Harrison transformation and charged black objects in Kaluza-Klein theory

We generate charged black brane solutions in $D-$dimensions in a theory of gravity coupled to a dilaton and an antisymmetric form, by using a Harrison-type transformation. The seed vacuum solutions that we use correspond to uplifted Kaluza-Klein black strings and black holes in $(D-p)$-dimensions. A generalization of the Marolf-Mann quasilocal formalism to the Kaluza-Klein theory is also presented, the global charges of the black objects being computed in this way. We argue that the thermodynamics of the charged solutions can be derived from that of the vacuum configurations. Our results show that all charged Kaluza-Klein solutions constructed by means of Harrison transformations are thermodynamically unstable in a grand canonical ensemble. The general formalism is applied to the case of nonuniform black strings and caged black hole solutions in $D=5, 6$ Einstein-Maxwell-dilaton gravity, whose geometrical properties and thermodynamics are discussed. We argue that the topology changing transition scenario, which was previously proposed in the vacuum case, also holds in this case. Spinning generalizations of the charged black strings are constructed in six dimensions in the slowly rotating limit. We find that the gyromagnetic ratio of these solutions possesses a nontrivial dependence on the nonuniformity parameter.Comment: 42 pages, 12 figure

Nuclear Structure Corrections to Deuterium Hyperfine Structure and Lamb Shift

The low-energy theorem for the forward Compton scattering is generalized to the case of an arbitrary target spin. The generalization is used to calculate the corresponding contribution to the deuterium hyperfine structure. The nuclear-structure corrections are quite essential in this case due to the deuteron large size. Corrections of this type calculated here remove the discrepancy between the theoretical and experimental values of the deuterium hyperfine splitting. Explicit analytical result is obtained also for the deuteron polarizability contribution to the Lamb shift.Comment: 14 pages, latex, no figure

Entanglement via Barut-Girardello coherent state for suq(1,1)su_{q}(1, 1) quantum algebra: bipartite composite system

Using noncocommutative coproduct properties of the quantum algebras, we introduce and obtain, in a bipartite composite system, the Barut-Girardello coherent state for the q-deformed $su_{q}(1,1)$ algebra. The quantum coproduct structure ensures this normalizable coherent state to be entangled. The entanglement disappears in the classical $q \to 1$ limit, giving rise to a factorizable state.Comment: 12 page

Instability of generalised AdS black holes and thermal field theory

We study black holes in AdS-like spacetimes, with the horizon given by an arbitrary positive curvature Einstein metric. A criterion for classical instability of such black holes is found in the large and small black hole limits. Examples of large unstable black holes have a B\"ohm metric as the horizon. These, classically unstable, large black holes are locally thermodynamically stable. The gravitational instability has a dual description, for example by using the $AdS_7 \times S^4$ version of the AdS/CFT correspondence. The instability corresponds to a critical temperature of the dual thermal field theory defined on a curved background.Comment: 1+16 pages. 1 figure. LaTeX. Minor clarification

Rotating nonuniform black string solutions

We explore via linearized perturbation theory the Gregory-Laflamme instability of rotating black strings with equal magnitude angular momenta. Our results indicate that the Gregory-Laflamme instability persists up to extremality for all even dimensions between six and fourteen. We construct rotating nonuniform black strings with two equal magnitude angular momenta in six dimensions. We see a first indication for the occurrence of a topology changing transition, associated with such rotating nonuniform black strings. Charged nonuniform black string configurations in heterotic string theory are also constructed by employing a solution generation technique.Comment: 36 pages, 10 figures, final versio

New nonuniform black string solutions

We present nonuniform vacuum black strings in five and six spacetime dimensions. The conserved charges and the action of these solutions are computed by employing a quasilocal formalism. We find qualitative agreement of the physical properties of nonuniform black strings in five and six dimensions. Our results offer further evidence that the black hole and the black string branches merge at a topology changing transition. We generate black string solutions of the Einstein-Maxwell-dilaton theory by using a Harrison transformation. We argue that the basic features of these solutions can be derived from those of the vacuum black string configurations.Comment: 30 pages, 12 figures; v2: more details on numerical method, references added; v3: references added, minor revisions, version accepted by journa

New stable phase of non uniform black strings in AdSd{AdS}_d

We consider the non uniform $AdS$ black string equations in arbitrary number of dimension in a perturbative approach up to order 2 and in a non perturbative. We restrict the study in the perturbative approach to the backreacting modes, since they provide the first relevant corrections on the thermodynamical quantities of the solutions. We also present some preliminary results in the construction of non-perturbative solutions, in particular, we present a first part of the non uniform - uniform black string phase diagram. Our results suggests the existence of a new stable phase for $AdS$ non uniform black strings, namely long non uniform black string, with the extra direction length of the order of the $AdS$ curvature.Comment: Results extended. 14 pages, 5 figure

Non Uniform Black Strings and Critical Dimensions in AdSdAdS_d

We study the equations of black strings in spacetimes of arbitrary dimensions with a negative cosmological constant and construct numerically non uniform black strings solutions. Our results suggest the existence of a localised black hole in asymptotically locally $AdS$ spacetime. We also present evidences for a dependence of the critical dimension on the horizon radius.The critical dimension represents the dimension where the order of the phase transition between uniform and non uniform black string changes. Finally, we argue that both, the regular asymptotically locally $AdS$ solution and $AdS$ black string solutions with a very small horizon radius, present a negative tension. This turns out to be an unexpected feature of the solutions.Comment: 13 pages, 5 figure

About the possibility of five-dimensional effective theories for low-energy QCD

The AdS/QCD models suggest an interesting idea that the effective theory of low-energy QCD may be formulated as a 5-dimensional field theory in the weak coupling regime in which the fifth coordinate plays a role of inverse energy scale. Taking the point of view that this is just an efficient parametrization of the non-perturbative dynamics of strong interactions, we discuss on a qualitative level an alternative possibility for a simpler 5-dimensional parametrization of main phenomena in the low-energy QCD. We propose to interpret the effect of chiral symmetry breaking as an effective appearance of compactified extra dimension with the radius of the order of inverse scale of chiral symmetry breaking. Following some heuristic arguments two dual scenarios for the emergence of the excited light mesons are introduced: In the first scenario, the meson resonances are interpreted as the effects of Kaluza-Klein excitations of quarks inside mesons, in the second one, as the formation of gluon strings wound around the compactified dimension an appropriate number of times. Matching of these scenarios permits to express the slope of radial Regge trajectories through the order parameters of the chiral symmetry breaking, with the compactification radius being excluded. This example shows qualitatively that the extra dimension may play an auxiliary role providing a short way for deriving new relations.Comment: 11 pages, accepted by Eur. Phys. J.

Holography: 2-D or not 2-D?

As was recently pointed out by Cadoni, a certain class of two-dimensional gravitational theories will exhibit (black hole) thermodynamic behavior that is reminiscent of a free field theory. In the current letter, a direct correspondence is established between these two-dimensional models and the strongly curved regime of (arbitrary-dimensional) anti-de Sitter gravity. On this basis, we go on to speculatively argue that two-dimensional gravity may ultimatley be utilized for identifying and perhaps even understanding holographic dualities.Comment: 8 pages, Revtex; (v2) references and footnote added; (v3) discussion on page 5 revise