arXiv subjects

El Hassan Saidi

Publications and source records attributed to El Hassan Saidi.

At least 37 records · Page 2Linked to original sources

arXiv2012

On Flavor Symmetry in Lattice Quantum Chromodynamics

Using a well established method to engineer non abelian symmetries in superstring compactifications, we study the link between the point splitting method of Creutz et al of refs [1,2] for implementing flavor symmetry in lattice QCD; and singularity theory in complex algebraic geometry. We show amongst others that Creutz flavors for naive fermions are intimately related with toric singularities of a class of complex Kahler manifolds that are explicitly built here. In the case of naive fermions of QCD$_{2N}$, Creutz flavors are shown to live at the poles of real 2-spheres and carry quantum charges of the fundamental of $[SU(2)]^{2N}$. We show moreover that the two Creutz flavors in Karsten-Wilczek model, with Dirac operator in reciprocal space of the form $iγ_1 F_1+iγ_2 F_2 + iγ_3 F_3+\frac{i}{\sin α}γ_4 F_4$, are related with the small resolution of conifold singularity that live at $\sin α=0$. Other related features are also studied.

hep-th↗

arXiv2011

Graphene and Cousin Systems

Graphene is a new material that exhibits remarkable properties from both fundamental and applied issues. This is a 2D matter system whose physical and mechanical features have been approached by using tight binding model, first principle calculations based on DFT and membrane theory. Graphene as a carbon molecule has also hidden symmetries that motivated extensions in various dimensions such as chain-type configurations, that are frequently observed as the graphene bridge narrowed down to a few- or single-atom width, graphene multi-layers thought of as electric capacitors, doped graphene to gain more physical properties as well as cousin systems such as diamond and hyperdiamond. In this work, we use tight binding model ideas and field theory method as well as the hidden symmetries of the underlying crystals to study physical aspects of 2D graphene and its homologues. We also study the relation between 2D graphene with the Boriçi-Creutz fermions considered recently in literature as an adequate model to perform numerical simulations in 4D lattice QCD where the two Dirac zeros are interpreted in terms of the light quarks up and down.

cond-mat.str-el↗

arXiv2011

Graphene, its Homologues and Their Classification

Using tight binding model, lattice QFT and group theory methods, we study a class of lattice QFT models that are cousins of graphene; and which are classified by finite dimensional ADE Lie groups containing the usual crystallographic symmetries as discrete subgroups. We show in particular that the electronic properties of the 1D lattice poly-acetylene chain are given by a SU(2) model and those of the well known 2D graphene by SU(3). We also give two other models classified by SU(4) and SO(6) symmetries; they respectively describe 3D diamond and 3D lattice with octahedral sites. It is shown as well that the dispersion energies of this set of models are completely characterized by the roots of the Lie algebras underlying the symmetry groups. Other features, such as SO(5) lattice involving sp^{3}d hybridization as well as the relation between the 4D hyperdiamond, having a SU(5) symmetry and the 4D lattice QCD, are also discussed.

hep-th↗

arXiv2011

On Dirac Zero Modes in Hyperdiamond Model

Using the SU(5) symmetry of the 4D hyperdiamond and results on the study of 4D graphene given in "Four Dimensional Graphene" (L.B Drissi, E.H Saidi, M. Bousmina, CPM-11-01, Phys. Rev. D (2011)), we engineer a class of 4D lattice QCD fermions whose Dirac operators have two zero modes. We show that generally the zero modes of the Dirac operator in hyperdiamond fermions are captured by a tensor Ω_{μ}^{l} with 4\times5 complex components linking the Euclidean SO(4) vector μ; and the 5-dimensional representation of SU(5). The Boriçi-Creutz (BC) and the Karsten-Wilzeck (KW) models as well as their Dirac zero modes are rederived as particular realizations of Ω_{μ}^{l}. Other features are also given. Keywords: Lattice QCD, Boriçi-Creutz and Karsten-Wilzeck models, 4D hyperdiamond, 4D graphene, SU(5) Symmetry.

hep-lat↗

arXiv2011

On Black Attractors in 8D and Heterotic/Type IIA Duality

Motivated by the study of black attractors in 8D supergravity with 16 supersymmetries, we use the field theory approach and 8D supersymmetry with non trivial central charges to shed light on the exact duality between heterotic string on T^2 and type IIA on real connected and compact surfaces Σ2. We investigate the two constraints that should be obeyed by Σ2 and give their solutions in terms of intersecting 2-cycles as well their classification using Dynkin diagrams of affine Kac-Moody algebras. It is shown as well that the moduli space of these dual theories is given by SO(1,1)x((SO(2,r+2))/(SO(2)xSO(r+2))) where r stands for the rank of the gauge symmetry G_{r} of the 10D heterotic string on T^2. The remarkable cases r=-2,-1,0 as well as other features are also investigated.

hep-th↗

arXiv2009

Quiver Gauge Models in F-Theory on Local Tetrahedron

We study a class of 4D $\mathcal{N}=1$ supersymmetric GUT- type models in the framework of the Beasley-Heckman-Vafa theory. We first review general results on MSSM and supersymmetric GUT; and we describe useful tools on 4D quiver gauge theories in F- theory set up. Then we study the effective supersymmetric gauge theory in the 7-brane wrapping 4-cycles in F-theory on local elliptic CY4s based on a complex tetrahedral surface $\mathcal{T}$ and its blown ups $\mathcal{T}_{n}$. The complex 2d geometries $\mathcal{T}$ and $\mathcal{T}_{n}$ are \emph{non planar} projective surfaces that extend the projective plane $\mathbb{P}^{2}$ and the del Pezzos. Using the power of toric geometry encoding the toric data of the base of the local CY4, we build a class of \emph{4D} $\mathcal{N}=1$ non minimal GUT- type models based on $\mathcal{T}$ and $\mathcal{T}_{n}$. An explicit construction is given for the SU$(5) $ GUT-type model.

hep-th↗

arXiv2009

Tetrahedron in F-theory Compactification

Complex tetrahedral surface $\mathcal{T}$ is a non planar projective surface that is generated by four intersecting complex projective planes $CP^{2}$. In this paper, we study the family $\{\mathcal{T}_{m}\} $ of blow ups of $\mathcal{T}$ and exhibit the link of these $\mathcal{T}_{m}$s with the set of del Pezzo surfaces $dP_{n}$ obtained by blowing up n isolated points in the $CP^{2}$. The $\mathcal{T}_{m}$s are toric surfaces exhibiting a $U(1) \times U(1) $ symmetry that may be used to engineer gauge symmetry enhancements in the Beasley-Heckman-Vafa theory. The blown ups of the tetrahedron have toric graphs with faces, edges and vertices where may localize respectively fields in adjoint representations, chiral matter and Yukawa tri-fields couplings needed for the engineering of F- theory GUT models building.

hep-th↗

arXiv2008

Topological String on Toric CY3s in Large Complex Structure Limit

We develop a non planar topological vertex formalism and we use it to study the A-model partition function $\mathcal{Z}_{top}$ of topological string on the class of toric Calabi-Yau threefolds (CY3) in large complex structure limit. To that purpose, we first consider the $T^{2}\times R$ special Lagrangian fibration of generic CY3-folds and we give the realization of the class of large $μ$ toric CY3-folds in terms of supersymmetric gauged linear sigma model with \emph{non zero} gauge invariant superpotentials $% \mathcal{W}(Φ) $. Then, we focus on a one complex parameter supersymmetric $U(1) $ gauged model involving six chiral superfields ${Φ_{i}}$ with $\mathcal{W}=μ(\prod\nolimits_{i=0}^{5}Φ_{i}) $ and we use it to compute the function $\mathcal{Z}_{top}$ for the case of the local elliptic curve in the limit $μ\to \infty $.

hep-th↗

arXiv2008

Refining the Shifted Topological Vertex

We study aspects of the refining and shifting properties of the 3d MacMahon function $\mathcal{C}_{3}(q) $ used in topological string theory and BKP hierarchy. We derive the explicit expressions of the shifted topological vertex $\mathcal{S}_{λμν}(q) $ and its refined version $\mathcal{T}_{λμν}(q,t) $. These vertices complete results in literature.

hep-th↗

arXiv2008

Computing the Scalar Field Couplings in 6D Supergravity

Using non chiral supersymmetry in 6D space time, we compute the explicit expression of the metric the scalar manifold $SO(1,1) \times \frac{SO(4,20) }{SO(4) \times SO(20)}$ of the 10D type IIA superstring on generic K3. We consider as well the scalar field self-couplings in the general case where the non chiral 6D supergravity multiplet is coupled to generic n vector supermultiplets with moduli space $SO(1,1) \times \frac{SO(4,n)}{SO(4) \times SO(n)}$. We also work out a dictionary giving a correspondence between hyperKahler geometry and the Kahler geometry of the Coulomb branch of 10D type IIA on Calabi-Yau threefolds. Others features are also discussed.

hep-th↗

arXiv2008

On Black Hole Effective Potential in 6D/7D N=2 Supergravity

Using the harmonic superspace method and the duality between real and complex representations of hypermultiplets, we compute the explicit scalar field expression of the quaternionic metric $G_{mn}$ of the moduli space SO(1,1)x[SO(4,k)/(SO(4)xSO(k))] of 6D N=2 supergravity with generic k Maxwell supermultiplets. The obtained metric includes the particular case k=20 associated with 10D type IIA superstring on K3. Uplifting to 7D N=2 supergravity is described and aspects of 6D/7D black attractor effective potentials are studied.

hep-th↗

arXiv2008

Non Planar Topological 3-Vertex Formalism

Using embedding of complex curves in the complex projective plane $\bf{P }^{2}$, we develop a \emph{non planar} topological 3-vertex formalism for topological strings on the family of local Calabi-Yau threefolds $X^{(m,-m,0) }=\mathcal{O}(m)\oplus \mathcal{O}(-m)\to E^{(t,\infty)}$. The base $E^{(t,\infty)}$ stands for the degenerate elliptic curve with Kahler parameter $t$; but a large complex structure $μ$; i.e $| μ| \longrightarrow \infty $. We also give first results regarding A-model topological string amplitudes on $X^{(m,-m,0)}$. The 2D $U(1) $ gauged $\mathcal{N}=2$ supersymmetric sigma models of the degenerate elliptic curve $ E^{(t,\infty)}$ as well as for the family $X^{(m,-m,0)}$ are studied and the role of D- and F-terms is explicitly exhibited.

hep-th↗

arXiv2008

Generalized MacMahon G(q) as q-deformed CFT Correlation Function

Using $Γ_{\pm}(z) $ vertex operators of the $c=1$ two dimensional conformal field theory, we give a 2d-quantum field theoretical derivation of the conjectured d- dimensional MacMahon function G$_{d}(q) $. We interpret this function G$_{d}(q) $ as a $(d+1) $- point correlation function $\mathcal{G}_{d+1}(z_{0},...,z_{d}) $ of some local vertex operators $\mathcal{O}%_{j}(z_{j}) $. We determine these operators and show that they are particular composites of q-deformed hierarchical vertex operators $% Γ_{\pm}^{(p)}$, with a positive integer p. In agreement with literature's results, we find that G$_{d}(q) $, $d\geq 4$, cannot be the generating functional of all \textit{d- dimensional} generalized Young diagrams .

hep-th↗

arXiv2008

BPS and non BPS 7D Black Attractors in M-Theory on K3

We study the BPS and non BPS black attractors in 7D N=2 supergravity embedded in 11D M-theory compactified on K3. Combining Kahler and complex moduli in terms of SO(3) representations, we build the Dalbeault like (DL) basis for the second cohomology of K3 and set up the fundamental relations of the special "hyperKahler" geometry of the underlying moduli space of the 7D theory. We study the attractor eqs of the 7D black branes by using the method of the criticality of the effective potential and also by using the extension of the so called 4D new attractor approach to 7D N=2 supergravity. A comment, regarding a 6D/7D correspondence, along the line of Ceresole-Ferrara-Marrani used for 4D/5D, ref.arXiv:0707.0964, is made.

hep-th↗

arXiv2006

Topological string in harmonic space and correlation functions in $S^3$ stringy cosmology

We develop the harmonic space method for conifold and use it to study local complex deformations of $T^{\ast}S^{3}$ preserving manifestly $SL(2,C) $ isometry. We derive the perturbative manifestly $SL(2,C) $ invariant partition function $\mathcal{Z}_{top}$ of topological string B model on locally deformed conifold. Generic $n$ momentum and winding modes of 2D $c=1$ non critical theory are described by highest $% \upsilon_{(n,0)}$ and lowest components $\upsilon_{(0,n)}$ of $SL(2,C) $ spin $s=\frac{n}{2}$ multiplets $% (\upsilon _{(n-k,k)}) $, $0\leq k\leq n$ and are shown to be naturally captured by harmonic monomials. Isodoublets ($n=1$) describe uncoupled units of momentum and winding modes and are exactly realized as the $SL(2,C) $ harmonic variables $U_α^{+}$ and $V_α^{-}$. We also derive a dictionary giving the passage from Laurent (Fourier) analysis on $T^{\ast}S^{1}$ ($S^{1}$) to the harmonic method on $T^{\ast}S^{3}$ ($S^{3}$). The manifestly $SU(2,C) $ covariant correlation functions of the $S^{3}$ quantum cosmology model of Gukov-Saraikin-Vafa are also studied.

hep-th↗

arXiv2006

D-string fluid in conifold: II. Matrix model for D-droplets on S^{3} and S^{2}

Motivated by similarities between Fractional Quantum Hall (FQH) systems and aspects of topological string theory on conifold, we continue in the present paper our previous study (hep-th/0604001, hep-th/0601020) concerning FQH droplets on conifold. Here we focus our attention on the conifold sub-varieties $\mathbb{S}^{3}$\textbf{\}and\textbf{\}$\mathbb{S}^{2}$ and study the non commutative quantum dynamics of D1 branes wrapped on a circle. We give a matrix model proposal for FQH droplets of $N$ point like particles on $\mathbb{S}^{3}$\textbf{\}and\textbf{\}$\mathbb{S}^{2}$ with filling fraction $ν=\frac{1}{k}$. We show that the ground state of droplets on $% \mathbb{S}^{3}$ carries an isospin $j=k\frac{N(N-1)}{2}$ and gives remarkably rise to $2j+1$ droplets on $\mathbb{S}^{2}$ with Cartan-Weyl charge $| j_{z}| \leq j$.

hep-th↗

arXiv2006

QFT method for indefinite Kac-Moody Theory: A step towards classification

We propose a quantum field theory (QFT) method to approach the classification of indefinite sector of Kac-Moody algebras. In this approach, Vinberg relations are interpreted as the discrete version of the QFT_{2} equation of motion of a scalar field and Dynkin diagrams as QFT_{2} Feynman graphs. In particular, we show that Dynkin diagrams of su(n+1) series (n\geq 1) can be interpreted as free field propagators and T_{p,q,r} diagrams as the vertex of ϕ^{3} interaction. Other results are also given.

hep-th↗

arXiv2006

D-string fluid in conifold: I. Topological gauge model

Motivated by similarities between quantum Hall systems à la Susskind and aspects of topological string theory on conifold as well as results obtained in hep-th/0601020, we study the dynamics of D-string fluids running in deformed conifold in presence of a strong and constant RR background B-field. We first introduce the basis of D-string system in fluid approximation and then derive the holomorphic non commutative gauge invariant field action describing its dynamics in conifold. This study may be also viewed as embedding Susskind description for Laughlin liquid in type IIB string theory. FQH systems on real manifolds $R\times S^{2}$ and $S^{3}$ are shown to be recovered by restricting conifold to its Lagrangian sub-manifolds. Aspects of quantum behaviour of the string fluid are discussed.

hep-th↗