119225338
Strings on bubbling geometries
We study gauge theory operators which take the form of a product of a trace with a Schur polynomial, and their string theory duals. These states represent strings excited on bubbling AdS geometries which are dual to the Schur polynomials. These geometries generically take the form of multiple annuli in the phase space plane. We study the coherent state wavefunction of the lattice, which labels the trace part of the operator, for a general Young tableau and their dual description on the droplet plane with a general concentric ring pattern. In addition we identify a density matrix over the coherent states on all the geometries within a fixed constraint. This density matrix may be used to calculate the entropy of a given ensemble of operators. We finally recover the BMN string spectrum along the geodesic near any circle from the ansatz of the coherent state wave-function.
6410332
Fivebranes from gauge theory
We study theories with 16 supercharges and a discrete energy spectrum. One class of theories has symmetry group SU(2|4). They arise as truncations of N=4 super Yang-Mills theory. They include the plane-wave matrix model, 2+1 super Yang-Mills theory on RxS{sup 2} and N=4 super Yang-Mills theory on RxS{sup 3}/Z{sub k}. We explain how to obtain their gravity duals in a unified way. We explore the regions of the geometry that are relevant for the study of some 1/2 BPS and near BPS states. This leads to a class of two dimensional (4,4) supersymmetric sigma models with nonzero H flux, including a massive deformed WZW model. We show how to match some features of the string spectrum with the Yang-Mills theory. The other class of theories are also connected to N=4 super Yang-Mills theory and arise by making some of the transverse scalars compact. Their vacua are characterized by a 2D Yang-Mills theory or 3D Chern-Simons theory. These theories realize peculiar super-Poincare symmetry algebras in 2+1 or 1+1 dimensions with ''noncentral'' charges. We finally discuss gravity duals of N=4 super Yang-Mills theory on AdS{sub 3}xS{sup 1}.
119482794
The Supergravity dual of the BMN matrix model
We propose type IIA supergravity solutions dual to the 1/2 BPS vacua of the BMN matrix model. These dual solutions are analyzed using the Polchinski-Strassler method and have brane configurations of concentric shells of D2 branes (or NS5 branes) with various radii and D0 charge. These branes can be viewed as polarized from N D0 branes by a transverse R-R magnetic 6-form flux and an NS-NS 3-form flux. In the region far from branes, the solutions reduce to perturbation around the near horizon geometry of N D0 branes, by turning on these R-R and NS-NS fluxes, which are dual to the deformation of the BFSS matrix model by adding mass terms and the Myers term. The solutions with these additional fluxes preserve 16 supersymmetries. We also briefly discuss these fluxes in the possible supergravity duals of M(atrix) theories on less supersymmetric plane-waves.
119367735
Instantons, supersymmetric vacua, and emergent geometries
We study instanton solutions and superpotentials for the large number of vacua of the plane-wave matrix model and a 2+1 dimensional Super Yang-Mills theory on RxS{sup 2} with 16 supercharges. We get the superpotential in the weak-coupling limit from the gauge theory description. We study the gravity description of these instantons. Perturbatively, with respect to a background, they are Euclidean branes wrapping cycles in the dual gravity background. Moreover, the superpotential can be given by the energy of the electric charge system characterizing each vacuum. These charges are interpreted as the eigenvalues of matrices from a reduction for the 1/8 BPS sector of the gauge theories. We also discuss qualitatively the emergence of the extra spatial dimensions appeared on the gravity side.
119224646
Giant gravitons and correlators
A bstractWe calculate non-extremal correlators of Schur polynomials and single trace operators. We analyse their dual descriptions from the approach of the variation of DBI and WZ actions of the giant gravitons. We show a regularization procedure under which the extremal correlators of Schur polynomials and single trace operators match exactly with string theory computation. Other aspects of the extremal and non-extremal correlators are also discussed.
118578636
Nonplanar integrability
In this article we study operators with a dimension Δ ∼ O(N) and show that simple analytic expressions for the action of the dilatation operator can be found. The operators we consider are restricted Schur polynomials. There are two distinct classes of operators that we consider: operators labeled by Young diagrams with two long columns or two long rows. The main complication in working with restricted Schur polynomials is in building a projector from a given Sn+m irreducible representation to an Sn × Sm irreducible representation (both specified by the labels of the restricted Schur polynomial). We give an explicit construction of these projectors by reducing it to the simple problem of addition of angular momentum in ordinary non-relativistic quantum mechanics. The diagonalization of the dilatation operator reduces to solving three term recursion relations. The fact that the recursion relations have only three terms is a direct consequence of the weak mixing at one loop of the restricted Schur polynomials. The recursion relations can be solved exactly in terms of symmetric Kravchuk polynomials or in terms of Clebsch-Gordan coefficients. This proves that the dilatation operator reduces to a decoupled set of harmonic oscillators and therefore it is integrable.
118305489
Observation of a large-gap topological-insulator class with a single Dirac cone on the surface
Recent experiments and theories have suggested that strong spin–orbit coupling effects in certain band insulators can give rise to a new phase of quantum matter, the so-called topological insulator, which can show macroscopic quantum-entanglement effects. Such systems feature two-dimensional surface states whose electrodynamic properties are described not by the conventional Maxwell equations but rather by an attached axion field, originally proposed to describe interacting quarks. It has been proposed that a topological insulator with a single Dirac cone interfaced with a superconductor can form the most elementary unit for performing fault-tolerant quantum computation. Here we present an angle-resolved photoemission spectroscopy study that reveals the first observation of such a topological state of matter featuring a single surface Dirac cone realized in the naturally occurring Bi_2Se_3 class of materials. Our results, supported by our theoretical calculations, demonstrate that undoped Bi_2Se_3 can serve as the parent matrix compound for the long-sought topological device where in-plane carrier transport would have a purely quantum topological origin. Our study further suggests that the undoped compound reached via n-to-p doping should show topological transport phenomena even at room temperature.
118372786
GAMMA-RAY POLARIZATION OF THE SYNCHROTRON SELF-COMPTON PROCESS FROM A HIGHLY RELATIVISTIC JET
The high polarization observed in the prompt phase of some gamma-ray bursts invites extensive study of the emission mechanism. In this paper, we investigate the polarization properties of the synchrotron self-Compton (SSC) process from a highly relativistic jet. Amagnetic-dominated, baryon-loaded jet ejected from the central engine travels with a large Lorentz factor. Shells with slightly different velocities collide with each other and produce shocks. The shocks accelerate electrons to a power-law distribution and, at the same time, magnify the magnetic field. Electrons move in the magnetic field and produce synchrotron photons. Synchrotron photons suffer from the Compton scattering (CS) process and then are detected by an observer located slightly off-axis. We analytically derive the formulae of photon polarization in the SSC process in two magnetic configurations: a magnetic field in the shock plane and perpendicular to the shock plane. We show that photons induced by the SSC process can be highly polarized, with the maximum polarization Pi similar to 24% in the energy band [0.5, 5] MeV. The polarization depends on the viewing angles, peaking in the plane perpendicular to the magnetic field. In the energy band [0.05, 0.5] MeV, in which most gamma-ray polarimeters are active, the polarization is about twice that in the Thomson limit, reaching Pi similar to 20%. This implies that the Klein-Nishina effect, which is often neglected in the literature, should be carefully considered.
145047134
Finslerian MOND vs . observations of Bullet Cluster 1 E 0657-558
It is known that theory of MOND with spherical symmetry cannot account for the convergence κ-map of Bullet Cluster 1E0657-558. In this paper, we try to set up a Finslerian MOND, a generalization of MOND in Finsler spacetime. We use Ric = 0 to obtain the gravitational vacuum field equation in a four-dimensional Finsler spacetime. To leading order in the post-Newtonian approximation, we obtain the explicit form of the Finslerian line element. It is simply the Schwarzschild’s metric except for the Finslerian rescaling coefficient f(v) of the radial coordinate r, i.e. R = f(v(r))r. By setting f(v(r)) = (1 − √ a0r/GM) , we obtain the famous MOND in a Finslerian framework. Taking a dipole and a quadrupole term into consideration, we give the convergence κ in gravitational lensing astrophysics in our model. Numerical analysis shows that our prediction is to a certain extent in agreement with the observations of Bullet Cluster 1E0657-558. With the theoretical temperature T taking the observed value 14.8 keV, the mass density profile of the main cluster obtained in our model is the same order as that given by the best-fit King β-model.
119108453
Effects of spacetime anisotropy on the galaxy rotation curves
The observations on galaxy rotation curves show significant discrepancies from the Newtonian theory. This issue could be explained by the effect of the anisotropy of the spacetime. Conversely, the spacetime anisotropy could also be constrained by the galaxy rotation curves. Finsler geometry is a kind of intrinsically anisotropic geometry. In this paper, we study the effect of the spacetime anisotropy at galactic scales in the Finsler spacetime. It is found that the Finslerian model has close relations with the Milgrom’s MOND. By performing the best-fit procedure to the galaxy rotation curves, we find that the anisotropic effects of the spacetime become significant when the Newtonian acceleration GM/r2 is smaller than the critical acceleration a0. Interestingly, the critical acceleration a0, although varies between different galaxies, is in the order of magnitude $cH_{0}/2\pi\sim10^{-10}~\mathrm{m\,s}^{-2}$.
38766511
BESIII luminosity readout design based on embedded system
Zero-Degree Detector (ZDD) is a new Detector of Beijing Electron Spectrometer III (BESIII) for both double gamma event detection and luminosity monitoring to substitute the old luminosity monitor. A new luminosity readout is described in this paper which is designed in double width AMC/MTCA form factor with a large Xilinx Virtex5 FPGA in addition to normal electronic signal formation. A FPGA embedded PowerPC is used for data reading, accumulation and data transmission over a gigabit Ethernet. The setting of parameters like the discriminator threshold in Front End electronics is done via a special serial link under control of firmware in the same FPGA. This readout system has been put in operation since fall of 2012.