268 research outputs found

    Higher Derivative Terms in Three Dimensional Supersymmetric Theories

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    In this work, we systematically analyze higher derivative terms in the supersymmetric effective actions for three dimensional scalar field theories using N=1\mathcal{N} =1 superspace formalism. In these effective actions, we show that auxiliary fields do not propagate and their effective actions can be expressed in terms of the physical fields. So, the theory does not change its field content upon addition of higher derivative terms. We use derivative expansion to generate four, five and six dimensional terms for an interacting scalar field theory with N=1\mathcal{N} =1 supersymmetry. We show that along with pure fermionic and bosonic terms, there are various five and six dimensional topological terms that mix bosonic and fermionic fields. Finally, we use these results to obtain higher derivative topological terms in the effective action for two M2-branes.Comment: 18 pages, 0 figures, Accepted for publication in JHE

    Four Dimensional Supersymmetric Theories in Presence of a Boundary

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    In this paper, we study N=1\mathcal{N} =1 supersymmetric theories in four dimensions in presence of a boundary. We demonstrate that it is possible to preserve half the supersymmetry of the original theory by suitably modifying it in presence of a boundary. This is done by adding new boundary terms to the original action, such that the supersymmetric variation of the new terms exactly cancels the boundary terms generated by the supersymmetric transformation of the original bulk action. We also analyze the boundary projections of such supercharges used in such a theory. We study super-Yang-Mills theories in presence of a boundary using these results. Finally, we study the Born-Infeld action in presence of a boundary. We analyse the boundary effects for the Born-Infeld action coupled to a background dilaton and an axion field. We also analyse the boundary effects for an non-abelian Born-Infeld action. We explicitly construct the actions for these systems in presence of a boundary. This action preserves half of the original supersymmetry.Comment: 18 pages, no figures, Accepted for publication in Phys. Lett.

    Planck-Scale Corrections to Friedmann Equation

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    Recently, Verlinde proposed that gravity is an emergent phenomenon which originates from an entropic force. In this work, we extend Verlinde's proposal to accommodate generalized uncertainty principles (GUP), which are suggested by some approaches to \emph{quantum gravity} such as string theory, black hole physics and doubly special relativity (DSR). Using Verlinde's proposal and two known models of GUPs, we obtain modifications to Newton's law of gravitation as well as the Friedmann equation. Our modification to the Friedmann equation includes higher powers of the Hubble parameter which is used to obtain a corresponding Raychaudhuri equation. Solving this equation, we obtain a leading Planck-scale correction to Friedmann-Robertson-Walker (FRW) solutions for the p=ωρp=\omega \rho equation of state.Comment: 15 pages, no figure, to appear in Central Eur.J.Phys. arXiv admin note: text overlap with arXiv:1301.350

    Minimal Length, Friedmann Equations and Maximum Density

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    Inspired by Jacobson's thermodynamic approach[gr-qc/9504004], Cai et al [hep-th/0501055,hep-th/0609128] have shown the emergence of Friedmann equations from the first law of thermodynamics. We extend Akbar--Cai derivation [hep-th/0609128] of Friedmann equations to accommodate a general entropy-area law. Studying the resulted Friedmann equations using a specific entropy-area law, which is motivated by the generalized uncertainty principle (GUP), reveals the existence of a maximum energy density closed to Planck density. Allowing for a general continuous pressure p(ρ,a)p(\rho,a) leads to bounded curvature invariants and a general nonsingular evolution. In this case, the maximum energy density is reached in a finite time and there is no cosmological evolution beyond this point which leaves the big bang singularity inaccessible from a spacetime prospective. The existence of maximum energy density and a general nonsingular evolution is independent of the equation of state and the spacial curvature kk. As an example we study the evolution of the equation of state p=ωρp=\omega \rho through its phase-space diagram to show the existence of a maximum energy which is reachable in a finite time.Comment: 15 pages, 1 figure, minor revisions, To appear in JHE

    WAP Based Email Management Application

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    WAP technology becomes the most appropriate and the useful tools to access the information about the different information and services anytime and anywhere. However this study identified the requirement model to manage the email by mobile device, which can be obtained easily way and flexibility to access and check the incoming emails by this service. This study introduces an application to manage the incoming emails for those who interested in using the mobile device. However, this service will help to reduce the time for the users to check their incoming emails, especially when they are away from their work or any place can not provide the Web services. For these reasons this study carry out the manage email by mobile to obtain the appropriate solution

    The armament of the Almoravid army

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    El estado almorávide se sustentaba en elementos bélicos y militares. El ejército era la base fundamental de su existencia. Yusuf Ibn Tašufin, el fundador del gran estado almorávide, procuró organizar el ejército almorávide y proveerlo del equipamiento y el armamento necesario, hasta que se convirtió en uno de los ejércitos más poderosso del momento, al sustituir el armamento sencillo propio de los combates de la vida beduina por un tipo de armamento que le permitió superar a sus enemigos en el Magreb, al-Andalus y los reinos cristianos. Este tipo de armamento incluía armas ligeras, pesadas, económicas, personales y defensivas (fortificaciones). El presente estudio detalla algunas de esas armas, incluyendo armamento de tipo químico, que se utilizaba dependiendo del tipo de combate o batalla al que se enfrentaban.The Almoravid state was based on war and military elements. In fact, the army was considered a crucial element. Yusuf Ibn Tashufin, the founder of the great Almoravid state, sought to organize the Almoravid army and provide the necessary equipment and weapons so it became one of the most powerful armies of the time, by menas of replacing the simple type of weapons used in Bedouin life style by new types of weapons that allowed them to overcome their enemies in the Maghrib, Al-andalus and the Christian kingdoms. These weapons include light, heavy, economic, personal and defensive weapons (fortifications). This paper provide further details about some of these weapons, including weapons of chemical nautre, which were used in some batles they faced

    Topological dyonic Taub-Bolt/NUT-AdS: Thermodynamics and first law

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    Motivated by the absence of Misner string in the Euclidean Taub-Bolt/NUT solutions with flat horizons, we present a new treatment for studying the thermodynamics of these spactimes. This treatment is based on introducing a new charge, N=σnN=\sigma \, n (where nn is the nut charge and σ\sigma is some constant) and its conjugate thermodynamic potential ΦN\Phi_N. Upon identifying one of the spatial coordinates, the boundary of these solutions contains two annulus-like surfaces in addition to the constant-r surface. For these solutions, we show that these annuli surfaces receive electric, magnetic and mass/energy fluxes, therefore, they have nontrivial contributions to these conserved charges. Calculating these conserved charges we find, Qe=Qe2NΦmQ_e = Q^{\infty}_e-2N\Phi_m, Qm=Qm+2NΦeQ_m =Q^{\infty}_m+2N\Phi_e and M=M2NΦN\mathfrak{M} =M-2N\Phi_N, where QeQ^{\infty}_e, QmQ^{\infty}_m, MM are electric charge, magnetic charge and mass in the n=0n=0 case, while Φe\Phi_e and Φm\Phi_m are the electric and magnetic potentials. The calculated thermodynamic quantities obey the first law of thermodynamics while the entropy is the area of the horizon. Furthermore, all these quantities obey Smarr's relation. We show the consistency of these results through calculating the Hamiltonian and its variation which reproduces the first law.Comment: 22 pages, one figur

    Dyonic Taub-NUT-AdS: Unconstraint thermodynamics and phase Structure

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    Here we extend the approach developed in \cite{adel_2} to study the thermodynamics of Taub-NUT-AdS and dyonic Taub-NUT-AdS solutions. Furthermore, we investigate in details possible phase structures of the dyonic Taub-NUT-AdS solution. We show that the first law, Gibbs-Duhem and Smarr's relations are all satisfied for both solutions. Our study of phase structures shows some intriguing features, which were not reported before, among which the existence of two distinguished critical points with a region of continuous phase transitions in between, and the possibility of merging them into one point. To analyze these phases we consider both canonical and mixed ensembles. The two distinguished critical points occur for the canonical case as well as the mixed cases with 1/2ϕe<11/2 \le \phi_e < 1. Another interesting case is the mixed ensemble with ϕe1\phi_e \ge 1, where we have one critical point but the continuous phase transition region in the PTP-T diagram is close to the origin, in contrast with what happens in Reissner-Nordstrom-AdS solutions and Van der Waals fluids, i.e., the continuous phase transition happens only for low enough pressures and temperatures!Comment: 35 pages, 18 figure
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