IRIS Università degli Studi di Bolognahttps://cris.unibo.itIl sistema di repository digitale IRIS acquisisce, archivia, indicizza, conserva e rende accessibili prodotti digitali della ricerca.Mon, 23 May 2022 22:50:49 GMT2022-05-23T22:50:49Z101531CHARGED SHELLS AND ELEMENTARY PARTICLEShttp://hdl.handle.net/11585/165645Titolo: CHARGED SHELLS AND ELEMENTARY PARTICLES
Abstract: We review the General Relativistic model of a (quasi-)pointlike particle represented by a massive shell of electrically charged matter, which displays an ADM mass M equal to the electric charge |Q| in the small-volume limit. We employ the Israel–Darboux's junction equations to explicitly derive this result, and then study the modifications introduced by the existence of a minimum length scale λ. For λ of the order of the Planck length (or larger), we find that the ADM mass becomes equal to the bare mass m0 of the shell, like it occurs for the neutral case.
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/11585/1656452013-01-01T00:00:00ZPolytropic stars in bootstrapped Newtonian gravityhttp://hdl.handle.net/11585/781383.1Titolo: Polytropic stars in bootstrapped Newtonian gravity
Wed, 01 Jan 2020 00:00:00 GMThttp://hdl.handle.net/11585/781383.12020-01-01T00:00:00ZExtended effective field theory of inflationhttp://hdl.handle.net/11585/629536Titolo: Extended effective field theory of inflation
Mon, 01 Jan 2018 00:00:00 GMThttp://hdl.handle.net/11585/6295362018-01-01T00:00:00ZBootstrapped Newtonian quantum gravityhttp://hdl.handle.net/11585/763786Titolo: Bootstrapped Newtonian quantum gravity
Wed, 01 Jan 2020 00:00:00 GMThttp://hdl.handle.net/11585/7637862020-01-01T00:00:00ZBlack holes by gravitational decouplinghttp://hdl.handle.net/11585/650545Titolo: Black holes by gravitational decoupling
Mon, 01 Jan 2018 00:00:00 GMThttp://hdl.handle.net/11585/6505452018-01-01T00:00:00ZCorpuscular slow-roll inflationhttp://hdl.handle.net/11585/619302.3Titolo: Corpuscular slow-roll inflation
Abstract: We show that a corpuscular description of gravity can lead to an inflationary scenario similar to Starobinsky’s model without requiring the introduction of the inflaton field. All relevant properties are determined by the number of gravitons in the cosmological condensate or, equivalently, by their Compton length. In particular, the relation between the Hubble parameter H and its time derivative dot H required by cosmic microwave background observations at the end of inflation, as well as the (minimum) initial value of the slow-roll parameter, are naturally obtained from the Compton size of the condensate.
Mon, 01 Jan 2018 00:00:00 GMThttp://hdl.handle.net/11585/619302.32018-01-01T00:00:00ZMicrocanonical Description of (Micro) Black Holeshttp://hdl.handle.net/11585/97862.1Titolo: Microcanonical Description of (Micro) Black Holes
Abstract: The microcanonical ensemble is the proper ensemble to describe black holes which are not in thermodynamic equilibrium, such as radiating black holes. This choice of ensemble eliminates the problems, e.g., negative specific heat (not allowed in the canonical ensemble) and loss of unitarity, encountered when the canonical ensemble is used. In this review we present an overview of the weaknesses of the standard thermodynamic description of black holes and show how the microcanonical approach can provide a consistent description of black holes and their Hawking radiation at all energy scales. Our approach is based on viewing the horizon area as yielding the ensemble density at fixed system energy. We then compare the decay rates of black holes in the two different pictures. Our description is particularly relevant for the analysis of micro-black holes whose existence is predicted in models with extra-spatial dimensions.
Sat, 01 Jan 2011 00:00:00 GMThttp://hdl.handle.net/11585/97862.12011-01-01T00:00:00ZCMB acoustic scale in the entropic-like accelerating universehttp://hdl.handle.net/11585/103878Titolo: CMB acoustic scale in the entropic-like accelerating universe
Abstract: We consider generalizations of the entropic accelerating universe recently proposed in [D. A. Easson, P. H. Frampton, and G. F. Smoot, Phys. Lett. B 696, 273 (2011).] and [D. A. Easson, P. H. Frampton, and G. F. Smoot, arXiv:1003.1528.] and show that their background equations can be made equivalent to a model with a dark energy component with a constant parameter of state wX=-1+2γ/3, where γ is related to the coefficients of the new terms in the Friedmann equations. After discussing all the Friedmann equations for an arbitrary γ, we show how to recover the standard scalings for dust and radiation. The acoustic scale ℓA, related to the peak positions in the pattern of the angular power spectrum of the cosmic microwave background anisotropies, is also computed and yields the stringent bound |γ|≪1. We then argue that future data might be able to distinguish this model from pure ΛCDM (corresponding to γ=0).
Sat, 01 Jan 2011 00:00:00 GMThttp://hdl.handle.net/11585/1038782011-01-01T00:00:00ZBlack Hole Remnants at the LHChttp://hdl.handle.net/11585/116349.1Titolo: Black Hole Remnants at the LHC
Abstract: We investigate possible signatures of black hole events at the LHC in the hypothesis that such objects will not evaporate completely, but leave a stable remnant. For the purpose of defining a reference scenario, we have employed the publicly available Monte Carlo generator CHARYBDIS2, in which the remnant's behavior is mostly determined by kinematic constraints and conservation of some quantum numbers, such as the baryon charge. Our findings show that electrically neutral remnants are highly favored and a significantly larger amount of missing transverse momentum is to be expected with respect to the case of complete decay.
Sun, 01 Jan 2012 00:00:00 GMThttp://hdl.handle.net/11585/116349.12012-01-01T00:00:00ZSelf-healing of unitarity in Higgs inflationhttp://hdl.handle.net/11585/289930.1Titolo: Self-healing of unitarity in Higgs inflation
Abstract: We reconsider perturbative unitarity violation in the standard model Higgs inflation model. We show that the Cutkosky cutting rule implied by perturbative unitarity is fulfilled at one-loop. This is a strong indication that unitarity is restored order by order in perturbation theory. We then resum certain one-loop diagrams and show that the relevant dressed amplitude fulfills the Cutkosky rule exactly. This is an example of the self-healing mechanism. The original Higgs inflation model is thus consistent and does not require any new physics beyond the standard model at least up to the Planck scale.
Wed, 01 Jan 2014 00:00:00 GMThttp://hdl.handle.net/11585/289930.12014-01-01T00:00:00Z