K. P. Yogendran

Publications (10)0 Total impact

• Source

  Available from: ArXiv

  Article: Solitons as Probes of the Structure of Holographic Superfluids

  Ville Keränen, Esko Keski-Vakkuri, Sean Nowling, K. P. Yogendran
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  ABSTRACT: Detailed features of solitons in holographic superfluids are discussed. Using solitons as probes, we study the behavior of holographic superfluids by varying the scaling dimension of the condensing operator, and build a comparison to the BEC-BCS comparison phenomena. Further evidence for this analogy is provided by the behavior of solitons' length scales as well as by the superfluid critical velocity. Comment: Contribution to the NJP Focus Issue on "Strongly Correlated Quantum fluids"
  12/2010;
• Source

  Available from: ArXiv

  Article: Inhomogeneous Structures in Holographic Superfluids: II. Vortices

  Ville Keranen, Esko Keski-Vakkuri, Sean Nowling, K. P. Yogendran
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  ABSTRACT: We study vortex solutions in a holographic model of Herzog, Hartnoll, and Horowitz, with a vanishing external magnetic field on the boundary, as is appropriate for vortices in a superfluid. We study relevant length scales related to the vortices and how the charge density inside the core of the vortex behaves as a function of temperature or chemical potential. We extract the critical superfluid velocity from the vortex solutions, study how it behaves as a function of the temperature, and compare it to earlier studies and to the Landau criterion. We also comment on the possibility of a Berezinskii-Kosterlitz-Thouless vortex confinement-deconfinement transition.
  12/2009;
• Source

  Available from: ArXiv

  Article: Inhomogeneous Structures in Holographic Superfluids: I. Dark Solitons

  Ville Keranen, Esko Keski-Vakkuri, Sean Nowling, K. P. Yogendran
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  ABSTRACT: We begin an investigation of inhomogeneous structures in holographic superfluids. As a first example, we study domain wall like defects in the 3+1 dimensional Einstein-Maxwell-Higgs theory, which was developed as a dual model for a holographic superconductor. In [1], we reported on such "dark solitons" in holographic superfluids. In this work, we present an extensive numerical study of their properties, working in the probe limit. We construct dark solitons for two possible condensing operators, and find that both of them share common features with their standard superfluid counterparts. However, both are characterized by two distinct coherence length scales (one for order parameter, one for charge condensate). We study the relative charge depletion factor and find that solitons in the two different condensates have very distinct depletion characteristics. We also study quasiparticle excitations above the holographic superfluid, and find that the scale of the excitations is comparable to the soliton coherence length scales.
  11/2009;
• Source

  Available from: ArXiv

  Article: Dark Solitons in Holographic Superfluids

  Ville Keranen, Esko Keski-Vakkuri, Sean Nowling, K. P. Yogendran
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  ABSTRACT: We construct dark soliton solutions in a holographic model of a relativistic superfluid. We study the length scales associated with the condensate and the charge density depletion, and find that the two scales differ by a non-trivial function of the chemical potential. By adjusting the chemical potential, we study the variation of the depletion of charge density at the interface. Comment: 5 pages, Revtex, 5 figures, some typos corrected. Reference added
  06/2009;
• Source

  Available from: Yunseok Seo

  Article: Baryon-charge Chemical Potential in AdS/CFT

  Shin Nakamura, Yunseok Seo, Sang-Jin Sin, K. P. Yogendran
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  ABSTRACT: We present a closed framework of AdS/CFT with finite U(1)B-charge chemical potential. We show how the gauge-invariant identification of the chemical potential with the bulk gauge field emerges from the standard AdS/CFT dictionary. Physical importance and necessity of the Minkowski embeddings within the present framework is also shown numerically in the D3-D7 systems. We point out that the D3-D7 model with only the black-hole embeddings does not have the low-temperature and low-chemical-potential region in the grand-canonical ensemble, hence it is incomplete. A physical interpretation that explains these numerical results is also proposed.
  09/2007;
• Source

  Available from: Yunseok Seo

  Article: A New Phase at Finite Quark Density from AdS/CFT

  Shin Nakamura, Yunseok Seo, Sang-Jin Sin, K. P. Yogendran
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  ABSTRACT: We explore phases of N=2 super Yang-Mills theory at finite quark density by introducing quark chemical potential in a D3-D7 setup. We formulate the thermodynamics of brane embeddings and find that we need to renormalize the finite chemical potential due to the divergence of the thermodynamic potentials and we find that the density versus chemical potential equation of state has rich structure. This yields two distinct first order phase transitions in a small window of quark density. In order words, there is a new first order phase transition in the region of deconfined quarks. In this new phase, the chemical potential is a decreasing function of the density. We suggest that this might be relevant to the difference in sQGP--wQGP phases of QCD.
  11/2006;
• Source

  Available from: Joris Raeymaekers

  Article: Supersymmetric D-branes in the D1-D5 background

  Joris Raeymaekers, K. P. Yogendran
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  ABSTRACT: We construct supersymmetric D-brane probe solutions in the background of the 2-charge D1-D5 system on M, where M is either K3 or T^4. We focus on `near-horizon bound states' that preserve supersymmetries of the near-horizon AdS_3 x S^3 x M geometry and are static with respect to the global time coordinate. We find a variety of half-BPS solutions that span an AdS_2 subspace in AdS_3, carry worldvolume flux and can wrap an S^2 within S^3 and/or supersymmetric cycles in M. Comment: Latex, 24 pages. v2: references added, modified Discussion, published version
  07/2006;
• Source

  Available from: Dileep P. Jatkar

  Article: Matrix dynamics of fuzzy spheres

  Dileep P. Jatkar, Gautam Mandal, Spenta R. Wadia, K. P. Yogendran
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  ABSTRACT: We study the dynamics of fuzzy two-spheres in a matrix model which represents string theory in the presence of RR flux. We analyze the stability of known static solutions of such a theory which contain commuting matrices and SU(2) representations. We find that irreducible as well as reducible representations are stable. Since the latter are of higher energy, this stability poses a puzzle. We resolve this puzzle by noting that reducible representations have marginal directions corresponding to non-spherical deformations. We obtain new static solutions by turning on these marginal deformations. These solutions now have instability or tachyonic directions. We discuss condensation of these tachyons which correspond to classical trajectories interpolating from multiple, small fuzzy spheres to a single, large sphere. We briefly discuss spatially independent configurations of a D3/D5 system described by the same matrix model which now possesses a supergravity dual. Comment: 26 pages, 3 figures, uses JHEP.cls; (v2) references added
  10/2001;
• Source

  Available from: Spenta R. Wadia

  Article: D1/D5 system with B-field, noncommutative geometry and the CFT of the Higgs branch

  Avinash Dhar, Gautam Mandal, Spenta R. Wadia, K.P. Yogendran
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  ABSTRACT: The D1/D5 system is considered in the presence of the NS B field. An explicit supergravity solution in the asymptotically flat and near horizon limits is presented. Explicit mass formulae are presented in both cases. This solution has no D3 source branes and represents a true bound state of the D1/D5 system. We study the motion of a separated D1-brane in the background geometry described above and reproduce the Liouville potential that binds the D1 brane. A gauge theory analysis is also presented in the presence of Fayet–Iliopoulos (FI) parameters which can be identified with the self-dual part of the NS B field. In the case of a single D5-brane and an arbitrary number of D1-branes we can demonstrate the existence of a bound state in the Higgs branch. We also point out the connection of the SCFT on the resolved Sym with recent developments in non-commutative Yang–Mills theory.
  Nuclear Physics B. 10/1999;
• Article: Inhomogeneous Structures in Holographic Superfluids I

  Ville Keränen, Esko Keski-Vakkuri, Sean Nowling, K. P. Yogendran
  [show abstract] [hide abstract]
  ABSTRACT: We begin an investigation of inhomogeneous structures in holographic superfluids. As a first example, we study domain wall like defects in the 3+1 dimensional Einstein-Maxwell-Higgs theory, which was developed as a dual model for a holographic superconductor. In [1], we reported on such "dark solitons" in holographic superfluids. In this work, we present an extensive numerical study of their properties, working in the probe limit. We construct dark solitons for two possible condensing operators, and find that both of them share common features with their standard superfluid counterparts. However, both are characterized by two distinct coherence length scales (one for order parameter, one for charge condensate). We study the relative charge depletion factor and find that solitons in the two different condensates have very distinct depletion characteristics. We also study quasiparticle excitations above the holographic superfluid, and find that the scale of the excitations is comparable to the soliton coherence length scales.
  Keränen , V , Keski-Vakkuri , E , Nowling , S & P. Yogendran , K 2010 , ' Inhomogeneous Structures in Holographic Superfluids I : Dark Solitons ' , Physical Review D : Particles, Fields, Gravitation and Cosmology , vol 81 , no. 12 , pp. 126011 .