1,120 research outputs found
Trans-Planckian footprints in inflationary cosmology
No full textAbstractWe consider a minimum uncertainty vacuum choice at a fixed energy scale Λ as an effective description of trans-Planckian physics, and discuss its implications for the linear perturbations of a massless scalar field in power-law inflationary models. We find possible effects with a magnitude of order H/Λ in the power spectrum, in analogy with previous results for de Sitter space–time
GAUSS-BONNET BRANE COSMOLOGY WITH RADION STABILIZATION
No full textWe study cosmology in a five-dimensional brane-world with a stabilizing effective potential for the radion and matter localized on the two branes. We consider the corrections induced by the Gauss-Bonnet contribution to the total action performing and expansion around the two possible static solutions up to second order in the ratio between brane matter energy density and brane tensions. The Friedmann and acceleration equations on the visible brane are obtained and discussed
Cosmological unparticle correlators
No full textAbstractWe introduce and study an extension of the correlator of unparticle matter operators in a cosmological environment. Starting from FRW spaces we specialize to a de Sitter space–time and derive its inflationary power spectrum which we find to be almost flat. We finally investigate some consequences of requiring the existence of a unitary boundary conformal field theory in the framework of the dS/CFT correspondence
THERMODYNAMICS OF A COLLAPSING SHELL IN AN EXPANDING UNIVERSE
No full textWe describe the quasi-static collapse of a radiating, spherical shell of matter in de Sitter space-time using a thermodynamical formalism. It is found that the specific heat at constant area and other thermodynamical quantities exhibit singularities related to phase transitions during the collapse
ULTRA HIGH ENERGY COSMIC RAYS AND DE SITTER VACUA
No full textThe production of ultra high-energy cosmic rays in de Sitter invariant vacuum states is considered. Assuming the present-day universe is asymptoting toward a future de Sitter phase, we argue the observed flux of cosmic rays places a bound on the parameter that characterizes these de Sitter invariant vacuum states, generalizing earlier work of Starobinsky and Tkachev. If this bound is saturated, we obtain a new top-down scenario for the production of super-GZK cosmic rays. The observable predictions bear many similarities to the previously studied scenario where super-GZK events are produced by decay of galactic halo super-heavy dark matter particles
Brane-world black holes and the scale of gravity
No full textA particle in four dimensions should behave like a classical black hole if the horizon radius is larger than the Compton wavelength or, equivalently, if its degeneracy (measured by entropy in units of the Planck scale) is large. For spherically symmetric black holes in 4 + d dimensions, both arguments again lead to a mass threshold M C and degeneracy scale M deg of the order of the fundamental scale of gravity M G. In the brane-world, deviations from the Schwarzschild metric induced by bulk effects alter the horizon radius and effective four-dimensional Euclidean action in such a way that M C ≃ M deg might be either larger or smaller than M G. This opens up the possibility that black holes exist with a mass smaller than M G and might be produced at the LHC even if M G ≳ 10 TeV, whereas effects due to bulk graviton exchanges remain undetectable because suppressed by inverse powers of M G. Conversely, even if black holes are not found at the LHC, it is still possible that M C ≫ M G and M G ≃ 1 TeV
Vacuum Energy, Cosmological Constant and Standard Model Physics
No full textThe conditions for the cancellation of one loop contributions to vacuum energy (both U.V. divergent and finite) coming from the Standard Model (SM) fields are examined. It is proven that this is not possible unless one introduces besides several bosons, at least one massive fermion having mass within specific ranges. On examining one of the simplest SM extensions satisfying the constraints one finds that the mass range of the lightest massive boson is compatible with the present Higgs mass bounds. We do not consider effects associated with condensates or renormalization group running
The Prosecution of Public Corruption in the United States. Political and Judicial Strategies - and, in the Background, an Expression of the Legality Principle Crisis
No full textThrough the exam of the jurisprudence of the U.S.Supreme Court and of the federal criminal courts, the Author identifies two different trends of the political and judicial strategy in the field of repression of public corruption in the U.S. The first trend (as in McCormick v. U.S. and in McDonnell v. U.S.) aims to avoid criminal liability in campaign cases; the second trend (as in Evans v. U.S., in Skilling v. U.S. and in Ocasio v. U.S.), instead, tends to affirm criminal liability in the other cases. This latter trend seems to the Author uncoherent with the legality principle. A broad interpretation of criminal law federal statutes is affirmed by the U.S. Supreme Court and by the federal courts and prosecutors using vague federal statutes different from the bribery statutes: the Mail and Wire Fraud (i.e., the honest services fraud); the Hobbs Act (i.e., the extortion under color of official right) and the general conspiracy statute (§ 371 U.S.C.). The aim of the federal criminal justice is to harshly punish and investigate corruption by affirming the federal jurisdiction. However, the consistency of this aim with the principle of legality and the related guarantees is particularly problematic
La concussione riformata, tra diritto penale e processo. Note a margine di un'importante sentenza delle Sezioni Unite
No full textL'A. svolge riflessioni a margine della sentenza 'Maldera', con la quale le Sezioni Unite della Corte di cassazione si sono pronunciate sulla più rilevante questione interpretativa posta dalla recente riforma dei delitti contro la pubblica amministrazione, attuata con la l. 6 novembre 2012, n. 190: "quale sia la linea di demarcazione tra la fattispecie di concussione (prevista dal novellato art. 317 c.p.) e quella di induzione indebita a dare o promettere utilità (prevista dall'art. 319-quater c.p., di nuova introduzione), soprattutto con riferimento al rapporto tra la condotta di costrizione e quella di induzione e alle connesse problematiche di successione di leggi penali nel tempo". L'A. valuta nel complesso positivamente la sentenza, che facendosi interprete dello spirito della riforma, teso a soddisfare istanze della lotta internazionale alla corruzione, circoscrive fortemente l'ambito di applicazione della concussione e, pertanto, gli spazi di impunità del 'privato' che prometta o effettui la dazione dell'indebito al funzionario pubblico.The Reformed Crime of 'Concussione': between Criminal Law and Procedure. Commentary to an Important Ruling by the Supreme Cassation Court ------- The Author discusses the "Maldera" ruling by the Supreme Cassation Court (Sezioni Unite) whereby the latter ruled on the most relevant interpretative issue raised by the recent reform of crimes against the public administration, which was implemented by Law No. 190 dated November 6, 2012. The issued submitted to the Court was aimed at identifying the boundary between the offence of "concussione" (i.e. a particular type of extortion perpetrated by a public officer, governed by article 317 of the Italian Criminal Code and amended by the aforementioned reform of 2012) and the offence of "induzione indebita a dare o promettere utilità" (i.e., a particular type of corruption whereby a public officer induces a private person to give or promise something, introduced for the first time by the same reform and governed by the new version of article 319 quarter of the Criminal Code), primarily with regard to the distinction between obliging and inducing somebody to do something, as well as the related issue of the chronological succession of criminal provisions over time. The Author shares the Court's view as to the necessity of narrowing the scope of the Italian offence of "concussione", in order to reduce the area of impunity for private persons who give or promise some utility to public officers. Such interpretation, in fact, seems to be in line with the spirit of the 2012 reform, which is in turn aimed at fostering international efforts in the fight against corruption and bribery
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