We compute in a theoretical quantum field theory
framework the effects that a classic environment will have on an elementary one-fermion
state, assumed for simplicity to be that of one electron, in the presence of a
magnetic field. We consider its total energy and its spin angular momentum as
relevant observables of the state. We show that the changes of these quantities
produced by the combined environmental and magnetic effects can be expressed in
a simple and compact form. We obtain expressions that only depend on the values
of the external environment and magnetic fields, and on the special spin
features of the free fermion state. We call these effects “fermion
epigenetics” and try to motivate this definition discussing possible relevant
analogies with the corresponding medical treatment of epigenetics in organic
cells.

We consider the effects that a magnetic field has on the observable
properties of an elementary one-fermion state, assumed for simplicity to be
that of one electron. We show that for a weak intensity of the field these
effects can be very simply computed in a quantum field theory theoretical
framework, assuming the minimal form of the electromagnetic interaction and the
validity of the Dirac equation. The effects proceed via preliminary, magnetic
field induced, modification of the four components of the spinor field. These
generate consequent modifications of the various observable properties of the
fermion, which can always be simply expressed in terms of the four spinor field
components. A few general features of the various effects are discussed, and a
number of possible analogies with the fascinating medical description of the
epigenetic process for an organic cell are finally proposed.

Abstract:
We propose a quantum gravity-extended form of the classical length contraction law obtained in special relativity. More specifically, the framework of our discussion is the UV self-complete theory of quantum gravity. We show how our results are consistent with (i) the generalized form of the uncertainty principle (GUP), (ii) the so-called hoop-conjecture, and (iii) the intriguing notion of “classicalization” of trans-Planckian physics. We argue that there is a physical limit to the Lorentz contraction rule in the form of some minimal universal length determined by quantum gravity, say the Planck Length, or any of its current embodiments such as the string length, or the TeV quantum gravity length scale. In the latter case, we determine the critical boost that separates the ordinary “particle phase,” characterized by the Compton wavelength, from the “black hole phase,” characterized by the effective Schwarzschild radius of the colliding system. 1. Introduction and Background High energy particle physics is based on the notion that smaller and smaller distance scales can be investigated by increasing the energy of the probe particle. Elementary projectiles colliding with a target can resolve distances comparable with their quantum mechanical wavelength. The more is the energy, the shorter is the wavelength in agreement with the relativistic rule of length contraction. Quantum mechanics and special relativity work together to open a window on the microscopic world. This simple picture becomes less clear when we begin to approach the Planck scale of distance or energy and consider the concomitant quantum gravity effects. This problem has long been ignored on the basis that the Planck energy, roughly ？GeV, is so huge that no particle accelerator will ever be able to approach it. However, the picture is completely different when we consider the string-inspired unified models with large extra-dimensions, where the unification scale can be as low as some TeV. In this kind of scenario, quantum gravity effects, including microblack hole production in partonic hard scattering, have been suggested to occur near the LHC peak energy, that is, 14？TeV [1–10]. In this new physics, the distinction between “point-like” elementary particles and “extended” quantum gravity excitations, whatever they are, that is, black holes, -branes, string balls, and so forth, turns out to be fuzzy, so that standard notions, such as the Lorentz-Fitzgerald length contraction, require a substantial revision, at least insofar as its domain of validity is concerned. For instance, a

Abstract:
We study the phases of a Schwarzschild black hole in the Anti-deSitter background geometry. Exploiting fluid/gravity duality, we construct the Maxwell equal area isotherm？？ in the temperature-entropy plane, in order to eliminate negative heat capacity BHs. The construction we present here is reminiscent of the isobar cut in the pressure-volume plane which eliminates unphysical part of the Van der Walls curves below the critical temperature. Our construction also modifies the Hawking-Page phase transition. Stable BHs are formed at the temperature , while pure radiation persists for . turns out to be below the standard Hawking-Page temperature and there are no unstable BHs as in the usual scenario. Also, we show that, in order to reproduce the correct BH entropy , one has to write a black hole equation of state, that is, , in terms of the geometrical volume . 1. Introduction Black holes (BHs) are among the most intriguing solutions of Einstein equations. Their geometric description is fully provided by the theory of general relativity and is discussed in many excellent textbooks. However, this is only half of the story. Since the original works by Bekenstein and Hawking, some new aspects of the BH behavior emerged once quantum field theory is coupled to a BH background geometry. Even if this is only a “semiclassical” quantum gravity formulation, the outcome has profoundly changed the prospective of the BH behavior. A stellar mass, classical, BH is characterized by the unique feature of being a perfect absorber with a vanishing luminosity. From a thermodynamical point of view, a classical BH is a zero temperature black body. However, nuclear size BHs, interacting with quantized matter, are almost perfect black bodies as they emit black body radiation at a characteristic nonvanishing temperature! Moreover, BHs are assigned a thermodynamical property identified with entropy. Thus, there are two complementary descriptions of BH physics: one in terms of pure space-time geometry and the other in terms of thermodynamics. The two descriptions are related to each other through the so-called “first law” of BH (thermo)dynamics as follows: where = total mass energy, = Hawking temperature, = entropy, = the Coulomb potential on the horizon, = electric charge, = angular velocity of the horizon, and = angular momentum. The first law (1) is the basis of the thermodynamical description of the BH as a “fluid” where is the variation of total energy split into variation of “internal,” “electrostatic,” and “rotational” pieces, which are then given a thermodynamical meaning. By

Abstract:
We study the residual symmetry $SL(2,R)\otimes U(1)$ of the chiral gravity in the light-cone gauge. Quantum gravitational effects renormalize the Kac-Moody central charge and introduce, through the Lorentz anomaly, an arbitrary parameter. Due to the presence of this free parameter the Kac-Moody central charge has no forbidden range of values, and the strong gravity regime is open to investigations.

Abstract:
We provide a new exact solution of the Einstein equations which generalizes the noncommutative geometry inspired Schwarzschild metric, we previously obtained. We consider here more general relations between the energy density and the radial pressure and find new a geometry describing a regular ``dirty black hole''. We discuss strong and weak energy condition violations and various aspects of the regular dirty black hole thermodynamics.

Abstract:
In this Letter, we propose a new scenario emerging from the conjectured presence of a minimal length $\ell$ in the spacetime fabric, on the one side, and the existence of a new scale invariant, continuous mass spectrum, of un-particles on the other side. We introduce the concept of \textit{un-spectral dimension} $\mathbb{D}_U$ of a $d$-dimensional, euclidean (quantum) spacetime, as the spectral dimension measured by an "un-particle" probe. We find a general expression for the un-spectral dimension $\mathbb{D}_U$ labelling different spacetime phases: a semi-classical phase, where ordinary spectral dimension gets contribution from the scaling dimension $d_U$ of the un-particle probe ; a critical "Planckian phase", where four-dimensional spacetime can be effectively considered two-dimensional when $d_U=1$; a "Trans-Planckian phase", which is accessible to un-particle probes only, where spacetime as we currently understand it looses its physical meaning.

Abstract:
Kerrr in the title is not a typo. The third "r" stands for "regular", in the sense of pathology-free, rotating black hole. We exhibit a long search-for, exact, Kerr-like, solution of the Einstein equations with novel features: i) no curvature ring singularity; ii) no "anti-gravity" universe with causality violating timelike closed world-lines; iii) no "super-luminal" matter disk. The ring singularity is replaced by a classical, circular, rotating string with Planck tension representing the inner engine driving the rotation of all the surrounding matter. The resulting geometry is regular and smoothly interpolates among inner Minkowski space, borderline deSitter and outer Kerr universe. The key ingredient to cure all unphysical features of the ordinary Kerr black hole is the choice of a "noncommutative geometry inspired" matter source as the input for the Einstein equations, in analogy with spherically symmetric black holes described in earlier works.

Abstract:
We study un-particle dynamics in the framework of standard quantum field theory. We obtain the Feynman propagator by supplementing standard quantum field theory definitions with integration over the mass spectrum. Then we use this information to construct effective actions for scalar, gauge vector and gravitational un-particles.

Abstract:
In this paper, we are going to put in a single consistent framework apparently unrelated pieces of information, i.e. zero-point length, extra-dimensions, string T-duality. More in details we are going to introduce a modified Kaluza-Klein theory interpolating between (high-energy) string theory and (low-energy) quantum field theory. In our model zero-point length is a four dimensional ``virtual memory'' of compact extra-dimensions length scale. Such a scale turns out to be determined by T-duality inherited from the underlying fundamental string theory. From a low energy perspective short distance infinities are cut off by a minimal length which is proportional to the square root of the string slope, i.e. \sqrt{\alpha^\prime}. Thus, we provide a ``bridge'' between the ultra-relativistic string domain and the low energy arena of point-particle quantum field theory.