The cosmological constant problem is reanalyzed by imposing the limitation of the number of degrees of freedom (d.o.f.) due to entropy bounds directly in the calculation of the energy density of a field theory. It is shown that if a quantum field theory has to be consistent with gravity and holography, i.e. with an upper limit of storing information in a given area, the ultraviolet momentum cut-off is not the Planck mass, M_{p}, as naively expected, but where N_{u}is the number of d.o.f. of the universe. The energy density evaluation turns out completely consistent with Bousso’s bound on the cosmological constant value. The scale , that in the “fat graviton” theory corresponds to the graviton size, originates by a self-similar rearrangement of the elementary d.o.f. at different scales that can be seen as an infrared-ultraviolet connection.

Abstract:
The restoration of spontaneous symmetry breaking for a scalar field theory for an accelerated observer is discussed by the one-loop effective potential calculation and by considering the effective potential for composite operators. Above a critical acceleration, corresponding to the critical restoration temperature, T_{c}, for a Minkowski observer by Unruh relation, i.e. a_{c}/2π=T_{c}, the symmetry is restored. This result confirms other recent calculations in effective field theories that symmetry restoration can occur for an observer with an acceleration larger than some critical value. From the physical point of view, a constant acceleration mimics a gravitational field and the critical acceleration to restore the spontaneous symmetry breaking corresponds to a huge gravitational effect which prevents boson condensation.

Abstract:
The Equation of State and the properties of matter in the high temperature deconfined phase are analyzed by a quasiparticle approach for $T> 1.2~T_c$. In order to fix the parameters of our model we employ the lattice QCD data of energy density and pressure. First we consider the pure SU(3) gluon plasma and it turns out that such a system can be described in terms of a gluon condensate and of gluonic quasiparticles whose effective number of degrees of freedom and mass decrease with increasing temperature. Then we analyze QCD with finite quark masses. In this case the numerical lattice data for energy density and pressure can be fitted assuming that the system consists of a mixture of gluon quasiparticles, fermion quasiparticles, boson correlated pairs (corresponding to in-medium mesonic states) and gluon condensate. We find that the effective number of boson degrees of freedom and the in-medium fermion masses decrease with increasing temperature. At $T \simeq 1.5 ~T_c$ only the correlated pairs corresponding to the mesonic nonet survive and they completely disappear at $T \simeq 2 ~T_c$. The temperature dependence of the velocity of sound of the various quasiparticles, the effects of the breaking of conformal invariance and the thermodynamic consistency are discussed in detail.

Abstract:
By considering the non-perturbative effects associated with the fundamental modular region, a new phase of a Gluon Plasma at finite density is proposed. It corresponds to the transition from glueballs to non-perturbative gluons which condense at a non vanishing momentum. In this respect the proposed phase is analogous to the color superconducting LOFF phase for fermionic systems.

Abstract:
A macroscopic model of the tumor Gompertzian growth is proposed. The new approach is based on the energetic balance among the different cell activities, described by methods of statistical mechanics and related to the growth inhibitor factors. The model is successfully applied to the multicellular tumor spheroid data.

Abstract:
A model of the opinion dynamics underlying the political decision is proposed. The analysis is restricted to a bipolar scheme with a possible third political area. The interaction among voters is local but the final decision strongly depends on global effects such as, for example, the rating of the governments. As in the realistic case, the individual decision making process is determined by the most relevant personal interests and problems. The phenomenological analysis of the national vote in Italy and Germany has been carried out and a prediction of the next Italian vote as a function of the government rating is presented.

Abstract:
A macroscopic model of the tumor Gompertzian growth is proposed. This approach is based on the energetic balance among the different cell activities, described by methods of statistical mechanics and related to the growth inhibitor factors. The model is successfully applied to the multicellular tumor spheroid data.

Abstract:
The relation between symmetry breaking in non-commutative cut-off field theories and transitions to inhomogeneous phases in condensed matter is discussed. The non-commutative dynamics can be regarded as an effective description of the mechanisms which lead to inhomogeneous phase transitions and their relation to the roton-like excitation spectrum. The typical infrared-ultraviolet mixing in non-commutative theories contains the peculiar ingredients to describe the interplay between short and long distance particle interactions which is responsible for the non-uniform background and the roton spectrum both in bosonic and fermionic condensates.

Abstract:
We consider hadron production in high energy collisions as an Unruh radiation phenomenon. This mechanism describes the production pattern of newly formed hadrons and is directly applicable at vanishing baryochemical potential, mu = 0. It had already been found to correctly yield the hadronisation temperature, T_h = sqrt(sigma / 2 pi) = 165 MeV in terms of the string tension sigma. Here we show that the Unruh mechanism also predicts hadronic freeze-out conditions, giving s/T_h^3 = 3 pi^2 / 4 = 7.4 in terms of the entropy density s and E/N = \sqrt(2 pi sigma) = 1.09 for the average energy per hadron. These predictions provide a theoretical basis for previous phenomenological results and are also in accord with recent lattice studies.