons, while protons join the thermal bath latest. Implications of these results for GRBs are discussed.
Download:
F. Vietri
Title: Geodesic Deviation on a Kaluza-Klein Background
Speaker: F. Vietri
Authors: F. Vietri, V. Lacquaniti, G. MontaniDownload:
S.S. Xue
Title: Overcritical field in astrophysical conditions, plasma (Dyadosphere) of photons and electron-positron pairs and Gamma-Gay Bursts
Speaker: S.S. Xue
Authors: S.S. XueAbstract: After a brief recall on electron-positron creation, annihilation and plasma oscillation in external electric fields, an strong field on the surface of massive core of neutron star with a large porotn number is discussed. We point out the possibility that an overcritical field on the surface of massive core can be created in astrophysicsal conditions, which during gravitationally collapsing leads to the Dyadosphere: the plasma of photons and electron-positron pairs, accounting for the complex origin of daily observed Gamma-Gay-Bursts phenomenon.
Download:
Title: Electron-Positron Pair Production in Space- or Time-Dependent Electric Fields
Speaker: S.S. Xue
Authors: H. Kleinert, R. Ruffini, S.S. XueAbstract: Treating the production of electron and positron pairs by a strong electric field from the vacuum as a quantum tunneling process we derive, in semiclassical approximation, a general expression for the pair production rate in a z-dependent electric field E(z) pointing in the z-direction. We also allow for a smoothly varying magnetic field parallel to E(z). The result is applied to a confined field, a semi-confined field,and a linearly increasing field. The boundary effects of the confined fields onpair-production rates are exhibited. A simple variable change in all formulasleads to results for electric fields depending on time rather than space. In addition, we discuss tunneling processes in which empty atomic bound states are spontaneously filled by negative-energy electrons from the vacuum under positron emission. In particular, we calculate the rate at which the atomic levels of a bare nucleus of finite size r_n and large Z>> 1 are filled by spontaneous pair creation.
A. Zhuk
Title: Early inflation in non-linear multidimensional cosmological models
Speaker: A. Zhuk
Authors: A. Zhuk, T. SaidovAbstract: We consider a multidimensional cosmological model with non-linear quadratic R2 and quartic R4 actions. As a matter source, we include a monopole form field, D-dimensional bare cosmological constant and tensions of branes located in fixed points. In the spirit of the Universal Extra Dimension models, the Standard Model fields are not localized on branes but can move in the bulk. It is found a range of parameters which ensures the stable compactification of the internal space in zero minima of effective potentials. Such effective potentials may have interesting and rather complicated form with a number of local minima, maxima and saddle points. Then, we investigate inflation in these models. It is shown that R2 and R4 models can have up to 10 and 23 e-foldings, respectively. These values are not sufficient to solve the homogeneity and isotropy problem however they are long enough to explain the CMB anisotropy. Additionally, R4 model can provide conditions for sufficient topological inflation. However, this eternal inflation model has spectral index ns ~ 0.61 < 1.
Download:
S. Zonetti
Title: Fluid Entropy as a Time Evolution Operator in Canonical Quantum Gravity
Speaker: S. Zonetti
Authors: S. Zonetti, G. MontaniAbstract: The so called problem of time, one of the central issues of the canonical appraches to a quantum theory of gravity, will be briefly presented, focusing on the possible resolution via the introduction of reference fluids. Following the established relation between matter fields and reference frames, the Schutz model for a perfect fluid, constructed from thermodynamical quantities, will be coupled to the metric field. Using the Kuchar-Brown mechanism it will be possible to build a meaningful time evolution operator in the canonical theory.
Download:
PDF