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 Black holes (6)
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 M(atrix) Theories (3)
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Articles 1  17 of 17
FullText Articles in Physics
Black Hole Thermalization, D0 Brane Dynamics, And Emergent Spacetime, Paul L. Riggins '12, Vatche Sahakian
Black Hole Thermalization, D0 Brane Dynamics, And Emergent Spacetime, Paul L. Riggins '12, Vatche Sahakian
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When matter falls past the horizon of a large black hole, the expectation from string theory is that the configuration thermalizes and the information in the probe is rather quickly scrambled away. The traditional view of a classical unique spacetime near a black hole horizon conflicts with this picture. The question then arises as to what spacetime does the probe actually see as it crosses a horizon, and how does the background geometry imprint its signature onto the thermal properties of the probe. In this work, we explore these questions through an extensive series of numerical simulations of D0 branes ...
From Surface Operators To NonAbelian Volume Operators In Puff Field Theory, Vatche Sahakian
From Surface Operators To NonAbelian Volume Operators In Puff Field Theory, Vatche Sahakian
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Puff field theory (PFT) is a low energy decoupling regime of string theory that still retains the nonlocal attributes of the parent theory—while preserving isotropy for its nonlocal degrees of freedom. It realizes an extended holographic dictionary at strong coupling and dynamical nonlocal states akin to defects or the surface operators of local gauge theories. In this work, we probe the nonlocal features of PFT using D3 branes. We find supersymmetric configurations that end on defects endowed with nonAbelian degrees of freedom. These are 2+1 dimensional defects in the 3+1 dimensional PFT that may be viewed as ...
New Mechanism For Nonlocality From String Theory: UvIr Quantum Entanglement And Its Imprints On The Cmb, Gregory Minton '08, Vatche Sahakian
New Mechanism For Nonlocality From String Theory: UvIr Quantum Entanglement And Its Imprints On The Cmb, Gregory Minton '08, Vatche Sahakian
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Puff field theories (PFT) arise as the decoupling limits of D3 branes in a Melvin universe and exhibit spatially nonlocal dynamics. Unlike other realizations of nonlocality in string theory, PFTs have full SO(3) rotational symmetry. In this work, we analyze the strongly coupled regime of a PFT through gravitational holography. We find a novel mechanism at the heart of the phenomenon of nonlocality: a quantum entanglement of UV and IR dynamics. In the holographic bulk, this translates to an apparent horizon splitting the space into two regions—with the UV completion of the PFT sitting at the horizon. We ...
Emergence Of The Fuzzy Horizon Through Gravitational Collapse, Anand Murugan '07, Vatche Sahakian
Emergence Of The Fuzzy Horizon Through Gravitational Collapse, Anand Murugan '07, Vatche Sahakian
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For a large enough Schwarzschild black hole, the horizon is a region of space where gravitational forces are weak; yet it is also a region leading to numerous puzzles connected to stringy physics. In this work, we analyze the process of gravitational collapse and black hole formation in the context of lightcone Mtheory. We find that, as a shell of matter contracts and is about to reveal a black hole horizon, it undergoes a thermodynamic phase transition. This involves the binding of D0 branes into D2’s, and the new phase leads to large membranes of the size of the ...
Hairy Strings, Vatche Sahakian
Hairy Strings, Vatche Sahakian
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Zero modes of the worldsheet spinors of a closed string can source higher order moments of the bulk supergravity fields. In this work, we analyze various configurations of closed strings focusing on the imprints of the quantized spinor vacuum expectation values onto the tails of bulk fields. We identify supersymmetric arrangements for which all multipole charges vanish; while for others, we find that one is left with NeveuSchwarz–NeveuSchwarz, and RamondRamond dipole and quadrupole moments. Our analysis is exhaustive with respect to all the bosonic fields of the bulk and to all higher order moments. We comment on the relevance ...
On The Polarization Of Closed Strings By RamondRamond Fluxes, Vatche Sahakian
On The Polarization Of Closed Strings By RamondRamond Fluxes, Vatche Sahakian
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In the GreenSchwarz formalism, the closed string worldsheet of the IIB theory couples to RamondRamond (RR) fluxes through spinor bilinears. We study the effect of such fluxes by analyzing the supersymmetry transformation of the worldsheet in general backgrounds. We show that, in the presence RR fields, the closed string can get `polarized', as the spinors acquire nonzero vevs in directions correlating with the orientation of closeby Dbranes. Reversing the argument, this may allow for worldsheet configurations—with nontrivial spinor structure—that source RR moments.
Closed Strings In RamondRamond Backgrounds, Vatche Sahakian
Closed Strings In RamondRamond Backgrounds, Vatche Sahakian
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We write the IIB GreenSchwarz action in certain general classes of curved backgrounds threaded with RamondRamond fluxes. The fixing of the kappa symmetry in the lightcone gauge and the use of supergravity Bianchi identities simplify the task. We find an expression that truncates to quartic order in the spacetime spinors and relays interesting information about the vacuum structure of the worldsheet theory. The results are particularly useful in exploring integrable string dynamics in the context of the holographic duality.
Holography With RamondRamond Fluxes, Vatche Sahakian
Holography With RamondRamond Fluxes, Vatche Sahakian
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Starting from the nonlinear sigma model of the IIB string in the lightcone gauge, we analyze the role of RR fluxes in Holography. We find that the worldsheet theory of states with only left or right moving modes does not see the presence of RR fields threading a geometry. We use this significant simplification to compute part of the strong coupling spectrum of the two dimensional NCOS theory. We also reproduce the action of a closed string in a PPwave background using this general formalism; and we argue for various strategies to find new systems where the closed string theory ...
The Large M Limit Of NonCommutative Open Strings At Strong Coupling, Vatche Sahakian
The Large M Limit Of NonCommutative Open Strings At Strong Coupling, Vatche Sahakian
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Twodimensional NonCommutative Open String (NCOS) theory, welldefined perturbatively, may also be studied at strong coupling and for large Dstring charge by making use of the Holographic duality. We analyze the zero mode dynamics of a closed string in the appropriate background geometry and map the results onto a sector of strongly coupled NCOS dynamics. We find an elaborate classical picture that shares qualitative similarities with the SL(2,R) WZW model. In the quantum problem, we compute propagators and part of the energy spectrum of the theory; the latter involves interesting variations in the density of states as a function ...
Transcribing Spacetime Data Into Matrices, Vatche Sahakian
Transcribing Spacetime Data Into Matrices, Vatche Sahakian
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In certain supergravity backgrounds, D0 branes may polarize into higher dimensional Dp branes. We study this phenomenon in some generality from the perspective of a local inertial observer and explore polarization effects resulting from tidallike forces. We find D2 brane droplets made of D0 branes at an extremum of the BornInfeld action even in scenarios where the RR fields may be zero. These solutions lead us to a local formulation of the UVIR correspondence. A holographic Planck scale bound on the number of D0 branes plays an important role in the analysis. We focus on the impact of higher order ...
On D0 Brane Polarization By Tidal Forces, Vatche Sahakian
On D0 Brane Polarization By Tidal Forces, Vatche Sahakian
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Gravitational tidal forces may induce polarization of D0branes, in analogy to the same effects arising in the context of constant background gauge fields. Such phenomena can teach us about the correspondence between smooth curved spacetime and its underlying noncommutative structure. However, unlike polarization by gauge fields, the gravitational counterpart involves concerns regarding the classical stability of the corresponding polarized states. In this work, we study this issue with respect to the solutions presented in hepth0010237 and find that they are classically unstable. The instability however appears with intricate features with all but a few decay channels being lifted. Through a ...
Holography, A Covariant C Function, And The Geometry Of The Renormalization Group, Vatche Sahakian
Holography, A Covariant C Function, And The Geometry Of The Renormalization Group, Vatche Sahakian
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We propose a covariant geometrical expression for the c function for theories which admit dual gravitational descriptions. We state a c theorem with respect to this quantity and prove it. We apply the expression to a class of geometries, from domain walls in gauged supergravities, to extremal and near extremal Dpbranes, and the AdS Schwarzschild black hole. In all cases, we find agreement with expectations.
The Phases Of 2d Ncos, Vatche Sahakian
The Phases Of 2d Ncos, Vatche Sahakian
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We study the phases of the (1+1)dimensional NonCommutative Open String theory on a circle. We find that the length scale of noncommutativity increases at strong coupling, the coupling in turn being dressed by a power of Dstring charge. The system is stringy at around this length scale, with dynamics involving an interplay between the open and wrapped closed strings sectors. Above this energy scale and at strong coupling, and below it at weak coupling, the system acquires a less stringy character. The near horizon geometry of the configuration exhibits several intriguing features, such as a flip in the ...
Comments On D Branes And The Renormalization Group, Vatche Sahakian
Comments On D Branes And The Renormalization Group, Vatche Sahakian
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We review the de BoerVerlindeVerlinde formalism for the renormalization group in the context of Dpbrane vacua for p < 5. We comment on various aspects of the dictionary between bulk and boundary and relate the discussion to the RandallSundrum scenario. We find that the gravitational coupling for the RandallSundrum gravity on the Dpbrane worldvolume is dressed by the cfunction of the YangMills theory. We compute the beta function and find the expected uneventful flow prescribed by the classical dimension of the YangMills operator.
Black Holes And FiveBrane Thermodynamics, Emil Martinec, Vatche Sahakian
Black Holes And FiveBrane Thermodynamics, Emil Martinec, Vatche Sahakian
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The phase diagram for Dpbranes in M theory compactified on T^{4},T^{4}/Z_{2},T^{5}, and T^{6} is constructed. As for the lowerdimensional tori considered in our previous work [E. Martinec and V. Sahakian, Phys. Rev. D 59, 124005 (1999)], the black brane phase at high entropy connects onto matrix theory at low entropy; we thus recover all known instances of matrix theory as consequences of the Maldacena conjecture. The difficulties that arise for T^{6} are reviewed. We also analyze the D1D5 system on T^{5}; we discuss its relation to matrix models of M5branes ...
Black Holes And The Sym Diagram. Ii, Emil Martinec, Vatche Sahakian
Black Holes And The Sym Diagram. Ii, Emil Martinec, Vatche Sahakian
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The complete phase diagram of objects in M theory compactified on tori T^{p},p=1,2,3, is elaborated. Phase transitions occur when the object localizes on cycle(s) (the GregoryLaflamme transition), or when the area of the localized part of the horizon becomes one in string units (the HorowitzPolchinski correspondence point). The lowenergy, nearhorizon geometry that governs a given phase can match onto a variety of asymptotic regimes. The analysis makes it clear that the matrix conjecture is a special case of the Maldacena conjecture.
Black Holes And The Sym Phase Diagram, Miao Li, Emil Martinec, Vatche Sahakian
Black Holes And The Sym Phase Diagram, Miao Li, Emil Martinec, Vatche Sahakian
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Making combined use of the matrix and Maldacena conjectures, the relation between various thermodynamic transitions in super YangMills (SYM) theory and supergravity is clarified. The thermodynamic phase diagram of an object in DLCQ M theory in four and five noncompact space dimensions is constructed; matrix strings, matrix black holes, and black pbranes are among the various phases. Critical manifolds are characterized by the principles of correspondence and longitudinal localization, and a triple point is identified. The microscopic dynamics of the matrix string near two of the transitions is studied; we identify a signature of black hole formation from SYM physics.