118398823
M2-M5 systems in = 6 Chern-Simons theory
We study two aspects of M5-branes in N = 6 U(N) × U(N) Chern-Simons gauge theory. We first examine multiple M2-branes ending on a M5-brane. We study Basu-Harvey type cubic equations, fuzzy funnel configurations, and derive the M5-brane tension from the N = 6 theory. We also find a limit in which the above M2-M5 system reduces to a D2-D4 system and we recover the Nahm equation from the N = 6 theory. We then examine domain wall configurations in mass-deformed N = 6 theory with a manifest SU(2) × SU(2) × U(1) global symmetry. We derive tensions of domain walls connecting between arbitrary M5-brane vacua of the deformed theory and observe their consistency with gravity dual expectations.
118796950
Studies on 1/4 BPS and 1/8 BPS geometries
We analyze more explicitly four sectors of 1/4 BPS geometries and 1/8 BPS geometries, corresponding to BPS states in N=4 SYM, constructed previously. These include the states with several SO(6) angular momenta as well as those with SO(4) AdS spins. We also discuss their relations to the dual gauge theory.
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.
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.
118812509
BPS geometry, AdS/CFT, and string theory
We first study BPS geometries dual to half-BPS states of field theories with 32 supercharges. These field theories are N = 4 SYM on R×S3, M2 brane theory and M5 brane theory. The dynamics of the half-BPS states in N = 4 SYM is reduced to a matrix quantum mechanics, and they are characterized by droplets on the two dimensional phase space. The geometries dual to these states are specified by boundary conditions on a two-plane, which are identified as the phase space. The phase space gives unified description of half-BPS perturbative and non-perturbative excitations aboveAdS5×S. The half-BPS geometries in the M theory case are described by a Toda equation with similar but more complicated boundary conditions on a two-plane. We then study BPS geometries dual to the vacua of field theories with 16 supercharges. The first class of theory has a bosonic U(1) × SO(4) × SO(4) symmetry, they include the mass deformed M2 brane theory, D4 or M5 brane theory on S3, and intersecting NS5 brane theory. Their vacua are characterized by droplets on a cylinder or torus. The second class of theory has a SU(2|4) symmetry, they include the 0+1d plane-wave matrix model, 2+1d super Yang-Mills theory on R×S2, N = 4 Super Yang-Mills on R×S/Zk, and NS5 brane theory on R× S5. The vacua of these theories are described by electrostatic configurations with many disks under external potential. The region between disks describe NS5 brane geometries. Finally we study instanton solutions and superpotentials for the vacua of the plane-wave matrix model and 2+1d super Yang-Mills theory and discuss the emergence of the vacuum geometries.
15191903
Bubbling AdS space and 1/2 BPS geometries
We consider all 1/2 BPS excitations of AdS × S configurations in both type-IIB string theory and M-theory. In the dual field theories these excitations are described by free fermions. Configurations which are dual to arbitrary droplets of free fermions in phase space correspond to smooth geometries with no horizons. In fact, the ten dimensional geometry contains a special two dimensional plane which can be identified with the phase space of the free fermion system. The topology of the resulting geometries depends only on the topology of the collection of droplets on this plane. These solutions also give a very explicit realization of the geometric transitions between branes and fluxes. We also describe all 1/2 BPS excitations of plane wave geometries. The problem of finding the explicit geometries is reduced to solving a Laplace (or Toda) equation with simple boundary conditions. We present a large class of explicit solutions. In addition, we are led to a rather general class of AdS5 compactifications of M-theory preserving = 2 superconformal symmetry. We also find smooth geometries that correspond to various vacua of the maximally supersymmetric mass-deformed M2 brane theory. Finally, we present a smooth 1/2 BPS solution of seven dimensional gauged supergravity corresponding to a condensate of one of the charged scalars.
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.
122891013
New directions in lattice gauge theory
Abstract Three topics are presented which are among those being actively explored by the RBC collaboration. In the first we extend the regularization independent renormalization scheme of the Rome-Southampton group, applying it to matrix elements computed using the Fermilab heavy quark effective action. Next we discuss the use of G-parity boundary conditions to permit the direct calculation of physical, on-shell K → ππ amplitudes. Both a theoretical description of our approach and first numerical results from studying π − π states are given. Finally, a brief summary and present status of the QCDOC project is given.
119087062
Effects of iron doping on the topological insulator surfaces
Topological insulators embody a newly discovered state of matter characterized by conducting spin-momentum locked surface states that span the bulk band gap. So far, most of the study on topological insulator surfaces has been limited to understanding their properties without strong Coulomb perturbation or breaking of time reversal symmetry. We have used deposited iron, with a large positive ionization state and significant magnetic moment as a strong probe to modify the surface electronic structure of the Bi2Se3 surface at the gap energy scale. We observe that such perturbation leads to the creation of multiple Dirac fermions consistent with Z2 or Mod(2) symmetry. Taken collectively, these results are a helpful guide in manipulating topological surfaces for probing fundamental physics or developing device applications.
34447410
A prototype of self-triggering front-end unit for radio detection of ultra high energy neutrinos
Since the Tianshan Radio Experiment for Neutrino Detection (TREND) has successfully announced its first result, the Giant Radio Array for Neutrino Detection (GRAND) prototype is proposed to validate the concept of extensive air shower detection with a very high background rejection. High speed digitizing (1GHz), 12bits dynamic range and less than 10ns timing precision based on GPS are expected in the GRAND prototype experiment. This paper describes the overall structure of the data acquisition for GRAND prototype, concentrating on the development of the front-end electronics. The self-triggering front-end unit is a key part of the electronics system. It generally consists of two trigger boards (FTRIG), one digitizing board (DFADC), and one timestamp board (GPSTIM). Its main function is to get the amplitude and time stamp information of the input signal from the antenna. FTRIG board is for fast hardware trigger; GPSTIM board is for time stamp based on GPS (RMS <; 10ns); DFADC board is for dual 12bits 1GHz digitizing and fiber transmission. A prototype of the self-triggering front-end unit was built and a field test confirmed the full functionality of the prototype. The new prototype is considered to be evaluated on the speed and reliability as the ultimate design.
18903410
Generalized Painlevé–Gullstrand descriptions of Kerr–Newman black holes
Generalized Painlevé–Gullstrand metrics are explicitly constructed for the Kerr–Newman family of charged rotating black holes. These descriptions are free of all coordinate singularities; moreover, unlike the Doran and other proposed metrics, an extra tunable function is introduced to ensure all variables in the metrics remain real for all values of the mass $$M$$, charge $$Q$$, angular momentum $$aM$$, and cosmological constant $${\Lambda } > -\frac{3}{a^2}$$. To describe fermions in Kerr–Newman spacetimes, the stronger requirement of non-singular vierbein one-forms at the horizon(s) is imposed and coordinate singularities are eliminated by local Lorentz boosts. Other known vierbein fields of Kerr–Newman black holes are analysed and discussed; and it is revealed that some of these descriptions are actually not related by physical Lorentz transformations to the original Kerr–Newman expression in Boyer–Lindquist coordinates—which is the reason complex components appear (for certain ranges of the radial coordinate) in these metrics. As an application of our constructions the correct effective Hawking temperature for Kerr black holes is derived with the method of Parikh and Wilczek.