arXiv subjects

Emil Nissimov

Publications and source records attributed to Emil Nissimov.

At least 55 records · Page 3Linked to original sources

arXiv2013

Charge-Confining Gravitational Electrovacuum Shock Wave

In previous publications we have extensively studied spherically symmetric solutions of gravity coupled to a non-standard type of non-linear electrodynamics containing a square root of the ordinary Maxwell Lagrangian (the latter is known to yield QCD-like confinement in flat space-time). A class of these solutions describe non-standard black holes of Reissner-Nordstroem-(anti-)-de-Sitter type with an additional constant radial vacuum electric field, in particular, a non-asymptotically flat Reissner-Nordstroem-type black hole. Here we study the ultra-relativistic boost (Aichelburg-Sexl-type) limit of the latter and show that, unlike the ordinary Reissner-Nordstroem case, we obtain a gravitational electrovacuum shock wave as a result of the persistence of the gauge field due to the "square-root" Maxwell Lagrangian term. Next, we show that this gravitational electrovacuum shock wave confines charged test particles (both massive and massless) within a finite distance from its front.

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arXiv2012

Gravity, Nonlinear Gauge Fields and Charge Confinement/Deconfinement

We discuss in some detail the properties of gravity (including f(R)-gravity) coupled to non-standard nonlinear gauge field system containing a square root of the usual Maxwell Lagrangian. The latter is known to produce in flat spacetime a QCD-like confinement. Inclusion of gravity triggers various physically interesting effects: new mechanism for dynamical generation of cosmological constant; non-standard black hole solutions with constant vacuum electric field and with "hedge-hog"-type spacetime asymptotics, which are shown to obey the first law of black hole thermodynamics; new "tubelike" solutions of Levi-Civita-Bertotti-Robinson type; charge-"hiding" and charge-confining "thin-shell" wormhole solutions; dynamical effective gauge couplings and confinement-deconfinement transition effect when coupled to quadratic R^2-gravity.

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arXiv2012

Dynamical Couplings, Dynamical Vacuum Energy and Confinement/Deconfinement from R^2-Gravity

We study within Palatini formalism an f(R)-gravity with f(R)= R + αR^2 interacting with a dilaton and a special kind of nonlinear gauge field system containing a square-root of the standard Maxwell term, which is known to produce confinement in flat space-time. Reformulating the model in the physical Einstein frame we find scalar field effective potential with a flat region where the confinement dynamics disappears, while in other regions it remains intact. The effective gauge couplings as well as the induced cosmological constant become dynamical. In particular, a conventional Maxwell kinetic term for the gauge field is dynamically generated even if absent in the original theory. We find few interesting classes of explicit solutions: (i) asymptotically (anti-)de Sitter black holes of non-standard type with additional confining vacuum electric potential even for the electrically neutral ones; (ii) non-standard Reissner-Nordstroem black holes with additional constant vacuum electric field and having non-flat-spacetime "hedgehog" asymptotics; (iii) generalized Levi-Civitta-Bertotti-Robinson "tube-like" space-times.

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arXiv2011

Lightlike Braneworlds in Anti-de Sitter Bulk Space-times

We consider five-dimensional Einstein-Maxwell-Kalb-Ramond system self-consistently coupled to a lightlike 3-brane, where the latter acts as material, charge and variable cosmological constant source. We find wormhole-like solutions whose total space-time manifold consists of either (a) two "universes", which are identical copies of the exterior space-time region (beyond the horizon) of 5-dimensional Schwarzschild-anti-de Sitter black hole, or (b) a "right" "universe" comprising the exterior space-time region of Reissner-Nordstroem-anti-de Sitter black hole and a "left" "universe" being the Rindler "wedge" of 5-dimensional flat Minkowski space. The wormhole "throat" connecting these "universes", which is located on their common horizons, is self-consistently occupied by the lightlike 3-brane as a direct result of its dynamics given by an explicit reparametrization-invariant world-volume Lagrangian action. The intrinsic world-volume metric on the 3-brane turns out to be flat, which allows its interpretation as a lightlike braneworld.

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arXiv2011

Hiding and Confining Charges via "Tube-like" Wormholes

We describe two interesting effects in wormhole physics. First, we find that a genuinely charged matter source may appear neutral to an external observer - a phenomenon opposite to the famous Misner-Wheeler "charge without charge" effect. This phenomenon takes place when coupling a bulk gravity/nonlinear-gauge-field system to a charged lightlike brane as a matter source. The "charge-hiding" effect occurs in a wormhole solution which connects a non-compact "universe", comprising the exterior region of Schwarzschild-(anti-)de-Sitter (SdS) or purely Schwarzschild black hole beyond the Schwarzschild horizon, to a Levi-Civita-Bertotti-Robinson-type (LCBR) "tube-like" "universe" via a wormhole "throat" occupied by the brane. In this solution the whole electric flux produced by the brane is expelled into the "tube-like" "universe" and the brane is detected as neutral by an observer in the non-compact "universe". Next, we find a truly charge-confining wormhole solution when we couple the bulk gravity/nonlinear-gauge-field system to two oppositely charged lightlike branes. The latter system possesses a "two-throat" wormhole solution, where the "left-most" and the "right-most" "universes" are two identical copies of the exterior region of SdS black hole beyond the Schwarzschild horizon, whereas the "middle" "universe" is of LCBR "tube-like" form with geometry dS_2 x S^2. It comprises the finite-extent intermediate region of dS_2 between its two horizons. Both "throats" are occupied by the two oppositely charged lightlike branes and the whole electric flux produced by the latter is confined entirely within the middle "tube-like" "universe". A crucial ingredient is the special form of the nonlinear gauge field action, which contains both the standard Maxwell term as well as a square root of the latter. This theory was previously shown to produce a QCD-like confining dynamics in flat space-time.

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arXiv2011

Hiding Charge in a Wormhole

Existence of wormholes can lead to a host of new effects like Misner-Wheeler "charge without charge" effect, where without being generated by any source an electric flux arrives from one "universe" and flows into the other "universe". Here we show the existence of an intriguing opposite possibility. Namely, a charged object (a charged lightlike brane in our case) sitting at the wormhole "throat" expels all the flux it produces into just one of the "universes", which turns out to be of compactified ("tube-like") nature. An outside observer in the non-compact "universe" detects, therefore, a neutral object. This charge-hiding effect takes place in a gravity/gauge-field system self-consistently interacting with a charged lightlike brane as a matter source, where the gauge field subsystem is of a special non-linear form containing a square-root of the Maxwell term and which previously has been shown to produce a QCD-like confining gauge field dynamics in flat space-time.

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arXiv2011

Asymptotically de Sitter and anti-de Sitter Black Holes with Confining Electric Potential

We study gravity interacting with a special kind of QCD-inspired nonlinear gauge field system which earlier was shown to yield confinement-type effective potential (the "Cornell potential") between charged fermions ("quarks") in flat space-time. We find new static spherically symmetric solutions generalizing the usual Reissner-Nordstroem-de-Sitter and Reissner-Nordstroem-anti-de-Sitter black holes with the following additional properties: (i) appearance of a constant radial electric field (in addition to the Coulomb one); (ii) novel mechanism of {\em dynamical generation} of cosmological constant through the non-Maxwell gauge field dynamics; (iii) appearance of confining-type effective potential in charged test particle dynamics in the above black hole backgrounds.

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arXiv2010

Space-Time Compactification, Non-Singular Black Holes, Wormholes and Braneworlds via Lightlike Branes

We describe a concise general scheme for constructing solutions of Einstein-Maxwell-Kalb-Ramond gravity-matter system in bulk space-time interacting self-consistently with one or more (widely separated) codimension-one electrically charged lightlike branes. The lightlike brane dynamics is explicitly given by manifestly reparametrization invariant world-volume actions. We present several explicit classes of solutions with different physical interpretation as wormhole-like space-times with one, two or more "throats", singularity-free black holes, brane worlds and space-times undergoing a sequence of spontaneous compactification-decompactification transitions.

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arXiv2010

Space-Time Compactification/Decompactification Transitions Via Lightlike Branes

We consider Einstein-Maxwell-Kalb-Ramond gravity-matter system in bulk space-time interacting self-consistently with two (widely separated) codimension-one electrically charged lightlike branes. The lightlike brane dynamics is explicitly given by manifestly reparametrization invariant world-volume actions in two equivalent dual to each other formulations (Polyakov-type and Nambu-Goto-type ones) proposed in our previous work. We find an explicit solution of the pertinent Einstein-Maxwell-Kalb-Ramond-lightlike-brane equations of motion describing a "two-throat" wormhole-like space-time consisting of a "left" compactified Bertotti-Robinson universe connected to a "middle" non-compact Reissner-Nordstroem-de-Sitter space-time region, which in turn is connected to another "right" compactified Bertotti-Robinson universe. Each of the lightlike branes automatically occupies one of the "throats", so that they dynamically induce a sequence of spontaneous space-time compactification/decompactification transitions.

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arXiv2010

Space-Time Compactification Induced By Lightlike Branes

The aim of the present paper is two-fold. First we describe the Lagrangian dynamics of a recently proposed new class of lightlike p-branes and their interactions with bulk space-time gravity and electromagnetism in a self-consistent manner. Next, we discuss the role of lightlike branes as natural candidates for wormhole "throats" and exemplify the latter by presenting an explicit construction of a new type of asymmetric wormhole solution where the lightlike brane connects a "right" universe with Reissner-Nordstroem geometry to a "left" Bertotti-Robinson universe with two compactified space dimensions.

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arXiv2009

Asymmetric Wormholes via Electrically Charged Lightlike Branes

We consider a self-consistent Einstein-Maxwell-Kalb-Ramond system in the bulk D=4 space-time interacting with a variable-tension electrically charged lightlike brane. The latter serves both as a material and charge source for gravity and electromagnetism, as well as it dynamically generates a bulk space varying cosmological constant. We find an asymmetric wormhole solution describing two "universes" with different spherically symmetric black-hole-type geometries connected through a "throat" occupied by the lightlike brane. The electrically neutral "left universe" comprises the exterior region of Schwarzschild-de-Sitter (or pure Schwarzschild) space-time above the inner (Schwarzschild-type) horizon, whereas the electrically charged "right universe" consists of the exterior Reissner-Nordstroem (or Reissner-Nordstroem-de-Sitter) black hole region beyond the outer Reissner-Nordstroem horizon. All physical parameters of the wormhole are uniquely determined by two free parameters - the electric charge and Kalb-Ramond coupling of the lightlike brane.

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arXiv2009

Einstein-Rosen "Bridge" Needs Lightlike Brane Source

The Einstein-Rosen "bridge" wormhole solution proposed in the classic paper [1] does not satisfy the vacuum Einstein equations at the wormhole throat. We show that the fully consistent formulation of the original Einstein-Rosen "bridge" requires solving Einstein equations of bulk D=4 gravity coupled to a lightlike brane with a well-defined world-volume action. The non-vanishing contribution of Einstein-Rosen "bridge" solution to the right hand side of Einstein equations at the throat matches precisely the surface stress-energy tensor of the lightlike brane which automatically occupies the throat ("horizon straddling") - a feature triggered by the world-volume lightlike brane dynamics.

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arXiv2009

Non-singular black holes from gravity-matter-brane lagrangians

We consider self-consistent coupling of bulk Einstein-Maxwell-Kalb-Ramond system to codimension-one charged lightlike p-brane with dynamical (variable) tension (LL-brane). The latter is described by a manifestly reparametrization-invariant world-volume action significantly different from the ordinary Nambu-Goto one. We show that the LL-brane is the appropriate gravitational and charge source in the Einstein-Maxwell-Kalb-Ramond equations of motion needed to generate a self-consistent solution describing non-singular black hole. The latter consists of de Sitter interior region and exterior Reissner-Nordstroem region glued together along their common horizon (it is the inner horizon from the Reissner-Nordstroem side). The matching horizon is automatically occupied by the LL-brane as a result of its world-volume lagrangian dynamics, which dynamically generates the cosmological constant in the interior region and uniquely determines the mass and charge parameters of the exterior region. Using similar techniques we construct a self-consistent wormhole solution of Einstein-Maxwell system coupled to electrically neutral LL-brane, which describes two identical copies of a non-singular black hole region being the exterior Reissner-Nordstroem region above the inner horizon, glued together along their common horizon (the inner Reissner-Nordstroem one) occupied by the LL-brane. The corresponding mass and charge parameters of the two black hole "universes" are explicitly determined by the dynamical LL-brane tension. This also provides an explicit example of Misner-Wheeler "charge without charge" phenomenon. Finally, this wormhole solution connecting two non-singular black holes can be transformed into a special case of Kantowski-Sachs bouncing cosmology solution.

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arXiv2009

Spherically Symmetric and Rotating Wormholes Produced by Lightlike Branes

Lightlike p-branes (LL-branes) with dynamical (variable) tension allow simple and elegant Polyakov-type and dual to it Nambu-Goto-like world-volume action formulations. Here we first briefly describe the dynamics of LL-branes as test objects in various physically interesting gravitational backgrounds of black hole type, including rotating ones. Next we show that LL-branes are the appropriate gravitational sources that provide proper matter energy momentum tensors in the Einstein equations of motion needed to generate traversable wormhole solutions, in particular, self-consistent cylindrical rotating wormholes, with the LL-branes occupying their throats. Here a major role is being played by the dynamical LL-brane tension which turns out to be negative but may be of arbitrary small magnitude. As a particular solution we obtain traversable wormhole with Schwarzschild geometry generated by a LL-brane positioned at the wormhole throat, which represents the correct consistent realization of the original Einstein-Rosen "bridge" manifold.

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arXiv2009

"Mass Inflation" With Lightlike Branes

We discuss properties of a new class of p-brane models, describing intrinsically lightlike branes for any world-volume dimension, in various gravitational backgrounds of interest in the context of black hole physics. One of the characteristic features of these lightlike p-branes is that the brane tension appears as an additional nontrivial dynamical world-volume degree of freedom. Codimension one lightlike brane dynamics requires that bulk space with a bulk metric of spherically symmetric type must possess an event horizon which is automatically occupied by the lightlike brane while its tension evolves exponentially with time. The latter phenomenon is an analog of the well known "mass inflation" effect in black holes.

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arXiv2009

Lightlike Branes as Natural Candidates for Wormhole Throats

We first briefly present a consistent world-volume Lagrangian description of lightlike p-branes (LL-branes) in two equivalent forms - a Polyakov-type and a dual to it Nambu-Goto-type formulations. The most important characteristic features of LL-brane dynamics are: (i) the brane tension appears as a non-trivial additional dynamical degree of freedom; (ii) consistency of LL-brane dynamics in a spherically or axially symmetric gravitational background of codimension one requires the presence of an event horizon which is automatically occupied by the LL-brane ("horizon straddling"). Next we consider a bulk Einstein-Maxwell system interacting self-consistently with a codimension one LL-brane. We find spherically symmetric traversable wormhole solutions of Misner-Wheeler type produced by the LL-brane sitting at the wormhole throat with wormhole parameters being functions of the dynamical LL-brane tension.

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arXiv2009

Lightlike Brane as a Gravitational Source of Misner-Wheeler-Type Wormhole

Consistent Lagrangian description of lightlike p-branes (LL-branes) is presented in two equivalent forms - a Polyakov-type formulation and a dual to it Nambu-Goto-type formulation. An important characteristic feature of the LL-branes is that the brane tension appears as a non-trivial additional dynamical degree of freedom. Next, properties of p=2 LL-brane dynamics (as a test brane) in D=4 Kerr or Kerr-Newman gravitational backgrounds are discussed in some detail. It is shown that the LL-brane automatically positions itself on the horizon and rotates along with the same angular velocity. Finally, a Misner-Wheeler-type of Reissner-Nordstroem wormhole is constructed in a self-consistent electrically sourceless Einstein-Maxwell system in the D=4 bulk interacting with a LL-brane. The pertinent wormhole throat is located precisely at the LL-brane sitting on the outer Reissner-Nordstroem horizon with the Reissner-Nordstroem mass and charge being functions of the dynamical LL-brane tension.

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arXiv2008

Lightlike p-Branes: Mass "Inflation" and Lightlike Braneworlds

Lagrangian description of lightlike p-branes is presented in two equivalent forms - a Polyakov-type formulation and a dual to it Nambu-Goto-type formulation. Next, the properties of lightlike brane dynamics in generic gravitational backgrounds of spherically symmetric and axially symmetric type are discussed in some detail: "horizon straddling" and "mass inflation" effects for codimension-one lightlike branes and ground state behavior of codimension-two lightlike "braneworlds".

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