Volume 61, Number 12, 2016
Advances in Quantum Field Theory and Hamiltonian Systems
Naturalness and String Phenomenology in the LHC Era Ignatios Antoniadis Romanian Journal of Physics 61,
316 (2016)
I discuss the status of the mass hierarchy problem and prospects for beyond the Standard Model physics in the light of the Higgs scalar discovery at the LHC and the experimental searches for new physics. In particular, I discuss in this context low energy supersymmetry and large extra dimensions with low string scale.
Foliated Backgrounds for MTheory Compactifications (II) E. M. Babalic, C. I. Lazaroiu Romanian Journal of Physics 61,
1726 (2016)
We summarize the foliation approach to $\cal N = 1$ compactifications of elevendimensional supergravity on eightmanifolds $M$ (without boundary) down to AdS$_3$ spaces for the case when the internal part $\xi$ of the supersymmetry generator is chiral on some proper subset $\cal W$ of $M$. In this case, a topological nogo theorem implies that the complement $M \ \cal{W}$ must be a dense open subset, while $M$ admits a singular foliation $\bar{\cal F}$ (in the sense of Haefliger) which is defined by a closed oneform $\omega$ and is endowed with a longitudinal $G_2$ structure. The geometry of this foliation is determined by the supersymmetry conditions. We also describe the topology of $\bar{\cal F}$ in the case when $\omega$ is a Morse form.
SecondOrder Lagrangian Formulation of Linear FirstOrder Field Equations Constantin Bizdadea, SolangeOdile Saliu Romanian Journal of Physics 61,
2736 (2016)
A secondorder Lagrangian formulation with respect to a set of linear firstorder field equations (either relativistic or not) is proposed. The general formalism is illustrated in the case of firstorder field equations containing a single spatial derivative.
Dynamical Aspects of a Massless Tensor Gauge Field of Degree $(k+1)$ EugenMihăiţă Cioroianu Romanian Journal of Physics 61,
3751 (2016)
This paper aims to the determination of the number of degrees of freedom and also a generating set of gauge transformations for a theory whose dynamics is governed by a secondorder Lagrangian that describes the evolution of an Abelian tensor gauge field of degree $(k + 1)$.
Regular versus Chaotic Dynamics in Systems Generated by AreaPreserving Maps. Applications to the Study of Some Transport Phenomena Dana Constantinescu Romanian Journal of Physics 61,
5266 (2016)
In this paper we consider a class of discrete dynamical systems obtained through mapping technique from 3/2 d.o.f. Hamiltonian systems and we present some results concerning the existence and the position of internal transport barriers and a method for creating transport barriers in a prescribed position. Then we apply the results for mappings that model the magnetic field configuration in tokamaks and we interpret them.
Generalization of a Fractional Model for the Transport Equation Including External Perturbations Dana Constantinescu, Iulian Petrisor Romanian Journal of Physics 61,
6776 (2016)
A generalized fractional transport equation for particles is proposed and studied. This model includes local effects (through FokkerPlanck equation) and nonlocal spatial effects (Levy flights modelled using fractional derivatives). External perturbations are introduced in the model as source term in the fractional equation. A specific code based on matrix approach is built in order so study numerically the model.
Generalized Conditional Symmetries, Related Solutions of the KleinGordonFock Equation with Central Symmetry Radu Constantinescu Romanian Journal of Physics 61,
7788 (2016)
The generalized conditional symmetry (GCS) method is applied to a specific case of the Klein–Gordon–Fock (KGF) equation with central symmetry. We first investigate the conditions which yield the KGF equation that admits special class of secondorder GCSs. The determining system for the unknown functions is solved in several special cases. New symmetry operators and related exact solutions, different in form and structure from the ones obtained using other methods, are pointed out. Several surface plots of solutions are displayed.
Noncommutative Gravity via $SO(2,3)$ Noncommutative Gauge Theory Marija Dimitrijević Ćirić, Voja Radovanović Romanian Journal of Physics 61,
8998 (2016)
In this paper the noncommutative gravity is treated as a gauge theory of the noncommutative $SO(2, 3)_\star$ group on the noncommutative space with the constant noncommutativity. The enveloping algebra approach and the SeibergWitten map are used to relate noncommutative and the commutative gauge theory. By combining different actions a noncommutative gravity model is constructed in such a way that the cosmological constant term is not present in the commutative limit, but it is generated by the noncommutativity and it appears in the higher order expansion. We calculate the second order correction to this model and obtain terms that are zeroth, first, ... and fourth power of the curvature tensor. Finally, we discuss physical consequences of those correction terms in the low energy limit.
On Canonical Transformation and TachyonLike ``Particles'' in Inflationary Cosmology Goran S. Djordjevic, Dragoljub D. Dimitrijevic, Milan Milosevic Romanian Journal of Physics 61,
99109 (2016)
We examine a classical and quantum dynamics of systems described by the DBItype Lagrangian with tachyonlike potentials and corresponding DBI Lagrangians on (non)Archimedean spaces. The dynamic of tachyon fields in spatially homogeneous and in zerodimensional limits is analysed. A formalism for connecting a wide class of potentials and DBI Lagrangians with the locally equivalent canonical Lagrangians is presented. The results for exponentially decaying and inverse cosine hyperbolic are reviewed and for the potentials of the form $V(x) = x^{n}$ are discussed in more details. Classical actions and corresponding quantum propagators are calculated for these potentials in the Feynman path integral approach, on both Archimedean and nonArchemedean spaces.
MKdV Equations Related to the $D_4^{(2)}$ Algebra V. S. Gerdjikov, D. M. Mladenov, A. A. Stefanov, S. K. Varbev Romanian Journal of Physics 61,
110123 (2016)
We present a oneparameter families of mKdVtype equations related to ${\frak g} \simeq D_{4}^{(1)}$ and ${\frak g} \simeq D_{4}^{(2)}$. They are a set of partial differential equations, integrable via the inverse scattering method. They admit a Hamiltonian formulation and the corresponding Hamiltonians are also given. The RiemannHilbert problems for the two Lax operators are formulated on a set of $2h$ rays $l_nu$. We show that to each ray $l_\nu$ one can relate a subalgebra of $\frak g$ which is direct sum of $sl(2)$ subalgebras.
Statistical Approach of Modulation Instability in the Class of NLS Equations D. Grecu, A. S. Carstea, A.T. Grecu, Anca Vişinescu Romanian Journal of Physics 61,
124134 (2016)
In this review the modulation instability of NLS type equations is investigated using the statistical approach developed by Alber (1978). Two representative equations are studied, namely the well known cubic NLS eq. and a derivative NLS one. Improving the existing results in the literature (for dNLS eq.) only the Gaussian approximation is used in the decoupling of higher order two point correlation functions that appear in writing the kinetic equation satisfied by the twopoint correlation function $\rho(1, 2) = \langle \Psi(x_1)\Psi^*(x_2) \rangle$. Explicit results are obtained for a Lorentzian initial distribution function, the instability being restricted to the long wave lengths region of the perturbations and the long range correlations in the initial state. This seems to be an universal behavior in this class of equations.
YangMills Models in the Causal Approach: Perturbation Theory Up to the Second Order D. R. Grigore Romanian Journal of Physics 61,
135156 (2016)
We consider the standard model up to the second order of the perturbation theory (in the causal approach) and derive the most general form of the interaction Lagrangian for an arbitrary number of Higgs fields.
Integrability of a Family of 2Dim Cubic Systems with Degenerate Infinity Maoan Han, Valery G. Romanovski, Xiang Zhang Romanian Journal of Physics 61,
157166 (2016)
We study a family of cubic systems with degenerate infinity introduced in the paper [Chavarriga et al., Integrability of cubic systems with degenerate infinity, Differential Equations Dynam. Systems 6 (1998), 425438]. For systems of the family having a monodromic singularity at the origin the sets in the space of parameters corresponding to the systems with a local analytic first integral are found.
Enhancement of Hidden Symmetries and ChernSimons Couplings Marc Henneaux, Axel Kleinschmidt, Victor Lekeu Romanian Journal of Physics 61,
167182 (2016)
We study the role of Chern–Simons couplings for the appearance of enhanced symmetries of Cremmer–Julia type in various theories. It is shown explicitly that for generic values of the Chern–Simons coupling there is only a parabolic Lie subgroup of symmetries after reduction to three spacetime dimensions but that this parabolic Lie group gets enhanced to the full and larger Cremmer–Julia Lie group of hidden symmetries if the coupling takes a specific value. This is heralded by an enhanced isotropy group of the metric on the scalar manifold. Examples of this phenomenon are discussed as well as the relation to supersymmetry. Our results are also connected with rigidity theorems of Borellike algebras.
Nonlinear Control of Chaotic Circuits Carmen Ionescu, Gabriel Florian, Emilian Panaintescu, Iulian Petrisor Romanian Journal of Physics 61,
183193 (2016)
The paper investigates a specific type of nonlinear dynamical systems represented by electronic circuits with nonlinear elements, known as Chua circuits. Despite they are described by simple equations, with only one nonlinear function, they have a complex behavior, very rich in dynamical states and with interesting transitions from chaos to regular dynamics. The interest will be given to the problem of controlling the chaotic behavior using a technique specific for Hamiltonian systems. The main results which will be reported will concern the possibility of attaching a Lagrangian function and of transforming the Chua system into a variational one. The optimization of the dynamics will be achieved through a quadratic control term.
Supersymmetric Compactifications of MTheory with M2 Brane Potentials Andrei Micu Romanian Journal of Physics 61,
194203 (2016)
In this note we propose new flux configurations for Mtheory compactifications which preserve supersymmetry and nevertheless give rise to potentials for spacefilling M2 branes.
On the Stochastic Anisotropic Sheared Magnetic Field Lines Diffusion Marian Negrea, VirgilNicolae Cancea Romanian Journal of Physics 61,
204216 (2016)
In the present paper the decorrelation trajectory method has been used in order to calculate some averaged quantities of interest for stochastic anisotropic magnetic field lines in a sheared slab magnetic configuration for several values of the magnetic Kubo number, of the shear parameter and of the stochastic anisotropy parameter. The study has shown that a rich variety of transport behaviors can be found by varying the previously parameters, mainly by varying the anisotropy parameter in the plane perpendicular to the average magnetic field.
Some Statistical Features of Particle Dynamics in Tokamak Plasma Iulian Petrisor Romanian Journal of Physics 61,
217234 (2016)
In order to study the transport of charged particles (ions, electrons) or dust particles in tokamak plasma, we have used the numerical simulations method based on the TURBO code. The method can be applied for any value of the Kubo numbers $K$, $K_s$ specific for the analyzed problem. The particle’s transport depends on the level of turbulence and on the inhomogeneity of the magnetic field. The magnetic shear is shown to have a contribution in order to obtain the plasma stability. We present the specific autocorrelations for the electrostatic fluctuations implementing the TURBO code and we have calculated and interpreted the radial and poloidal mean squared displacements, the kurtosis and the skewness.
Lagrangians and Hamiltonians Related to Foliations Paul Popescu, Marcela Popescu Romanian Journal of Physics 61,
235244 (2016)
Hamiltonians related to foliations, analogous to Riemannian foliations, are studied in the paper. One prove that each of the following data: a bundlelike Hamiltonian, a transverse hyperregular Hamiltonian, a hyperregular Hamiltonian foliated cocycle or a geodesic orthogonal property are equivalent to the fact that a foliation have to be a Riemannian one. Relations with the analogous Lagrangian case, considered previously by the authors, are studied.
Parallel Processing of Large Data Sets in Particle Physics Marina Rotaru, Mihai Ciubăncan, Gabriel Stoicea Romanian Journal of Physics 61,
245252 (2016)
The analysis of the LHC data aims to minimize the vast amounts of data and the number of observables used. After slimming and skimming the data, the remaining terabytes of ROOT files hold a selection of the events and a flat structure for the variables needed that can be more easily inspected and traversed in the final stages of the analysis. PROOF has an efficient mechanism to distribute the analysis load by taking advantage of all the cores in modern CPUs through PROOFLite, PROOF Cluster or PROOF on Demand tools. In this paper we compared performance of different methods of file access (NFS, XROOTD, RFIO). The tests were done on Bucharest ATLAS Analysis Facility.
On the Quantization of the Massive MaxwellChernSimons Model SilviuConstantin Sararu Romanian Journal of Physics 61,
253259 (2016)
The massive Maxwell–Chern–Simons model and a higher order derivative extension of it are analyzed from the point of view of the Hamiltonian path integral quantization in the framework of the gaugeunfixing approach.
Toric Data and Killing Forms on Homogeneous SasakiEinstein Manifold $T^{1,1}$ Vladimir Slesar, Mihai Visinescu, Gabriel Eduard Vîlcu Romanian Journal of Physics 61,
260275 (2016)
We investigate the complex structure of the conifold $C(T^{1,1})$ basically making use of the interplay between symplectic and complex approaches of the Kähler toric manifolds. The description of the CalabiYau manifold $C(T^{1,1})$ using toric data allows us to write explicitly the complex coordinates and apply standard methods for extracting special Killing forms on the base manifold. As an outcome, we obtain the complete set of special Killing forms on the fivedimensional SasakiEinstein space $T^{1,1}$.
HigherDimensional Unified Theories with Continuous and Fuzzy Coset Spaces as Extra Dimensions G. Zoupanos, D. Gavriil, G. Manolakos Romanian Journal of Physics 61,
276296 (2016)
We review the Coset Space Dimensional Reduction (CSDR) scheme and the best model constructed so far. Then we present some details of an alternative CSDR programme, in which the extra dimensions are considered to be fuzzy. Specifically, we present a fourdimensional ${\cal N} = 4$ SYM theory, orbifolded by $\mathbb{Z}_3$, which mimics the behaviour of a dimensionally reduced ${\cal N} = 1$, tendimensional gauge theory over a set of fuzzy spheres at intermediate high scales. This leads to the trinification GUT $SU(3)^3$ at slightly lower, which in turn can be spontaneously broken to the MSSM in low scales.
