Baryonic Response of Dense Holographic QCD

The response function of a homogeneous and dense hadronic system to a time-dependent (baryon) vector potential is discussed for holographic dense QCD (D4/D8 embedding) both in the confined and deconfined phases. Confined holographic QCD is an uncompressible and static baryonic insulator at large N_c and large \lambda, with a gapped vector spectrum and a massless pion. Deconfined holographic QCD is a diffusive conductor with restored chiral symmetry and a gapped transverse baryonic current. Similarly, dense D3/D7 is diffusive for any non-zero temperature at large N_c and large \lambda. At zero temperature dense D3/D7 exhibits a baryonic longitudinal visco-elastic mode with a first sound speed \lambda/\sqrt{3} and a small width due to a shear viscosity to baryon ratio \eta/n_B=\hbar/4. This mode is turned diffusive by arbitrarily small temperatures, a hallmark of holography.Comment: V2: 47 pages, 7 figures, references added, typos correcte

Transport Properties of a Josephson-Coupled Network in a Superconductive Ceramic of YBa2Cu4O8

Ceramic YBa2Cu4O8 samples composed of sub-micron size grains are considered as random Josephson-coupled networks of 0 and π junctions, and they show successive phase transitions. The first transition occurs inside each grain at Tc1 and the second transition occurs among the grains at Tc2 (> Tc1), where a negative divergence of nonlinear susceptibility is found. This critical phenomenon at Tc2 suggests the onset of the chiral-glass phase, as predicted by Kawamura and Li. We measured the temperature dependencies of the current-voltage characteristics of the samples and derived the linear and nonlinear resistivities. With decreases in temperature, linear resistivity decreased monotonously and remained at a finite value at temperatures less than Tc2, while nonlinear resistivity diminished continuously for temperatures moving towards Tc2. These results are consistent with the theoretical predictions.Proceedings of the 25th International Conference on Low Temperature Physics (LT 25), August 6-13, 2008, Amsterdam, Netherland

Intraocular Gnathostoma spinigerum: a case report

Live intraocular nematode is a rare occurrence that is mostly reported in South East Asian countries. Herewith we report such a case from Nayagarh district of Odisha. A 28 year old female presented with swelling, redness, lacrimation, pain & diminished vision of left eye since 2 1/2 years. Slit lamp examination revealed a worm piercing iris muscle. The worm was removed by paracentesis of anterior chamber and sent to the Department of Microbiology. It was identified to be Gnathostoma spinigerum basing on the typical morphology of its cephalic end. The patient responded completely to oral albendazole therapy

Cold Nuclear Matter In Holographic QCD

We study the Sakai-Sugimoto model of holographic QCD at zero temperature and finite chemical potential. We find that as the baryon chemical potential is increased above a critical value, there is a phase transition to a nuclear matter phase characterized by a condensate of instantons on the probe D-branes in the string theory dual. As a result of electrostatic interactions between the instantons, this condensate expands towards the UV when the chemical potential is increased, giving a holographic version of the expansion of the Fermi surface. We argue based on properties of instantons that the nuclear matter phase is necessarily inhomogeneous to arbitrarily high density. This suggests an explanation of the "chiral density wave" instability of the quark Fermi surface in large N_c QCD at asymptotically large chemical potential. We study properties of the nuclear matter phase as a function of chemical potential beyond the transition and argue in particular that the model can be used to make a semi-quantitative prediction of the binding energy per nucleon for nuclear matter in ordinary QCD.Comment: 31 pages, LaTeX, 1 figure, v2: some formulae corrected, qualitative results unchange

Holographic Nuclear Physics

We analyze the phases of the Sakai-Sugimoto model at finite temperature and baryon chemical potential. Baryonic matter is represented either by 4-branes in the 8-branes or by strings stretched from the 8-branes to the horizon. We find the explicit configurations and use them to determine the phase diagram and equation of state of the model. The 4-brane configuration (nuclear matter) is always preferred to the string configuration (quark matter), and the latter is also unstable to density fluctuations. In the deconfined phase the phase diagram has three regions corresponding to the vacuum, quark-gluon plasma, and nuclear matter, with a first-order and a second-order phase transition separating the phases. We find that for a large baryon number density, and at low temperatures, the dominant phase has broken chiral symmetry. This is in qualitative agreement with studies of QCD at high density.Comment: 27 pages, 26 figures. v2: Added a comment about higher derivative corrections to the DBI action in the smeared instanton in section 2.1. v3: References added, version published in JHEP. v4: misprints correcte

Self-bound dense objects in holographic QCD

We study a self-bound dense object in the hard wall model. We consider a spherically symmetric dense object which is characterized by its radial density distribution and non-uniform but spherically symmetric chiral condensate. For this we analytically solve the partial differential equations in the hard wall model and read off the radial coordinate dependence of the density and chiral condensate according to the AdS/CFT correspondence. We then attempt to describe nucleon density profiles of a few nuclei within our framework and observe that the confinement scale changes from a free nucleon to a nucleus. We briefly discuss how to include the effect of higher dimensional operator into our study. We finally comment on possible extensions of our work.Comment: 17 pages, 5 figures, figures replaced, minor revision, to appear in JHE

A Holographic QCD and Excited Baryons from String Theory

We study baryons of arbitrary isospin in a stringy holographic QCD model. In this D4-D8 holographic setting, the flavor symmetry is promoted to a gauge symmetry in the bulk, and produces, as KK modes of the gauge field, pions and spin one mesons of low energy QCD. Baryons of arbitrary isospins are represented as instanton solitons with isospin and spin quantum numbers locked, in a manner similar to the Skyrmion model. The soliton picture leads to a natural effective field theory of arbitrary baryons interacting with mesons. Couplings of baryons to axial mesons, including pions, are dominated in the large $N_c$ limit by a direct coupling to the flavor field strength in five dimensions. We delineate the relevant couplings and determine their strengths. This work generalizes part of hep-th/0701276 and arXiv:0705.2632 [hep-th] to all excited baryons. Due to technical difficulties in introducing relativistic higher spin fields, we perform all computations in the nonrelativistic regime, which suffices for the leading $N_c$ predictions.Comment: 33 pages, two references added, JHEP versio