Discreteness of the spectrum of the compactified D=11 supermembrane with non-trivial winding

We analyze the Hamiltonian of the compactified D=11 supermembrane with non-trivial central charge in terms of the matrix model constructed recently by some of the authors. Our main result provides a rigorous proof that the quantum Hamiltonian of the supersymmetric model has compact resolvent and thus its spectrum consists of a discrete set of eigenvalues with finite multiplicity.Comment: 16 pages, final versio

Highly-parallelized simulation of a pixelated LArTPC on a GPU

The rapid development of general-purpose computing on graphics processing units (GPGPU) is allowing the implementation of highly-parallelized Monte Carlo simulation chains for particle physics experiments. This technique is particularly suitable for the simulation of a pixelated charge readout for time projection chambers, given the large number of channels that this technology employs. Here we present the first implementation of a full microphysical simulator of a liquid argon time projection chamber (LArTPC) equipped with light readout and pixelated charge readout, developed for the DUNE Near Detector. The software is implemented with an end-to-end set of GPU-optimized algorithms. The algorithms have been written in Python and translated into CUDA kernels using Numba, a just-in-time compiler for a subset of Python and NumPy instructions. The GPU implementation achieves a speed up of four orders of magnitude compared with the equivalent CPU version. The simulation of the current induced on 10^3 pixels takes around 1 ms on the GPU, compared with approximately 10 s on the CPU. The results of the simulation are compared against data from a pixel-readout LArTPC prototype

Measurement of Littlest Higgs Model Parameters

The effects of the extended gauge sector present in the Littlest Higgs model in the reactions e + e − → f ¯ f and e + e − → Zh are examined. We find that the search reach at the 500 GeV ILC essentially covers the entire region where this model is relevant to the hierarchy proble and extends the reach of the LHC. In addition, we show that the ILC allows for an accurate determination of the model parameters, to the precision of a few percent, provided that the LHC measures the mass of the new heavy neutral gauge field. Little Higgs models [1] feature the Higgs as a pseudo Nambu-Goldstone boson of an approximate global symmetry which is broken by a vev at a scale of a few TeV. The breaking is realized in such a way that the Higgs mass only receives quantum corrections at two loops. In contrast to supersymmetry, the one-loop contribution to the Higgs mass from a SM particle is canceled by a contribution from a new particle of the same spin. Little Higgs theories thus predict the existence of new top-like quarks, gauge bosons, and scalars near the TeV scale. Measurement of the couplings of these new particles would verify the structure of the cancelation of the Higgs mass quadratic divergences and prove the existence of the little Higgs mechanism. The most economical little Higgs model is the so-called “Littlest Higgs ” (LH) [1]. This scenario is based on a non-linear sigma model with an SU(5) global symmetry, which is broken to the subgroup SO(5) by a vev f. The natural scale for f is around a TeV; if f is much larger, the Higgs mass must again be finely tuned and this model no longer addresses the hierarchy problem. The SU(5) contains a gauged subgroup [SU(2) × U(1)] 2 which is broken by the vev to the SM electroweak group [SU(2)L × U(1)Y]. The global SU(5) breaking leaves 14 massless Goldstone bosons, four of which are eaten by the gauge bosons of the broken gauge groups, giving these gauge bosons a mass of order f. These new bosons correspond to two a heavy neutral bosons, ZH and AH, and two heavy charged boson

The impact of Metal-Ligand Cooperation in Hydrogenation of Carbon Dioxide Catalyzed by Ruthenium PNP Pincer

The metal–ligand cooperative activation of CO2 with pyridine-based ruthenium PNP pincer catalysts leads to pronounced inhibition of the activity in the catalytic CO2 hydrogenation to formic acid. The addition of water restores catalytic performance by activating alternative reaction pathways and leads to unprecedented Ru-catalyzed CO2 hydrogenation activity. The mechanism of the underlying chemical transformations is proposed on the basis of DFT calculations, kinetic experiments, and NMR reactivity studies

Discovery of a multiply lensed submillimeter galaxy in early HerMES Herschel/SPIRE data

‘In these times, during the rise in the popularity of institutional repositories, the Society does not forbid authors from depositing their work in such repositories. However, the AAS regards the deposit of scholarly work in such repositories to be a decision of the individual scholar, as long as the individual's actions respect the diligence of the journals and their reviewers.’ Original article can be found at: http://iopscience.iop.org/ Copyright American Astronomical SocietyWe report the discovery of a bright (f (250 μm)>400 mJy), multiply lensed submillimeter galaxy HERMES J105751.1+573027 in Herschel/SPIRE Science Demonstration Phase data from the HerMES project. Interferometric 880 μm Submillimeter Array observations resolve at least four images with a large separation of ∼9″. A high-resolution adaptive optics Kp image with Keck/NIRC2 clearly shows strong lensing arcs. Follow-up spectroscopy gives a redshift of z = 2.9575, and the lensing model gives a total magnification of μ ∼ 11 ± 1. The large image separation allows us to study the multi-wavelength spectral energy distribution (SED) of the lensed source unobscured by the central lensing mass. The far-IR/millimeter-wave SED is well described by a modified blackbody fit with an unusually warm dust temperature, 88 ± 3 K. We derive a lensing-corrected total IR luminosity of (1.43 ± 0.09) × 1013 L⊙, implying a star formation rate of ∼2500 M⊙ yr-1. However, models primarily developed from brighter galaxies selected at longer wavelengths are a poor fit to the full optical-to-millimeter SED. A number of other strongly lensed systems have already been discovered in early Herschel data, and many more are expected as additional data are collected.Peer reviewe