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Dive into the research topics where Ioannis Giannakis is active.

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Featured researches published by Ioannis Giannakis.


Physical Review D | 2000

Recovery of the Schwarzschild metric in theories with localized gravity beyond linear order

Ioannis Giannakis; Hai-cang Ren

We solve the Einstein equations in the Randall-Sundrum framework with a static, spherically symmetric matter distribution on the physical brane and obtain an approximate expression for the gravitational field outside the source to the second order in the gravitational coupling. This expression when confined on the physical brane coincides with the standard form of the Schwarzschild metric. Therefore, the Randall-Sundrum scenario is consistent with the Mercury precession and other tests of general relativity.


Physics Letters B | 2005

Chromomagnetic instability and the LOFF state in a two flavor color superconductor

Ioannis Giannakis; Hai-cang Ren

We explore the relation between the chromomagnetic instability of a homogeneous two flavor color superconductor and the LOFF state. We perturb the free energy of the 2SC by generating a small net momentum for the quark pair. We find that the imaginary Meissner mass of a particular gluon implies that the LOFF state is energetically favored.


Nuclear Physics | 2005

The Meissner effect in a two flavor LOFF color superconductor

Ioannis Giannakis; Hai-cang Ren

Abstract We calculate the magnetic polarization tensor of the photon and of the gluons in a two flavor color superconductor with a LOFF pairing that consists of a single plane wave. We show that at zero temperature and within the range of the values of the Fermi sea displacement that favors the LOFF state, all the eigenvalues of the magnetic polarization tensor are non-negative. Therefore the chromomagnetic instabilities pertaining to a gapless color superconductor disappear.


Physical Review D | 2002

Ginzburg-Landau free energy functional of color superconductivity at weak coupling

Ioannis Giannakis; Hai-cang Ren

We derive the Ginzburg-Landau free energy functional of color superconductivity in terms of the thermal diagrams of QCD in its perturbative region. The zero mode of the quadratic term coefficient yields the same transition temperature, including the preexponential factor, as the one obtained previously from the Fredholm determinant of the two-quark scattering amplitude. All coefficients of the free energy can be made identical to those of a BCS model by setting the Fermi velocity of the latter equal to the speed of light. We also calculate the induced symmetric color condensate near


Physical Review D | 2001

Possible extensions of the 4D Schwarzschild horizon in the 5D brane world

Ioannis Giannakis; Hai-cang Ren

{T}_{c}


Physics Letters B | 2002

Linearized analysis of the Dvali–Gabadadze–Porrati brane model

Ioannis Giannakis; Hai-cang Ren

and find that it scales as the cubic power of the dominant antisymmetric color component. We show that in the presence of an inhomogeneity and a nonzero gauge potential, while the color-flavor locked condensate dominates in the bulk, the unlocked condensate, the octet, emerges as a result of a simultaneous color-flavor rotation in the core region of a vortex filament or at the junction of super and normal phases.


Physics Letters B | 2005

A neutral two-flavor LOFF color superconductor

Ioannis Giannakis; De-fu Hou; Hai-cang Ren

We show that, in the absence of matter in the bulk, the Einstein equations and the Gauss-normal form of the metric place stringent restrictions on the form of the event horizon in a brane world. As a consequence, the off-brane extension of the standard four-dimensional (4D) Schwarzschild horizon in the Randall-Sundrum AdS{sub 5} spacetime, as it is viewed from the brane can only be of a tubular shape, instead of a pancake shape. When it is viewed from the AdS{sub 5} horizon, such a tubular horizon is absent.


Physical Review Letters | 2004

Gauge field fluctuations and first-order phase transition in color superconductivity.

Ioannis Giannakis; De-fu Hou; Hai-cang Ren; Dirk H. Rischke

Abstract We solve the Einstein equations in the Dvali–Gabadadze–Porrati model with a static, spherically symmetric matter distribution on the physical brane and obtain an exact expression for the gravitational field outside the source to the first order in the gravitational coupling. Although, this expression when confined on the physical brane reproduces the correct 4− D Newtonian potential for distances r s ⪡ r ⪡ λ , where λ is a characteristic length scale of the model, it does not coincide with the standard linearized form of the 4− D Schwarzschild metric. The solution reproduces the 5− D Schwarzschild metric in the linearized approximation for r ⪢ λ .


Physical Review D | 2002

Angular momentum mixing in crystalline color superconductivity

Ioannis Giannakis; James T. Liu; Hai-cang Ren

In this Letter we construct analytically a LOFF color superconducting state that is both color and charge neutral using the weak coupling approximation. We demonstrate that this state is free from chromomagnetic instabilities. Its relevance to the realistic quark matter at moderately high baryon density is discussed.


Nuclear Physics | 2003

Linearized gravity in the Karch–Randall braneworld

Ioannis Giannakis; James T. C. Liu; Hai Cang Ren

We study the gauge field fluctuations in dense quark matter and determine the temperature of the induced first-order phase transition to the color-superconducting phase in weak coupling. We find that the local approximation of the coupling between the gauge potential and the order parameter, employed in the Ginzburg-Landau theory, has to be modified by restoring the full momentum dependence of the polarization function of gluons in the superconducting phase.

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De-fu Hou

Central China Normal University

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Mark Evans

Rockefeller University

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Dirk H. Rischke

Goethe University Frankfurt

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