10026539
Constraining anisotropy of the universe from different groups of type-Ia supernovae
Recently released Planck data and other astronomical observations show that the universe may be anisotropic on large scales. Inspired by this, anisotropic cosmological models have been proposed. We note that the Finsler–Randers spacetime provides an appropriate framework for the anisotropic cosmology. By adding an arbitrary 1-form to the Friedmann–Robertson–Walker line element, a privileged axis in the universe is picked out. The distance–redshift relation is modified to be direction-dependent. We wish that the anisotropic cosmological model may be tested crossly by independent observations. Type-Ia supernovae (SNe Ia) calibrated from four different light curve fitters are used to constrain the possible anisotropy of the universe. The magnitudes of anisotropy are all between 2–5 %, but the systematic uncertainty cannot be excluded. The directions of the privileged axis seem to differ from each other. The statistical significance is not high enough to make a convincing conclusion. Nevertheless, the $$1\sigma $$1σ contours in the $$(l,b)$$(l,b) plane obtained from four groups of SNe Ia have an overlap, centering at $$(l,b)\approx (170^{\circ }, 0^{\circ })$$(l,b)≈(170∘,0∘). Monte Carlo simulation shows that the anisotropy is unlikely to be caused by the selection effect.
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.
197517382
Model for Gravity at Cluster Scales in Randers-Finslerian Spacetime and the Convergence $\kappa$ of Bullet Cluster 1E0657-558
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.
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.
7503241
Kac-Moody extensions of 3-algebras and M2-branes
We study the 3-algebraic structure involved in the recently shown M2-branes worldvolume gauge theories. We first extend an arbitrary finite dimensional 3-algebra into an infinite dimensional 3-algebra by adding a mode number to each generator. A unique central charge in the algebra of gauge transformations appears naturally in this extension. We present an infinite dimensional extended 3-algebra with a general metric and also a different extension with a Lorentzian metric. We then study ordinary finite dimensional 3-algebras with different signatures of the metric, focusing on the cases with a negative eigenvalue and the cases with a zero eigenvalue. In the latter cases we present a new algebra, whose corresponding theory is a decoupled abelian gauge theory together with a free theory with global gauge symmetry, and there is no negative kinetic term from this algebra.
118376775
Young diagrams, Brauer algebras, and bubbling geometries
A bstractWe study the 1/4 BPS geometries corresponding to the 1/4 BPS operators of the dual gauge theory side, in $ \mathcal{N} = {4} $ SYM. By analyzing asymptotic structure and flux integration of the geometries, we present a mapping between droplet configurations arising from the geometries and Young diagrams of the Brauer algebra. In particular, the integer k classifying the operators in the Brauer basis is mapped to the mixing between the two angular directions.
119183324
ON EXOTIC SPHERE FIBRATIONS, TOPOLOGICAL PHASES, AND EDGE STATES IN PHYSICAL SYSTEMS
We suggest that exotic sphere fibrations can be mapped to band topologies in condensed matter systems. These fibrations can correspond to geometric phases of two double bands or state vector bases with second Chern numbers m+n and -n, respectively. They can be related to topological insulators, magnetoelectric effects, and photonic crystals with special edge states. We also consider time-reversal symmetry breaking perturbations of topological insulator, and heterostructures of topological insulators with normal insulators and with superconductors. We consider periodic TI/NI/TI/NI′ heterostructures, and periodic TI/SC/TI/SC′ heterostructures. They also give rise to models of Weyl semimetals which have thermal and electrical transports.