International Journal of Modern Physics A

The standard procedure to determine (analytically) the values of the quark masses is to relate QCD two-point functions to experimental data in the framework of QCD sum rules. In the case of the light quark sector, the ideal Green function is the pseudoscalar correlator which involves the quark masses as an overall multiplicative factor. For the past thirty years this method has been affected by systematic uncertainties originating in the hadronic resonance sector, thus limiting the accuracy of the results. Recently, a major breakthrough has been made allowing for a considerable reduction of these systematic uncertainties and leading to light quark masses accurate to better than 8%. This procedure will be described in this talk for the up-, down-, strange-quark masses, after a general introduction to the method of QCD sum rules.

Position and momentum enter at the same level of importance in the formulation of classical or quantum mechanics. This is reflected in the invariance of Poisson brackets or quantum commutators under canonical transformations, which I regard as a global symmetry. A gauge symmetry can be defined in phase space (XM, PM) that imposes equivalence of momentum and position for every motion at every instant of the worldline. One of the consequences of this gauge symmetry is a new formulation of physics in space–time. Instead of one time there must be two, while phenomena described by one-time physics in 3+1 dimensions appear as various "shadows" of the same phenomena that occur in 4+2 dimensions with one extra space and one extra time dimensions (more generally, d+2). The 2T-physics formulation leads to a unification of 1T-physics systems not suspected before and there are new correct predictions from 2T-physics that 1T-physics is unable to make on its own systematically. Additional data related to the predictions, that provides information about the properties of the extra 1-space and extra 1-time dimensions, can be gathered by observers stuck in 3+1 dimensions. This is the probe for investigating indirectly the extra 1+1 dimensions which are neither small nor hidden. This 2T formalism that originated in 1998 has been extended in recent years from the worldline to field theory in d+2 dimensions. This includes 2T field theories that yield 1T field theories for the Standard Model and General Relativity as shadows of their counterparts in 4+2 dimensions. Problems of ghosts and causality in a 2T space-time are resolved automatically by the gauge symmetry, while a higher unification of 1T field theories is obtained. In this paper the approach will be described at an elementary worldline level, and the current status of 2T-physics will be summarized.

In this paper we review a part of the approaches that have been considered to explain the extraordinary discovery of the late time acceleration of the Universe. We discuss the arguments that have led physicists and astronomers to accept dark energy as the current preferable candidate to explain the acceleration. We highlight the problems and the attempts to overcome the difficulties related to such a component. We also consider alternative theories capable of explaining the acceleration of the Universe, such as modification of gravity. We compare the two approaches and point out the observational consequences, reaching the sad but foresightful conclusion that we will not be able to distinguish between a Universe filled by dark energy or a Universe where gravity is different from General Relativity. We review the present observations and discuss the future experiments that will help us to learn more about our Universe. This is not intended to be a complete list of all the dark energy models but this paper should be seen as a review on the phenomena responsible for the acceleration.

Moreover, in a landscape of hardly compelling theories, it is an important task to build simple measurable parameters useful for future experiments that will help us to understand more about the evolution of the Universe.

Considering the Froissart–Martin bound, Jin–Martin–Cornille bound and the optical theorem, we propose a novel parametrization for the total cross-section of proton–proton and antiproton–proton elastic scattering data. Using derivative dispersion relations we obtain the real part of the elastic scattering amplitude and thus the ρ parameter. Simultaneous fits to σtot and ρ are performed allowing very good statistical descriptions of the available data. Furthermore, predictions to σtot and ρ at energies not used in the fit procedures are presented. For σtot we obtain predictions at RHIC, LHC and future hadron collider energies.

Using Environmentally Friendly Renormalization, we present an analytic calculation of the series for the renormalization constants that describe the equation of state for the O(N) model in the whole critical region. The solution to the beta-function equation, for the running coupling to order two loops, exhibits crossover between the strong coupling fixed point, associated with the Goldstone modes, and the Wilson–Fisher fixed point. The Wilson functions γλ, γφ and γφ2, and thus the effective critical exponents associated with renormalization of the transverse vertex functions, also exhibit nontrivial crossover between these fixed points.

Following Auzzi' work (arXiv:0906.2366), where new vortex solution is found in weak coupled ABJM theory, we apply the ϕ-mapping topological current method to this vortex, and find the multivortices solution could be obtained naturally. Also this multivortices solution gives a clue of the possibility for the antivortex existence. Then we continue to investigate the vortices evolution of the solution, and this leads to the multivortices evolution that used to be hard to handle in conventional vortices scattering theory.

In general, elementary particles as well as extensive bodies have internal degrees of freedom that naturally turn their trajectories into accelerated curves. Hence, we propose to describe the kinematical properties of nongeodesic congruences and study how tidal forces are modified. Once the general scenario is well established, we analyze in details tidal effects due to electromagnetic fields, i.e. the relative acceleration between test charged particles. An algebraic analysis of these fields is developed together with a geometrical interpretation in terms of local field lines. In this framework, we compare general relativity and electrodynamics in terms of operationally equivalent objects.

We focus on Hořava–Lifshitz (HL) theory of gravity, and, in particular, on the Kehagias and Sfetsos's solution that is the analog of Schwarzschild black hole of General Relativity. In the weak-field and slow-motion approximation, we analytically work out the secular precession of the longitude of the pericentre ϖ of a test particle induced by this solution. Its analytical form is different from that of the general relativistic Einstein's pericentre precession. Then, we compare it to the latest determinations of the corrections to the standard Newtonian/Einsteinian planetary perihelion precessions recently estimated by E. V. Pitjeva with the EPM2008 ephemerides. It turns out that the planets of the solar system, taken singularly one at a time, allow one to put lower bounds on the adimensional HL parameter ψ0 of the order of 10-12(Mercury)-10-24 (Pluto). They are not able to account for the Pioneer anomalous acceleration for r > 20 AU.