Publications (34)56.14 Total impact

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ABSTRACT: We analyze the functional integral for quantum Conformal Gravity and show that with the help of a HubbardStratonovich transformation, the action can be broken into a local quadraticcurvature theory coupled to a scalar field. A oneloop effective action calculation reveals that strong fluctuations of the metric field are capable of spontaneously generating a dimensionally transmuted parameter which in the weakfield sector of the broken phase induces a Starobinskytype f(R)model with a gravicosmological constant. A resulting nontrivial relation between Starobinsky'sparameter and the cosmological constant is highlighted and implications for cosmic inflation are briefly discussed and compared with recent PLANCK and BICEP2 data. 
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ABSTRACT: We compute the corrections to the Schwarzschild metric necessary to reproduce the Hawking temperature derived from a Generalized Uncertainty Principle (GUP), so that the GUP deformation parameter is directly linked to the deformation of the metric. Using this modified Schwarzschild metric, we compute corrections to the standard General Relativistic predictions for the light deflection and perihelion precession, both for planets in the solar system and for binary pulsars. This analysis allows us to set bounds for the GUP deformation parameter from wellknown astronomical measurements. 
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ABSTRACT: There is a theoretical evidence that relativistically invariant quantum dynamics at (enough) large spacetime scales can result from a cooperative process of two intercorrelated nonrelativistic stochastic dynamics, operating at different energy scales. We show that the Euclidean transition amplitude for a relativistic particle is identical to the transition probability of a Brownian particle propagating in a granular space. We discuss the issue of the robustness of the specialrelativistic quantum mechanics thus obtained under small changes in the granularspace distribution. Experimental implications for early Universe cosmology are also briefly outlined.Journal of Physics Conference Series 03/2014; 504(1). DOI:10.1088/17426596/504/1/012012 
Foundations of Physics 12/2013; 44(8). DOI:10.1007/s1070101397696 · 1.14 Impact Factor

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ABSTRACT: We address the issue of (quantum) black hole formation by particle collision in quantum physics. We start by constructing the horizon wavefunction for quantum mechanical states representing two highly boosted noninteracting particles that collide in a onedimensional space. From this wavefunction, we then derive a probability that the system becomes a black hole as a function of the initial momenta and spatial separation between the particles. This probability allows us to extend the hoop conjecture to quantum mechanics and estimate corrections to its classical counterpart.Physics Letters B 11/2013; 732. DOI:10.1016/j.physletb.2014.03.037 · 6.02 Impact Factor 
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ABSTRACT: A localised particle in Quantum Mechanics is described by a wave packet in position space, regardless of its energy. However, from the point of view of General Relativity, if the particle's energy density exceeds a certain threshold, it should be a black hole. In order to combine these two pictures, we introduce a horizon wavefunction determined by the particle wavefunction in position space, which eventually yields the probability that the particle is a black hole. The existence of a minimum mass for black holes naturally follows, albeit not in the form of a sharp value around the Planck scale, but rather like a vanishing probability that a particle much lighter than the Planck mass be a black hole. We also show that our construction entails an effective Generalised Uncertainty Principle (GUP), simply obtained by adding the uncertainties coming from the two wavefunctions associated to a particle. Finally, the decay of microscopic (quantum) black holes is also described in agreement with what the GUP predicts.European Physical Journal C 06/2013; DOI:10.1140/epjc/s1005201326852 · 5.44 Impact Factor 
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ABSTRACT: We present a new theoretical evidence that a relativistically invariant quantum dynamics at large enough spacetime scales can be derived from two intercorrelated genuinely nonrelativistic stochastic processes that operate at different energy scales. This leads to Feynman amplitudes that are, in the Euclidean regime, identical to transition probability of a Brownian particle propagating through a granular space. Our observation implies a preferred frame and can have distinct experimental signatures. Ensuing implications for special and doublyspecial relativity, quantum field theory, quantum gravity and cosmology are discussed.Journal of Physics Conference Series 06/2013; 442(1):2054. DOI:10.1088/17426596/442/1/012054 
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ABSTRACT: We show that the special relativistic dynamics when combined with quantum mechanics and the concept of superstatistics can be interpreted as arising from two interlocked nonrelativistic stochastic processes that operate at different energy scales. This interpretation leads to Feynman amplitudes that are in the Euclidean regime identical to transition probability of a Brownian particle propagating through a granular space. Some kind of spacetime granularity could be therefore held responsible for the emergence at larger scales of various symmetries. For illustration we consider also the dynamics and the propagator of a spinless relativistic particle. Implications for doubly special relativity, quantum field theory, quantum gravity and cosmology are discussed.Foundations of Physics 05/2013; 44(5):512522. DOI:10.1007/s1070101397589 · 1.14 Impact Factor 
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ABSTRACT: We show that the special relativistic dynamics when combined with quantum mechanics and the concept of superstatistics can be interpreted as arising from two interlocked nonrelativistic stochastic processes that operate at different energy scales. This interpretation leads to Feynman amplitudes that are in the Euclidean regime identical to transition probability of a Brownian particle propagating through a granular space. Some kind of spacetime granularity could be held responsible for the emergence at larger scales of various symmetries. For illustration we consider also the dynamics and the propagator of a spinless relativistic particle. Implications for doubly special relativity, quantum field theory, quantum gravity and cosmology are discussed.European Physical Journal C 01/2013; 73(7). DOI:10.1140/epjc/s100520132491x · 5.44 Impact Factor 
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ABSTRACT: We study uncertainty relations as formulated in a crystallike universe, whose lattice spacing is of order of Planck length. For Planck energies, the uncertainty relation for position and momenta has a lower bound equal to zero. Connections of this result with double special relativity, and with't Hooft's deterministic quantization proposal, are briefly pointed out. We then apply our formulae to micro black holes, and we derive a new masstemperature relation for Schwarzschild (micro) black holes. In contrast to standard results based on Heisenberg and stringy uncertainty relations, we obtain both a finite Hawking's temperature and a zero restmass remnant at the end of the micro black hole evaporation.06/2012; DOI:10.1063/1.4727995 
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ABSTRACT: We show how a Brownian motion on a short scale can originate a relativistic motion on scales larger than the particle's Compton wavelength. Thus, Lorentz symmetry appears to be not a primitive concept, but rather it statistically emerges when a coarse graining average over distances of order, or longer than the Compton wavelength, is taken. We also present the generalizations needed to accommodate in our scheme the doubly special relativistic dynamics. In this way, a previously unsuspected, common stochastic origin of the two frameworks is revealed for the first time. Issues such as generalized commutation relations are also discussed.Journal of Physics Conference Series 05/2012; 361(1):012026. DOI:10.1088/17426596/361/1/012026 
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ABSTRACT: Using the concept known as a superstatistics path integral we show that a Wiener process on a short spatial scale can originate a relativistic motion on scales that are larger than particle's Compton wavelength. Viewed in this way, special relativity is not a primitive concept, but rather it statistically emerges when a coarse graining average over distances of order, or longer than the Compton wavelength is taken. Here we place a special emphasis on the modifications that are necessary to accommodate in our scheme the doubly special relativistic dynamics. In this way, a previously unsuspected, common statistical origin of the two frameworks is revealed. Salient issues such as generalized commutation relations and a connection with Feynman chessboard model are also discussed.International Journal of Modern Physics B 05/2012; 26(12):41003. DOI:10.1142/S0217979212410032 · 0.46 Impact Factor 
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ABSTRACT: We consider the production of primordial micro black holes (MBH) remnants in the early universe. These objects induce the universe to be in a matterdominated era before the onset of inflation. Effects of such an epoch on the CMB power spectrum are discussed and computed both analytically and numerically. By comparison with the latest observational data from the WMAP collaboration, we find that our model appears to explain the quadrupole anomaly of the CMB power spectrum.03/2012; DOI:10.1142/S2010194512006605 
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ABSTRACT: Using the concept known as a superstatistics path integral we show that a Wiener process on a short spatial scale can originate a relativistic motion on scales that are larger than particle's Compton wavelength. Viewed in this way, special relativity is not a primitive concept, but rather it statistically emerges when a coarse graining average over distances of order, or longer than the Compton wavelength is taken. We also present the modifications necessary to accommodate in our scheme the doubly special relativistic dynamics. In this way, a previously unsuspected, common statistical origin of the two frameworks is revealed.Journal of Physics Conference Series 02/2012; 343(1). DOI:10.1088/17426596/343/1/012048 
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ABSTRACT: In the framework of 't Hooft's "deterministic quantization" proposal, we show how to obtain from a composite system of two classical Bateman's oscillators a quantum isotonic oscillator. In a specific range of parameters, such a system can be also interpreted as a particle in an effective magnetic field, interacting through a spinorbit interaction term. In the limit of a large separation from the interaction region, the system can be described in terms of two irreducible elementary subsystems, corresponding to two independent quantum harmonic oscillators.Journal of Physics Conference Series 02/2012; 343(1). DOI:10.1088/17426596/343/1/012110 
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ABSTRACT: We formulate generalized uncertainty relations in a crystallike universe whose lattice spacing is of order of Planck length  a "world crystal". For energies near the border of the Brillouin zone, i.e., for Planckian energies, the uncertainty relation for position and momentum does not pose any lower bound. We apply these results to micro black holes physics, where we derive a new masstemperature relation for Schwarzschild micro black holes. In contrast to standard results based on Heisenberg and stringy uncertainty relations, our masstemperature formula predicts both a finite Hawking's temperature and a zero restmass remnant at the end of the black hole evaporation. We also briefly mention some connections of the world crystal paradigm with 't Hooft's quantization and double special relativity. 
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ABSTRACT: We formulate generalized uncertainty relations in a crystallike universe whose lattice spacing is of order of Planck length  a "world crystal". For energies near the border of the Brillouin zone, i.e. for Planckian energies, the uncertainty relation for position and momentum does not pose any lower bound. We apply these results to micro black holes physics, where we derive a new masstemperature relation for Schwarzschild micro black holes. In contrast to standard results based on Heisenberg and stringy uncertainty relations, our masstemperature formula predicts both a finite Hawking's temperature and a zero restmass remnant at the end of the black hole evaporation.International Journal of Modern Physics D 09/2011; 20(10):20032007. DOI:10.1142/S021827181102007X · 1.42 Impact Factor 
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ABSTRACT: We study uncertainty relations as formulated in a crystallike universe, whose lattice spacing is of order of Planck length. For Planck energies, the uncertainty relation for position and momenta has a lower bound equal to zero. Connections of this result with double special relativity, and with 't Hooft's deterministic quantization proposal, are briefly pointed out. We then apply our formulae to micro black holes, and we derive a new masstemperature relation for Schwarzschild (micro) black holes. In contrast to standard results based on Heisenberg and stringy uncertainty relations, we obtain both a finite Hawking's temperature and a zero restmass remnant at the end of the micro black hole evaporation.Journal of Physics Conference Series 07/2011; 306(1):012026. DOI:10.1088/17426596/306/1/012026 
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ABSTRACT: Building on our previous work [Phys.Rev.D82,085016(2010)], we show in this paper how a Brownian motion on a short scale can originate a relativistic motion on scales that are larger than particle's Compton wavelength. This can be described in terms of polycrystalline vacuum. Viewed in this way, special relativity is not a primitive concept, but rather it statistically emerges when a coarse graining average over distances of order, or longer than the Compton wavelength is taken. By analyzing the robustness of such a special relativity under small variations in the polycrystalline grainsize distribution we naturally arrive at the notion of doublyspecial relativistic dynamics. In this way, a previously unsuspected, common statistical origin of the two frameworks is brought to light. Salient issues such as the role of gauge fixing in emergent relativity, generalized commutation relations, Hausdorff dimensions of representative pathintegral trajectories and a connection with Feynman chessboard model are also discussed.Physical review D: Particles and fields 05/2011; DOI:10.1103/PhysRevD.86.025029 · 4.86 Impact Factor 
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ABSTRACT: We consider the production of primordial micro black holes (MBH) remnants in the early universe. These objects induce the universe to be in a matterdominated era before the onset of inflation. Effects of such an epoch on the CMB power spectrum are discussed and computed both analytically and numerically. By comparison with the latest observational data from the WMAP collaboration, we find that our model is able to explain the quadrupole anomaly of the CMB power spectrum.Physical review D: Particles and fields 09/2010; 83(6). DOI:10.1103/PhysRevD.83.063507 · 4.86 Impact Factor
Publication Stats
448  Citations  
56.14  Total Impact Points  
Top Journals
Institutions

2013–2014

Politecnico di Milano
Milano, Lombardy, Italy


2005–2013

Kyoto University
 Yukawa Institute for Theoretical Physics
Kioto, Kyōto, Japan


2012

Academia Sinica
 Institute of Physics
Taipei, Taipei, Taiwan


2009–2012

National Taiwan University
 • Department of Physics
 • "Leung" Center for Cosmology and Particle Astrophysics
T’aipei, Taipei, Taiwan


1999–2003

Universität Bern
 Institute for Theoretical Physics
Berna, Bern, Switzerland 
University of Milan
 Department of Physics
Milano, Lombardy, Italy
