Gian Paolo Vacca | Istituto Nazionale di Fisica Nucleare (original) (raw)
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Papers by Gian Paolo Vacca
arXiv (Cornell University), Apr 8, 2016
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ABSTRACT The study of the renormalized energy-momentum tensor (EMT) of quantum fluctuations in an... more ABSTRACT The study of the renormalized energy-momentum tensor (EMT) of quantum fluctuations in an inflationary universe driven by a massive scalar field is presented and compared with the known results in de Sitter space-time. When metric fluctuations are included, the renormalized EMT is characterized by a negative energy density which grows in time during the inflationary regime. We also approach the back-reaction problem as a second-order calculation in perturbation theory, and find that the average expansion rate is decreased, in agreement with the result on the EMT. Finally, we discuss common concerns and the implications of our results.
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Physical review, Nov 17, 2014
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arXiv (Cornell University), Jan 15, 2020
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Journal of Cosmology and Astroparticle Physics, Dec 20, 2018
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European Physical Journal C, 1999
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Physical review, Sep 8, 2015
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WORLD SCIENTIFIC eBooks, Nov 1, 2021
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arXiv (Cornell University), Jul 7, 2021
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Eur Phys J C, 1999
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Thinking, Observing and Mining the Universe, 2004
ABSTRACT The study of the renormalized energy-momentum tensor (EMT) of quantum fluctuations in an... more ABSTRACT The study of the renormalized energy-momentum tensor (EMT) of quantum fluctuations in an inflationary universe driven by a massive scalar field is presented and compared with the known results in de Sitter space-time. When metric fluctuations are included, the renormalized EMT is characterized by a negative energy density which grows in time during the inflationary regime. We also approach the back-reaction problem as a second-order calculation in perturbation theory, and find that the average expansion rate is decreased, in agreement with the result on the EMT. Finally, we discuss common concerns and the implications of our results.
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Nucleation and Atmospheric Aerosols, 2012
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arXiv (Cornell University), Sep 19, 2007
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The Odderon state in perturbative QCD is briefly reviewed. Recent calculations devoted to estimat... more The Odderon state in perturbative QCD is briefly reviewed. Recent calculations devoted to estimate the diffrative ηc production at high energies from the leading known Odderon states are discussed.
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DIFFRACTION 2002: Interpretation of the New Diffractive Phenomena in Quantum Chromodynamics and in the S-Matrix Theory, 2003
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A review of some theoretical aspects of small x QCD physics is given, with a particular emphasis ... more A review of some theoretical aspects of small x QCD physics is given, with a particular emphasis to the relation between the BFKL and the colour dipole approaches. The nonlinear evolution equations one may construct, as a better approximation beyond the linear analysis, are discussed together with their relation to a possible saturation regime.
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International Journal of Geometric Methods in Modern Physics, 2020
We consider a functional relation between a given Wilsonian renormalization group (RG) flow, whic... more We consider a functional relation between a given Wilsonian renormalization group (RG) flow, which has to be related to a specific coarse-graining procedure, and an infinite family of (UV cutoff) scale-dependent field redefinitions. Within this framework, one can define a family of Wilsonian proper-time (PT) exact RG equations associated to an arbitrary regulator function. New applications of these RG flow schemes to the Ising Universality class in three dimensions in the derivative expansion are shortly illustrated.
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AIP Conference Proceedings, 2017
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Physical Review D, 2014
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arXiv (Cornell University), Apr 8, 2016
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ABSTRACT The study of the renormalized energy-momentum tensor (EMT) of quantum fluctuations in an... more ABSTRACT The study of the renormalized energy-momentum tensor (EMT) of quantum fluctuations in an inflationary universe driven by a massive scalar field is presented and compared with the known results in de Sitter space-time. When metric fluctuations are included, the renormalized EMT is characterized by a negative energy density which grows in time during the inflationary regime. We also approach the back-reaction problem as a second-order calculation in perturbation theory, and find that the average expansion rate is decreased, in agreement with the result on the EMT. Finally, we discuss common concerns and the implications of our results.
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Physical review, Nov 17, 2014
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arXiv (Cornell University), Jan 15, 2020
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Journal of Cosmology and Astroparticle Physics, Dec 20, 2018
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European Physical Journal C, 1999
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Physical review, Sep 8, 2015
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WORLD SCIENTIFIC eBooks, Nov 1, 2021
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arXiv (Cornell University), Jul 7, 2021
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Eur Phys J C, 1999
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Thinking, Observing and Mining the Universe, 2004
ABSTRACT The study of the renormalized energy-momentum tensor (EMT) of quantum fluctuations in an... more ABSTRACT The study of the renormalized energy-momentum tensor (EMT) of quantum fluctuations in an inflationary universe driven by a massive scalar field is presented and compared with the known results in de Sitter space-time. When metric fluctuations are included, the renormalized EMT is characterized by a negative energy density which grows in time during the inflationary regime. We also approach the back-reaction problem as a second-order calculation in perturbation theory, and find that the average expansion rate is decreased, in agreement with the result on the EMT. Finally, we discuss common concerns and the implications of our results.
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Nucleation and Atmospheric Aerosols, 2012
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arXiv (Cornell University), Sep 19, 2007
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Bookmarks Related papers MentionsView impact
The Odderon state in perturbative QCD is briefly reviewed. Recent calculations devoted to estimat... more The Odderon state in perturbative QCD is briefly reviewed. Recent calculations devoted to estimate the diffrative ηc production at high energies from the leading known Odderon states are discussed.
Bookmarks Related papers MentionsView impact
DIFFRACTION 2002: Interpretation of the New Diffractive Phenomena in Quantum Chromodynamics and in the S-Matrix Theory, 2003
Bookmarks Related papers MentionsView impact
A review of some theoretical aspects of small x QCD physics is given, with a particular emphasis ... more A review of some theoretical aspects of small x QCD physics is given, with a particular emphasis to the relation between the BFKL and the colour dipole approaches. The nonlinear evolution equations one may construct, as a better approximation beyond the linear analysis, are discussed together with their relation to a possible saturation regime.
Bookmarks Related papers MentionsView impact
International Journal of Geometric Methods in Modern Physics, 2020
We consider a functional relation between a given Wilsonian renormalization group (RG) flow, whic... more We consider a functional relation between a given Wilsonian renormalization group (RG) flow, which has to be related to a specific coarse-graining procedure, and an infinite family of (UV cutoff) scale-dependent field redefinitions. Within this framework, one can define a family of Wilsonian proper-time (PT) exact RG equations associated to an arbitrary regulator function. New applications of these RG flow schemes to the Ising Universality class in three dimensions in the derivative expansion are shortly illustrated.
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AIP Conference Proceedings, 2017
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Physical Review D, 2014
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We give a heuristic classification of all universality classes of critical models with up to thre... more We give a heuristic classification of all universality classes of critical models with up to three field-theoretical scalar order parameters in 6− dimensions. Each class is uniquely characterized by its symmetry group and by the set of its universal scaling properties, neither of which are built-in by the formalism but instead emerge nontrivially as outputs of our computations. In particular for three fields we find, apart for a perturbatively unitary solution with O(2) symmetry already known in the literature, five novel non-trivial universality classes with discrete symmetries and with real bounded spectra, among which there is another perturbatively unitary model. We expect them to correspond to new nontrivial CFTs in less than six dimensions.
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