arXiv subjects

E. H Saidi

Publications and source records attributed to E. H Saidi.

36 records · Page 2Linked to original sources

arXiv2017

Partial Breaking in Rigid Limit of $\mathcal{N}=2$ Gauged Supergravity

Using a new manner to rescale fields in $\mathcal{N}=2$ gauged supergravity with n$_{V}$ vector multiplets and n$_{H}$ hypermultiplets, we develop the explicit derivation of the rigid limit of quaternionic isometry Ward identities agreeing with known results. We show that the rigid limit can be achieved, amongst others, by performing two successive transformations on the covariantly holomorphic sections $V^{M}\left( z,\bar{z}\right) $ of the special Kahler manifold: a particular symplectic change followed by a particular Kahler transformation. We also give a geometric interpretation of the $η_{i}$ parameters used in arXiv:1508.01474 to deal with the expansion of the holomorphic prepotential $\mathcal{F}\left( z\right) $ of the $\mathcal{N}=2$ theory. We give as well a D- brane realisation of gauged quaternionic isometries and an interpretation of the embedding tensor $\vartheta_{M}^{u}$ in terms of type IIA/IIB mirror symmetry. Moreover, we construct explicit metrics for a new family of $4r$- dimensional quaternionic manifolds $\boldsymbol{M}_{QK}^{\left( n_{H}\right) }$ classified by ADE Lie algebras generalising the $SO\left( 1,4\right) /SO\left( 4\right) $ geometry which corresponds to $A_{1}\sim su\left( 2\right) $. The conditions of the partial breaking of $\mathcal{N}=2$ supersymmetry in the rigid limit are also derived for both the observable and the hidden sectors. Other features are also studied.

hep-th↗

arXiv2016

Type II seesaw supersymmetric neutrino model for $θ_{13}\neq0$

Using the type II seesaw approach and properties of discrete flavor symmetry group representations, we build a supersymmetric $A_{4}\times A_{3}$\ neutrino model with $θ_{13}\neq0$. After describing the basis of this model--which is beyond the minimal supersymmetric Standard Model--with a superfield spectrum containing flavons in $A_{4}\times A_{3}$\ representations, we first generate the tribimaximal neutrino mixing which is known to be in agreement with the mixing angles $θ_{12}$ and $θ_{23}$. Then, we give the scalar potential of the theory where the $A_{3}$ discrete subsymmetry is used to avoid the so-called sequestering problem. We \textrm{next} study the deviation from the tribimaximal mixing matrix which is produced by perturbing the neutrino mass matrix with a nontrivial $A_{4}$ singlet. Normal and inverted mass hierarchies are discussed numerically. We also study the breaking of $A_{4}$\ down to $Z_{3}$\ in the charged lepton sector, and use the branching ratio of the decay $τ\rightarrow μμe$--which is allowed by the residual symmetry $Z_{3}$--to get estimations on the mass of one of the flavons and the cutoff scale $Λ$ of the model.

hep-ph↗

arXiv2016

MSSM-like from $SU_{5}\times D_{4}$ Models

Using finite discrete group characters and symmetry breaking by hyperflux as well as constraints on top- quark family, we study minimal low energy effective theory following from SU$_{5}\times D_{4}$ models embedded in F-theory with non abelian flux. Matter curves spectrum of the models is obtained from SU$_{5}\times S_{5}$ theory with monodromy $S_{5}$ by performing two breakings; first from symmetric group $S_{5}$ to $S_{4}$ subsymmetry; and next to dihedral $D_{4}$ subgroup. As a consequence, and depending on the ways of decomposing triplets of $S_{4}$, we end with three types of $D_{4}$- models. Explicit constructions of these theories are given and a MSSM- like spectrum is derived.

hep-th↗

arXiv2015

$\mathcal{N}=2$ Supersymmetry Partial Breaking and Tadpole Anomaly

We consider the $U(1) ^{n}$ extension of the effective $\mathcal{N}=2$ supersymmetric $U(1) \times U(1) $ model of $arXiv:1204.2141$; and study the explicit relationship between partial breaking of $\mathcal{N}=2$ supersymmetry constraint and D3 brane tadpole anomaly of type IIB string on Calabi-Yau threefolds in presence of H$^{RR}$ and H$^{NS}$ fluxes. We also comment on supersymmetry breaking in the particular $\mathcal{N}=2$ $U(1) $ Maxwell theory; and study its interpretation in connection with the tadpole anomaly with extra localized flux sources.

hep-th↗

arXiv2015

Building SO$_{10}$- models with $\mathbb{D}_{4}$ symmetry

Using characters of finite group representations and monodromy of matter curves in F-GUT, we complete partial results in literature by building SO$% _{10}$ models with dihedral $\mathbb{D}_{4}$ discrete symmetry. We first revisit the $\mathbb{S}_{4}$-and $\mathbb{S}_{3}$-models from the discrete group character view, then we extend the construction to $\mathbb{D}_{4}$.\ We find that there are three types of $SO_{10}\times \mathbb{D}_{4}$ models depending on the ways the $\mathbb{S}_{4}$-triplets break down in terms of irreducible $\mathbb{D}_{4}$- representations: $\left(α \right) $ as $\boldsymbol{1}_{_{+,-}}\oplus \boldsymbol{1}_{_{+,-}}\oplus \boldsymbol{1}_{_{-,+}};$ or $\left(β\right) \boldsymbol{\ 1}_{_{+,+}}\oplus \boldsymbol{1}_{_{+,-}}\oplus \boldsymbol{1}_{_{-,-}};$ or also $\left(γ\right) $ $\mathbf{1}_{_{+,-}}\oplus \mathbf{2}_{_{0,0}}$. Superpotentials and other features are also given.

hep-th↗

arXiv2012

Topological Aspects of Fermions on Hyperdiamond

Motivated by recent results on the index of the Dirac operator D=γ^{μ}D_{μ} of QCD on lattice and also by results on topological features of electrons and holes of 2-dimensional graphene, we compute in this paper the Index of D for fermions living on a family of even dimensional lattices denoted as L_{2N} and describing the 2N-dimensional generalization of the graphene honeycomb. The calculation of this topological Index is done by using the direct method based on solving explicitly the gauged Dirac equation and also by using specific properties of the lattices L_{2N} which are shown to be intimately linked with the weight lattices of SU(2N+1). The Index associated with the two leading N=1 and N=2 elements of this family describe precisely the chiral anomalies of graphene and QCD_4. Comments on the method using the spectral flow approach as well as the computation of the topological charges on 2-cycles of 2N-dimensional compact supercell in L_{2N} and applications to QCD_4 are also given.

hep-th↗

arXiv2011

Anomalous Quantum Hall Effect of 4D Graphene in Background Fields

Boriçi-Creutz (\emph{BC}) model describing the dynamics of light quarks in lattice \emph{QCD} has been shown to be intimately linked to the four dimensional extension of 2D graphene refereed below to as four dimensional graphene (\emph{4D-graphene}). Borrowing ideas from the field theory description of the usual \emph{2D} graphene, we study in this paper the anomalous quantum Hall effect (AQHE) of the \emph{BC} fermions in presence of a constant background field strength $\mathcal{F}_{μν}$ with a special focuss on the case $\mathcal{F}_{μν}=\mathcal{B}ε_{μν34}+\mathcal{E}ε_{12μν}$ with $\mathcal{B}$ and $ \mathcal{E}$ two real\ moduli and $\det \mathcal{F}_{μν}=\mathcal{B}^{2}\mathcal{\times E}^{2}$. First, we revisit the anomalous \emph{2D} graphene by using \emph{QFT} method. Then, we consider the AQHE of \emph{BC}fermions for both regular $\det \mathcal{F}_{μν}\neq 0$ and singular $ \det F_{μν}=0$ cases. We show, amongst others, that the exact solutions of the \emph{BC} fermions coupled to constant $\mathcal{F}_{μν}$ have a 5D interpretation; and the filling factor $ν_{BC}$ of the \emph{BC}\ model coupled to constant $\mathcal{F}_{μν}$ is given by $24% \frac{(2N+1) (2M+1)}{2}$ with $N,$ $M$ positive integers. Others features, such as $\mathcal{F}_{μν}^{QCD}\neq 0$ \textrm{and the extension of the obtained results to the lattice fermions like Karsten-Wilzeck (KW) fermions and naive ones}, are also discussed. Key words: Lattice QCD, Boriçi-Creutz fermions, Anomalous Quantum Hall Effect, filling factor, four dimensional graphene, Index theorem, Spectral flow.

hep-th↗

arXiv2011

Four Dimensional Graphene

Mimicking pristine 2D graphene, we revisit the BBTW model for 4D lattice QCD given in ref.[5] by using the hidden SU(5) symmetry of the 4D hyperdiamond lattice H_4. We first study the link between the H_4 and SU(5); then we refine the BBTW 4D lattice action by using the weight vectors λ_1, λ_2, λ_3, λ_4, λ_5 of the 5-dimensional representation of SU(5) satisfying Σ_iλ_i=0. After that we study explicitly the solutions of the zeros of the Dirac operator D in terms of the SU(5) simple roots α_1, α_2, α_3, α_4 generating H_4; and its fundamental weights ω_1, ω_2, ω_3, ω_4 which generate the reciprocal lattice H_4^\ast. It is shown, amongst others, that these zeros live at the sites of H_4^\ast; and the continuous limit D is given by ((id\surd5)/2) γ^\muk_μwith d, γ^μand k_μstanding respectively for the lattice parameter of H_4, the usual 4 Dirac matrices and the 4D wave vector. Other features such as differences with BBTW model as well as the link between the Dirac operator following from our construction and the one suggested by Creutz using quaternions, are also given. Keywords: Graphene, Lattice QCD, 4D hyperdiamond, BBTW model, SU(5) Symmetry.

hep-th↗

arXiv2011

Monte Carlo simulation of magnetic phase transitions in Mn doped ZnO

The magnetic properties of Mn-doped ZnO semi-conductor have been investigated using the Monte Carlo method within the Ising model. The temperature dependences of the spontaneous magnetization, specific heat and magnetic susceptibility have been constructed for different concentrations of magnetic dopant Mn and different carrier concentrations. The exact values of Mn concentration and carrier concentration at which high temperature transition occurs are determined. An alternative for the explanation of some controversies concerning the existence and the nature of magnetism in Mn diluted in ZnO systems is given. Other features are also studied.

cond-mat.mtrl-sci↗

arXiv2011

Graphene, Lattice QFT and Symmetries

Borrowing ideas from tight binding model, we propose a board class of Lattice QFT models that are classified by the ADE Lie algebras. In the case of su(N) series, we show that the couplings between the quantum states living at the first nearest neighbor sites of the lattice $\mathcal{L}_{su(N)}$ are governed by the complex fundamental representations \underline{${\mathbf{N}}$} and $\bar{\mathbf{N}}$ of $su(N)$; and the second nearest neighbor interactions are described by its adjoint $\underline{\mathbf{N}} \otimes \bar{\mathbf{N}}$. The lattice models associated with the leading su(2), su(3) and su(4) cases are explicitly studied and their fermionic field realizations are given. It is also shown that the su(2) and su(3) models describe respectively the electronic properties of the acetylene chain and the graphene. It is established as well that the energy dispersion of the first nearest neighbor couplings is completely determined by the $A_{N}$ roots $ \mathbfα$ through the typical dependence $N/2+\sum_{roots}\cos(\mathbf{k}.α) $ with $\mathbf{k}$ the wave vector. Other features such as DE extension and other applications are also discussed. Keywords: Tight Binding Model, Graphene, Lattice QFT, ADE Symmetries.

hep-lat↗

arXiv2010

Intersecting Black Attractors in 8D N=1 Supergravity

We study intersecting extremal black attractors in non chiral 8D N=1 supergravity with moduli space ((SO(2,N))/(SO(2)\times SO(N)))\times SO(1,1) and work out explicitly the attractor mechanism for various black p-brane configurations with the typical near horizon geometries AdS_{p+2} \times S^{m} \times T^{6-p-m}. We also give the classification of the solutions of the attractor equations in terms of the SO(N-k) subgroups of SO(2)\times SO(N) symmetry of the moduli space as well as their interpretations in terms of both heterotic string on 2-torus and its type IIA dual. Other features such as non trivial SO(1,7) central charges Z_{μ_1...μ_{p}} in 8D N=1 supergravity and their connections to p-form gauge fields are also given. Key Words: 8D Supergravity, Superstring compactifications, Attractor Mechanism, Intersecting Attractors. PACS numbers: 04.70.-s, 11.25.-w, 04.65.+e, 04.70.-s, 04.50.+h, 04.70.Dy

hep-th↗

arXiv2010

Electronic Properties and Hidden Symmetries of Graphene

Using the relation between the structural and the electronic properties of honeycomb, we study the hidden SU(3) symmetry of the graphene monolayer and exhibit the link with its electronic properties. We show that the conservation law of incoming and outgoing electronic momenta at each site of graphene is solved in terms of SU(3) representations; and the Fourier waves ϕ(k_{x},k_{y}) of the hopping electron may be classified by SU(3) highest weight multiplets ϕ_{p,q}(ξ). It is also shown that the phases arctan((k_{y})/(k_{x})) of the waves are quantized as (((p+q))/((p-q)))sqrt(3) with p, q positive integers. Other features are also discussed.

cond-mat.str-el↗

arXiv2010

Extremal Black Attractors in 8D Maximal Supergravity

Motivated by the new higher D-supergravity solutions on intersecting attractors obtained by Ferrara et al. in [Phys.Rev.D79:065031-2009], we focus in this paper on 8D maximal supergravity with moduli space [SL(3,R)/SO(3)]x[SL(2,R)/SO(2)] and study explicitly the attractor mechanism for various configurations of extremal black p- branes (anti-branes) with the typical near horizon geometries AdS_{p+2}xS^{m}xT^{6-p-m} and p=0,1,2,3,4; 2<=m<=6. Interpretations in terms of wrapped M2 and M5 branes of the 11D M-theory on 3-torus are also given. Keywords: 8D supergravity, black p-branes, attractor mechanism, M-theory.

hep-th↗

arXiv2008

Entropy of Pairs of Dual Attractors in 6D/7D

We study the attractor mechanism of dual pairs of black brane bounds in N=2 supergravity in six and seven dimensions. First, we consider the effective potentials of the 6D and 7D black branes as well as their entropies. The contribution coming from the SO(1,1) factor of the moduli spaces M_{6D} and M_{7D} of these theories is carefully analyzed and it is used to motivate the study of the dual black branes bounds; which in turn allow to fix the critical value of the dilaton at horizon. The attractor eqs of the black branes and the bound pairs are derived by combining the criticality conditions of the corresponding effective potentials and the Lagrange multiplier method capturing constraints eqs on the fields moduli.

hep-th↗

arXiv2004

RG Cascades in Hyperbolic Quiver Gauge Theories

In this paper, we provide a general classification of supersymmeric QFT$_{4}$s into three basic sets: ordinary, affine and indefinite classes. The last class, which has not been enough explored in literature, is shown to share most of properties of ordinary and affine super QFT$_{4}$s. This includes, amongst others, its embedding in type II string on local Calabi-Yau threefolds. We give realizations of these supersymmetric QFT$_{4}$s as D-brane world volume gauge theories. A special interest is devoted to hyperbolic subset for its peculiar features and for the role it plays in type IIB background with non zero axion. We also study RG flows and duality cascades in case of hyperbolic quiver theories. Comments regarding the full indefinite sector are made.

hep-th↗

arXiv2002

NC Geometry and Discrete Torsion Fractional Branes:I

Considering the complex n-dimension Calabi-Yau homogeneous hyper-surfaces ${\cal H}_{n}$ and using algebraic geometry methods, we develop the crossed product algebra method, introduced by Berenstein et Leigh in hep-th/0105229, and build the non commutative (NC) geometries for orbifolds ${\cal O}={\cal H}_{n}/{\bf Z}_{n+2}^{n}$ with a discrete torsion matrix $t_{ab}=exp[{\frac{i2π}{n+2}}{(η_{ab}-η_{ba})}]$, $η_{ab} \in SL(n,{\bf Z})$. We show that the NC manifolds ${\cal O}^{(nc)}$ are given by the algebra of functions on the real $(2n+4)$ Fuzzy torus ${\cal T}^{2(n+2)}_{β_{ij}}$ with deformation parameters $β_{ij}=exp{\frac{i2π}{n+2}}{[(η^{-1}_{ab}-η^{-1}_{ba})} q_{i}^{a} q_{j}^{b}]$, $q_{i}^{a}$'s being Calabi-Yau charges of ${\bf Z}_{n+2}^{n}$. We develop graph rules to represent ${\cal O}^{(nc)}$ by quiver diagrams which become completely reducible at singularities. Generic points in these NC geometries are be represented by polygons with $(n+2)$ vertices linked by $(n+2)$ edges while singular ones are given by $(n+2)$ non connected loops. We study the various singular spaces of quintic orbifolds and analyze the varieties of fractional $D$ branes at singularities as well as the spectrum of massless fields. Explicit solutions for the NC quintic ${\cal Q}^{(nc)}$ are derived with details and general results for complex $n$ dimension orbifolds with discrete torsion are presented.

hep-th↗

arXiv2000

Toric Geometry, Enhanced non Simply laced Gauge Symmetries in Superstrings and F-theory Compactifications

We study the geometric engineering of supersymmetric quantum field theories (QFT), with non simply laced gauge groups, obtained from superstring and F-theory compactifications on local Calabi-Yau manifolds. First we review the main lines of the toric method for ALE spaces with ADE singularities which we extend to non simply laced ordinary and affine singularities. Then, we develop two classes of solutions depending on the two possible realisations of the outer-automorphism group of the toric graph $Δ$(ADE). In F-theory on elliptic Calabi-Yau manifolds, we give explicit results for the affine non simply laced toric data and the corresponding BCFG mirror geometries. The latters extend known results obtained in litterature for the affine ADE cases. We also study the geometric engineering of $ N=1$ supersymmetric gauge theory in eight dimensions. In type II superstring compactifications on local Calabi-Yau threefolds, we complete the analysis for ordinary ADE singularities by giving the explict derivation of the lacking non simply ones. Finally we develop the basis of polyvalent toric geometry. The latter extends bivalent and trivalent geometries, considered in the geometric engineering method, and use it to derive a new solution for the affine $\hat D_4$ singularity. Other features are also discussed.

hep-th↗

arXiv1997

Note on the deformation of chiral algebra

We introduce a new type of deformation of the chiral symmetry based on the deformation of the Laurent expansion of the conformal energy momentum tensor. Two kinds of solutions of the deformed equations of continuity are worked out. Known results are recovered, others features are also discussed.

hep-th↗